Spelling suggestions: "subject:"sheep -- hutrition."" "subject:"sheep -- elutrition.""
11 |
A comparative analysis of nutrient utilisation and meat quality parameters of boer goats and South African mutton merinosSheridan, Rouxlene 12 1900 (has links)
Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: One of the reasons why meat supply does not meet human demand is that man has
concentrated on utilising relatively few animal species as a source of meat. Development of
unconventional livestock, such as goats, is advocated as a means of increasing global meat
production and consumption. Although South Africa possesses large numbers of domestic
ruminants, meat consumption has been limited mainly to sheep and cattle. Goats are used to
a lesser extent. This is partly attributed to a general belief that goat meat is inferior to mutton
and beef.
Numerous contradictions regarding comparative goat and sheep growth, carcass
characteristics and meat composition exist in literature. Concepts involved with most of the
contradictions includes average daHy gain (ADG), dressing percentage, carcass weight
distribution and organoleptic characteristics, especially tenderness, juiciness and flavour,
particularly as pertaining to animals reared/grown under intensive/feedlot conditions.
Therefore this project was undertaken to obtain more information on the growth, carcass and
organoleptic characteristics, as well as meat chemical compositions of Boer goat (BG) kids in
comparison with South African Mutton merino (MM) lambs, reared under feedlot conditions.
Thirty-two BG kids and 32 MM lambs were used for this investigation. All the animals were
castrated and weaned before entering the feedlot. Two pelleted diets (fed to 16
animals/species) with either a low (LE; 8.9 MJ/kg OM) or a high (HE, 10.9 MJ/kg OM)
metabolisabie energy level were fed individually, ad lib for either 28 or 56 days. Feed and
water intake, ADG and feed conversion efficiencies (FCE) were monitored. During the last week of the feeding trial, 12 BG kids and 12 MM lambs were used to evaluate the digestibility
of the two diets.
After either 28 or 56 days, the animals were slaughtered and the carcasses dissected into
South African commercial cuts. The m. semimembranosus and 8-9-10-rib cut of each carcass
was dissected for determination of chemical composition, drip loss, cooking loss, shear force
values and colour measurement. The m. gracilis was dissected from the hind leg of the
carcass and used for sensory evaluation.
MM's had significantly higher AOG's than BG's (e.g. MMHE56: 0.281; BGHE56: 0.162
kg/day). Within a diet there was no difference (P>0.05) in FCE between BG's and MM's and
only the MM's FCE differed between the LE and HE diet (e.g. BGLE28: 7.65; BGHE28: 6.37;
MMLE28: 8.73; MMHE28: 5.56 kg feed/kg weight gain). BGLE digested dry matter (OM),
crude protein (CP) and energy more efficiently and had a higher energy retention than MMLE.
The two diets had the same ME-value for the goats, which confirms that goats perform equally
well on a lower quality feed as their contemporaries on a higher quality feed. Neither species,
nor diet affected nitrogen retention. The BG had a 49 % lower (P<0.01) water intake per kg
weight gain than the MM on both the high and low energy diets. Both species had a lower
(P<0.01) water intake on the high than on the low energy diet. Furthermore, the BG had a
daily water intake of only 171 ml/kgo.75 compared to the 302 ml/kgo.75 of the MM.
The weight of the liver, empty stomach, head and feet (as a percentage of empty body weight)
were higher in goats than in sheep. The MM's had significantly heavier skins, probably due to
wool growth. Both kidney fat and gastro-intestinal tract (GIT) fat increased with age. The
animals slaughtered after 56 days in the feedlot had significantly longer and deeper carcasses
than their contemporaries slaughtered after 28 days. Within a diet and slaughter age, the MM
had significantly broader and deeper carcasses than the BG's. BG's had significantly less
weight per unit carcass length, and thus more slender carcasses than MM's. Diet had no
significant influence on the carcass weight distribution of the goats. However, MM's had
heavier carcasses (LE: 19.87 vs. 15.28 kg; HE: 24.01 vs. 17.05 kg) and proportionally heavier
ribs and buttocks than BG's.
