Thesis (MScAgric)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Statistical analysis was conducted on data from two Elsenburg herds, containing 105 Jersey and 232 Holstein cows. The data was examined for external factors which may affect milk yield and milk composition. The data consisted of 337 first lactation records, taken over a 20 year time period. Breed of cow had an effect on milk yield, butterfat and protein production, as did the year in which the cows were born and the age of the heifer at first calving. There was a significant interaction between the breed and year of birth. There are other external factors, which are difficult to quantify, which may have an effect on production. In the following trials, eight ruminally cannulated dairy cows (four Jerseys and four Holsteins) were used to determine the effect of breed on forage digestibility in the rumen. All cows received a high concentrate mixed ration, with supplementary wheat straw. An in situ rumen degradability trial was conducted with three different forages, viz. lucerne, wheat straw and NaOH-treated wheat straw. The bags were incubated in the rumen for time intervals of 2,4, 8, 12, 16,20,24, 36,48, 72 and 96 hours and samples were analysed for dry matter (DM) and neutral-detergent fibre (NDF). Higher rumen degradability values (P<0.01) ofDM and NDF were observed in Jerseys for all three forages. Differences were more apparent for wheat straw and treated wheat straw than for lucerne. The rate of passage of digesta from the rumen was measured in both breeds by a chromium mordanted wheat straw marker. The Holsteins manifested a higher rate of passage (P<0.05) than the Jerseys, while daily feed intakes were also higher (P<O.Ol) for the Holsteins than for the Jerseys. Daily feed intake, expressed as percentage of body weight was, however, slightly higher for the Jerseys than for the Holsteins. The pH value of the rumen fluid was measured at 0, 4, 8, 10 and 12 hours postfeeding. The only significant difference (P<O.OI)in pH between the breeds was at 4 hours post-feeding, when the ruminal pH dropped more rapidly in the Holsteins than in the Jerseys. The pH in the Holsteins dropped below 6.2, which may have inhibited fibrolytic microbe activity in the rumen, resulting in a lower effective degradability of forages. Total volatile fatty acids were higher in Holsteins from four to 10 hours after feeding, but no differences were observed in acetic acid:propionic acid ratios. It was concluded that Jerseys appear to utilize forages more efficiently than Holsteins and that the differences are more apparent in low quality forages than in high quality forages. / AFRIKAANSE OPSOMMING: Statistiese analises is op data van twee kuddes te Elsenburg uitgevoer, bestaande uit 105 Jersey- en 232 Holsteinkoeie. Die data is ondersoek vir eksterne faktore wat melkproduksie en melksamestelling kan beinvloed. Die data het uit 337 eerste-laktasierekords bestaan, wat oor 'n periode van 20 jaar ingesamel is. Ras van die koei, sowel as die jaar van geboorte en ouderdom met eerste kalwing het 'n invloed op melkproduksie, bottervet- en proteienopbrengs gehad. 'n Betekenisvolle interaksie is tussen ras en jaar van geboorte waargeneem. Ander moeilik kwantifiseerbare faktore mag ook 'n invloed op melkproduksie he. In daaropvolgende proewe is agt rumen-gekannuleerde melkkoeie (vier Jerseys en vier Holsteins) gebruik om die invloed van ras op ruvoerverteerbaarheid in die rumen te bepaal. Al die koeie het 'n hoe-kragvoerdieet ontvang, aangevul met koringstrooi. 'n In situ rumendegradeerbaarheidstudie is met drie verskillende ruvoere, naamlik lusernhooi, koringstrooi en NaOH-behandelde koringstrooi uitgevoer. Die ruvoere is vir tye van 2, 4, 8, 12, 16, 20, 24, 36, 48, 72 en 96 ure in die rumen geinkubeer en monsters is ontleed vir droemateriaal (DM) en neutraal-bestande vesel (NDF). Hoer rumen-degradeerbaarheidswaardes (P<O.Ol) van DM en NDF is in Jerseys waargeneem as in Holsteins vir al drie ruvoere. Verskille was meer opvallend vir koringstrooi en NaOH-behandelde koringstrooi as vir lusem. Uitvloeitempo van digesta uit die rumen is in beide rasse met behulp van chroomgemerkte koringstrooi bepaal. Hoer uitvloeitempo's is in die Holsteins waargeneem as in die Jerseys, terwyl daaglikse voerinnames ook hoer was (P<O.05) by die Holsteins as by die Jerseys. Daaglikse voerinname, uitgedruk as persentasie van liggaamsmassa, was egter effens hoer (P<O.OI)by die Jerseys as by die Holsteins. Die pH van die rumenvloeistof is op 0, 4, 8, 10 en 12 ure na voeding gemeet. Die enigste betekenisvolle verskil (P<O.OI)in pH tussen die rasse het op 4 ure na voeding voorgekom toe die pH van die rumeninhoud vinniger in die Holsteins as in die Jerseys gedaal het. Die pH in die Holsteins het onder 6.2 gedaal, wat moontlik fibrolitiese mikrobe-aktiwiteit in die rumen kon inhibeer, met 'n gevolglike daling in effektiewe degradeerbaarheid van die ruvoere. Vanaf 10 ure na voeding was die totale vlugtige vetsuurkonsentrasies hoer in die Holsteins, maar geen verskille in asynsuur:propionsuurverhoudings is waargeneem nie. Die gevolgtrekking is gemaak dat Jerseys skynbaar meer doeltreffend is om ruvoere te benut as Holsteins en dat die verskil tussen rasse meer opvallend is vir lae kwaliteit ruvoere as vir hoe kwaliteit ruvoere.

Thesis (MScAgric)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: An experiment was conducted to determine whether the quality of lucerne hay could be improved by artificial drying in a forced air bulk dryer (FABD) in comparison to lucerne hay produced by natural drying in the field. Lucerne fields were divided into four blocks of equal size and blocks were randomly assigned to each of the two treatments (natural or artificial drying). Lucerne was harvested at an early to mid flowering stage on six occasions. In two blocks, cut lucerne was left in the field to dry. Material in the remaining two blocks were left in the field for an initial drying period of no longer than 24 hours, after which it was transferred to a FABD. Samples oflucerne were taken at the time of harvest and then at regular intervals (on average 0, 4, 8,22,26,29,47,50,53, 56, 58,69, 72, 76 and 80 hours after cutting) in the field and in the FABD until the material was dry enough for baling (ca. 15-18% moisture). Collected lucerne samples were dried in a forced draught oven until constant mass to determine moisture content. The rate of moisture loss was compared. Samples of the lucerne hay in the field and in the FABD were taken after baling to determine forage quality by means of chemical analysis. Samples were analysed for crude protein (CP), total digestible nutrients (TDN), digestible organic matter (DOM), acid detergent fibre (ADF) and neutral detergent fibre (NDF) content. Good weather conditions for natural drying during the trial period resulted in lucerne hay of similar chemical composition. Naturally dried lucerne hay had CP, ADF and NDF contents of 17.3, 41.2 and 48.0%, respectively, while values for artificially dried lucerne were 17.6, 40.6 and 47.3%. It was concluded that artificial drying of lucerne does probably not produce lucerne of a better quality than field drying under good weather conditions. In the following trials eight ruminally cannulated cows (four Jerseys and four Holsteins) were used to compare protein and fibre degradability of lucerne harvested at different stages of maturity (ie. 4, 5 and 6 weeks' regrowth), and of different lucerne products (ie. lucerne hay, lucerne leaves and 8% leaves added to hay), dried in a forced air bulk dryer. All cows received a total mixed lactation diet for the duration of the trial period. The first in situ rumen degradability trial was conducted with lucerne harvested at three stages of maturity namely after 4,5 and 6 weeks' regrowth. Bags were incubated in the rumen for time intervals of 0, 2, 4, 8, 16, 24, 48 and 72 hours. Samples were analysed for dry matter (DM), crude protein (CP) and neutral-detergent fibre (NDF) content. The effective DM, protein and NDF degradabilities of lucerne hay did not differ (P>0.05) between Holstein and Jersey cows. In Holsteins, DM degradability values calculated at an outflow rate of 0.05/h for lucerne harvested after 4, 5 and 6 weeks' regrowth were 63.1, 57.1 and 55.0%, respectively. Values of 64.6, 58.6 and 55.7% were obtained in Jerseys. CP degradability values for lucerne harvested