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Meat quality of kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus)Mostert, Analene C. 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: Although kudu (Tragelaphus strepsiceros) and impala (Aepyceros melampus) are found in the
same geographical area, there is variation in their diets as kudu are predominantly browsers,
feeding on tree and shrub leaves, while impala are known as mixed feeders as they graze
and browse. Therefore this poses the question whether the diet would influence their meat
quality. The objective of this investigation was to evaluate the physical measurements and
chemical composition of M. longissimus dorsi, M. biceps femoris, M. semimembranosus, M.
semitendinosus and M. supraspinatus for kudu and impala, two southern African antelope
species. The effects of age (adult and sub-adult) and gender (male and female) were also
determined. The sensory characteristics of the M. longissimus dorsi muscle for sub-adult
kudu and impala were investigated. Correlations between the various physical
measurements and chemical composition of the meat were verified. Physical measurements
and chemical composition of the M. longissimus dorsi muscle were tested for correlations with
the sensory ratings of the meat.
Dressing percentage of impala (59.88%) (n=28) was higher than that of kudu (57.60%) (n=35).
The main effects (species, gender and age) showed no differences for drip loss and cooking
loss. However, muscles differed in terms of cooking loss with impala M. semitendinosus
having the highest (38.28%) value and kudu M. longissimus dorsi having the lowest value
(30.77%). For impala, the highest Warner–Bratzler shear (WBS) values were measured for M.
semimembranosus (5.90 kg/1.27cmø), followed by M. biceps femoris, M. longissimus dorsi,
and M. semitendinosus with the lowest WBS values measured for M. supraspinatus (3.61
kg/1.27cmø). All impala muscles had lower L* values and appeared darker in colour than
kudu muscles, except for M. supraspinatus. Adult animals also had lower L* values than the
sub-adult group. Kudu had significantly higher a* and b* values (more red) than impala.
Chroma values were higher for kudu, thus appearing brighter in colour. The respective
muscles of kudu and impala investigated differed significantly in terms of physical
characteristics. However, gender and age did not have an effect on the physical
measurements.
Moisture content was higher in kudu meat (76.46%) than in impala meat (75.28%). Muscles
differed for both moisture and fat content. The highest fat was found in M. supraspinatus
followed by M. biceps femoris, M. semitendinosus, M. semimembranosus and M. longissimus
dorsi. Protein content did not differ between species (kudu: 21.66%; impala: 22.26%), gender
(male: 21.98%; female: 21.95%) and age groups (adult: 21.74%; sub-adult: 22.18%). Kudu M.
longissimus dorsi (1.62%) had lower fat content than impala M. longissimus dorsi (2.22%) and
female animals had a higher fat content than male animals. Sub-adults (1.20 ± 0.02%) had
higher ash content than adults (1.10 ± 0.03%). The M. supraspinatus had the lowest protein and also the highest fat content, with M. semimembranosus having the lowest fat content but
the highest value for protein.
Myoglobin content did not differ between species, although females had higher (6.58 ± 0.20
mg/g) myoglobin content than males (5.11 ± 0.25 mg/g). Glycolitic muscles had the lowest
myoglobin content with the highest values found in M. supraspinatus, an oxidative muscle.
An interaction was noted between species and muscle for myoglobin content. Myoglobin
content in impala M. longissimus dorsi was higher than that in kudu M. longissimus dorsi;
however for all other muscles the myoglobin content was lower in impala.
Gender did not affect mineral content. Potassium levels were highest for kudu while
phosphorus was more prevalent in impala meat. Adult and sub-adult groups differed in terms
of potassium, calcium and zinc content. Potassium and calcium content were higher for subadult
animals while zinc content was higher in adult animals.
In impala meat, stearic acid (22.67%) was the major fatty acid, followed by palmitic acid
(16.66%). In contrast, oleic acid (24.35%) was the most profuse fatty acid in kudu, followed
by linoleic acid (22.95%). The SFA’s as a percentage of the total fatty acids differed between
impala (51.12%) and kudu meat (34.87%). Kudu meat had a higher concentration of total
PUFA (38.88%) than impala (34.06%) meat. The PUFA: SFA ratio for kudu meat (1.22) was
more favourable than that for impala meat (0.73). The ratio of n-6 PUFA’s to n-3 PUFA’s for
kudu and impala were determined as 2.22 and 3.76 respectively. From the current findings it
is evident that kudu and impala meat have advantageous fatty acid profiles and can be a
healthy substitute for other red meats.
Kudu meat (72.62 ± 1.86 mg/100g) had higher cholesterol than impala meat (55.35 ± 1.84
mg/100g). It is recommended that further studies be done in order to confirm the cholesterol
content of kudu meat.
Within species, no gender differences for any of the sensory characteristics tested were noted.
The impala meat had a more intense game aroma than the kudu meat, while kudu meat was
found to be more juicy than impala meat. It can therefore be concluded that the marketing of
game meat should be species-specific as there are distinct flavour and aroma differences
between kudu and impala meat. / AFRIKAANSE OPSOMMING: Alhoewel koedoes (Tragelaphus strepsiceros) en rooibokke (Aepyceros melampus) in
dieselfde geografiese area voorkom, is daar variasie in hulle diëte. Koedoes is hoofsaaklik
blaarvreters, terwyl rooibokke bekend staan as gemengde vreters aangesien hulle grassowel
as blaarvreters is. Die vraag ontstaan dus of die verskil in diëet die kwaliteit van hulle
vleis sal beϊnvloed. Die doel van hierdie ondersoek was dus om die fisiese metings en
chemiese samestelling van die M. longissimus dorsi, M. biceps femoris, M.
semimembranosus, M. semitendinosus en M. supraspinatus vir koedoes en rooibokke te
bepaal. Die invloed van ouderdom (volwasse en onvolwasse) en geslag (manlik en vroulik)
op hierdie eienskappe is ook geëvalueer. Die sensoriese eienskappe van die M. longissimus
dorsi van onvolwasse koedoes en rooibokke is ook ondersoek. Korrelasies tussen die fisiese
metings en chemiese samestelling van die vleis is ondersoek. Die fisiese metings en
chemiese samestelling van die M. longissimus dorsi is getoets vir korrelasies met die
resultate van die sintuiglike evaluering van die vleis.
Die gemiddelde uitslagpersentasie van rooibokke (59.88%) (n=28) was hoër as die van
koedoes (57.60%) (n=35). Daar was geen verskille in drupverlies en kookverlies vir die
hoofeffekte (spesie, geslag en ouderdom) nie. Spiere het wel verskil in terme van kookverlies,
met die hoogste waarde gemeet vir rooibok M. semitendinosus (38.28%) en die laagste
waarde vir koedoe M. longissimus dorsi (30.77%). In rooibokke was die hoogste Warner-
Bratzler skeurkrag waardes gemeet vir M. semimembranosus (5.76 kg/1.27cmø), gevolg deur
M. biceps femoris, M. longissimus dorsi, en M. semitendinosus met die laagste Warner-
Bratzler skeurkrag waardes gemeet vir M. supraspinatus (3.78 kg/1.27cmø). Alle
rooibokspiere het laer L* waardes gehad en was donkerder van kleur as koedoespiere,
behalwe vir M. supraspinatus. Laer L* waardes is ook verkry vir volwasse diere in
vergelyking met onvolwasse diere. Die a* en b* waardes was hoër in koedoe- as in
rooibokvleis, m.a.w. koedoevleis het rooier vertoon. Die onderskeie koedoe- en rooibokspiere
het betekenisvol verskil in terme van fisiese eienskappe, terwyl geslag en ouderdom geen
effek op die fisiese eienskappe gehad het nie.
Voginhoud was hoër in koedoe- (75.52%) as in rooibokvleis (74.52%). Verkille tussen spiere
is opgemerk vir beide vog- en vetinhoud. M. supraspinatus het die hoogste vetinhoud gehad,
gevolg deur M. biceps femoris, M. semitendinosus, M. semimembranosus en M. longissimus
dorsi. Geen verskille is opgemerk tussen spesies (koedoe: 21.66%; rooibok: 22.26%),
geslagte (manlik: 21.98%; vroulik: 21.95%) en ouderdomme (volwasse: 21.74%; onvolwasse:
22.18%) in terme van proteϊeninhoud nie. Die vetinhoud van koedoe M. longissimus dorsi
(1.62%) was laer as dié van rooibok M. longissimus dorsi (2.22%) en die vetinhoud van
vroulike diere was hoër as dié van manlike diere. Onvolwasse diere (1.20 ± 0.02%) het ‘n
hoër asinhoud as dié van volwasse diere (1.10 ± 0.03%) getoon. In terme van die onderskeie spiere het M. supraspinatus die laagste proteϊen- en die hoogste vetinhoud gehad, terwyl M.
semimembranosus die laagste vet- en die hoogste proteϊeninhoud gehad het.
Die mioglobieninhoud was nie beϊnvloed deur spesie nie, terwyl vroulike diere ‘n hoër (6.58 ±
0.20 mg/g) mioglobieninhoud as manlike diere (5.11 ± 0.25 mg/g) gehad het. Die M.
supraspinatus, ‘n oksidatiewe spier het die hoogste mioglobieninhoud gehad, terwyl
glikolitiese spiere die laagste mioglobieninhoud gehad het. ’n Interaksie tussen spesie en
spier was opgemerk vir mioglobieninhoud. Rooibok M. longissimus dorsi het ‘n hoër
mioglobieninhoud as koedoe M. longissimus dorsi gehad, terwyl die mioglobieninhoud vir al
die ander spiere laer was in rooibokke.
Mineraalinhoud was nie deur geslag beϊnvloed nie. Kaliumvlakke was hoër in koedoevleis,
terwyl fosforvlakke hoër was in rooibokvleis. Kalium- en kalsiuminhoud was hoër in
onvolwasse diere terwyl die sinkinhoud hoër was in volwasse diere.