Neither diet nor slaughter age influenced the proximate analysis of the m. semimembranosus,
but MM's had significantly lower moisture values than BG's. In the 8-9-10-rib cuts BG's had
significantly more moisture and protein and lower fat and energy values than MM's. OM, fat
and energy values increased with an increase in slaughter age in both species. BG's had
significantly higher concentrations of 11 of the 18 measured essential amino acids in their 8-9-
10-rib cuts than the MM's. Gaat carcasses had higher Ca, K, Mg, Na and P-Ievels than sheep
carcasses, regardless of the diet fed. There was a tendency for goat's m. semimembranosus
to have a lower Fe-content than that of sheep. BG carcasses had a lower carcass cholesterol content than that of lamb (66.77 vs. 99.28
mg/100g, respectively). Palmitic (C16:0), stearic (C18:0) and oleic (C18:1 n9) acid comprised
the greatest proportions of fatty acids in both the m. semimembranosus and 8-9-10-rib cut for
both species. On a LE-diet there was no significant difference between the saturated fatty
acid (SFA) to unsaturated fatty acid (UFA) ratio of goat meat and lamb. However, on the HEdiet,
lamb had a significantly higher SFA:UFA ratio than chevon (m. semimembranosus: 0.842
vs. 0.689; 8-9-10-rib cut: 1.407 vs. 0.892). Organoleptically, a difference was noted between
chevon and lamb. Each has a specific species flavour, which was not influenced by energy
level of the diet. BG meat was perceived to be stringier than that of the MM, but there was no
significant difference in Warner-Bratzler shear force values. Tenderness declined with age in
both species and there was also a tendency for goat meat to be less juicy than lamb. Chevon
had a more pronounced aftertaste than lamb. No objective differences could be distinguished
between the colour of the cooked chevon and lamb. There was a tendency for fresh lamb to
have a higher a*-value (redness) than chevon. Although diet did not influence drip loss, drip
loss increased with an increase in slaughter age. Only after 56 days did the MM's m.
semimembranosus have a significantly higher drip loss than the BG's (LE: 4.84 vs. 3.43%;
HE: 4.72 vs. 3.32%). In the m. semimembranosus of both species, cooking loss increased
with an increase in slaughter age.
Since diet did not influence the growth, carcass weight distribution, water holding capacity,
colour, shear force values or organoleptic qualities of chevon, BG's may be finished on a diet
with a lower ME-value than that usually formulated for sheep, without a reduction in
performance. This may render a direct economic advantage for BG feedlot finishing. Meat
from young feedlot goats is not inferior to that of lamb and it has a higher protein percentage
and lower fat percentage. Therefore, it can be considered as a healthy food commodity,
especially among low-income groups or people wishing to consume a low calorie diet. / AFRIKAANSE OPSOMMING:
'n Vergelykende analise van nutriëntverbruik en vleiskwaliteisparameters van
Boerbokke en Suid-Afrikaanse Vleismerino's:
Een van die hoofredes waarom die vraag na vleis die aanbod oorskrei, is die feit dat die mens
tot op hede net op 'n paar dierspesies as bron van vleis gekonsentreer het. Benutting van niekonvensionele
spesies, soos bokke, kan aanbeveel word ten einde die globale vleisproduksie
en -verbruik te verhoog. Ten spyte van die feit dat Suid-Afrika oor baie gedomestikeerde
herkouerspesies beskik, is vleisverbruik in die verlede tot hoofsaaklik skape en beeste beperk.
Bokke is tot 'n mindere mate gebruik. Dit kan gedeeltelik toegeskryf word aan die algemene
siening dat bokvleis ondergeskik aan skaap- en beesvleis is.
Verskeie teenstrydighede ten opsigte van vergelykings tussen bokke en skape se groei,
karkaseienskappe en vleissamestelling bestaan in die literatuur. Teenstrydige resultate ten
bpsigte van gemiddelde daaglikse toename (GOT), uitslagpersentasie, karkasgewigverspreiding
en organoleptiese eienskappe (veral taaiheid, sappigheid en geur) van diere
afgerond onder intensiewe/voerkraal-toestande, kom veral voor. Hierdie projek is vervolgens
uitgevoer ten einde meer inligting ten opsigte van die groei, karkas- en organoleptiese
eienskappe, sowel as die chemiese samestelling van die vleis van Boerbok (BB) lammers in
vergelyking met Suid-Afrikaanse Vleismerino (VM) lammers, onder voerkraal-toestande
grootgemaak, te verkry.
Twee-en-dertig BB lammers en 32 VM lammers is vir hierdie studie gebruik. AI die diere is
gekastreer en gespeen voor hulle in die voerkraal geplaas is. Twee verpilde diëte (gevoer
aan 16 diere/spesie) met óf 'n lae (LE, 8.9 MJ/kg DM) óf 'n hoë (HE, 10.9 MJ/kg DM)
metaboliseerbare energievlak is individueel, ad lib, vir óf 28 óf 56 dae aan die diere gevoer.
Voer- en waterinname, GOT en voeromsettingsdoeltreffendheid (VOD) is gemonitor. Gedurende die laaste week van die voedingsproef is 12 BB'e en 12 VM's gebruik ten einde
die verteerbaarheid van die twee diëte te bepaal.
Na 28 of 56 dae is die diere geslag en die karkasse in Suid-Afrikaanse kommersiële snitte
verdeel. Die m. semimembranosus en 8-9-10-rib snit van elke karkas is verwyder vir bepaling
van chemiese samestelling, drupverlies, kookverlies, skeurwaardes en kleurbepaling. Die m.
gracilis is uit die agterbeen uitgehaal en vir sensoriese evaluering gebruik.