after 4, 5 and 6 weeks' regrowth were 81.7, 77.2 and 77.6% in Holsteins and 81.3, 78.2 and 79.4% in Jerseys. NDF degradability values for lucerne harvested after 4, 5 and 6 weeks' regrowth were 35.8, 45.5 and 23.2% respectively in Holsteins and 35.1, 45.9 and 24.8% in Jerseys. Analysis of the effective DM, protein and NDF degradabilities across breeds indicated differences between lucerne harvested after 4, 5 and 6 weeks' regrowth. Rumen degradability of DM and protein was the highest for lucerne harvested after 4 weeks' regrowth. DM degradability values oflucerne harvested after 4,5 and 6 weeks' regrowth calculated at a flow rate of 0.05/h were 63.9, 57.9, 55.4%, respectively, while protein degradability values were 81.5, 77.7 and 78.5%. The lowest ruminal NDF degradability values were found for lucerne harvested after 6 weeks' regrowth. Values for NDF degradability calculated at a flow rate of 0.05/h for lucerne harvested after 4, 5 and 6 weeks' regrowth were 35.5, 45.7 and 23.7%, respectively. These results indicated that lucerne quality decreased in terms of DM, protein and NDF degradability as the plants mature. The second in situ rumen degradability trial was conducted with three different lucerne components dried in a forced air bulk dryer, namely lucerne hay, lucerne leaves and lucerne hay + 8% leaves. The procedure followed was the same as in the first in situ trial. Dacron bags, containing samples of the lucerne components were incubated in the rumen for time intervals of 0, 2, 4, 8, 16,24,48 and 72 hours. Samples were also analysed for DM, CP and NDF content and compared both between breeds and across breeds. DM and protein degradability values (rate and effective degradability) of the artificially dried lucerne hay were higher in Jerseys than in Holsteins. DM degradability values calculated for Holsteins at a flow rate of 0.05/h for lucerne hay, lucerne leaves and lucerne hay + 8% leaves were 57.6, 66.5 and 61.4%, respectively, while protein degradability values of 76.9, 75.5 and 77.9% were obtained. DM degradability values calculated for Jerseys were 62.9, 69.1 and 61.7%, respectively, while protein degradability values of 82.4, 77.6 and 78.5% were obtained. Analysis of the mean disappearance values across breeds indicated that protein degradability of lucerne hay in the rumen was higher than that of lucerne leaves. Protein degradability values calculated at a flow rate of 0.05/h for lucerne hay and lucerne leaves were 80.1 and 76.5% respectively. The NDF degradability of lucerne hay was, however, lower than what it was for lucerne leaves (24.6 vs. 29.7%). / AFRIKAANSE OPSOMMING: Studies omtrent die voedingswaarde van lusern vir melkkoeie. 'n Eksperiment is uitgevoer om te bepaal of die kwaliteit van lusernhooi verbeter kan word deur gebruik te maak van kunsmatige droging in plaas van die tradisionele landdroging. Lusernlande is in vier blokke verdeel en blokke is ewekansig aan elk van die twee behandelings (kunsmatige en landdroging) toegeken. Gesnyde materiaal in twee van die blokke is op die land gelaat vir die duur van die drogingsproses. Die materiaal in die oorblywende twee blokke is op die land gelaat vir 'n aanvanklike drogingsperiode van maksimum 24 uur, waarna dit in 'n massa-droogoond geplaas is. Lusernmonsters is net na sny op die land geneem en daarna met gereelde (gemiddeld 4,8,22,26,29,47,50, 53, 56, 58, 69, 72, 76 en 80 uur na sny) intervalle op die land en in die droër totdat die materiaal droog genoeg was om te baal. Lusernmonsters is in 'n droogoond gedroog totdat 'n konstante massa bereik is vir die bepaling van die voginhoud van die materiaal. Die tempo van vogverlies van die materiaal in die massadroër en op die land is bepaal. Monsters van die lusernhooi wat op die land en in die oond gedroog is, is na baal geneem en die chemiese samestelling van die lusernhooi is bepaal. Monsters is ontleed vir ruprotein- (RP), totale verteerbare voedingstof- (TVV), verteerbare organiese materiaal- (VOM), suur bestande vesel (SBV) en neutraal bestande vesel (NBV)-inhoud. Weersomstandighede was ideaal vir natuurlike droging van lusern en dit het aanleiding gegee daartoe dat die chemiese samestelling van die kunsmatig- en natuurlik gedroogde lusernhooi nie veel verskil het nie. Die RP, ADF en NDF inhoud van natuurlik gedroogde lusernhooi was 17.3,41.2 en 48.0% terwyl waardes van 17.6,40.6 en 47.3% vir kunsmatig gedroogde lusernhooi verkry is. Daar is bevind dat die kunsmatige droging van lusern nie 'n hoër kwaliteit hooi lewer as wat verkry kan word tydens landdroging wanneer weersomstandighede gunstig is nie. Hierna is twee degradeerbaarheidstudies gedoen. Agt koeie (vier Holsteins en vier Jerseys) met rumenkannulas, is gebruik om die proteïen- en veseldegradeerbaarheid van verskillende lusernkomponente te vergelyk. Lusern op verskillende groeistadia gesny, asook verskillende lusernprodukte wat kunsmatig gedroog is, is vergelyk. Al die koeie het gedurende die proeftydperk 'n hoë-konsentraat laktasierantsoen ontvang. Die eerste in situ degradeerbaarheidstudie is gedoen met lusern wat na 4-, 5- en 6 weke hergroei gesny is. Sakkies met lusernmonsters is in die rumen geplaas vir 0, 2, 4, 8, 16, 24,48 en 72 uur onderskeidelik. Monsters is na inkubasie in die rumen vir die DM-, RPen NBV -inhoud daarvan ontleed. Daar is bevind dat die DM-, proteïen en NBV degradeerbaarhede van lusernhooi nie verskil het (P.0>05) tussen Holstein- en Jerseykoeie nie. DM degradeerbaarhede wat by 'n deurvloeitempo van 0.05/h in Holsteinkoeie bereken is vir lusern wat na 4-,5- en 6 weke hergroei gesny is, was onderskeidelik 63.1, 57.1 en 55.0%. Die waardes wat vir Jerseys bereken is, was onderskeidelik 64.6,58.6 en 55.7%. Vir lusern wat na 4-,5- en 6 weke hergroei gesny is, was RP degradeerbaarhede 81.7, 77.2 en 77.6%, onderskeidelik, vir Holsteinkoeie en 81.3, 78.2 en 79.4%, onderskeidelik, vir Jerseys. NDFdegradeerbaarhede vir lusern wat na 4-,5- en 6 weke hergroei gesny is, was 35.8,45.5 en 23.2%, onderskeidelik, vir Holsteins en 35.1, 45.9 en 24.8%, onderskeidelik, vir Jerseys. 'n Vergelyking van die DM-, proteïen- en NBV-degradeerbaarhede wat gedoen is met die saamgevoegde data van al die diere, het daarop gedui dat verskille bestaan tussen die lusern wat na 4-, 5- en 6 weke hergroei gesny is. Die lusern wat na 4 weke hergroei gesny is, het die hoogste DM- en proteïendegradeerbaarheid in die rumen getoon. DMdegradeerbaarhede wat bereken is teen 'n deurvloei tempo van 0.05/h vir lusern wat na 4, 5- en 6 weke hergroei gesny is, was onderskeidelik 63.9,57.9 en 55.4% en proteindegradeerbaarhede was 81.5, 77.5 en 78.5%. Lusern wat na 6 weke hergroei gesny is het die laagste NDF-degradeerbaarheid gehad. Waardes wat bereken is teen 'n deurvloeitempo van 0.05/h vir lusern wat na 4-,5- en 6 weke hergroei gesny is, was onderskeidelik 35.5, 45.7 en 23.7%. Hierdie resultate dui daarop dat die kwaliteit van lusern afneem in terme van DM-, protein- en NBV-degradeerbaarhede namate die plante meer volwasse raak. Die tweede rumendegradeerbaarheidstudie is gedoen met 3 lusernprodukte wat in 'n massadroër gedroog is nl. lusernhooi, lusernblare en lusernhooi waarby 8% lusernblare gevoeg is. Dieselfde proefprosedure as tydens die eerste degradeerbaarheidstudie is gevolg. Sakkies met lusernmonsters, is in die rumen geplaas vir 0, 2, 4, 8, 16, 24, 48 en 72 uur. Monsters is ontleed vir DM-, proteïen- en NBV inhoud. Daar is gevind dat die proteïen degradeerbaarheid (tempo en effektiewe degradeerbaarheid) van kunsmatig gedroogde lusernhooi, hoër was by Jerseys as by Holsteins. DM degradeerbaarhede wat in Holsteinkoeie teen 'n deurvloeitempo van 0.05/h bereken is vir lusernhooi, lusernblare en lusernhooi + 8% blare, was 57.6, 66.5 en 61.4%, onderskeidelik, terwyl proteïen degradeerbaarhede 76.9, 75.5 en 77.9%, onderskeidelik, was. Vir Jerseys is DM-degradeerbaarhede van 62.9,69.1 en 61.7%, onderskeidlik, bereken terwyl proteïendegradeerbaarhede 82.4, 77.6 en 78.5% was. Gemiddelde verdwyningswaardes, wat bereken is deur data van al die diere saam te gebruik, dui daarop dat die proteïen degradeerbaarheid van lusernhooi in die rumen hoër was as in die geval van lusernblare. Die proteïen degradeerbaarhede wat bereken is teen 'n deurvloeitempo van 0.05/h, was 80.1 en 76.5%, onderskeidelik, vir lusernhooi en lusernblare. Die NBV -degradeerbaarheid van lusernhooi was egter laer as vir lusernblare (24.6 vs. 29.7%).