Steariensuur (22.67%), gevolg deur palmitiensuur (16.66%) was die mees algemene vetsure
in rooibokvleis. In teenstelling hiermee was oleϊensuur (24.35%), gevolg deur linoleϊensuur
(22.95%) die mees algemene vetsure in koedoevleis. Die totale versadigde vetsure was laer
in koedoevleis (34.87%) in vergelyking met rooibokvleis (51.12%), terwyl die totale polionversadigde
vetsure in koedoevleis (38.88%) hoër was as dié van rooibokvleis (34.06%).
Die verhouding van n-6 tot n-3 poli-onversadigde vetsure vir koedoe en rooibok was 2.22 en
3.76 onderskeidelik. Hierdie resultate bevestig dat koedoe- en rooibokvleis oor ‘n
vetsuurprofiel beskik wat ’n gesonde alternatief bied tot ander rooivleise.
Die cholesterolinhoud van koedoevleis (72.62 ± 1.86 mg/100g) was hoër as dié van
rooibokvleis (55.35 ± 1.84 mg/100g). Dit word egter aanbeveel dat verdere studies gedoen
word om die cholesterolinhoud van koedoevleis te bevestig.
Binne spesies was daar geen geslagsverkille vir enige van die sensoriese eienskappe nie.
Rooibokvleis het ‘n meer intense wildsvleis aroma as koedoevleis gehad, terwyl koedoevleis
meer sappig was as rooibokvleis. Hierdie resultate dui daarop dat die bemarking van
wildsvleis spesie-spesifiiek moet wees aangesien daar defnitiewe geur en aroma verskille
tussen koedoe- en rooibokvleis is.
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Production of salami from meat of aquatic and terrestrial mammalsKoep, Karin Sarah Coles 03 1900 (has links)
Thesis (MscAgric (Animal Sciences))--University of Stellenbosch, 2005. / The aim of this study was to develop a product using alternative red meat species, aquatic and
terrestrial mammals, which would be acceptable to the consumer and suitable from a food safety
aspect. Many of these alternative species are harvested seasonally. A product which is shelf
stable needs to be developed to provide a supply of this meat all year round. The species used in
this investigation were the Cape fur seal (Arctocephalus pusillus pusillus), the Grey seal
(Halichoerus grypus) from the northern hemisphere, the Minke whale (Balaenoptera
acutorostrata), horse, beef, mutton, blesbok (Damaliscus dorcas phillipsi) and springbok
(Antidorcas marsupialis).
Muscle (m. pectoralis) of Cape fur seal pups has a higher percentage fat (4.2g/100g) than the
bulls (2.4g/100g), but similar levels of protein (23.2g/100g). Bull blubber samples have a higher
percentage protein (26.6g/100g) than the pups (14.6g/100g), but a lower fat percentage
(67.1g/100 g) compared with the pups (77.2g/100g). In the Cape fur seal bull meat, saturated
fatty acids (SFA) contribute 33mg/100g, monounsaturated fatty acids (MUFA) 29mg/100 g and
polyunsaturated fatty acids (PUFA) 38mg/100g of the total fatty acid content. In pups, the three
fractions are 39, 30 and 31 mg/100g for SFA, MUFA and PUFA, respectively.
Salami,prepared using exclusively seal meat, or seal meat with beef and pork, was produced in a
pilot study, using two commercially available starter cultures. The pH values of all three
batches started off at ca. 5.6, and dropped to 4.3. Water activity readings started off at 0.96 and
dropped to 0.91 after 21 days. Salami produced from the meat of the Grey (Havert) seal and
Minke whale, using three starter cultures, had recorded pH values (in both species), which started
off between 5.68 and 5.92, and dropped to between 4.5 and 4.8 over the 21 days. Water activity
showed an initial value of 0.96, which dropped to 0.90 after 21 days. The final force (N/cm2)
that was needed to compress the salami samples was double that of the initial force required for
the same species and starter culture combination. The raw seal meat contained 349.6 (mg/100 g
sample) SFA, 271.6 (mg/100g sample) MUFA and 175.8 (mg/100g sample) PUFA, whilst the
raw whale meat contained 312.3, 251.9 and 179.6 (mg/100g sample) SFA, MUFA and PUFA
respectively.
Fifteen batches of salami were made from horse, beef, mutton, blesbok and springbok,
respectively, and starter cultures of Lactobacillus curvatus DF 38 (batch I), active bacteriocin producing Lactobacillus plantarum 423 (batch II) and then a mutant variation of Lactobacillus
plantarum 423m, which did not produce the bacteriocin (batch III). Batch I had a higher final
pH value (4.66), after 23 days, whereas the values for batches II and III were similar (4.42 and
4.46 respectively). On day 23 the water activity value was 0.90 for all starter cultures. Horse
salami, in batch I, was the leanest in terms of fat content (34.34g/100g salami), with mutton
salami having the highest fat content (37.52g/100g salami). Blesbok salami had the highest fat
content in batch II (42.77g/100g meat), with beef the leanest (35.71g/100g meat). Salami made
from horse and springbok proved to be the most desirable in terms of chemical composition,
especially fatty acid profiles, with regard to P: S and n-6: n-3 ratios.
Similar growth patterns in colony forming units (cfu) were recorded for L. plantarum 423, L.
plantarum 423m and L. curvatus DF38 in MRS broth (Merck) at 30oC, although batch I reached
asymptotic growth earlier. The percentage of L. plantarum 423 compared with the total
population of microflora in mutton salami remained almost the same (80-95% variety) during the
entire fermentation and maturation process. In horse salami, L. plantarum 423 was present at
relatively low cell numbers (55-50% on day 1 and before smoking), but increased to 70% after
smoking and stabilized to 70-80% for the remaining fermentation period. In beef salami, cell
numbers in batch II decreased slightly during the first five days (from 95 to 70%), followed by an
increase to 90%. In springbok salami, cell numbers in batch II remained fairly stable at 80-90%.
In blesbok salami, batch II slowly decreased during the first three days, from 88% to 70%, then
increased to 92% after 12 days and stabilized for the rest of the fermentation period. Similar
results were recorded for batch I.
Analytical sensory evaluation concluded that the salami prepared using starter culture I resulted
in end products with lower sensory qualities. Salami prepared using blesbok and mutton also
resulted in end products with lower sensory qualities and was perceived as significantly lower in
salami flavour (P≤0.05) and higher in venison-like and mutton-like flavour respectively. The
blesbok samples were rated significantly higher (P≤0.05) in sour meat aroma, sour meat flavour
and venison-like flavour than the rest of the samples. The blesbok salami was rated significantly
lowest for colour compared with the rest of the samples. The tastes of the springbok and horse
salami were significantly (P≤0.05) more acceptable than those of the beef and blesbok salami.
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The effect of agricultural production system on the meat quality of Dorper lambsClaasen, Claasen 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2008. / ENGLISH ABSTRACT: The aim of this study was to investigate the effect of South African production system (feedlot {FL-} or free-range {FR-}) and gender (ewes, rams or castrates) on growth and carcass characteristics of Dorper sheep.
Male lambs (castrates and rams) grew twice as fast as ewes (P<0.05) under FL-conditions while much smaller differences were observed between gender groups in FR-lambs. FL-lambs produced heavier carcasses (P=0.0003) with higher dressing percentages (P<0.05) and greater carcass fatness levels (P<0.052) than FR- lambs.
No differences attributable to production system were found on meat tenderness (as indicated by Warner Bratzler shear force strength) and on the intramuscular lipid concentration. In contrast, sensory evaluation results suggested that meat from FL-lambs was juicier and more tender than meat from FR-lambs. The sensory panel could not distinguish between FL and FR meat as far as the attributes of aroma and flavour were concerned.
Cholesterol results indicated that for intermuscular fat, higher cholesterol levels were observed for FL-lambs than for FR-lambs. The level of palmitic acid (C16:0) was significantly higher (P=0.0375) in the Longissimus dorsi (LD) muscles of FL-lambs.
For intramuscular fat from the Biceps femoris (BF) muscle, g-linolenic acid (C18:3n-6) was higher (P<0.0001) in FL- lambs. Results for intramuscular BF further indicated that ram lambs had the highest (P=0.0019) palmitic acid (C16:0) and sum of TUFA (P=0.0014), castrates had the highest (P=0.0260) α-linolenic acid (C18:3n-3) and g-linolenic acid (C18:3n-6), while ewe lambs had the highest (P=0.0014) SFA concentrations. Linoleic acid (C18:2n-6c) was significantly higher (P=0.0067) in the subcutaneous fat of FL-lambs while FR-lambs had more linolenic acid (C18:3n-3). For the kidney fat, FR-feeding increased (P < 0.05) stearic (C18:0), linolelaidic (C18:2n-6t), α-linolenic (C18:3n-3) and homo-g-linolenic acid (C20:3n-6) percentages. Conversely, linoleic acid (C18:2n-6c) was increased (P=0.0372) by FL-feeding. For the intermuscular fat, FR-lambs had higher linolenic acid (C18:3n-3) and SFA (P=0.0113 and P=0.0341) compared to FL-lambs. On the other hand, the sum of TUFA for the intermuscular fat was higher (P=0.0341) in FL-lambs compared to FR-lambs.
Results from the study imply that the consumer may not necessarily be able to discern between meat from FR- or FL-lambs, although they may possibly discriminate against the increase in visible fatness of FL-lambs. No clear advantage of production system in terms of human health could be demonstrated as far as the proximate chemical composition and the fatty acid composition of the meat was concerned. The faster growth and the associated shorter production cycle of FL-lambs could be an advantage under certain production systems. However, it needs to be weighed against the cost of concentrate feeding and the preference consumers are likely to develop for lamb produced in natural environments. / AFRIKAANSE OPSOMMING: Die doel van die studie was om Suid Afrikaanse produksiestelsel (voerkraal {VK-} of veld {VD}) en geslag (ooie, hamels of ramme) op die groeivermoë en karkaseienskappe van die Dorperskape te bepaal.