VM's het betekenisvolle hoër GOT's as BB'e (bv. VMHE56: 0.281; BBHE56: 0.162 kg/dag)
gehad. Binne 'n dieet was daar geen verskille (P>0.05) in VOD tussen BB'e en VM's nie en
net die VM's se VOD het tussen die LE- en HE-dieet verskil (bv. BBLE28: 7.65; BBHE28:
6.37; VMLE28: 8.73; VMHE28: 5.56 kg voer/kg gewigstoename). BBLE het die droë materiaal
(DM), ruproteïen (RP) en energie meer effektief verteer en het 'n hoër energieretensie as
VMLE gehad. Die twee diëte het dieselfde ME-waarde vir die bokke gehad, wat bevestig dat
bokke net so goed op 'n laer kwaliteit voer presteer as op 'n dieet van 'n hoër kwaliteit.
Stikstofretensie is nie deur spesie of dieet beïnvloed nie. Die BB het 'n 49% laer (P<0.01)
waterinname per kg massatoename op beide die HE- en LE-dieet gehad. Beide spesies het
'n laer (P<0.01) waterinname op die hoë as die lae energie dieet gehad. Verder het die BB
ook 'n daaglikse waterinname van slegs 171 ml/kg075 gehad in vergelyking met die 302
ml/kgO.75van die VM.
Die gewig van die lewer, leë pens, kop en pote (as persentasie van leë liggaamsgewig) was
hoër vir bokke as vir skape. Die VM's se velle was betekenisvol swaarder, waarskynlik as
gevolg van wolgroei. Beide niervet en kanaalvet het toegeneem met 'n toename in
slagouderdom. Die diere wat na 56 dae in die voerkraal geslag is, het betekensivol langer en
dieper karkasse gehad as dié na 28 dae. Binne 'n dieet en slagouderdom, het die skape
breër en dieper (P<0.05) karkasse as die bokke gehad. BB'e het betekenisvol minder gewig
per eenheid karkaslengte en dus maerder karkasse as VM's gehad. Dieet-energievlak het
geen betekenisvolle effek op die verspreiding van karkasgewig by bokke gehad nie. VM's het
egter swaarder karkasse (LE: 19.87 vs. 15.28 kg; HE: 24.01 vs. 17.05 kg) en proporsioneel
swaarder ribbes en boude as BB'e gehad.
Dieet of slagouderdom het nie 'n betekenisvolle effek op die chemiese samestelling (vog, vet,
proteïen en as) van die m. semimembransous gehad nie, maar VM's het laer (P<0.05)
vogwaardes as BB'e gehad. In die 8-9-10-rib snit het BB'e betekenisvolle hoër vog en
proteïen, maar laer vet- en energiewaardes as VM's gehad. In beide spesies het DM, vet en
energiewaardes toegeneem met 'n toename in slagouderdom. BG'e het 'n betekenisvolle
hoër konsentrasie in 11 van die 18 gemete essensiële aminosure in hul 8-9-10-rib snitte
gehad in vergelyking met VM's. Bokkarkasse het ook hoër Ca, K, Mg, N en P-vlakke as
skaapkarkasse gehad, ongeag die dieet. Daar was 'n neiging vir die bok m.
semimembranosus om 'n laer Fe-inhoud as dié van die skaap te hê. BB-karkasse het 'n laer cholesterol-inhoud as skaapkarkasse (66.77 vs. 99.28 mg/100g, onderskeidelik) gehad.
Palmitiensuur (C16:0), steariensuur (C18:0) en oleïensuur (C18:1n9) het die grootste
proporsies van die vetsure in beide die m. semimembranosus en 8-9-10-rib snit van beide
spesies uitgemaak. Op 'n LE-dieet was daar geen verskil tussen die versadigde (SFA) tot
onversadigde (UFA) vetsuur-verhouding van bok- en skaapvleis nie. Op 'n HE-dieet het
skaapvleis egter 'n betekenisvol hoër SFA:UFA-verhouding as bokvleis gehad (m.
semimembranosus: 0.842 vs. 0.689; 8-9-10-rib snit: 1.40 vs. 0.892, onderskeidelik).
Organolepties is 'n verskil tussen bok- en skaapvleis gevind. Elkeen het 'n spesifieke
spesiegeur, wat onafhanklik van die dieet was. Bokvleis is waargeneem as meer veselrig as
skaapvleis, maar daar was geen verskil in Warner-Bratzler skeurwaardes nie. In beide
spesies het sagtheid afgeneem met 'n toename in ouderdom en daar was 'n neiging vir
bokvleis om minder sappig as lamsvleis te wees. Bokvleis het ook 'n meer pertinente
nasmaak as lam gehad. Geen objektiewe verskil kon tussen die kleur van gekookte skaapen
bokvleis onderskei word nie. Daar was egter 'n tendens vir vars lamsvleis om 'n hoër a*-
waarde (rooiheid) as bokvleis te hê. Alhoewel dieet nie 'n invloed op drupverlies gehad het
nie, het drupverlies toegeneem met 'n toename in slagouderdom. Slegs na 56 dae het die VM
se m. semimembranosus 'n hoër (P>0.05) drupverlies as dié van die BB getoon (LE: 4.84 vs.