Thesis (MScAgric) -- University of Stellenbosch, 2002. / ENGLISH ABSTRACT: Experiment 1: Two studies were conducted to research the effect of divergent selection for multiple rearing ability on carcass weight, mutton production, meat quality and carcass characteristics of similar-aged Merino sheep. Data of 114 19-month-old Merino sheep, 40 ewes and 74 rams were used in this study. The study was done in two parts over 2 years. Only rams (52) were slaughtered over a two-week period in study A. Twenty-two rams and 40 ewes were slaughtered over a three-week period in study B. The sheep were descended from two selection lines that have been divergently selected for maternal multiple rearing ability since 1986. In brief, ewe and ram progeny of ewes rearing more than one lamb per joining (i.e. that reared twins at least once) were preferred as replacements in the high (H) line. Descendants of ewes that reared fewer than one lamb per joining (i.e. that were barren or lost all lambs born at least once) were preferred as replacements in the low (L) line. In study A the mean (±SE) slaughter weight of H line rams . were 12% heavier (P<O.OI) than that of L line contemporaries. A corresponding difference (P<O.OI) of 13% was found for carcass weight Adjustment for the higher live weight by analysis of covariance ofH line rams resulted in most of the line differences being eliminated (P>0.05). The difference between the weight of the loin retail cut remained significant (P<O.OI) in favour of the H line (1.64±0.04 vs. 1.37±0.08 kg, respectively). Skin weight (3.93±0.15 vs. 3.34±0.07 kg respectively; P<O.OI) and skin thickness (2.28±0.1l vs. 1.97±0.06 mm respectively; P<0.05) were greater in L line rams than in H line contemporaries. Rams in the L line also had heavier (P<0.05) trotters than the H line (l.05±0.03 vs. 0.96±0.02 kg respectively). In study B there were no interaction between line and sex and the data were pooled to present the main affects of sex and line. In study B the mean (±SE) slaughter weight of H line animals was 7% heavier (P=0.05) than that of L line contemporaries (44.02±0. 7 vs. 41.2±1.2 kg, respectively). A corresponding difference (P<0.05) of 11% was found for carcass weight between the two lines (pooled sexes) (l6.1±0.3 vs. 14.4±0.5 kg, respectively). There was no difference in the tenderness of the meat between the two selection lines but L line animals tended (P<0.16) to have more tender meat than H line contemporaries. Adjustment for the higher live weight of H line animals by analysis of covariance resulted in most of the line differences being eliminated (P>0.05). Hindquarter weight still remained significantly (P<O.OI) in favour of the H line after correction for live weight. Meat of L line animals was healthier based on their PUF A/SF A ratio. Experiment 2: This experiment was conducted to quantify the effect (noted in the first experiment) of selection for and against multiple rearing ability in Merino sheep on m. longissimus dorsi postmortem pH profiles. Data of 20 Merino sheep (10 rams and 10 ewes) were used. The sheep were slaughtered at a commercial abattoir. After slaughter pH was measured at 45 min, 2, 4, 8, 10, 12, 16, 20, 24, 33 and 48 h post slaughter, respectively. The pH was measured on the right side of each carcass in the m. longissimus dorsi between the 1st and the 6th lumbar vertebrae. The m. longissimus dorsi between the 1st and the 6th lumbar vertebrae of the left side was used for meat quality analysis. The initial pH of H line animals tended to be higher than that of L line contemporaries. At 48 h post-slaughter the pH of L line was higher (P<0.05) compared to that of H line animals. The meat of H line animals was tougher (99.79±3.58 vs. 88.32±3.38, P<0.05) than that of L line contemporaries, but there were no differences in the other meat quality characteristics. A higher initial pH (found in the first experiment, with a similar tendency in the second experiment) could indicate a lower susceptibility to stress in the H line. Experiment 3: An experiment was done to compare the meat-production potential between Merino and South African Mutton Merino (SAMM) ewes with increasing age. Slaughter data of . 653 Merino and SAMM ewes were used. Animals were slaughtered between 220 and 2719 days of age, which encompassed a range of slaughter weights from 27 to 100 kg. The ewes were differentiated according to age, 219 ewes being younger than 600 days and 416 being older than 600 days at slaughter. Young SAMM ewes had 10% heavier carcass weights than young Merino ewes and the difference was 47% between mature ewes. Mean maximum carcass weights of 33.44 and 22.65 kg were derived for the SAMM and Merino, at respective age of 2100 and 1900 days. SAMM ewes had a 47% thicker fat depth. Although Merinos were earlier maturing than the SAMM ewes, the latter breed had more subcutaneous fat at the mature stage. Experiment 4: The fourth experiment examined the effect of breed and sex on the carcass composition, yield of retail cuts, fat depth and chemical composition of meat from 35 South African Mutton Merino (SAMM) (17 rams and 18 ewes) and 61 Dormer (21 rams and 40 ewes) sheep. As there was no breed x sex interaction, the data were pooled to present the main effects of breed and sex. There were no differences in slaughter and carcass weight between Dormer and SAMM sheep. Dormers' had more fat (kidney, back fat depth) than SAMM sheep. The eye-muscle area of the Dormers' was 13% larger than that of the SAMM sheep. Rams were heavier (64.86±0.85 vs. 44.55±0.74 kg) than the ewes at slaughter. All the traits that were recorded, were heavier or higher in rams (P<0.05). After adjustment for higher live weight of the rams, the proportion of neck retail cut from the rams was higher than that from ewes and the proportion of hindquarter weight from the ewes was higher (P<0.05) than that from rams. After adjustment for the higher live weight of the rams, the moisture (75.35±0.37 and 73.35±0.37%) and lipid (2.68±0.33 and 3.80±0.33%) contents differed significantly (P<0.05) between the rams and ewes, respectively. With the significantly higher SFA value of the SAMM sheep and higher MUF A value of the Dormer sheep, meat from Dormer sheep could be regarded as healthier from a human prospective than that from SAMM sheep. Experiment 5: A study was done to test an ultrasound scanner (used on pigs) for the prediction of subcutaneous backfat and m. longissimus dorsi depth on Merino (52 rams), SA Mutton Merino (17 rams and 18 ewes) and Dormer (21 rams and 40 ewes) sheep. The sheep were scanned with an ultrasound scanner to predict the backfat and eye-muscle depth on the live animal. All animals were slaughtered to measure the true values of the fat depth and eye-muscle depth (25 and 45mm from the midline at the 13th rib). Overall regression equations over breeds (SAMM and Dormer, pooled breeds), and lines (H and L line Merinos, pooled lines) were obtained. Compared to previous research, the correlations between scanned values and true values were comparatively low (r = 0.07 - 0.25). Evidence from the literature suggested higher correlations of r = 0.53 - 0.56. Higher correlations could be achieved in older and fatter animals. The fact that the operator had no experience of scanning sheep could also have contributed to the low correlations. / AFRIKAANSE OPSOMMING: Eksperiment 1: Twee studies is gedoen om te kyk na die invloed van seleksie vir meerling grootmaakvermoe by Merino's op karkas-, vleiseienskappe en vleiskwaliteit is. Data van 114 19 maand oue Merino skaap, 40 ooie en 74 ramme is in die studie gebruik. Die studie is gedoen in twee dele oar 'n tydperk van twee jaar. Slegs ramme (52) is geslag oor 'n tydperk van twee weke in studie A. Twee en twintig ramme en 40 ooie is in studie B geslag oor 'n pericde van drie weke. Merino-ooie en -ramme afkomstig van 'n hoe (Il-lyn) en lae (L-lyn) lyn geselekteer vir rneerling grootmaakverrnoe is gebruik in 'n studie wat oor twee jaar uitgevoer is. Die twee lyne is intensief geselekteer vir en teen meerling grootmaakverrnoe vanaf 1986. Ram- en ooi-nageslag wat afkomstig is van ooie wat een of meer keer tweelinge in haar lewe per lam kans groot gemaak het is gebruik vir die H-lyn, terwyl ram en ooi nageslag afkomstig van ooie wat een of minder as een lam per lamkans groot gemaak het is gebruik vir die L-Iyn. In studie A is 52 rarnme (42 H-Iyn en 10 Llyn) geslag en slag- en karkaseienskappe is bestudeer. In ondersoek B is 22 ramme (16 l-l-lyn en 6 L-lyn) en 40 coie (34 H-Iyn en 7 L-Iyn) gebruik. Slag-, karkas- en vleiseienskappe is bestudeer. In ondersoek A is gevind dat die slagmassa van die Il-Iyn ramme 12% hcer en die karkasmassa 13% hcer is as die van die L-lyn ramme. Na kovariansie ontleding van die swaarder slagmassa van die H-Iyn diere, was die pote (1.05±0.03 vs. 0.96±0.02 kg; P<0.05) en velie swazrder (3.93±0.15 vs. 3.34±0.07 kg; P<O.Ol) en die velle dikker (2.28±0.11 vs. 1.97±0.06 mm; P<0.05) by L-Iyn diere as by H-lyn diere. Die groothandel lende snit van die H-Iyn diere was swaarder (1.64±0.04 vs. 1.37±0.08 kg; P<0.05) as die van L-Iyn diere. By studie B was daar geen interaksie tussen lyn en geslag nie, dus is die data verpoel om die betekenisvolheid van die hoofeffekte van lyn en geslag weer te gee. 'n Sewe persent hoer slagmassa is by H-Iyn diere waargeneem (44.02±0.7 vs. 41.20± 1.2 kg; P<0.05). 'n Ooreenstemmende verskil van (P<0.05) 11% is gevind in karkas massa tussen die twee lyne (16.1±0.3 vs. 14.4±0.5 kg). Daar was geen veskil in taaiheid van die vleis nie, maar diere van die H lyn se vleis het geneig (P<0.06) om taaier te wees. Na die kovariansie ontleding met massa as kovariant was die boude (P<O.OI) van die H-lyn diere en die lende (P<O.OI) groothandel snit van die ooie swaarder, verder was die verskille dieselfde as in ondersoek A Die vetsuurresultate toon dat net by die verhouding tussen die poli-onversadigde en vesadigde vetsure (PUF A/SF A) 'n verskil tussen die Iyne was. Die vetsuur resultate dui daarop dat die Llyn diere gesonder vleis vir menslike voeding het as die van die H Iyn diere. Eksperiment 2: In 'n tweede eksperiment is gekyk wat die invloed van seleksie vir meerling grootmaakvermoe by Merino skape op post mortem m. longissimus dorsi pH profiele is. Daar is gebruik gemaak van 20 Merino skape (10 ooie en 10 ramme), 10 H lyn en 10 Llyn diere. Die skape is geslag by 'n kornrnersiele abattoir. Die pH metings is geneem, 45 min, 2, 4, 6, 8, 10. 12, 16, 20, 24, 33 en 48 uur na slag. Die pH is geneem in die m. longissimus dorsi van die regter sy tussen die 1ste en 6de lumblale werwels. Die linker kant is gebruik vir vleiskwaliteits toetse Die pH lesing van H lyn diere wat 45 min na slagting geneem is het hoer geneig as in Llyn, terwyl pH lesings van die Llyn diere 48 h na slagting hoer was. Die vleis van die H lyn diere was taaier (99.79±3.58 vs. 88.32±3.38; P<0.05) as die van die Llyn diere, maar daar was geen verskille in die ander vleiskwaliteits toetse nie. Die hoe begin pH kan daarop dui dat die H lyn skape minder spanning voor slag ervaar he! Eksperiment 3: Die invloed van ouderdom op vleis produksie potensiaal, slag en karkasmassa en vetdikte by Suid Afrikaanse Vleis Merino (SAVM) en Merino ooie is ondersoek. Data van 635 Merino en SAVM ooie is gebruik. Die ooie was tussen 220 en 2719 dae oud met slagting en slagmassas wat gewissel het tussen 27 en 100 kg. Die ooie is opgedeel ten opsigte van ouderdorn. Die jong groep was ooie wat jonger as 600 dae oud was en die die res was bestempel as die ou groep. Die karkas massa van die jong SAVM ooie was 10% hcer as die van die Merino ooie en by die ou groep was die verskil 47% Ouer SAVM ooie het 52% dikker vet as die Merino ooie gehad. Merino ooie het 'n maksimum karkas massa van 22.65 kg op 'n ouderdom van 1900 dae gehad terwyl SAVM ooie 'n maksimum karkas massa van 33.44 kg op 'n ouderdom van 2100 dae gehad he! Al is die Merino 'n vroer ryp skaap as die SAVM, het die SAVM meer vet as volwasse dier. Eksperiment 4: In die experiment is gekyk na die effek van ras en geslag op slagmassa, karkasmassa, vleiseienskappe asook chemiese en vetsuur samestelling van die vleis van SAVM en Dormer skape. Slagdata van 61 Dormers' (21 ramme en 40 ooie) en 35 SAVM's (17 ramme en 18 ooie) is gebruik, Daar was geen interaksie tussen ras en geslag nie en dus is die data verpoel om die invloed van die hoof effekte (ras en geslag) te toets. Geen verskille is in die slagmassa tussen die Dormers en SAVM gevind nie. Die vet (onderhuids en niervet) van die Dormers was meer en die oogspier oppervlakte was 13% groter as die van SAVM skape. Ramme was swaarder (64.86±0.85 vs. 44.55±0.74 kg) as die ooie met slag. Na kovariansie ontleding van swaarder slagmassa van die ramme was die groothandel nek snit van die ramme swaarder (P<0.05) as die van die ooie en die boude van die ooie swaarder (P<O.Ol) in vergelyking met die van die ramme. Die voginhoud van vleis vanaf ramme was hoer (77.35±0.37 vs 75.35±0.37) as die van die coie. Ooie het 'n hcer persentasie vet in die vleis van die 11113de ribsnit gehad (2.68±0.33 vs. 3.80±0.33 %) Volgens die vetsuur analises het SAVM diere 'n hoer persentasie versadigde vetsure en die Dormers 'n groter persentasie mono-onversadigde vetsure gehad. Dit kan 'n aanduiding wees dat vleis vanaf Dormer skape gesonder is vir menslike gebruik. Eksperiment 5: Hierdie studie is gedoen om 'n ultraklank apparaat (gebruik by varke) te toets vir voorspelling van onderhuidse vet en oogspierdiepte by skape. Daar is gebruik gemaak van 52 Merino ramme (42 van die H-lyn en 10 van die Llyn), 61 Dormer skape (21 ramme en 40 ooie) en 35 SAVM skape (17 ramme en 18 ooie). Die vetdikte en oogspierdiepte op die lewende diere is bepaal met 'n ultraklank apparaat, waarna die diere geslag is en die werklike waardes direk op die koue karkas gemeet is. Regressie vergelykings is opgestel om korrelasies tussen ultraklank waardes en werklike waardes te kry. In hierdie proef was die korrelasies tussen geskatte en werklike waardes swak (r = 0.07-0.25). Beter korrelasies is egter weI deur ander navorsers gekry (r = 0.53- 0.56) Beter korrelasies kan in ouer en vetter diere verkry word. Die feit dat die operateur nie baie ondervinding met die skandering van skape gehad het nie kon bydrae tot die swak korrelasies.