Manlike lammers (ramme and hamels) het twee keer vinniger (P<0.05) as ooilammers onder VK-toestande gegroei, terwyl kleiner verskille tussen geslagsgroepe by VD-diere waargeneem is. VK-lammers het swaarder karkasse (P=0.0003), hoër uitslagpersentasies (P<0.05) en meer karkas vet (P<0.052) as VD -lammers vertoon.
Geen verskille as gevolg van produksiestelsel is op die sagtheid van vleis (soos aangedui deur Warner-Bratzler skeurkragwaardes) en die binnespierse vetinhoud gevind nie. Daarenteen het sensoriese analises aangedui dat vleis van VK-lammers sappiger en sagter as vleis van VD- lammers was. Die sensoriese paneel kon nie verskille aangaande die aroma en geur van vleis tussen VK- en VD-vleis onderskei nie.
Cholesterolvlakke was hoër vir VK-lammers as by VD-lammers. Die vlak van palmitiese suur (C16:0) was hoër (P=0.0375) in die Longissimus dorsi (LD) spier van VK-lammers.
Vir binnespierse vet van die Biceps femoris (BF) spier was g-linoleniese suur (C18:3n-6) hoër (P<0.0001) in VK-lammers. Resultate vir binnespierse vet van die BF spier het verder bewys dat ramlammers die hoogste (P=0.0019) palmitiese suur (C16:0) and totale onversadigde vetsure (P = 0.0014) getoon het, hamels die hoogste (P=0.0260) α-linoleniese suur (C18:3n-3) en g-linolenese suur (C18:3n-6) getoon het terwyl ooilammers die hoogste (P=0.0014) versadigde vetsuurvlakke getoon het. Linoliese suur (C18:2n-6c) was hoër (P=0.0067) in die onderhuidse vet van VK-lammers terwyl VD-lammers meer linoliese suur (C18:3n-3) gehad het. Resultate vir niervet het getoon dat VD-voeding die persentasies van steariese (C18:0), linoleladiese (C18:2n-6t), α-linoleniese (C18:3n-3) and homo-g-linoleniese suur (C20:3n-6) verhoog (P<0.05) het relatief tot VK-voeding. Linoliese suur (C18:2n-6c) is deur VK-voeding verhoog (P=0.0372). Vir intermuskulêre vet het VD-lammers hoër linoleniese suur (C18:3n-3) en versadigde vetsure (P=0.0113 en P=0.0341) as VK-lammers gehad. Die totale onversadigde vetsure vir tussenspiere vet was hoër (P=0.0341) in VK-lammers in vergelyking met VD-lammers.
Resultate van hierdie studie dui daarop dat verbruikers nie noodwendig tussen vleis van VD- en VK-lammers sal onderskei nie, alhoewel hulle dalk teen die sigbaar vetter vleis van VK-lammers kan diskrimineer. Geen definitiewe voordeel in terme van menslike gesondheid kon op grond van die chemiese samestelling van die vleis bevestig word nie. Vinniger groei van VK-lammers, en die korter produksiesiklus wat daarmee verband hou, mag onder sekere produksie stelsels ʼn voordeel wees. Die voordeel moet teen die hoër koste van VK-voeding en die voorkeur van verbruikers vir lam produksie in natuurlike omgewing opgeweeg word.
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Ostrich (Struthio camelus) chick survival to 6 months post hatch : estimation of environmental and genetic parameters and the effect of imprinting, foster parenting and deliberate careWang, Magretha Diane 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The South African Ostrich industry was established more than 100 years ago. Despite appreciable
fluctuations and modifications in demand, the industry perseveres, with meat and leather as the
current primary driving force. Low and variable early chick survival is globally considered as a
major constraint in the industry. In spite of obvious welfare and production implications, research
findings concerning ostrich chick survival are scant. Four studies involving chick survival to 24
weeks post hatch were thus performed.
South African Black ostrich (Struthio camelus var. domesticus) data obtained from a commercial
pair-bred ostrich flock maintained at the Oudtshoorn Experimental Farm, South Africa comprising
10418 records were utilized to run a series of single- and multiple-trait binomial analyses using
either linear models (ASREML) or threshold models (Monte Carlo Markov Chain methods,
employing Gibbs sampling software) respectively. Suitable fixed and random effect models
together with variance and (co)variance components were derived from these analyses. Ostrich
chick survival to 24 weeks post hatch was low (28%) with a large environmental component. Preincubation
storage time only affected 0 to 3 week survival, while incubator had a significant effect
on cumulative survival traits to 24 weeks as well as on 13 to 24 week survival. Female chicks
outperformed males at 0 to 12 weeks, 0 to 24 weeks, 4 to 12 weeks and 13 to 24 weeks with
regard to survival. Hen age was significant for all traits except survival during the first week as well
as for survival from 13 to 24 weeks post hatch. All analyses exhibited comparable low heritability
estimates for all survival traits except for 0 to 1 week survival and 13 to 24 week survival (h2 = 0.12
and 0.10; m2 = 0.08 and 0.07 respectively) which demonstrated higher additive genetic and
maternal components when threshold models, using Gibbs sampling algorithms, were employed.
Neither moisture loss nor day of external pipping exhibited notable additive genetic correlations
with any of the estimated survival traits. Day-old chick weight demonstrated a low correlation with
early chick survival (rg = 0.24 ± 0.19) with heavier chicks tending to have a higher survival
probability. The effects of rearing method on early chick survival and growth were also
investigated. Comparisons between chicks reared and fostered by adult ostriches in a semiextensive
environment and chicks imprinted onto humans under an intensive system and between
regular human handling in an intensive rearing system and the standard farm protocol of an
intensive rearing system were made. No difference in the early chick survival to 3 weeks post
hatch of chicks reared by foster parents and those chicks imprinted onto humans was
demonstrated. At later ages, those chicks reared by foster parents outperformed human imprinted
chicks. Human imprinted chicks exposed to regular handling demonstrate an enhanced early survival when compared to chicks exposed to conventional rearing protocol in intensive systems.
The study is seen to provide guidance for further research on this topic. / AFRIKAANSE OPSOMMING: Die Suid-Afrikaanse volstruisbedryf is meer as 100 jaar gelede gevestig. Die bedryf is volhoubaar,
ten spyte van ‘n fluktuerende aanvraag na volstruisprodukte. Vleis en leer is tans die produkte wat
die meeste tot die inkomste van boere bydra. Lae en wisselende kuikenoorlewing is ‘n belangrike
knelpunt in die bedryf. Navorsingsuitsette rakende kuikenoorlewing is skaars, ten spyte van
ooglopende welsyns- en produksie implikasies. Kuikenoorlewing tot en met 24 weke na uitbroei is
dus in vier afsondelike studies ondersoek.
Data van 10418 kuikens uit ‘n kommersiële broeipaargeteelde Suid-Afrikaanse Swart (Struthio
camelus var. domesticus) kudde op die Oudtshoorn Navorsingsplaas, Suid-Afrika is gebruik om
enkel- en meervoudige eienskappe met of liniêre modelle (ASREML) of drempelwaarde modelle
(Monte Carlo Markov Ketting metodes, met Gibbs monstering sagteware) te pas. Die metodes is
gebruik om toepaslike vaste- en toevalseffekte modelle saam met (ko)variansie komponente te
bekom. Kuikenoorlewing tot 24 weke na uitbroei was laag (28%), met ‘n groot
omgewingsbydraende komponent. Stoor van eiers voor pak het slegs kuikenoorlewing van 0 tot 3
weke beïnvloed, terwyl die broeikas wat gebruik is ‘n betekenisvolle invloed op kuikenoorlewing tot
24 weke ouderdom, sowel as op -oorlewing van 13 tot 24 weke gehad het. Wyfiekuikens het beter
oorleef as mannetjie kuikens vir oorlewing gemeet van 0 tot 12 weke, 0 tot 24 weke, 4 tot 12 weke
en van 13 tot 24 weke. Broeiwyfie ouderdom het ‘n betekenisvolle invloed op kuikenoorlewing in
die eerste week na uitbroei en van 13 tot 24 weke na uitbroei, gehad. Kuikenoorlewing was relatief
laag oorerflik, behalwe vir oorlewing van 0 tot 1 week en vir oorlewing van 13 tot 24 weke van
ouderdom (h2 = 0.12 en 0.10; m2 = 0.08 en 0.07 onderskeidelik). Drempelwaarde modelle met
Gibbs monstering algoritmes het hoër additiewe en maternale variansie verhoudings in vergelyking
met liniêre modelle aangedui. Genetiese korrelasies van vogverlies en die dag van uitwendige pik
met kuikenoorlewing was oor die algemeen onbeduidend. Dagoudkuikengewig is laag
gekorreleerd met vroeë kuikenoorlewing (rg = 0.24 ± 0.19), met swaarder kuikens wat oor die
algemeen beter oorleef. Die gevolge van verskillende grootmaak metodes op vroeë
kuikenoorlewing en -groei is ook ondersoek. Vergelykings tussen kuikens grootgemaak deur
volwasse volstruise as pleegouers in ‘n semi-intensiewe omgewing en kuikens grootgemaak deur
mense onder ‘n intensiewe stelsel en tussen kuikens grootgemaak deur gewone menslike
hantering in ‘n intensiewe grootmaak sisteem onder standard plaas protokol was bestudeer. Geen
verskille was gevind in vroeë kuikenoorlewing tot 3 weke na uitbroei, van die kuikens grootgemaak
deur volwasse volstruise en tussen die kuikens grootgemaak deur mense . By latere ouderdomme,
het die kuikens wat grootgemaak was deur volwasse volstruise beter oorlewing getoon as die
kuikens grootgemaak deur mense. Kuikens grootgemaak deur mense wat blootgestel was aan gereelde hantering het verhoogde vroeë oorlewing getoon in vergelyking met kuikens grootgemaak
deur konvensionele grootmaak protokol in intensiewe stelsels. Die studie kan dus beskou word om
leiding te verskaf vir verdere navorsing oor hierdie onderwerp.