3.43%; HE: 4.72 vs. 3.32%, onderskeidelik). In die m. semimembranosus van beide spesies
het kookverlies toegeneem met 'n toename in slagouderdom.
Aangesien dieet nie 'n effek op die groei, karkasgewig-verspreiding, waterhouvermoë, kleur,
skeurwaardes of organoleptiese eienskappe van bokvleis gehad het nie, kan BB'e op 'n dieet
met 'n laer ME-waarde as wat normaalweg vir skape geformuleer word, afgerond word,
sonder om 'n verlaging in produksie te verwag. Dit mag 'n direkte ekonomiese voordeel vir
afronding van BB'e in die voerkraal inhou. Vleis van jong voerkraalbokke is nie
minderwaardig teenoor die van skape nie e-n dit het 'n hoër proteren- en laer vetpersentasie.
Dus kan bokvleis as 'n gesonde voedselbron gesien word, veralonder lae-inkomste groepe of
mense wat 'n lae kalorie-dieet wil inneem.
|
12 |
Essential amino acid requirements for growth in woolled sheepNolte, Joubert van Eeden 03 1900 (has links)
Thesis (PhD(Agric) (Animal Sciences))--University of Stellenbosch, 2006. / This project consisted of five studies. The objectives were to determine the essential
amino acid (AA) requirements of growing woolled lambs (Merino and Dohne Merino)
and the essential AA profile of duodenal digesta pre-dominantly derived from microbial
protein. The limiting essential AA`s in high rumen degradable protein (RDP) diets to
growing lambs, where microbial protein is the primary source of AA`s, were also
identified.
The first study determined the essential AA profile of duodenal protein on a high rumen
degradable diet and evaluated the impact of dietary RDP concentration and source [true
RDP vs. non-protein nitrogen (NPN)] on the AA composition of supplied in the
duodenum. The first trial in this study evaluated the effects of increasing true RDP levels
on the essential AA composition of duodenal protein primarily derived from rumen
microbes. The lambs had free access to wheat straw and fresh water. The daily RDP
supplements were administered in two equal doses into the rumens through rumen
cannulas at 07:00 and 19:00. Duodenal digesta was extracted with 6h intervals through
T-type cannulas, inserted proximally to the common bile duct. Sampling time was
advanced 2h every day to obtain duodenal samples on every even hour of a 24h period
after three days. As expected, deficient RDP limited the supply of essential AA`s in the iv
duodenum. When the true RDP supplements increased, the duodenal flow of essential
AA`s also increased concomitantly, but appeared to level off at the higher RDP levels.
Despite the positive quantitative effects of true RDP supplementation on AA supply to the
duodenum, the AA profile in the duodenum was unaltered. Consequently, the essential
AA profile of duodenal protein of sheep receiving high RDP diets, where microbial
protein is the primary source of AA`s in the duodenum, is relatively constant and
insensitive to dietary RDP concentration.
In the second trial the effects of RDP source (true RDP vs. NPN) on the essential AA
profile of duodenal protein on high RDP diets were evaluated by substituting increasing
amounts of urea for true RDP in isonitrogenous teatments. Higher NPN increments
reduced the daily supply of essential AA`s in the duodenum. In corroboration of the first
trial, the AA profile of the duodenal protein was very constant, irrespective of the RDP
source. Since microbial protein is the major source of duodenal AA`s on high RDP diets,
this study supports the view that microbial protein has a relatively constant AA profile,
but microbial protein yield varies according to several rate limiting factors in the rumen.
A constant microbial AA profile allows accurate estimates of microbial essential AA
supply in the small intestine if microbial protein production and fluid and particulate
outflow rates from the rumen can be accurately predicted. This allows the development
of more accurate undegradable protein (UDP) supplementation strategies, based on the
essential AA requirements of animals.
In the second study growing male Merino and Dohne Merino lambs were slaughtered at
different weights and body condition scores. The digesta was removed from the stomachs
and intestines and every organ or body part were weighed to determine the whole empty
body (WEB) composition. The WEB was partitioned into the carcass, internall offal
(stomachs, intestines, organs and blood) and external offal (head, feet, skin and wool).
No differences were apparent in the proportional weight distribution of similar body
components of the same breed at different ages. In a comparison between breeds, the
proportional weight contributions of the carcasses from both breeds to the WEB weight
were remarkably similar at both slaughtering stages. The Dohne Merino lambs had
proportionally larger internal offals and smaller external offals than the Merino lambs at
both slaughters. Unless the essential amino acid compositions of the internal and external
offals were identical to the carcass, the dissimilarities in weight and protein allocation to these two components within the WEB`s of Merino and Dohne Merino lambs imply a
distinct WEB essential AA composition for each breed.
The apparent digestibilities of dry matter (DM), crude protein (CP), energy, acid
detergent fibre (ADF), neutral detergent fibre (NDF), fat and ash did not differ between
Merino and Dohne Merino lambs. Energy retention was also similar for the two breeds,
but the Merino lambs retained considerably more N than the Dohne Merino lambs. This
may also impact on the respective amino acid requirements of the lambs. Since the
Merino lambs utilise N more efficiently, they may have potentially lower essential amino
acid requirements to achieve a similar growth rate.