Assignment (MPhil)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Many species of tilapia such as Oreochromis mossambicus are euryhaline, able to adapt to different salinity waters. Their ability to withstand high salinity levels has given rise to the possibility of using tilapia as baitfish for tuna line fishery. The purpose of the study was to determine the survival rate of tilapia O. mossambicus during direct transfer from freshwater to the salinity levels of 0, 15, 20, 22.5, 25, 27.5, 30, 32.5, and 35 ppt. The data was analysed through means of univariate ANOVAand regression analysis. O. mossambicus showed no mortality to all salinity regimes up to 25 ppt. Mortality was observed at 27.5 ppt, with 100% mortality at 35 ppt. LC 50 and LC 90 were found to be 30.5 and 34.2 ppt, respectively. The results indicate that tilapia (0. mossambicus) will survive a direct transfer to salinities up to 25 ppt. acclimation will be required in the event of transfer to salinity levels above 25 ppt, in order to prevent significant levels of mortalities. / AFRIKAANSE OPSOMMING: Meeste van die tilapia spesies soos Oreochremis mossambicus het die vermoë om by water van verskillende soutgehaltes aantepas. Dit is hierdie vermoë om hoë sout vlakke te weerstaan wat die moontlikheid vir gebruik as lewende aas in die tuna langlyn visvangbedryf moontlik maak. Die doel van hierdie studie was om die oorlewingsvlak van tilapia, O. mossambicus te bepaal by die oorplasing van varswater direk na soutwater by vlakke van 0, 15, 20, 22.5, 25, 27.5, 30, 32.5, en 35 dele per duisend. Die data is verwerk deur gebruik te maak van eenvariant ANOVAen regressie analises. O. mossambicus het geen mortaliteite tot gevolg gehad by al die oorplasings van vlakke tot en met 25 dele per duisend sout nie. Mortaliteite is wel gevind vanaf 27.5 dele per duisend, met 100 % mortaliteite by 35 dele per duisend. LC 50 en LC90 was gewees 30.5 en 34.2 dele per duisend onderskeidelik. Die resultate toon aan dat tilapia (0. mossambicus) sal oorleef by direkte oorplasing na soutwater by vlakke van tot en met 25 dele per duisend. Tilapia wat na hoër vlakke as 25 dele per duisend oorgeplaas wil word, sal eers geleidelik moet akklimatiseer om mortaliteite te beperk.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: The ostrich industry has overcome many challenges since it originated. However, it is still vulnerable to sudden changes in customer preferences and economic cycles. As feed costs are the greatest expense in ostrich production, optimising feed formulations is vital. This will be possible if the growth and development of the ostrich can be simulated by modelling software. Various studies were conducted to describe ostrich growth in the form of equations that can be used in modelling software to increase the accuracy of predictions. In the first study, birds were given the choice of four diets with varying energy (8.5 or 13.5 MJ ME/kg feed) and protein (180 or 120 g/kg feed) levels. The birds preferred the high density diet (high energy and protein) in each growth phase. A growth curve of assumed optimal growth was constructed. The chemical fractions of the body were shown to increase non-linearly with advancing age and equations were established to predict the change of the body composition over time. In the second trial, birds received a formulated growth diet and were fed according to their nutrient requirements. Growth data was collected on the separate body components of maturing birds. Feather and skin nodule growth was defined for birds hatched in the summer. Allometric equations were set up to determine, predict and model the ostrich skin size and skin weight, some bones, some organs and the commercially valuable muscles through the growth cycle. The final trial was conducted to determine the effect of diet density (energy and amino acid level) on the growth of ostrich body components. A four-stage, 3 x 5 (energy x protein) factorial design was developed with varying energy and protein feeding regimes. Protein (amino acid) level had no influence on body component growth. Energy level had no effect on feather growth, skin nodule growth, bone and organ growth and muscle growth. Increased levels of dietary energy increased the skin size and skin weight. Increasing the dietary energy level also had a significant effect on the total body fat of the birds. Allometric equations were set up for each variable to predict the effect of diet on ostrich growth. Results in this study provide a framework for simulation modelling. Predicting ostrich growth and development is paramount to accurate diet formulations and lower feeding costs. / AFRIKAANSE OPSOMMING: Die volstruisindustrie het reeds vele struikelblokke oorkom, maar bly steeds kwesbaar vir skielike veranderinge in die ekonomiese klimaat asook in die voorkeure van die verbruiker. Een van die belangrikste insetkostes in volstruisproduksie is voer en daarom is dit noodsaaklik om voerformulerings te optimiseer. Die doel van hierdie tesis was om by te dra tot die ontwikkeling van modellering sagteware wat die groei en ontwikkeling van die volstruis naboots. Die spesifieke doel was om volstruisgroei te bestudeer en te bespreek deur middel van vergelykings wat gebruik kan word om die akkuraatheid van die simulasiemodelle te verhoog. Tydens die eerste studie is die voëls die keuse van vier diëte gegee waarvan die energie- (8.5 of 13.5 MJ ME/kg voer) en proteïen- (180 of 120 g/kg voer) vlakke verskil het. Die voëls het in die hoëdigtheid voer (hoog in energie en proteïen) in elke groeifase gekies. Uit hierdie data, wat aanvaar is om optimale groei te verteenwoordig, is ‘n groeikurwe gekonstrueer wat getoon het dat die chemise komponente van die liggaam nie-linieêr toegeneem het oor tyd. Vergelykings is hieruit afgelei wat die verandering in die liggaamsamestelling oor tyd kan voorspel. In die tweede studie het die voëls ʼn vier-fase geformuleerde groeidieët ontvang en is na gelang van hulle voedings behoeftes gevoer. Groeidata is ingesamel van die individuele liggaams-komponente van die groeiende volstruise. Veer- en velgroei is gedefinieer vir die voëls wat in die somer uitgebroei het. Allometriese vergelykings is opgestel om te bepaal hoe die volstruis se velgrootte, velgewig, sekere bene en organe, asook die kommersiële belangrike spiere gedurende die groei-siklus verander. Die finale studie is uitgevoer om die effek van voedingsvlak (energie- en aminosuurvlak) op die groei van die volstruis se liggaamskomponente te bepaal. ʼn Vier-fase, 3 x 5 (energie x proteïen) faktoriale ontwerp is gebruik met veranderende energie- en proteïenvlakke. Proteïen- (aminosuur) vlakke het geen invloed op die groei van die liggaamskomponente gehad nie. Energievlak het geen effek op die veer-, vel-, velknoppie-, been-, organe- en spiergroei gehad nie. Toenemende vlakke van energie het wel gelei tot ʼn toename in die velgrootte en massa. Die toename in voedingsengergie-vlakke het ook ʼn betekenisvolle effek op die totale liggaamsvet van die voëls gehad. Allometriese vergelykings is opgestel vir elk van die veranderlikes om die effek van dieët op elke komponent van die volstruis te bepaal. Die resultate van hierdie studies verskaf ‘n raamwerk vir die simulering en modellering van die groei en ontwikkeling van die volstruis. Akkurate voorspellings van die groei en ontwikkeling van die volstruis is noodsaaklik vir akkurate dieëtformulering en verlaagde voedingskostes.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Two studies were done to determine the distribution rate and efficiency of dietary melamine (MEL) to poultry meat and eggs. The possibility of MEL distribution into meat and eggs after feeding cyromazine (CYR) was also investigated. Five separate diets were formulated for broiler and layer chickens containing graded levels of MEL. In the broiler trial (Experiment 1), a number of 480 day-old Cobb 500 broiler chickens were divided into five treatment groups. Diets contained 0 (CON), 50 (MEL50), 100 (MEL100), 500 (MEL500) mg/kg MEL or 4 mg/kg CYR (CYR4). The duration of the trial was 36 days and breast muscle, kidney and liver samples were harvested on Days 11, 13, 15, 18, 22, 29 and 36 after the start of the feeding and analyzed for MEL. For the duration of the trial, all experimental diets were presented ad libitum and feed intake, weight gain, mortality rate, feed conversion ratio (FCR), protein efficiency rate of birds and the European production efficiency rate were determined. In the layer trial (Experiment 2), 120 Hyline Silver hens (24 weeks of age) were randomly divided into five treatment groups. The treatment diets were the same as for Experiment 1. The duration of the trial was 20 days and layers received the treatment diets for the first 10 days after which the control diet was provided for another 10 days. Feed intake, mortality rate, egg production and egg weights were recorded daily, while live weight was recorded at the beginning and end of the trial. Dietary MEL levels of up to 500 mg/kg did not have any detrimental effect on production parameters for broilers. In the layer trial, feed intake and egg weights were negatively affected by the MEL500 treatment. Dietary MEL was absorbed by broilers and layers and rapidly distributed to the kidneys, livers, muscles and eggs. As the dietary MEL concentration increased from 50 and 100 mg/kg to 500 mg/kg, an increase (P < 0.01) was observed in muscle tissue and egg MEL residue concentrations. Melamine concentration for broilers peaked at 22 days of age and decreased until day of slaughter. The kidneys contained the highest MEL residue levels, compared to other organ tissues, such as muscle and liver. In layer hens, a MEL distribution plateau in eggs was reached between Days 1 and 4 and decreased from Day 7 to 10. The distribution of MEL in eggs was higher to albumin than to the yolk. Upon withdrawal, MEL concentration in these tissues declined to undetectable levels within seven days. No MEL could be detected in meat or eggs when birds received the CYR4 treatment. The distribution efficiency (DEf) of MEL to meat and eggs did not appear to be dose dependant. For meat, the DEf varied between 1.2 and 2.7% and for eggs it varied between 0.7 and 0.8%. / AFRIKAANSE OPSOMMING: Twee studies is uitgevoer om die verspreidings tempo en effektiwiteit van melamien (MEL) na hoender vleis en -eiers te bepaal. Die moontlikheid van MEL verspreiding na vleis en eiers deur die voeding van cyromazien (CYR) is ook ondersoek. Vyf aparte diëte is geformuleer vir braaikuikens en lê-henne wat verskillende MEL insluitings vlakke bevat het. Vir die braaikuiken proef (Eksperiment 1), is 480 dag oud Cobb 500 braaikuikens ingedeel in vyf behandelings groepe. Diëte het 0 (CON), 50 (MEL50), 100 (MEL100), 500 (MEL500) mg/kg MEL en 4 mg/kg CYR (CYR4) bevat. Die tydsduur van hierdie proef was 36 dae en bors-, spier-, nier- en lewer monsters is ingesamel op Dae 11, 13, 15, 18, 22, 29 en 36 wat geëvalueer is vir MEL. Tydens die verloop van die proef is alle eksperimentele diëte ad libitum gevoer en voerinname, massa toename, mortaliteit, voeromsettings verhouding, proteïen effektiwiteits tempo asook die Europese produksie effektiwiteits tempo is bepaal. Vir die lê-hen proef (Eksperiment 2), is 120 Hyline Silver henne (24 weke oud) ewekansig verdeel in vyf behandelings groepe. Die behandelings diëte het dieselfde MEL en CYR konsentrasies bevat as Eksperiment 1. Die tydsduur van hierdie proef was altesaam 20 dae waarvan henne behandelings diëte vir die eerste 10 dae ontvang het, waarna henne vir die daarop volgende 10 dae ‘n kontrole dieët wat 0 mg/kg MEL bevat gevoer is. Voerinname, mortaliteit, eier produksie en eier gewig is daagliks opgeteken, terwyl lewende massa aan die begin en einde van die proef gemeet is. Melamien dieët vlakke tot 500 mg/kg het geen negatiewe effek op braaikuiken produksie parameters gehad nie. Vir lê-henne, is slegs voerinname en eier gewig negatief beïnvloed vir MEL500. Melamien is na inname geabsorbeer deur braaikuikens en lê-henne en het vinnig versprei na die niere, lewer, spiere en eiers. Soos die MEL vlakke van die behandelings diëte toegeneem het van 50 en 100 mg/kg na 500 mg/kg, het ‘n beduidende (P < 0.01) toename in spierweefsel en eier MEL residu konsentrasies voorgekom. Melamien konsentrasies vir braaikuikens het gepiek op 22 dae en geleidelik afgeneem tot op dag 36. In lê-henne het ‘n MEL verspreidings platu in eiers plaasgevind tussen Dag 1 en 4 en geleidelik afgeneem tydens Dag 7 en 10. Die niere het die hoogste MEL residu vlakke bevat in vergelyking met die lewer- en spierweefsels. Die verspreiding van MEL in eiers was hoër na die albumien as na die dooier. Tydens onttrekking het die MEL konsentrasie vlakke in hierdie weefsels in so ‘n mate afgeneem dat dit onbespeurbaar was binne sewe dae. Geen MEL kon in vleis- en eiermonsters gemeet word vir CYR4 nie. Die verspreidings doeltreffendheid (DEf) van MEL na vleis en eiers was nie dosis afhanklik nie. Vir vleis het die DEf gevarieër tussen 1.2 en 2.7% en vir eiers tussen 0.7 en 0.8%.