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Estimation of genetic parameters for fertility traits and the effect of milk production on reproduction performance in South African Holstein cowsPotgieter, Johannes Phillipus 03 1900 (has links)
Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Profitable milk production and genetic improvement in dairy herds are largely dependant on fertile
cows capable of calving down on an annual basis. Several studies indicate declines in the
reproductive performance of Holstein cows over the last 30 years. Calving interval (CI) and services
per conception (SPC) are being used by dairy farmers as indicators of the reproductive performance
of dairy cows. However, using these traits as cow fertility indicators is problematic as CI is dependent
on subsequent calving dates while SPC is strongly linked to inseminator proficiency. The aim of the
study is therefore, firstly, to describe alternative fertility traits derived from insemination and calving
dates and pregnancy check results. The effects of some non-genetic factors on these traits are
discussed. Means±sd for interval traits from calving to first insemination (CFS) and the interval from
calving to conception (DO) were respectively 77±30 and 134±74 days while the number of services
per conception (SPC) averaged 2.55±1.79. The percentage of first servics occurring within 80 days
post-partum (FS80d) and the proportion of cows being confirmed pregnant within 100 (PD100d) and
200 days post-partum (PD200d) were 0.64±0.48, 0.36±0.48 and 0.71±0.45, respectively. Although
fertility traits were affected significantly by lactation number, calving year and month, herds
(managers) had the largest effect.
Fertility is a complex trait, however, the challenge is finding traits that best describe this trait. Genetic
parameters for these traits could give an indication of the response to selection in dairy herds. In the
second part of this study, genetic parameters and correlations between fertility traits, sourced from
standard reproduction management data bases, are analysed for Holstein cows using bivariate linearlinear
and linear-threshold animal models. Insemination events (n = 69 181) from 26 645 lactations of
9 046 Holstein cows from 14 herds, calving down during the period from 1991 to 2007, were
available. The outcome of each AI event was known. Insemination records were linked to the calving
date of each cow, lactation number as well as dam and sire identification. Fertility traits indicating the
ability of cows to show heat early in the breeding period, and to become pregnant, were derived. Data were analysed using bivariate linear-linear and linear-threshold animal models with fixed effects being
herd (14 levels), year (17 levels), season (4 levels) and lactation number (6 levels). The model
included the random effects of animal and animal permanent environment (PE). Heritability estimates
ranged from 0.04±0.01 to 0.10±0.02 for FS80d, from 0.07±0.01 to 0.08±0.02 for PD100d and from
0.06±0.04 to 0.08±0.02 for PD200d depending on the two-trait combination. Although heritability
estimates of most fertility traits were below 0.10, they were in close agreement with results published
by other researchers using linear models. Genetic correlations between different fertility parameters
analyzed in this study indicated that it is unlikely that a single characteristic would serve well for
selection purposes; instead, combining different traits could be used in selection programmes to
improve fertility. Further research in constructing an optimal fertility index is warranted.
In the third part of this study, genetic parameters for South African Holstein cows for fertility and
production traits were estimated from 2415 lactation records. Two-trait analysis of fertility and milk
yield was investigated as a method to estimate fertility breeding values when culling, or selection
based on milk yield in early lactation, determines presence or absence of fertility observations in later
lactations. Fertility traits were days from calving to first service (CFS), days from calving to conception
(DO), percentage cows inseminated within 80d post-partum (FS80d), number of service per
conception (SPC), and the binary traits percentage of cows pregnant within 100d and 200d postpartum
(PD100d, Pd200d). Milk production traits were 300 day milk, fat and protein yield. For fertility
traits, range of estimates of heritability (h2) was 0.006 to 0.08 for linear traits and 0.05 to 0.12 for
binary traits. The range for permanent environmental variance (c2) was 0.016 to 0.032. In this study
genetic correlations of fertility with milk production traits were unfavourable ranging between −0.93 to 0.76. / AFRIKAANSE OPSOMMING: Winsgewende melkproduksie en genetiese verbetering in melkkuddes hang grootliks af van vrugbare
koeie wat op ‘n jaarlikse basis kalf. Verskeie studies toon dat die reproduksievermoë van
Holsteinkoeie oor die afgelope 30 jaar afgeneem het. Melkboere gebruik tussenkalfperiode (TKP) en
aantal inseminasies per konsepsie (KIPK) as aanduidings van die reproduksievermoë van melkkoeie.
Dit is egter moeilik om hierdie eienskappe as vrugbaarheidseienskappe vir melkkoeie te gebruik
omdat TKP afhanklik is van opeenvolgende kalfdatums terwyl KIPK baie sterk gekoppel is aan die
inseminasievermoë van die insemineerders. In die eerste gedeelte van die studie word alternatiewe
vrugbaarheidseienskappe, wat afgelei is van inseminasie- en kalfdatums en die uitslag van
dragtigheidsondersoeke, beskryf. Die invloed van ‘n aantal nie-genetiese faktore op dié eienskappe
word ook bespreek. Gemiddeldes±standaard afwykings vir die periode vanaf kalwing tot eerste
inseminasie (CFS), die periode van kalwing tot konsepsie (DO) was 77±30 en 134±74 dae
onderskeidelik, terwyl die aantal inseminasies per konsepsie (SPC) 2.55±1.79 was. Die persentasie
eerste inseminasies wat binne 80 dae na kalwing (FS80d), en die persentasie koeie wat dragtig
bevestig is binne 100 (PD100d) en 200 dae na kalwing (PD200d) was 0.64±0.48, 0.36±0.48 en
0.71±0.45, onderskeidelik. Hoewel vrugbaarheidseienskappe betekenisvol beïnvloed is deur
laktasienommer, jaar en seisoen van kalwing, het kuddes (bestuurders) die grootste effek op
eienskappe gehad.
Vrugbaarheid is ‘n ingewikkelde eienskap en die uitdaging is om eienskappe te vind wat dit die beste
beskryf. Genetiese parameters vir eienskappe wat oorweeg word sal ‘n aanduiding gee van die
seleksieresponse in melkkuddes. In die tweede gedeelte van die studie is genetiese parameters van
vrugbaarheidseienskappe en korrelasies tussen dié eienskappe beraam. Eienskappe is bekom vanaf
reproduksiebestuursprogramme wat in melkkuddes gebruik word. Al die inseminasierekords (n =
69 181) van 26 645 laktasies van 9 046 Holsteinkoeie van 14 melkkuddes wat tussen 1991 en 2007 gekalf het, was beskikbaar. Die uitslag van elke inseminasie was bekend. Inseminasierekords is met
die kalfdatum, laktasienommer, identifkasienommers van die moeder en vader van elke koei,
gekoppel. Vrugbaarheidseienskappe wat die vermoë van koeie aandui om vroeg na kalwing op hitte
te kom en beset te raak, is verkry. Die data is ontleed deur gebruik te maak van twee-eienskap liniêreliniêr-
en liniêr-drempel-diere modelle met vaste effekte kudde (14 vlakke), jaar (17 vlakke), siesoen (4
vlakke) en laktasienommer (6 vlakke). Die modelle het die ewekansige effekte van dier- en dierpermananente
omgewingseffkte (PE) ingesluit. Genetiese, diere PE en residuele korrelasies is
vervolgens beraam. Oorerflikhede varieer vanaf 0.04±0.01 tot 0.10±0.02 vir FS80d, vanaf 0.07±0.01
tot 0.08±0.02 vir PD100d en vanaf 0.06±0.04 tot 0.08±0.02 vir PD200d, afhangende van die tweeeienskap
kombinasie. Ten spyte daarvan dat die oorerflikhede van die meeste vrugbaarseienskappe
laer as 0.10 is, is die resultate in ooreenstemming met ander navorsers wat liniëre modelle gebruik
het. Genetiese korrelasies tussen verskillende vrugbaarheidseienskappe toon dat daar nie enkel
beste eienskap is wat vir seleksiedoeleindes gebruik kan word nie. Dit sou waarskynlik beter wees om
verskillende eienskappe te kombineer om die vrugbaarheid in melkkoeie te verbeter. Verdere
navorsing is nodig om ‘n optimale vrugbaarheidseienskap te ontwikkel.
Dit is belangrik dat die verband tussen reproduksie en melkproduksie vir melkkoeie bepaal word. In
die derde gedeelte van die studie is genetiese parameters vir vrugbaarheid- en melkproduksieeienskappe
vir Suid Afrikaanse Holsteinkoeie beraam. ‘n Totaal van 2415 laktasierekords was
beskikbaar. Vrugbaarheid en melkproduksie is volgens ‘n twee-eienskap analise ontleed as ‘n metode
om teelwaardes vir vrugbaarheid te bepaal in gevalle waar die uitskot of seleksie gebaseer op
melkproduksie in vroeglaktasie die teenwoordigheid of afwesigheid van vrugbaarheidseienskappe in
latere laktasies bepaal. Vrugbaarheidseienskappe was die periode (aantal dae) tussen kalfdatum en
eerste inseminasie (CFS), die aantal dae van kalf tot konsepsie (DO), die persentasie koeie wat by 80
dae na kalf vir die eerste keer geïnsemineer was (FS80d), die aantal inseminasies per konsepsie
(SPC), en binêre eienskappe van die persentasie koeie wat by 100 dae en 200 dae na kalf beset was
(PD100d en PD200d). Melkproduksie-eienskappe was 300-dae melk., vet- en proteïnproduksie. Vir
vrugbaarheidseienskappe het die oorerflikheidswaardes (h2) vanaf 0.006 tot 0.08 vir liniêre
eienskappe gevarieer en tussen 0.05 tot 0.12 vir binêre eienskappe. Die permanente
omgewingsvariansie (c2) het tussen 0.016 tot 0.032 gevarieer. In hierdie studie was die genetiese
korrelasies tussen vrugbaarheidseienskappe en melkproduksie-eienskappe ongunstig en het dit
tussen −0.93 tot 0.76 gevarieer.