The WEB essential AA compositions of growing Merino and Dohne Merino lambs were
determined in the third study. Based on the ideal protein concept, the WEB essential AA
profile was accepted as representative of the AA requirements for growth. The use of a
single body part as a representation of the WEB AA profile was also evaluated.
Differences in the proportional weight and protein contribution of the three body
components (carcass, internal offal and external offal) of the two breeds strongly
suggested that the WEB AA composition of the breeds would differ, because of likely
differences in the AA profiles of these components. The essential AA profiles of the
carcasses from the two breeds were surprisingly similar. However, the essential AA
compositions of the internal offal and external offal differed substantially from each
other, as well as from the carcass. In addition, the internal offal and external offals of
each breed had characteristic essential AA profiles. Inevitably, the WEB essential AA
profiles of Merino and Dohne Merino lambs differed considerably. Only the leucine and
phenylalanine concentrations in the WEB`s of Merino and Dohne Merino lambs did not
differ. Significant differences in the concentrations of eight essential AA`s implied that
the two breeds have different AA requirements for growth. The different AA
compositions of the internal and external offal within each breed also illustrated that the
use of a single body component, like the carcass, as a predictor of WEB essential AA
composition contains considerable inaccuracies.
The essential AA index indicated that the duodenal protein, primarily derived from rumen
microbes, provided approximately 81 % of the qualitative AA requirements of growing
lambs. During periods of sufficient availability of very low-quality forage, as the diet in this study simulated, microbial protein is not able to support maximum growth. The first
two limiting AA`s (histidine and methionine) could not even support daily growth rates of
100 g/d. This is very low and stresses the need for effective undegradable AA
supplementation under these conditions.
Chemical scores identified histidine as the first limiting AA in high RDP diets
(predominantly microbial protein), followed by methionine, leucine, arginine and
phenylalanine. However, the requirements for histidine and arginine are frequently over
estimated and these AA`s should actually be considered semi-essential, which could
render methionine, leucine and phenylalanine the first three limiting AA`s to growing
lambs receiving high RDP diets. Because of the limitations of static measurement
systems for the determination of AA requirements, a more comprehensive evaluation
method was introduced for determination of the limiting AA`s in duodenal protein of
lambs on high RDP diets, in the fourth study.
The fourth study focused on the identification of limiting AA`s to growing lambs being
limit-fed a high RDP diet. The diet consisted primarily of soybean hulls, for its’ low
rumen UDP content. Microbial protein production was calculated as 13 % of total
digestible nutrient intake and complementary AA supplements prepared to simulate the
WEB AA profile, determined in the previous study, in the small intestine. To eliminate
the influence of the rumen on the AA supplements, the latter were infused into the
abomasums via flexible tubing. Each essential AA was in turn removed from the control
treatment (simulating the WEB composition) and the effect on N retention measured.
When methionine or the branched-chain amino acids (BCAA`s) were removed from the
infusate, N retention of the lambs was reduced. Consequently, methionine and at least
one of the BCAA`s limited growth performance of young lambs when microbial protein
was the predominant source of AA`s.
The concomitant increased plasma concentrations of total AA`s when methionine or the
BCAA`s were removed from the infusate corroborates the effects on N retention, since it
indicates that AA utilisation was reduced when these AA imbalances were introduced.
Amino acid imbalances had no effect on apparent DM, organic matter (OM) or NDF
digestion, but N digestibility was reduced. The final study verified whether the BCAA’s were co-limiting the growth of lambs, or if
any single BCAA was responsible for the limitation. Again the WEB AA profile of
growing lambs was simulated in the small intestine via abomasal infusions to lambs
receiving a soybean hull-based diet. Leucine, isoleucine and valine were individually or
simultaneously removed from the infusate and the impact on N retention measured. On
an individual basis valine had the largest negative impact on the efficiency of N
utilisation. However, the simultaneous removal of the BCAA`s resulted in the lowest N
retention, suggesting that valine might be limiting, but the three BCAA`s are more likely
to be co-limiting in diets to growing lambs where microbial protein is the primary source
of AA`s. Once again, neither DM, OM or NDF digestibility were affected by the AA
imbalances. Nitrogen digestibility was, however, negatively affected by AA imbalances.