Thesis (MScAgric) -- Stellenbosch University, 1984. / INTRODUCTION: This study was initiated by the various reports of improved animal performance resulting from supplementary feeding of grazing ruminants and in this respect, it may be regarded as a feasibility study of the ability of the natural pasture at the applied stocking rates, to supply the animal with its nutrient requirements, since before providing the animal with supplementary nutrients, it is necessary to identify those which may possibly limit animal production. The criti= cal test of such a limiting nutrient would be an improved animal performance, resulting from supplementation of the nutrient suspected as being limiting, under grazing conditions.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: This research study consists of three investigations with regard to ostrich (Struthio camelus var. domesticus) production, meat quality and the processing of ostrich meat into a value added meat product. The first study was conducted in order to establish whether the gradual replacement of soybean oilcake meal with cottonseed oilcake meal (CSOCM) as a protein source in the diet of slaughter ostriches would affect ostrich growth performance and meat quality. A total of 105 ostriches were divided into five feeding groups according to the CSOCM inclusion level: Control (0% CSOCM), 3%, 6%, 9% and 12% CSOCM, and fed with experimental diets from 6 to 13 months of age. As a result of feeding CSOCM, the final live weight and the average daily gain significantly increased in the 12% CSOCM group compared to the other treatment diets. The proximate composition, cholesterol content, mineral and fatty acid profile of the meat remained unaffected. Considering all the results, CSOCM may be used as an alternative protein source to soybean oilcake meal in ostrich nutrition, resulting in decreased feed costs. Secondly, a descriptive sensory analysis, together with chemical and physical measurements, was performed to determine whether the manipulation of the fatty acid composition in the fan fillet (Iliofibularis muscle) as a result of feeding CSOCM would be detected on a sensory level. Two levels of CSOCM were investigated; 0% as a control and 9% CSOCM. No significant differences were found for the physical measurements (cooking loss (%) and shear force) as well as for the pH and proximate composition of the raw fan fillet. The Control group presented a higher (P<0.05) mono-unsaturated fatty acid (MUFA) content in the cooked fan fillet whereas the 9% CSOCM group showed a favourable increased (P<0.05) poly-unsaturated fatty acid (PUFA) content when compared to the cooked Control samples. As a result, the poly-unsaturated:saturated fatty acid (PUFA:SFA) ratio in the 9% CSOCM group was also higher (P<0.05). No differences (P>0.05) were found between the treatments for the n-6:n-3 (omega 6 to omega 3) ratio. The 9% CSOCM group had a more intense beef aroma, had a higher level of initial and sustained juiciness as well as increased tenderness (P<0.05). Inclusion of 9% CSOCM resulted in a favourable cooked ostrich fan fillet. Finally, the effect of feeding CSOCM on a processed ostrich meat product was investigated. Fan fillet (Iliofibularis muscle) from 13 month old birds receiving no cottonseed oilcake meal (Control) or 9% cottonseed oilcake meal (9% CSOCM) was used. Olive oil was used as a replacement for pork fat, and warthog (Phacochoerus africanus) meat was used to replace commercial pork meat in the production of a semi dry sausage, cabanossi. Olive oil was included at three levels (0%, 1% and 2%). Six treatments were investigated: Control 0% olive oil, Control 1% olive oil, Control 2% olive oil, 9% CSOCM 1% olive oil, 9% CSOCM 2% olive oil en 9% CSOCM 2% olive oil. The Control and 9% CSOCM ostrich meat did not differ significantly in chemical composition nor fatty acid profile. After smoking and drying the fat content in the cabanossi containing 0%, 1% and 2% olive oil averaged 7.2%, 7.45% and 8.65% respectively. Processed meat products containing less than 10% fat are classified as a low-fat meat product. Olive oil is a mono-unsaturated vegetable oil containing mainly Oleic acid (C18:1n9c), and low quantities of saturated fatty acids and polyunsaturated fatty acids. Total mono unsaturated fatty acids in the cabanossi increased from 47.0% to 73.0% of total fat, whilst total saturated fatty acids and total polyunsaturated fatty acids decreased from 40.6% to 19.9% and 11.6% to 6.6% respectively as olive oil increased from 0% to 2%. The inclusion of olive oil at 2% resulted in cabanossi with increased (P<0.05) tenderness, juiciness and cured red meat colour, all factors that appeal greatly to the consumer. Overall flavour was not adversely affected by the inclusion of olive oil. This investigation indicated that the use of CSOCM had no negative effect on the production performance of ostriches whilst a 9% CSOCM inclusion level resulted in meat that was found to be favourable by a trained sensory panel. Furthermore, the use of CSOCM as a feed component also had no negative effect on a processed product (cabanossi) derived from the meat obtained from the birds fed this feed component. The CSOCM used in this investigation had low levels of gossypol (10 to 20ppm) and more research is required on the effect of the use of CSOCM with higher levels of gossypol on the production performance of ostriches. / AFRIKAANSE OPSOMMING: Die studie het bestaan uit drie ondersoeke met betrekking tot volstruis (Struthio camelus var. domesticus) -produksie, -vleiskwaliteit en die vervaardiging van waarde-toegevoegde geprosesseerde volstruis-vleisprodukte. Die doel van die eerste studie was om vas te stel of die geleidelike vervanging van sojaboonoliekoekmeel met katoensaad-oliekoekmeel (CSOCM) as ‘n proteïenbron in die voeding van volstruise, die groeipersentasie en vleiskwaliteit van die Iliofibiularis spier (fan fillet) sal affekteer. ‘n Totaal van 105 volstruise is verdeel in vyf voedingsgroepe volgens die katoensaad oliekoekmeel insluitingsvlak: Kontrole (0% CSOCM), 3%, 6%, 9% en 12% CSOCM. Die onderskeie voedingsgroepe was van ses tot 13 maande ouderdom op die eksperimentele voere geplaas. Die resultate het aangedui dat die voëls in die 12% CSOCM behandelingsgroep ‘n betekenisvolle (P<0.05) toename in finale lewende massa asook gemiddelde daaglikse toename gehad het. Die proksimale samestelling, cholesterol-inhoud, mineraal- en vetsuursamestelling van die vleis was nie geaffekteer deur die insluiting van CSOCM nie. Die CSOCM kan dus wel as ‘n alternatiewe proteïenbron in die voeding van volstruise gebruik word. Laasgenoemde bevinding kan ook lei tot verlaagde voerkostes, aangesien CSOCM heelwat goedkoper is as sojaboon-oliekoekmeel. Die tweede deel van die studie was van ‘n chemiese asook sensoriese aard. ‘n Beskrywende sensoriese analiese is uitgevoer om vas te stel of die manipulering van die vetsuursamestelling in die volstruis fan fillet as gevolg van die CSOCM sensories waargeneem kan word. Die chemiese en fisiese eienskappe van die vleis is ook ondersoek. Twee vlakke van CSOCM inhoud is ondersoek; 0% (as kontrole) en 9% CSOCM. Geen betekenisvolle verskille is gevind vir die fisiese vleiskwaliteit (kookverliespersentasie en taaiheid), asook vir die proksimale samestelling en pH van die fan fillet nie. Die gekookte fan fillet van die Kontrole behandeling het ‘n betekenisvolle (P<0.05) toename in mono-onversadigde vetsure (MUFA) getoon en die 9% CSOCM het ‘n voordelige toename in poli-onversadigde vetsuur-inhoud (PUFA) gehad. Die poli-onversadigde tot versadigde vetsuurverhouding (PUFA:SFA) was as ‘n gevolg ook betekenisvol hoër. Geen verskille (P>0.05) is opgemerk in die omega-6 tot omega-3 poli-onversadigde vetsuurverhouding (n-6:n-3) nie. Met betrekking tot die sensoriese eienskappe het die 9% CSOCM ‘n meer opvallende beesvleis aroma, hoër vlakke van aanvanklike sappigheid en ook sagter vleis in vergelyking met die kontrole behandeling gehad (P<0.05). Insluiting van 9% CSOCM het gelei tot ‘n gekookte volstruis fan fillet van voornemende kwaliteit. Laastens is daar ondersoek ingestel op die