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The effects of a multiple-enzyme combination in maize-soya diets for broiler chickensFourie, Juan-Louis 03 1900 (has links)
Thesis (MscAgric (Animal Sciences))--University of Stellenbosch, 2007. / The effect of a multiple-enzyme combination in mash and pelleted vegetarian maize-soya
diets for broilers was evaluated in terms of apparent excreta- and ileal nitrogen- and amino
acid digestibility and production performance. Two separate digestibility trials and one
performance trial were conducted. For Trial 1, the apparent nitrogen (N) - and amino acid
(AA) digestibility was determined by the collection of the excreta (total collection method)
and in Trial 2 from digesta collected at the terminal ileum (ileal digestibility method).
Production performance was also recorded in Trial 1. In Trial 3, the effect of the multipleenzyme
combination in potentially improving performance of broilers in commercial
conditions was evaluated. Broilers were fed a balanced- and low apparent energy (AME)
vegetarian maize-soya diet with the addition of the multiple-enzyme combination. The
addition of enzymes improved the apparent excreta- and ileal N digestibility of the mash diets
during the period 14-21 d, and the ileal N-digestibility of the pelleted diets at 28 and 35 d of
age. Conflicting results with regard to apparent excreta- and ileal AA digestibility were found.
By both methods the digestibilities of threonine (Thr), methionine (Met) and phenylalanine
(Phe) (14-21 d) and Cys (22-28 d and 29-35 d) were improved by the addition of the enzyme
combination to the mash diets. Over the entire experimental period (14-35 d) the ileal
digestibilities of histidine (His), Cys and leucine (Leu)of the mash diets were improved by 0.2
%, 0.2 % and 1.9 % respectively, following enzyme addition. By both methods the
digestibilities of Thr, arginine (Arg), Met, Cys, Phe and Leu (14-21 d), serine (Ser), Arg,
glutamic acid (Glu), Val, His, aspartic acid (Asp), lysine (Lys), proline (Pro), Met, tyrosine
(Tyr), Phe and Leu (22-28 d), and Pro (29-35 d) were improved by the combination of
enzymes and pelleting. For the entire experimental period (21-35 d), the ileal digestibilities of
Ser, His, Lys, Met, Tyr, Cys, Phe and Leu was improved by the combination of enzymes and
pelleting, indicating enzymatic activity was not destroyed by cold pelleting at 60 - 80º. The
improvements in apparent nitrogen- and AA digestibilities were, in most cases, not reflected
in production performance, although the combination of enzymes and pelleting resulted in
improved body weight gain (BWG) for the first two weeks of chicks life and significantly
improved the feed conversion ratio (FCR) during the second week of the chicks’ life. The
effect of the multiple-enzyme combination on the production performance of broilers on a low
AME- and commercial diet was mostly non-significant except for a significantly lower feed
iii
intake of the balanced diet for the fourth and fifth week of chick’s life following enzyme
addition. A financial calculation showed, however, that the enzyme combination might
increase profitability of a nutritionally balanced vegetarian maize-soya diet for broilers.
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A nutritional and financial evaluation of breeding African Grey parrots (Psittacus erithacus)Dennison, D. T. 12 1900 (has links)
Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2004. / African Grey Parrots are now being bred on a commercial scale in South Africa, mainly for the export market. In order to produce the best breeding results it is necessary to formulate balanced diets but no research has been done on the feeding value for African Grey parrots of ingredients used in formulating diets. Once the apparent metabolisable energy (AME) of extruded maize for African Greys has been established it will be possible to calculate the AME of other ingredients such as full fat soya, soya oil cake or sunflower oil cake. By feeding an extruded mix containing a known amount of maize mixed with a known amount of soya oil cake and establishing experimentally the AME of the mix, the AME of soya oil cake for African Greys can be calculated by difference. This information will make it possible to decide whether AME results obtained for poultry can be used in formulating diets for African Grey parrots.
The study consisted of two parts where the determination of the apparent metabolisable energy (AME) of extruded maize and the practical application thereof in formulating parrot diets, and the economic viability of a commercial African Grey parrot breeding operation was investigated. A reference procedure adopted by several European laboratories for the in vivo determination of metabolisable energy (ME) was used to determine the apparent metabolisable energy (AME) of extruded whole maize for African Grey parrots. The long term goal is to make a well balanced, extruded diet for these birds. Extruded maize is the form in which maize is generally included in commercial parrot diets and was therefore chosen as the experimental feed. Maize can be conveniently extruded with other single ingredients such as full fat soyabean meal, soyabean oil cake meal or sunflower oil cake meal to determine, by difference, the AME of those ingredients. For the first part of the study, ten, 3-year-old African Grey parrots were individually housed and fed in cages designed to facilitate collection of the faeces. Cage design varied between a tall type (n=6) and a low type (n=4). The parrots were acclimatized to their new environment before the trial commenced to ensure normal feeding behaviour.
The average AME value established for the ten African Grey Parrots was 16.8 MJ/kg. In the trial it became apparent that it is very difficult to get consistent results with the cages used and a modified cage design is proposed for the future. The second part of the study investigated the economic viability of breeding African Grey parrots commercially, with extruded maize as part of their diet. It was generally concluded that the breeding of African Grey parrots for the pet market can be considered as an economical venture.
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Die gebruik van Mamalvite en Flavomisien in die grootmaak van suiwelkalwersVermaak, Maizie Maria 03 1900 (has links)
Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2006. / South Africa produces only 0,50 % of the world’s milk. Although the number of milk producers is decreasing in South Africa, the milk production per se is increasing. The total number of small producers is decreasing while the number of big producers is increasing.
The cost to raise replacement heifers is very high. Replacement heifers are the cows of tomorrow and should be seen as a valuable investment for the longterm survival and profitability of the dairy farm. A successful heifer rearing program is one in which:
• Heifers are economically raised to be of adequate size and body condition to calve at a reasonable age.
• Heifers produce high levels of milk during the first lactation.
In the current study, the effect of Flavomycin and Mamalvite supplementation to young calves was investigated. According to manufacturer’s claims, Flavomycin would result in improved gains, improved conception rates, shorter calving intervals, increased milk production and improved weaning weights. Mamalvite, according to the manufacturer, should reduce risk of infections, increase feed utilization, increase feed intake and production, and also increase rumen microbial efficiency.
Thirty two Holstein calves, four days of age, were randomly divided into four groups of eight. All calves received 4 kg whole milk daily and had free access to calf starter pellets. Treatments were: 30 ml Mamalvite daily supplemented in the milk and 5 g Flavomycin daily per os (Treatment 1), 30 ml Mamalvite daily supplemented in the milk (Treatment 2), 5 g Flavomycin daily per os (Treatment 3) and a control group that received milk only (Treatment 4). All the calves were weighed weekly.
According to the results obtained in the current study, neither Flavomycin, nor Mamalvite, nor a combination of the two resulted in an improvement in calf weight gains. It was concluded that it does not appear to be an economically viable option to supplement Mamalvite or Flavomycin to calves that are reared in a well managed environment.
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The effect of sugar, starch and pectin as microbial energy sources on in vitro forage fermentation kineticsMalan, Marcia 03 1900 (has links)
Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Ruminants have a compound stomach system that enables them to utilize forages more efficiently than
monogastric animals. However, forages alone do not contain sufficient nutrients to meet the requirements of
high producing dairy cows. Forages are high in fibre and their nutrient availability depends on the degree of
cell wall degradability. Improvements in forage fermentation would increase energy intake and subsequently
milk production and performance by dairy cows. It is therefore important to find ways to improve forage
degradation and utilization in the rumen.
The use of different non-fibre carbohydrate (NFC) sources has different effects on animal performance.
Supplementing forage based diets with energy sources containing sugar, starch or pectin results in variation
in performance measurements such as milk yield, milk composition and dry matter intake (DMI).
This thesis reports on two studies in which the effect of energy supplementation on forage fermentation and
digestion parameters was investigated. In the first study an in vitro gas production protocol was used to
determine the effect of sugar (molasses), starch (maize meal) and pectin (citrus pulp) on total gas production
and rate of gas production of different forages. The forage substrates included wheat straw (WS), oat hay,
(OH) lucerne hay (LUC), ryegrass (RYE) and kikuyu grass (KIK). The three energy sources, as well as a
control (no energy source) were incubated in vitro with each of the above mentioned forages. Rumen fluid
was collected from two lactating Holstein cows receiving a diet consisting of oat hay, lucerne, wheat straw
and a concentrate mix. Forages alone (0.25 g DM) and/or together (0.125 g DM) with either molasses
(0.1412 g DM), citrus pulp (0.1425 g DM) or maize meal (0.125 g DM) were weighed into glass vials and
incubated for 72 hours. The weights of the energy sources were calculated on an energy equivalent basis.
Blank vials, that contained no substrates, were included to correct for gas production from rumen fluid alone. The substrates were incubated in 40 ml buffered medium, 2 ml of reducing solution and 10 ml rumen fluid.
Gas pressure was recorded automatically every five minutes using a pressure transducer system and the
method based on the Reading Pressure Technique (Mauricio et al., 1999). Gas pressure was converted to
gas volume using a predetermined regression equation. In the first gas production trial, the gas production
included gas produced by the energy sources, while in the second gas production trial, the energy source
gas production was deducted from the total gas production to determine the effect of energy source on gas
production of respective forage substrates per se. Data were fitted to two non-linear models adapted from
Ørskov and McDonald (1979). Significant forage x energy interactions were observed for the non-linear
parameter gas production (b) in Model 1 and for b and lag phase (L) in Model 2 in both trials. In the first gas
production trial, the higher fermentability of the energy sources supplemented to forage substrates,
increased b (Model 1 & 2) of the LUC and WS. The gas production rate was affected in different ways for
different forages, with the most noticeable effect on WS when it was supplemented with energy sources. All
the energy sources increased c of WS irrespective of the model used. Energy sources had no effect on the
L of LUC, OH or RYE, but decreased the L of WS and KIK. In the second trial, maize meal had no effect on
b for any of the forages (Model 1 & 2), while molasses (Model 1 & 2) decreased b for all forage substrates,
and citrus pulp (Model 1 & 2) decreased b of OH and RYE, to lower values than those of the control
treatments. Gas production rate was not affected by molasses for any of the forage substrates, while citrus
pulp (Model 1 & 2) increased c of OH and maize meal increased c of OH and KIK. Lag phase was only
affected by energy sources in WS and KIK, where all the energy sources had lower L values than the control
treatment. It was concluded that forage fermentability is affected differently by different energy sources.