This project succeeded in establishing the essential AA profile of duodenal protein in
sheep receiving high RDP diets. The WEB essential AA compositions of growing lambs
from two prominent sheep breeds in South Afica were then determined and the duodenal
essential AA profile evaluated against the calculated AA requirements. Finally, the AA`s
that limit growth in diets where microbial protein is the predominant source thereof were
identified. These results contribute to the current knowledge of AA requirements in
growing lambs, and highlight areas for future research, as discussed in the General
Conclusion.
|
13 |
Hodnocení průběhu porodu u bahnic plemene suffolk / Analysis of the Lambing Process in Suffolk EwesŠULCOVÁ, Veronika January 2015 (has links)
The Suffolk is the most well-known of the English lowland sheep breeds. A black-faced sheep with short-stapled wool, the breed is used primarily for meat production. The Suffolk is classified as one of the breeds with the best ability to fatten and its meat yield is approximately 60%. The breed is characterised by its good adaptability to different climate and breeding conditions and overall good health. The ewes are known for their high fertility rate, shorter oestrus cycle, excellent maternal instincts, and high milk production. As a result of these characteristics, the Suffolk has become a very popular breed around the world. This thesis focuses on the breeding of Suffolk sheep as one of the best breeds for the production of slaughter lambs. The thesis also looks at reproduction as a part of sheep breeding, as well as at the factors that have an effect on pregnancy, the birthing process, and the newborn lamb. The main objective of this thesis was to process the lambing data for a specific herd of Suffolk sheep, including performing an evaluation of the basic reproductive indicators, calculating the birth weight of lambs, and determining the ideal age for including ewes in the breeding herd. The basic reproductive indicators include fertility, fertilisation, breeding intensity, and weaned lamb production. In the studied herd of sheep, these indicators were calculated as follows: fertility 182%; fertilisation 91%; breeding intensity 155%; and weaned lamb production 159%. The average birth weight of the lambs was 3.9 kg and the average optimal age for inclusion in the breeding herd was determined to be 17.5 months.
|
14 |
Effects of Clearcutting on Forage Production, Quality and Decomposition in the Caatinga Woodland of Northeast Brazil: Implications to Goat and Sheep NutritionKirmse, Robert D. 01 May 1984 (has links)
Clearing of trees from the so-called caatinga woodland that characterizes the vegetation of the semi-arid region of northeast Brazil offers possibilities for increasing forage production. This research analyzed the first-year effects of clearing caatinga on dry season forage for goats and sheep. In addition, factors affecting litter decomposition on cleared and uncleared caatinga were assessed to evaluate the viability of deferring grazing of forages during the wet season for use later in the dry season.
Removing the trees resulted in a sixfold increase in production of herbaceous vegetation, however, 88 percent of the increased yield on the cleared areas was in the form of stems from herbaceous vegetation. Seventy-two percent of the stems were unpalatable to goats and sheep because of the massive size of those stems. Leaf litter from trees was an important component of the diets of goats and sheep during the dry season and clearing reduced production of this forage threefold.
Clearing resulted in increased decomposition of leaf litter. Changes in microclimate played only a minor role in this difference. The reduction in the amount of leaf litter from trees relative to litter from herbs had the greatest effect on decomposition rates of dry season forage because tree litter decomposed less rapidly than did herbaceous litter. The slow decomposition of leaf litter during the dry season suggests that deferment. of cleared or uncleared caatinga for use as forage in the latter part of the dry season is feasible.
An analysis of the diets of esophageally fistulated goats and sheep indicated that clearing may be a viable alternative for improving the amount and the in vitro dry matter digestibility of the forage consumed during the dry season the first-year post-treatment. These increases were attributed to an absolute greater abundance of preferred herbaceous forages (i.e., foliage and leaf litter) and to the persistent green foliage on coppicing woody plants. Dietary nitrogen appeared to limit intake, and clearing did not improve availability of this nutrient to sheep and goats at the higher levels of grazing pressure applied in this study. Other ecosystem considerations such as watershed protection and long-term community stability must also be considered in decisions to remove the tree canopy of the caatinga.
|
15 |
Short-term effects of mixed grazing by cattle and sheep in highland sourveld.Hardy, Mark Benedict. January 1994 (has links)
Data derived from a long-term grazing trial were used to
determine short-term effects of mixed grazing by cattle and sheep
in Highland Sourveld.
Five cattle to sheep ratio treatments (viz. 1 :0, 3:1, 1 :1, 1 :3,
0:1) were applied, each at three stocking rates (viz. 0.5 (low),
0.71 (medium) and 1.0 (high) animal unit equivalents (AUE) ha¯¹).
Ratios were expressed in terms of AUE cattle: AUE sheep. Stocking
rate and ratio treatments were balanced at the start of each
grazing season. Fourteen-month old Hereford steers and 'two-tooth'
Merino wethers were used as experimental animals.
The trial comprised two components, viz. an animal production
component and a simulated component. The animal production
component was conducted only in the medium stocking rate
treatment where the effect cattle to sheep ratio on the
performance of cattle and sheep was determined for each of four
grazing seasons (viz. 1989/90,
four-paddock rotational grazing
The low and high stocking rate
1990/91, 1991/92, 1992/93). A
management system was applied.
treatments were implemented by
simulating a four-paddock rotational grazing system and using a
single paddock for each stocking rate/ratio combination. Grazing
of the simulated treatments coincided with the grazing of a
specific 'test' paddock in each ratio of the medium stocking rate
treatment. These 'test' paddocks and the simulated treatment
paddocks were monitored to determine the impact of mixed grazing
by cattle and sheep on individual grass plants and the sward.