vervanging van varkvet met olyfolie in die vervaardiging van ‘n volstruis cabanossi. Chemiese asook sensoriese analises is uitgevoer op die gedroogde en gerookte volstruis cabanossi. Vir die vervaardiging van laasgenoemde produkte is die fan fillet van 13 maande oue voëls van die Kontrole (0% CSOCM) en 9% CSOCM behandelings gebruik. Addisioneel tot die volstruisvleis is daar ook vlakvarkvleis (Phacochoerus africanus) gebruik om die kommersiële varkvleis te vervang. Olyfolie was ingesluit teen drie vlakke (0%, 1% en 2% van die totale mengsel). Ses behandelings was ondersoek: Kontrole 0% olyfolie, Kontrole 1% olyfolie, Kontrole 2% olyfolie, 9% CSOCM 1% olyfolie, 9% CSOCM 2% olyfolie en 9% CSOCM 2% olyfolie. Daar was geen verskille (P>0.05) in die chemiese en vetsuursamestellings van die Kontrole en 9% CSOCM volstruisvleis nie. Na die droging en rooksiklus was die gemiddelde vet-inhoud van die 0%, 1% en 2% olyfolie cabanossi monsters onderskeidelik 7.2%, 7.45% en 8.65%. Geprosesseerde vleisprodukte met ‘n vet-inhoud van minder as 10% word in die kommersiële vleisindustrie na lae vet vleisprodukte verwys. Olyfolie is baie ryk aan MUFA, veral Oleïensuur (C18:1n9c) en dit bevat ook lae hoeveelhede SFA en PUFA. Die totale MUFA inhoud in die cabanossi het toegeneem van 47.0% tot 73.0% terwyl die totale SFA en PUFA onderskeidelik afgeneem het van 40.6% tot 19.9% en 11.6% tot 6.6%, met ‘n olyfolie toename van 0% tot 2%. Die insluiting van olyfolie teen 2% het gelei tot ‘n sagter cabanossi wat meer sappig was met ‘n meer opvallende rooi gekuurde vleiskleur, wat almal eienskappe is wat dié produk meer aantreklik maak vir die verbruiker. Hierdie studie het aangedui dat CSOCM geen negatiewe effek gehad het op die produksie van volstruise nie. Volstruisvleis van die behandelingsgroep wat CSOCM teen 9% van die dieet ontvang het, het wel vleis geproduseer wat as aanvaarbaar aanskou was deur ‘n opgeleide sensoriese paneel. Die gebruik van CSOCM as ‘n voerbestandeel het ook geen negatiewe effek gehad op ‘n geprosesseerde produk (cabanossi) gemaak van die volstruisvleis nie. Die CSOCM wat in die huidige studie gebruik is, het baie lae vlakke van gossypol (10 – 20dpm) gehad en verdere ondersoek is noodsaaklik om die effek van CSOCM met hoër vlakke van gossypol op die produksie van volstruise te bevestig.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Kikuyu over-sown with ryegrass is the most widely used pasture system in the Southern Cape of South Africa. During the winter months the kikuyu component remains dormant and cows are solely dependent on the ryegrass component of the pasture. Ryegrass has a low growth rate (25 - 30 kg DM ha-1 day-1) during the winter and early spring months (June - September), resulting in roughage shortages. There are various strategies that can be adopted to overcome these shortages. Most commonly, lucerne hay is bought in. The cost (R 1800 - R 2400 ton-1), however, is high and all farms do not have the capacity to store hay in large quantities. Significant wastages occur when feeding lucerne in ring feeders or feed troughs. Silage made of surplus grass, maize or cereal crops can also be fed. Many farms do not have the implements required for ensiling and due to financial pressure, most farms are at full capacity and as such no surplus pasture is available for ensiling. The purpose of this study was to determine whether a high fibre concentrate supplement and restricted pasture intake strategy could be followed to overcome roughage shortages during the winter months. Forty eight lactating Jersey cows were blocked according to 4 % fat corrected milk yield (19.1 ± 2.2 kg day-1 (±s.d.)), days in milk (104 ± 62.7) and lactation number (4.4 ± 1.8). Cows within blocks were then randomly allocated to one of the three treatments. Treatments were defined according to the amount of a high fibre concentrate supplement that was allocated as well as the level of pasture allocated: Treatment 1 - Low concentrate treatment (LC) received 4 kg concentrate cow-1 day-1 and 10 kg DM pasture cow-1 day-1; Treatment 2 - Medium concentrate treatment (MC) received 7 kg concentrate cow-1 day-1 and 7 kg DM pasture cow-1 day-1; Treatment 3 - High concentrate treatment (HC) received 10 kg concentrate cow-1 day-1 and 5 kg DM pasture cow-1 day-1. Eight ruminally cannulated Jersey cows were used in the rumen study portion of the trial. These cows were divided into two groups of four and were allocated to the MC and LC treatments. They were used in a cross-over design, where all cows were subjected to both treatments. The metabolisable energy, crude protein and neutral detergent fibre contents of the high fibre concentrate supplement was 10.9 MJ kg-1, 145 g kg-1 and 231 g kg-1, respectively. Cows of the three treatments grazed separately, allowing for the restriction of pasture intake according to treatments specifications. The average daily milk yield and milk fat content of treatments LC, MC and HC was 16.2a, 17.3ab and 18.1b kg day-1 (P < 0.05) and 4.91a, 4.96a and 4.58b % (P < 0.05), respectively. The average stocking rate for treatment LC, MC and HC was 5.07a, 6.07b and 7.64c cows ha-1 respectively. Thirty seven percent of pasture was saved on the HC treatment strategy compared to the LC treatment. Cows gained body weight during the study at a rate of 0.62a, 0.28b and 0.27b kg day-1 (P < 0.05) for the LC, MC and HC treatments, respectively. None of the hourly rumen pH values differed between treatments LC and HC. The rumen pH of cows on treatment LC did, however, spend a longer time below pH 6.0 and pH 5.8 compared to the rumen pH of cows on treatment HC (P < 0.05). The digestibility of dry matter and neutral detergent fibre of pasture of cows on treatment LC and treatment HC at 30 hours of incubation was 82.3 and 73.5 % (P < 0.05) and 43.5 and 39.2 % (P < 0.05), respectively. The results show that winter roughage shortages can be managed by feeding higher levels of a high fibre concentrate supplement and restricting pasture intake, although a decrease in milk fat content can be expected. / AFRIKAANSE OPSOMMING: Kikoejoe, oorgesaai met raaigras, is die mees algemene weidingstelsel in die Suid-Kaap van Suid-Afrika. Tydens die wintermaande is die kikoejoe-komponent dormant en diere is afhanklik van die raaigras-komponent. Raaigras het ‘n lae groeitempo (25 - 30 kg DM ha-1 dag-1) gedurende die winter- en vroeë lentemaande (Junie - September) en dit lei tot ruvoertekorte. Daar is verskeie strategieë wat toegepas kan word om die ruvoertekorte te oorkom. Die gewildste is die aankoop van lusern hooi, alhoewel die prys (R 1800 - R 2400 ton-1) die gebruik daarvan beperk. Boere het ook nie altyd die kapasiteit om groot hoeveelhede lusern te stoor nie en baie hooi word vermors as koeie dit uit hooivoerders en voerbakke vreet. Kuilvoer wat gemaak word van surplus weiding, mielies of graangewasse kan ook gebruik word. Baie boere het nie die implemente om kuilvoer te maak nie en as gevolg van finansiële druk, funksioneer die meeste plase reeds op vol kapasiteit en is daar dus nie altyd voldoende surplus ruvoer waarvan kuilvoer gemaak kan word nie. Die doel van hierdie studie was om te bepaal of ‘n hoë-vesel kragvoer en beperkte weiding-inname gebruik kan word om ruvoertekorte gedurende die wintermaande te oorkom. Agt-en-veertig lakterende Jerseykoeie is geblok volgens 4 % vet-gekorrigeerde melkopbrengs (19.1 ± 2.2 kg dag-1(±s.d.)), dae in melk (104 ± 62.7) en laktasie nommer (4.4 ± 1.8). Koeie binne blokke is vervolgens ewekansig aan een van drie behandelingsgroepe toegeken. Die groepe is gedefinieer volgens die hoeveelheid hoë-vesel kragvoer en weiding wat toegeken is: Behandelingsgroep 1 - Lae-vesel kragvoergroep (LC) het 4 kg kragvoer koei-1 dag-1 en 10 kg DM weiding koei-1 dag-1 ontvang; Behandelingsgroep 2 - Medium-vesel kragvoergroep (MC) het 7 kg kragvoer koei-1 dag-1 en 7 kg DM weiding koei-1 dag-1 ontvang; Behandelingsgroep 3 - Hoë-vesel kragvoergroep (HC) het 10 kg kragvoer koei-1 dag-1 en 5 kg DM weiding koei-1 dag-1 ontvang. Agt rumen gekanuleerde Jerseykoeie was gebruik in die rumen studie gedeelte van die proef. Die koeie was verdeel