These observations may have important implications, in practice, on rumen health and milk production, and
the data obtained can potentially be used as guidelines in feed formulations.
In the second study, in vitro digestibility trials were undertaken to determine the effect of sugar (molasses
and sucrose), starch (maize meal and maize starch) and pectin (citrus pulp and citrus pectin) on neutral
detergent fibre (NDF) and dry matter (DM) degradability of forages. Forage substrates used included wheat
straw, oat hay, lucerne hay, ryegrass and kikuyu grass. Rumen fluid was collected from two lactating
Holstein cows receiving a diet consisting of oat hay, wheat straw and a concentrate mix. In vitro
degradability was done with an ANKOM Daisy II incubator and forage substrates were incubated with or
without the respective energy sources for 24, 48 and 72 hours. The substrates were incubated in 1076 ml
buffered medium, 54 ml of reducing solution and 270 ml rumen fluid. The residues were washed, dried and
analyzed for NDF. In the study with the applied energy sources (molasses, maize meal and citrus pulp)
there were a forage x energy source interactions. Supplementation with the applied energy sources all
improved dry matter degradability (DMD) of forages (24 and 72 hours), when compared to the control
treatment, except for RYE supplemented with maize meal and citrus pulp at 24 hours. Molasses seemed to
have had the biggest effect on DMD in all forage substrates. Supplementation with maize meal had no effect
on neutral detergent fibre degradability (NDFD) of any forage substrate, except for an improvement in NDFD
of LUC at 72 hours. Molasses improved NDFD of LUC at 24h, but had no effect on the other forage
substrates. Citrus pulp improved NDFD of OH (72 hours), as well as LUC and WS (24 and 72 hours). It is
postulated that the NDF of the energy sources was more digestible than that of the respective forages, and
that the improved NDFD values could be ascribed to the contribution of the energy source NDFD. Overall,
pasture grasses had a higher NDFD than the hays and straw, and appear to be more readily fermentable by rumen microbes than the low quality hays and straw explaining the higher NDFD. In the study involving the
purified energy sources (sucrose, maize starch and citrus pectin), forage x energy source interactions were
observed. In general, supplementation with these energy sources improved DMD at 24 and 72 hours except
for RYE and KIK (72 hours). Pasture grasses (RYE and KIK) had a higher NDFD than LUC, OH and WS. At
72 hours, NDFD was 37.1% for LUC, 42.5% for OH and 40.3% for WS, compared to 70.5% for KIK and
64.9% for RYE. A possible explanation is that KIK and RYE samples came from freshly cut material,
harvested after a 28d re-growth period. In general, sucrose (24 and 72 hours) and citrus pectin (72 hours)
had no effect on NDFD of forage substrates. However, supplementing oat hay (24 hours) with starch and
citrus pectin, and wheat straw (24 and 72 hours) with starch lowered NDFD, when compared to the control
treatment. It is hypothesized that microbes fermented the easily fermentable energy sources first, before
attacking forage NDF. The study suggested that forage NDFD values are not fixed, and may be altered by
type of energy supplementation. / AFRIKAANSE OPSOMMING: Die meervoudige maagsisteem van herkouers stel hulle in staat om ruvoer meer effektief te benut as
enkelmaagdiere. Ruvoere alleen bevat egter nie genoeg voedingstowwe om die behoeftes van hoogproduserende
melkbeeste te bevredig nie. Ruvoere is ryk aan vesel en hul voedingstofbeskikbaarheid word
bepaal deur die graad van selwand degradeerbaarheid. ‘n Verhoging in ruvoerfermentasie sal energieinname
verhoog en gevolglik ook melkproduksie en prestasie. Dit is dus belangrik om maniere te vind om
ruvoerdegradeerbaarheid en -verbruik in die rumen te verbeter.
Die gebruik van verskillende nie-vesel koolhidraat (NFC) bronne het verskillende uitwerkings op die prestasie
van diere. Energie-aanvullings soos suiker, stysel en pektien tot ruvoer-gebasseerde diëte, beïnvloed
prestasiemaatstawwe soos melkproduksie, melksamestelling en droëmateriaalinname (DMI) op verskillende
maniere.
Hierdie tesis lewer verslag oor twee studies waar die invloed van energie-aanvullings op ruvoerfermentasie
en verteringsmaatstawwe ondersoek is. In die eerste studie is ‘n in vitro gasproduksieprotokol gebruik om
die invloed van suiker (melasse), stysel (mieliemeel) en pektien (sitruspulp) op totale gasproduksie (b) en
tempo van gasproduksie (c) van verskillende ruvoersubstrate te bepaal. Ruvoersubstrate wat gebruik is,
was koringstrooi (WS), hawerhooi (OH), lusernhooi (LUC), raaigras (RYE) en kikuyugras (KIK). Die drie
energiebronne, sowel as ‘n kontrole (geen energiebron), is in vitro geïnkubeer saam met elk van die
genoemde ruvoere. Rumenvloeistof is verkry van twee lakterende Holsteinkoeie, wat ‘n dieet ontvang het
bestaande uit hawerhooi, koringstrooi en ‘n kragvoermengsel. Ruvoere is alleen en/of in kombinasie met
melasse (0.1412 g DM), sitruspulp (0.1425 g DM) of mieliemeel (0.125 g DM) in glasbottels afgeweeg en vir
72 uur geïnkubeer. Die massas van die energiebronne is op ‘n energie-ekwivalente basis bereken. Leë
bottels wat geen substraat bevat het nie, is ingesluit om te korrigeer vir gasproduksie afkomstig vanaf
rumenvloeistof alleen. Substrate is in 40 ml van ‘n buffermedium, 2 ml reduserende oplossing en 10ml
rumenvloeistof geïnkubeer. Gasdruk is elke vyf minute outomaties aangeteken deur gebruik te maak van ‘n
drukmetersisteem en die metode is gebasseer op die Reading gasdruktegniek. Gasdruk is omgeskakel na
gasvolume deur gebruik te maak van ‘n voorafbepaalde regressievergelyking. In die eerste proef het totale
gasproduksie die gas wat deur die onderskeie energiebronne geproduseer is, ingesluit. In die tweede proef
is gasproduksie afkomstig van die energiebronne afgetrek van totale gasproduksie, om sodoende die invloed
van die energiebronne per se op die gasproduksie van die onderskeie ruvoersubstrate, te bepaal. Data is
met behulp van twee nie-liniëre modelle gepas. Betekenisvolle ruvoer x energie-interaksies is in albei
proewe waargeneem vir die nie-liniëre parameter b (gasproduksie) in Model 1, en vir b en L (sloerfase) in
Model 2. In die eerste proef het die energiebronne se hoë fermentasie gelei to ‘n verhoging in b (Model 1 &
2) van LUC en WS. Energie-aanvullings het die c-waarde van die onderskeie ruvoere verskillend beïnvloed,
met WS wat die mees opvallende effek gehad het. Al die energiebronne het die c-waarde van WS verhoog,
ongeag watter model gebruik is. Energiebronne het geen invloed op die L-waarde van LUC, OH of RYE
gehad nie, maar het wel die L-waarde van WS en KIK verlaag. In die tweede proef het mieliemeel geen
invloed op die b-waarde van enige van die ruvoere gehad nie (Model 1 & 2), terwyl melasse (Model 1 & 2)
die b-waarde van alle ruvoere verlaag het, en sitruspulp (Model 1 & 2) OH en RYE se b waardes verlaag het
tot laer as die kontroles. Melasse het geen invloed op die c-waarde van die onderskeie ruvoersubstrate
gehad nie, terwyl sitruspulp (Model 1 & 2) die c-waarde van OH, en mieliemeel die c-waarde van OH en KIK,
verhoog het. Energiebronne het slegs ‘n invloed op die sloerfase in WS en KIK gehad, waar dit L verlaag
het tot laer waardes as dié van die kontroles. Daar is gevind dat ruvoer-fermenteerbaarheid verskillend
beïnvloed word deur verskillende energiebronne. Bogenoemde resultate kan in die praktyk betekenisvolle
invloede hê op rumengesondheid en melkproduksie en die data wat verkry is, kan potensieël gebruik word
as riglyne in voerformulerings.
In die tweede studie is in vitro verteerbaarheidsproewe gedoen om die effek van suiker (molasse en
sukrose), stysel (mieliemeel en mieliestysel) en pektien (sitruspulp en sitrus-pektien) op neutraalonoplosbare
vesel (NDF) en droë materiaal (DM) degradeerbaarheid van ruvoere, te bepaal.
Ruvoersubstrate wat gebruik is, was WS, OH, LUC, RYE en KIK. Rumen vloeistof is verkry van twee
lakterende Holstein koeie, wat ‘n dieet ontvang het bestaande uit hawerhooi, koringstrooi en ‘n konsentraat
mengsel. Die in vitro degradeerbaarheidsproef is gedoen met ‘n ANKOM Daisy II inkubator.
Ruvoersubstrate is geïnkubeer met of sonder die onderskeie energiebronne vir 24, 48 en 72 uur. Die
substrate is geïnkubeer in 1076 ml buffer medium, 54 ml reduserende oplossing en 270 ml rumen vloeistof.