The whole of the experimental area was rested during the growing
season prior to the start of the trial and all paddocks were
burnt in the dormant season just before the start of the first
grazing season. The trial therefore commenced with a with a
uniform sward of immature herbage in all paddocks allocated to
each group of animals. ln the second and subsequent growing
seasons only those paddocks which had been rested in the previous season were burned prior to the onset of growth in early spring.
Rainfall for the first three grazing seasons was similar to the
long-term mean of 790mm whilst the last season was considered
'dry' with 554mm recorded during 1992/93.
In all grazing seasons, as the proportion of cattle in the
species mix increased, sheep performance increased. A decline in
sheep performance was recorded in each ratio treatment from the
first to the third season. This decline was attributed to the
increased maturity and thus lower quality of herbage on offer to
the sheep, and the fact that only one paddock available to the
animals in the second and third grazing seasons had been burned
prior to the start of the season. Sheep performed best during
the 'dry' season where herbage quality was maintained for longer
into the grazing season than in previous seasons. In contrast,
cattle performance was affected by the stocking rate (animals
ha¯¹) of cattle rather than the presence of sheep. As the
quantity of herbage on offer per steer declined steer performance
declined.
Animal performance data were also used to predict the effects of
adding cattle to a sheep production enterprise and vice versa.
The general trends were that the introduction of cattle into a
low stocking rate, sheep-only production enterprise would allow
for an increase in the stocking rate of sheep while maintaining
the performance of the sheep. In this way the carrying capacity
of a farm may be improved.
Stocki ng rate and ratio treatments varied from those established
at the start of each grazing season due to the differential
performance of the cattle and sheep in each treatment. As the
proportion of cattle in the species mix increased, stocking rate
increased and the ratio widened in favour of cattle. Stocking
rate (AUE ha¯¹), calculated a posteriori for each season, was the
major influence on the severity of grazing on individual plants
and within patches. As stocking rate of cattle and sheep at the
various ratios increased, the extent and severity of grazing increased. At stocking rates in excess of O.8AUE ha¯¹ however,
sheep-only grazing resulted in a greater proportion of plants,
per species and per area, being grazed more severely than was the
case for an equivalent stocking rate (AUE ha¯¹
) of cattle.
Furthermore, cattle and sheep had similar effects on patch size
distribution when stocked at the same number of AUE ha¯¹.
There were no measurable effects of stocking rate and ratio on
proportional species composition and basal cover over a two year
monitoring period. A technique for estimating basal cover in
tufted grasslands was developed and is presented as an appendix
to the thesis.
Data were also used to evaluate the use of AUE as an integral
part of the grazing capaci ty concept. Results indicated that
cattle and sheep cannot be equated in terms of AUE when referring
to the grazing impact. It is suggested that the definition of
grazing capacity should include the species of livestock and
assume a grazing management system appropriate to the grazing
habit of the animals concerned.
Resul ts of the trial provide strong indications that, in the
long-term, the current recommendations of grazing cattle together
with sheep in order to prevent the degradation or loss of veld
condition which occurs in sheep-only grazing systems, will not
succeed. A four-paddock rotation grazing system does not appear
to be an appropriate veld management system for sustainable sheep
production in sour grassveld. An alternative approach to veld
management is suggested in which the sheep are confined to only
those areas of the farm which were burnt at the start of the
grazing season. Ideally, sheep should not allocated to the same
paddock for two consecutive grazing seasons. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1994.
|
16 |
Getting into the guts of a salty problem : poor animal production from saltbush pastures is due to inefficient rumen fermentationMayberry, Dianne January 2009 (has links)
The main hypothesis tested in this thesis was that poor animal production from saltbush pastures is due to the negative effects of high sodium chloride (NaCl) and potassium chloride (KCl) on the ruminal environment, and subsequent effects on microbial populations and products of rumen fermentation. This main hypothesis was tested in two experiments. In the first experiment (Chapter Four) the effects of saltbush and a formulated high-salt diet on the ruminal environment and microbial populations were measured over 24-hours following feeding. Feeding both the saltbush and high-salt diet increased the salinity of the rumen fluid, but the formulated high-salt diet caused a decrease in ruminal pH while the saltbush caused an increase. This resulted in differences in the composition of the ruminal microbial populations between the sheep fed different diets. In the second experiment (Chapter Five) the effects of saltbush and a formulated highsalt diet on rumen fermentation were measured. Sheep fed saltbush had inefficient rumen fermentation and this was only partially explained by the high salt content of the diet. Diets containing high levels of NaCl and KCl provided low levels of net energy to sheep, but sheep fed saltbush lost more energy as methane and faecal energy compared to sheep fed the formulated high-salt diet. Inefficient rumen fermentation could help to explain poor animal production from saltbush pastures. Energy supplements such as barley grain can improve the value of saltbush pastures as feed for sheep, but there is no information on how much supplement is required. A third experiment (Chapter Six) was designed to test the hypothesis that there would be an optimal amount of barley required to improve the efficiency of rumen fermentation in sheep fed saltbush. Barley and straw were combined in a pellet and substituted for saltbush at 0, 20, 40, 60, 80 and 100% of the maintenance ration. Feeding barley and straw improved the efficiency of rumen fermentation in sheep fed saltbush, with an optimal level of supplementation at 60% of the maintenance diet. This is likely to be lower (approximately 20% of maintenance) if barley is fed without straw.