in twee groepe wat dan aan die LC en HC behandelings groepe toegeken is in ’n omslag ontwerp met twee behandelings en twee periodes. Die metaboliseerbare energie, ruproteïen en neutraal bestande veselinhoud van die hoë-vesel kragvoer was 10.9 MJ kg-1, 145 g kg-1 en 231 g kg-1 onderskeidelik. Die drie behandelingsgroepe het apart gewei, sodat weidingtoekenning beperk kon word en weidinginname bepaal kon word. Die gemiddelde daaglikse melkopbrengs en melk vet % van behandelingsgroepe LC, MC en HC was 16.2a, 17.3ab en 18.1b kg dag-1 (P < 0.05) en 4.92a, 4.96a en 4.58b% (P < 0.05) onderskeidelik. Die gemiddelde veelading van behandelingsgroepe LC, MC en HC was 5.07, 6.07 en 7.64 koeie ha-1 onderskeidelik. Volgens die strategie van die HC behandelingsgroep strategie is sewe-en-dertig persent weiding bespaar, in vergelyking met die LC behandelingsgroep. Koeie in behandelingsgroepe LC, MC en HC het in massa toegeneem gedurende die studie teen ‘n tempo van 0.62, 0.28 en 0.27 kg day-1 (P < 0.05), onderskeidelik. Rumen pH-waardes het nie tussen behandelingsgroepe LC en HC verskil nie. Behandelingsgroep LC se rumen pH was vir ’n langer periode onder pH 6.0 en pH 5.8 as in die geval van behandeling HC. Die verteerbaarheid van droëmateriaal en neutraalbestande vesel van wieding van koeieop behandelingsgroepe LC en HC na 30 ure van inkubasie was 82.3 en 73.5 % (P < 0.05) en 43.5 en 39.2 % (P < 0.05), onderskeidelik. Die resultate dui daarop dat winter ruvoertekorte bestuur kan word deur die voeding van hoër vlakke hoë-vesel kragvoer en die beperking van weidinginname, hoewel ‘n afname in melk vet % verwag kan word.

Thesis (MScAgric)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: In many parts of the world, soil is depleted of selenium (Se), leading to selenium-poor plants, animals and, therefore, humans. It was recognised that a study to examine the functionality of new products on the market to address this problem was required. The purpose of this research were threefold: to compare the effects of sodium selenite (NaSe) and organically bound selenium sources on small ruminant performance, to investigate the bioavailability of these Se sources, and analyse their influence on carcass characteristics, meat quality and antioxidant capabilities. Fourty growing Döhne Merino wethers from the Southern Cape region, a selenium-deficient area, were used for the study. The animals were all fed the same basal diet in the adaptation period and were then allocated to one of four treatment groups: Control (CT), inorganic selenium (IS), organically bound Se A (OSA) or B: (OSB). The period of supplementation was 90 days. This first study assessed the effect of the different Se sources on growth and Se bioavailability in the wethers. The wethers and the feed they consumed were regularly weighed to determine their growth and feed conversion rate (FCR) in the trial period. To gauge their Se level, blood samples were collected via jugular venipuncture at monthly intervals. The wool around the jugular was shorn and samples were collected on day 0 and day 90 for comparative Se level analysis. Liver, skeletal muscle and kidney samples were collected at day 90, directly after slaughter, to determine the Se level in these tissues. No effect could be reported in the growth and FCR of the wethers between the supplementation groups. For whole blood Se levels there was an effect in the early part of the study, with a greater increase in Se levels for the organically bound Se groups, but in the end no effect on whole blood levels could be seen between the different Se treatments. Neither could any difference between the inorganic Se and organic bound Se treatments be found in the liver – however, the total Se concentration of the wool, kidney and meat samples was greater in those animals offered organically bound Se when compared with those receiving a comparable dose of inorganic Se. The second study evaluated the antioxidant capabilities of the different Se supplements in the wethers. Blood samples were taken monthly for plasma collection to test for Glutathione peroxidase (GSH-Px) activity and total antioxidative capacity (TAC) with the oxygen radical absorbance capacity (ORAC) assay. Liver, skeletal muscle and kidney samples were collected at day 90, immediately after slaughter and measured for GSH-Px activity. With TAC, there was a significant effect for the treatment period between day 0 and day 90, however the treatments did not show any significant difference. No significant differences could be established between the different Se treatments for the GSH-Px analysis in any of the tissues. For the mean plasma values of the treatments no significant differences can be reported, but a significant difference was observed at day 30 in the contrast between the organically bound Se and the other treatment groups. The third study was to evaluate the quality and lipid oxidation of muscle from those wethers supplemented with different Se sources. Skeletal muscle samples were collected at day 90, directly after slaughter to determine this. No differences in the meat quality of the wethers could be detected between Se sources after the 90-day supplementation period. Lipid oxidation was measured by determining TBA reactive substances (TBARS) and once again no differences could be detected. Based on the results found in this investigation, it may be inferred that organically bound Se (OSA & OSB) supplementation will hold a number of advantages for small ruminants over inorganic Se supplementation. Animals fed the organically bound Se had reached adequate Se levels sooner on the organically bounded treatments than the inorganically bounded treated animals. The greater bioavailability of organically bounded Se over inorganic Se was proven by the increased Se levels in certain tissues and organs. Additionally, only the organically bounded Se could find a pathway to the wool, confirming that it was carried in an organic form (probably selenomethionine) in the body. Organically bound Se will therefore have a positive impact on small ruminant health and production, which will result in an indirect advantage for consumer health. / AFRIKAANSE OPSOMMING: Die grond in groot dele van die wêreld word selenium-arm en dit lei na selenium-arm plante, diere en mense. Dit is waargeneem dat ‘n studie wat kyk na die funksionaliteit van nuwe produkte op die mark om die probleem aan te spreek nodig is. Die doelwit van die studie was om verskillende selenium (Se) bronne te vergelyk en die uitwerking daarvan op klein herkouer prestasie te evalueer. Daar is gekyk na die biobeskikbaarheid, invloed daarvan op die karkas eienskappe en antioksidant vermoëns van die verskillende Se bronne. Veertig groeiende Dohne Merino-hamels van die Suid-Kaap-streek, 'n Se arm gebied is gebruik vir die studie. Die diere is almal dieselfde basale dieet gevoer in die aanpassing periode en dan toegeken aan een van vier behandelings: kontrole (CT), anorganiese Se (IS), organies gebinde Se A (OSA) of B: (OSB). Die tydperk van die aanvulling was 90 dae. In die eerste studie is gekyk na die effek van die verskillende bronne van Se op die groei en die biobeskikbaarheid daarvan aan die hamels. Die hamels en voer verbruik, is gereeld geweeg sodat hul groei en voer omset verhouding (VOV) in die proef tydperk te bepaal. Bloedmonsters is versamel deur middel van die jugulêre venipuncture vir die Se vlak bepaling daarvan. Lewer, skeletspier en nier monsters is versamel op dag 90, direk na die slagting vir die Se vlak bepaling. Die wol rondom die nekslagaar is geskeer en monsters is versamel op dag 0 en 90 vir Se vlak analise. Geen effek kan gerapporteer word vir die groei en VOV van die hamels tydens die aanvullings periode nie. Vir die bloed Se vlakke was daar 'n uitwerking in die vroeë deel van die studie, met 'n vinniger toename in Se vlakke vir die organies gebinde Se groepe, maar aan die einde kon geen effek gesien word tussen die verskillende Se behandelings nie. Geen verskil tussen die NaSe en organiese gebonde Se behandelings kon gevind word in die lewer nie. Die totale Se konsentrasie van die wol-, nier-en vleis