Residue is gewas, gedroog en geanaliseer vir NDF. In die proef met toegepaste energiebronne (molasse,
mieliemeel en sitruspulp), was daar ruvoer x energiebron interaksies. Toegepaste energiebron aanvullings
het almal DMD van ruvoersubstrate (24 en 72 uur) verbeter, uitsluitend vir RYE wat aangevul is met
mieliemeel (24 uur) en sitruspulp (24 uur). Van al die ruvoersubstrate het molasse die grootste effek gehad
op DMD. Mieliemeel aanvullings het geen effek gehad op neutraal-onoplosbare vesel degradeerbaarheid
(NDFD) van ruvoersubstrate nie, behalwe vir ‘n verbetering in NDFD van LUC by 72 uur. Molasse het NDFD
van lucern by 24 uur verbeter, maar geen effek gehad op ander ruvoersubstrate nie. Sitruspulp het NDFD
van OH (72 uur), asook LUC en WS (24 & 72 uur) verbeter. Daar word beweer dat die NDF van
energiebronne meer verteerbaar is as die van ruvoersubstrate, en dat die verbetering in NDFD waardes
toegeskryf kan word aan die bydraes van energiebronne se NDFD. Weidingsgrasse (RYE & KIK) het oor die
algemeen ‘n hoër NDFD as hooie en strooi gehad. Rumen mikrobes blyk ook om dié grasse vinniger te
verteer as lae kwaliteit hooie en strooi, wat gevolglik die hoër NDFD verduidelik. In die proef met suiwer
energiebronne (sukrose, mieliestysel en sitrus-pektien) is ruvoer x energiebron interaksies waargeneem.
Energiebronaanvullings het DMD by 24 en 72 uur verbeter, buiten vir RYE en KIK (72 uur). Weidingsgrasse
het hoër NDFD as LUC, OH en WS. By 72 uur was die NDFD van LUC 37.1%, OH 42.5%, WS 40.3%, in
vergelyking met 70.5% vir KIK en 64.9% vir RYE. ‘n Moontlike verklaring vir die hoër NDFD van KIK en
RYE, is omdat dit vars gesnyde material is, geoes na slegs 28 dae hergroei. Oor die algemeen het sukrose
(24 & 72 uur) en sitrus-pektien (72 uur) geen effek gehad op NDFD van ruvoersubstrate nie, terwyl stysel en
pektien aanvullings tot OH (24 uur), en stysel aanvullings tot WS (24 & 72 uur) NDFD verlaag het. Daar
word hipotetieseer dat mikrobes eers die vinnig fermenteerbare energiebronne fermenteer, voordat hulle
ruvoer NDF aanval. Hierdie studie beweer dat ruvoer NDFD waardes nie vas is nie, en dat dié waardes
beïnvloed mag word deur energiebron aanvullings.
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30 |
Genetic analyses of South African terminal sire sheep breedsZishiri, Oliver Tendayi 03 1900 (has links)
Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2009. / ENGLISH ABSTRACT: Fluctuations and a general decline in the ratio between wool and meat prices resulted in marked changes in the
South African sheep industry. Commercial producers now exploit other mechanisms such as terminal
crossbreeding of Merino-type with meat type breeds or dual-purpose breeds to attain short-term benefits
resulting from price fluctuations between wool and mutton without compromising the wool-producing capacities
of ewe flocks. Most components of lamb production have low heritability. However, heterosis can be achieved by
mating wool-type breeds with specialist meat breed rams. Genetic improvement of livestock depends on defining
breeding objectives, estimation of genetic parameters and accurately identifying the right animals to be used for
future breeding. Genetic parameters for traits of economic importance in terminal sire sheep breeds that could
be used on Merino-type ewes in commercial operations in South Africa had not been published for the national
flock apart from a preliminary study having been conducted by Olivier et al. (2004). Selection objectives were
poorly defined due to lack of parameter estimates for variance and covariance components. Against this
background, this study obtained pedigree information and live weight data from the National Small Stock
Improvement Scheme for the Dormer, Ile de France and Merino Landsheep and estimated non-genetic factors
and genetic parameters influencing early growth traits. Genetic and phenotypic trends for early growth traits
were constructed for the three breeds to monitor genetic progress.
Non-genetic factors influencing early growth traits in the Dormer, Ile de France and Merino Landsheep were
estimated using data obtained from the National Small Stock Improvement Scheme of South Africa. The original
data sets for the Dormer, Ile de France and Merino Landsheep consisted of the following number of records
respectively: 52 202, 35 553 and 7 772. However, pre-weaning weights were available for the Ile de France and
Merino Landsheep breeds only and post-weaning weights were available only for the Dormer breed. The data
sets were complicated to such an extent that smaller data sets had to be generated to analyse for fixed effects.
The traits that were analysed were birth weight, pre-weaning weight, weaning weight and post-weaning weight.
The fixed effects, identified as having a significant effect (P < 0.01) on early growth traits were sex of lamb, birth
type, age of dam, contemporary groups, age at which the trait was recorded and month of birth and year of birth in the Merino Landsheep breed. Although some significant interactions were found, they were subsequently
ignored owing to their very small effects. In all three breeds, male lambs were significantly (P < 0.001) heavier
than female lambs and single-borne lambs were significantly heavier at birth than multiple borne lambs. The age
of dam had a significant curvilinear regression on all early growth traits in all three terminal sire sheep breeds. It
was concluded from the study that the influence of non-genetic factors on early growth traits should be adjusted
for or eliminated statistically in genetic evaluations to get accurate genetic parameter estimations.
(Co)variance estimates for birth weight, weaning weight and post-weaning weight were obtained for the Dormer
breed using restricted maximum likelihood procedures (REML). Direct heritabilities (h2) in single-trait analyses
were 0.21 ± 0.03, 0.23 ± 0.02 and 0.29 ± 0.05 for birth weight, weaning weight and post-weaning weight,
respectively. Direct heritabilities of 0.28 ± 0.04, 0.55 ± 0.06 and 0.32 ± 0.02 for birth weight, weaning weight and
post-weaning weight respectively were obtained using three-trait analysis. Direct maternal genetic effects (m2)
were excluded from the analyses because of the failure to partition maternal effects into maternal genetic and
maternal permanent environmental effects (m2 and c2). This culminated as a consequence of poor data and
population structures emanating from the loss of genetic links across flocks due to the random entrance and exit
of flocks from the recording scheme. Maternal permanent environment was estimated at 0.15 ± 0.02, 0.13 ± 0.02
and 0.20 ± 0.03 for birth weight, weaning weight and post-weaning weight respectively using single-trait analysis.
The correlation between direct effects and maternal effects (ram) was excluded from the analyses due the
structure of the data. Genetic, phenotypic and environmental correlations between early growth traits were low to
moderate. The medium to high heritability estimates for early growth traits obtained in the study led to the
conclusion that Dormer sheep can successfully be used in terminal crossbreeding programs to improve meat
production characteristics.
Direct heritability estimates were 0.31 ± 0.14, 0.09 ± 0.02 and 0.14 ± 0.003 for birth weight, pre-weaning weight
and weaning weight respectively using single-trait analysis for the Ile de France breed. Maternal effects were
significant for all the traits studied despite the failure to properly partition them into their components due to the
loss of genetic linkages across generations emanating from poor data structure. Genetic, phenotypic and
environmental correlations were estimated using three-trait analysis and were found to be low to moderate for
early growth traits. Direct genetic and maternal permanent environmental ratios were also computed and they
did not differ much from the results obtained using single-trait analyses. The reasonable genetic parameter
estimates obtained in the study led to the conclusion that the Ile de France can be selected to use as sires in
crossbreeding programs.
Genetic parameters were estimated for early growth traits in the Merino Landsheep breed. REML estimates of
birth weight, pre-weaning weight and weaning weight were obtained using animal models in single-trait
analyses. The direct heritability estimate for birth weight was 0.23 ± 0.13 using an animal model with additive
direct genetic effects and dam permanent environmental effects as the only random factors. The dam permanent
environmental effect for birth weight amounted to 0.10 ± 0.07. Direct heritability for pre-weaning weight was 0.36
± 0.05 and the dam permanent environmental effect 0.56 ± 0.03. Weaning weight was estimated using an animal model that contained direct additive effects and dam permanent environmental effects. The direct heritability
estimate for weaning weight was 0.17 ± 0.03. Maternal genetic effects were estimated to be 0.02 ± 0.01.
Genetic and phenotypic trends were constructed for early growth traits in the Dormer, Ile de France and Merino
Landsheep breeds. The traits that were considered were birth weight, pre-weaning weight, weaning weight and
post-weaning weight. However, pre-weaning weights were available for the Ile de France and Merino Landsheep
breeds only and post-weaning weights were available only for the Dormer breed. The Dormer exhibited
significant improvement in the phenotypic and genetic aspects of early growth traits during the 17 years of
evaluation (1990-2007). The average predicted direct breeding values of birth weight decreased by 0.055 %
during the evaluation period. The predicted direct breeding value for weaning weight increased by 0.12 % during
the 17 year period. Post-weaning weight improved by 0.32 % per annum. The Ile de France registered an
increase in the predicted breeding value of birth weight which amounted to 0.025 % per annum. Averaged direct
breeding values for pre-weaning weight increased at an annual rate of 0.23 %. and that of weaning weight
increased by 1.21 %. In the Merino Landsheep the predicted direct breeding value for birth weights decreased
by 0.04 % per annum and pre-weaning and weaning weights increased by 0.36 % and 0.10 % respectively. The
trends were obviously biased due to inconsistencies in data structure and very few records available for analysis
in this breed.