|
17 |
The effect of processing and supplementing millet stover with groundnut haulms and cereal brans on feed intake and growth performance of sheep.Abdou, Nourou. January 2010 (has links)
Feeding of animal has become increasingly a big challenge for smallholder farmers in the
dry season in most of Sahelian countries. Sheep has an important role in social and
economical activity of smallholder farmers. Millet stover (MS) and groundnut haulms (GH)
are the main crop residues used. Among concentrates, millet bran (MB) and wheat bran
(WB) are mostly used by smallholder farmers in feeding animals. However, these crop
residues and concentrates are used inadequately. MS is a poor quality roughage diet,
legume residues such as GH and brans are rich in nutritive value. The general objective of
this study was to develop a feeding technology transferable to smallholder farmers by
supplementing MS with GH, MB and WB to increase the growth performance of sheep
during the dry season.
The first study evaluated the effect of chopping millet stover (Pennisetum glaucum L. R.
Br.) in sheep feeding and the degradability in sacco of feeds. Two Holstein cows were used
to determine the degradability in sacco of feeds. The potential dry matter degradability
(g/kg) were 846, 809, 730, 410, 550 and 370 for millet bran (MB), wheat bran (WB),
groundnut haulms (GH), millet stover, leaves plus sheath and stems of MS respectively.
The potential nitrogen degradability (g/kg) of MB, WB and GH were 865, 908 and 817
respectively. The nitrogen content was 7.4, 15.1, 22.0 and 26.2 g/kg for MS, GH, millet
bran and wheat bran respectively. The effects of chopping millet stover (MS) on dry matter
intake in Oudah bicolor sheep were studied in Maradi, Niger. Four treatments were T0
(unchopped MS), T1 (MS chopped, 50 cm), T2 (MS chopped, 25 cm) and T3 (MS
chopped, 10 cm). A randomized block design was applied on 36 sheep, implying 9 sheep
per treatment (T0, T1, T2 and T3). The treatment T2 or 25 cm chopping size gave the best
MS intake of 560 g/day.
The second study evaluated the effects of supplementing millet stover (MS) with groundnut
haulms (GH), millet bran (MB) and wheat bran (WB). These supplements can improve the
feed value of MS and promote live weight gain of sheep in the dry season. The purpose of
this study was to develop a feeding technology transferable to smallholder farmers by
supplementing MS. The study was conducted in two successive phases. The phase 1 of 66
days, evaluated the effect of GH, MB and WB supplementations on MS intake and growth
performance of sheep, the phase 2 of 14 days, assessed the effect of GH, MB and WB
supplementations on intake and digestibility of MS. Six treatments were constituted,
namely, 1, 2, 3, 4, 5 and 6 formed by four levels of GH (0, 200, 400, 600g) and two others
(600g GH + 100g MB) and (600g GH + 75 g WB) respectively. A randomized block design
was applied on 36 Oudah bicolor sheep, implying 6 male lambs per treatment (1, 2, 3, 4, 5
and 6). The GH supplementation levels had a linear effect (P<0.001) on dry matter intake
(DMI) of MS, cell wall and nitrogen. Millet stover intake (MSI) decreased significantly
with increasing level of GH. However the total dry matter intake (TDMI) significantly
increased with GH levels. MB increased (P<0.05) both TDMI, TOMI and nitrogen intake
(NI), (P<0.001). WB increased MSI (P<0.05), TDMI and TOMI (P<0.01), NI (P<0.001)
and cell wall intakes. GH supplementation had both a linear and quadratic effect on DM
digestibility of MS, cell wall and nitrogen digestibility. GH had a linear and significant
effect (P<0.001) on live weight gain (LWG) and efficiency. The maximum average daily
gain (80.5 g/day) was obtained with treatment 6 followed by the treatment 5 (68 g/day).
The animals of treatment 1 received MS stover alone and lost their weight (-19.13 g/day).
It is concluded that groundnut haulms, millet bran and wheat bran had good nutritive value
whereas millet stover had low nutritive value. The 25 cm chopping size was the one to
propose to smallholder farmers. The supplementation of MS as the basal diet with GH and
brans enhanced sheep production through improvements in digestibility and intakes of
TDM, TOM, cell wall and nitrogen.
Key words: Millet stover; groundnut haulms; millet bran; wheat bran, chopping; intake;
degradability; growth performance; Oudah bicolor sheep. / Thesis (M.Sc.Agric.)-University of KwaZulu-Natal, Pietermaritzburg, 2010.
|
Page generated in 0.0857 seconds