In conclusion, it was evident that the additive genetic variation was available for all the early growth traits in all
the three breeds. Although adequate genetic variation for substantial genetic progress was available, only
modest rates of progress were attained for all the traits in all three breeds. The only possible exception was
weaning weight in the Ile de France breed, which improved at > 1 % per annum. At least all changes were in the
desired direction. Breeders should be encouraged to record data consistently, as one of the major shortcomings
in the data for all breeds were a lack of continuity in the submission of data to the NSIS. More informative
analyses ought to be feasible if this requisite could be met. / AFRIKAANSE OPSOMMING: Die wisselende en algemene afname in die prysverhouding van wol tot vleis het merkbare veranderinge in die
Suid-Afrikaanse skaapbedryf teweeggebring. Kommersïele produsente maak nou gebruik van ander metodes
soos terminale kruisteling van Merino-tipe ooie met vleis tipe vaars of dubbel-doel rasse om korttermynvoordele
uit die wisselende wol en vleis pryse te behaal, sonder om die wol-produksie potensiaal van die ooi-kudde te
benadeel. Die meeste van die lamproduksie eienskappe het ‘n lae oorerflikheid. Nietemin, kan heterose wel
behaal word deur die kruisteling van wol-tipe rasse met spesialis vleisramme. Genetiese verbetering van vee is
afhanklik van die beskrywing van die teeltdoelwitte, die akkurate beraming van genetiese parameters en die
noukeurige identifikasie van die geskikste diere vir toekomstige teling. Genetiese parameters vir ekonomies
belangrike eienskappe van terminale ramrasse wat gebruik kan word op Merino-tipe ooie in die kommersiële
skaapbedryf in Suid-Afrika is nog nie gepubliseer vir die nasionale kudde nie, behalwe vir ‘n voorlopige studie
wat gedoen is deur Olivier et al. (2004). Seleksiedoelwitte is nie duidelik beskryf nie a.g.v ‘n tekort aan akkurate
parameterberamings vir (ko)variansie komponente. Hierdie studie het dus stamboominligting en lewende gewig
data verkry vanaf die Nasionele Kleinveeverbeteringsskema vir die Dormer-, Ile de France- en die Merino
landskaaprasse en nie-genetiese faktore sowel genetiese parameters vir vroeë lamgewigte beraam. Genetiese
en fenotipiese tendense vir vroeë lamgewigte is vervolgens opgestel vir drie rasse om genetiese vordering te
evalueer.
Die oorspronklike datastelle vir die Dormer, Ile de France en die Merino Landskaap het uit die volgende aantal
rekords bestaan, onderskeidelik: 52 202, 35 553 en 7 772. Voor-speen gewigte was net beskikbaar vir die Ile de
France- en die Merino Landskaaprasse, en na-speen gewigte was net beskikbaar vir die Dormerras. Die
beperkings in die datastelle het genoodsaak dat dat kleiner datastelle ontwikkel moes word om die vaste effekte
te analiseer. Die eienskappe wat ge-analiseer was, was geboortegewig, voor-speengewig, speengewig en naspeengewig.
Die vaste effekte wat vroeë lamgewigte betekenisvol (P < 0.01) beïnvloed het, was geslag van die
lam, geboortestatus, ouderdom van die ooi, kontemporêre groep, die ouderdom waarop die eienskap
aangeteken is en (in sommige gevalle) die maand en jaar van geboorte. Alhoewel daar sommige betekenisvolle
interaksies was, is dit nie in die finale modelle ingesluit nie, omdat dit min tot die verklaarde variasie bygedra het.
In al die rasse het ramlammers swaarder (P < 0.001) geweeg as ooilammers. Enkelinge was ook swaarder
(P<0.001) as meerlinge. Die ouderdom van die moer van die lam het ‘n beduidende kromlynige invloed op alle
vroeë lamgewigte by al drie terminale ramrasse gehad. Die gevolgtrekking van hierdie studie is dat die invloed
van nie-genetiese faktore op vroeë lamgewigte in ag geneem moet word, of dat dit moet statisies elimineer word
in die genetiese evaluasie om akkurate genetiese beramings te verkry.
(Ko)variansie beramings vir geboortegewig, speengewig en na-speengewig is deur gebruik te maak van die
“restricted maximum likelihood procedures” (REML) vir die Dormerras verkry. Die direkte oorerflikheid (h2) wat
verkry was deur die mees geskikste diere model in ‘n enkel-eienskap analise te gebruik was onderskeidelik 0.21
±0.02, 0.23 ±0.02 en 0.29± 0.05 vir geboortegewig, speengewig en na-speengewig. Direkte ooreenstemende
oorerflikheid wat uit die drie-eienskap analise was 0.28±0.04, 0.55±0.06 en 0.32±0.02 onderskeidelik vir
geboortegewig, speengewig en na-speengewig. Direkte maternale genetiese effekte (m2) is uitgesluit vanaf die
analise weens die onvermoë om die maternale effekte te verdeel in maternale genetiese effekte en maternale
permanente omgewings effekte (m2 en c2). Dit was a.g.v onvolledige data en populasiestrukture wat gelei het tot
die gebrek in genetiese bande oor kuddes, wat ontstaan het weens kuddes wat slegs tydelik data tot die skema
bygedra het. Maternale permanente omgewingeffekte is geskat op onderskeidelik 0.15±0.02, 0.13±0.02 en
0.20±0.03 vir geboortegewig, speengewig en na-speengewig met die gebruik van die enkel-eienskap analise.
Die korrelasie tussen direkte effekte en maternale effekte (ram) is uitgesluit a.g.v die gebrekkige struktuur van die
data. Genetiese-, fenotipiese- en omgewingskorrelasies tussen die vroeë lamgewigte was laag tot matig. Die
matige tot hoë oorerflikheidberamings vir vroeë lamgewigte uit hierdie studie het gelei tot die gevolgtrekking dat
Dormer skape suksesvol gebruik kan word in terminale kruisteel programme om vleisproduksie te verbeter.
Direkte oorerflikheid skattings was 0.31±0.14, 0.09±0.02 en 0.14±0.003 vir die geboorte gewig, voor-speen
gewig en speen gewig onderskeidelik met die gebruik van ‘n enkel-faktor analise vir dir Ile de France skaap ras.
Maternale effekte was beduidend vir al die eienskappe wat bestudeer was , ten spyte van die onvermoë om dit
behoorlik te verdeel in hul komponente weens die verlies van genetiese bande dwarsoor die generasies wat
uitvloei vanaf ‘n swak data struktuur. Genetiese, fenotipiese en omgewings korrelasies was geskat deur gebruik
te maak van ‘n drie-faktor analise en was gevind om laag tot matig te wees vir die vroeë groei eienskappe.
Direkte genetiese en maternale permanente omgewings ratios was bereken en dit het nie veel verskil van die
resultate verkry deur die enkel-faktor analise. Die aanvaarbare genetiese parameter skattings verkry in hierdie
studie het gelei tot die gevolgtrekking dat die Ile de France geselekteer kan word as teelramme in kruisteel
programme.
Genetiese parameters was geskat vir vroeë groei eienskappe in die Merino Landskaa ras. REML skattings van
geboorte gewig, voor-speen gewig en speen gewig was verkry deur diere modelle in enkel-faktor analises. Die
direkte oorerflikheid skatting vir geboorte gewig was 0.23±0.13 met die gebruik van die diere model met
additiewe direkte genetiese effekte en ooi permanente omgewings faktore as die enigste ewekansige faktore.
Die ooi permanente omewings effek vir geboorte gewig was 0.10±0.07.
Direkte oorerflikheid vir voor-speen gewig was 0.36±0.05 en die ooi permanente omgewings effek 0.56±0.03.
Speen gewig was geskat deur die gebruik van ‘n diere model wat die direkte additiewe effekte en die ooi
permanente omgewings effekte bevat het. Die direkte oorerflikheids skatting vir speen gewig was 0.17±0.03.
Maternale genetiese effekte was geskat as 0.02±0.01.
Genetiese en fenotipiese tendense is verkry vir vroeë lamgewigte in die Dormer-, Ile de France- en Merino
Landskaaprasse. Die eienskappe wat oorweeg is, was geboortegewig, voor-speengewig, speengewig en naspeengewig.
Voor-speengewigte was net beskikbaar was vir die Ile de France- en die Merino Landskaap rasse
en die na-speense gewigte net vir die Dormerras. Die Dormer het beduidende verbetering vertoon in die
fenotipiese en genetiese aspekte vir vroeë lamgewigte gedurende die 17 jaar van evaluasie (1990-2007). Die
gemiddelde voorspelde direkte teeltwaarde van speen gewig het met 0.12% per jaar gestyg gedurende die 17-
jaar periode. Na-speen gewig het met 0.32% per jaar verbeter. By die Ile de France het ‘n toename in die
voorspelde teelwaarde van geboortegewig (0.025% per jaar) voorgekom. Gemiddelde direkte teelwaardes vir
voor-speengewig het toegeneem teen ‘n jaarlikse tempo van 0.23% en speengewig het met 1.21% per jaar
toegeneem. In die Merino Landskaapras het die voorspelde direkte teelwaarde vir geboortegewig met 0.04%
per jaar gedaal, terwyl voor-speen- en speengewigte met 0.36% en 0.10% onderskeidelik toegeneem het. Die
tendense was ooglopend gekompromiteer weens probleme met die data struktuur, en a.g.v van die relatief min
rekords wat beskikbaar was vir die analise in die ras.
Dit was duidelik dat die additiewe genetiese variasie beskikbaar was vir al die vroeë groei eienskappe in al die
drie rasse. Alhoewel voldoende genetiese variasie vir wesentlike genetiese vordering beskikbaar was, is daar
slegs matige vordering verkry vir al die eienskappe in al drie rasse. Die enigste moontlike uitsondering was
speengewig in die Ile de France ras, wat met 1.21 % per jaar gestyg het. Alle veranderinge was minstens in die
gewensde rigting. Telers word versoek om data deurlopend en akkuraat aan te teken , aangesien een van die
groot tekortkominge met die data van al die rasse ‘n tekort aan deurlopendheid in die indiening van die data aan
die NISS was. ‘n Meer verteenwoordigende analise sal uitvoerbaar wees, as daar aan al die bogenoemde
aanbeveling voldoen kan word.
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