Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The aim of this study was to investigate the effect of feedlot production on the growth and carcass characteristics, as well as the distribution of the main tissues (muscle, fat and bone) and meat quality of Merino, South African Mutton Merino (SAMM) and Dorper lambs. The Merino and SAMM 2008 outperformed (P<0.05) the 2007 SAMM and both Dorper production groups in terms of average daily gain, while the Merino and both SAMM production groups achieved the best feed conversion ratio (P<0.05). The highest percentage A2 graded carcasses was achieved after 42 days under feedlot conditions by the Merino and both Dorper production groups, but it took only 21 days in the feedlot for the SAMM lambs to achieve the same result. Slaughter weight, carcass weight and dressing percentage all increased significantly with an increase in the number of days under feedlot conditions for all three breeds, while a decrease in the percentage head, trotters and red offal was also documented. The fatter retail cuts (thick rib, flank, prime rib and loin) increased (P<0.05) in percentage with an increase in the number of days under feedlot conditions. A significant decrease in the percentage leaner retail cuts (raised shoulder and hind-quarters) was found when the amount of days under feedlot conditions increased. The highest profit is obtained by the prime rib, loin and hind-quarters in a lamb carcass. For the Merino and Dorper lambs these three cuts, or a combination of the three showed the highest combined percentages after 42 and 63 days under feedlot conditions, respectively. The late maturing SAMM lambs achieved the highest percentages for these three cuts after 63 and 84 days under feedlot conditions in 2007 and 2008 respectively. Visceral and renal fat deposition increased throughout the production period for all breeds. The Dorper lambs attained the highest subcutaneous fat depth, and also produced the heaviest, but fattest carcasses. For A2-graded carcasses, Dorper lambs had the highest dressing percentage and lowest subcutaneous fat depth, followed by the SAMM and then Merino breed. A decrease in the percentage muscle and bone was found with an increase in the number of days under feedlot conditions, whilst an increase in the percentage fat was found under the same conditions. Meat quality was mostly affected by the 48h post mortem pH. This pH value is affected by the cooling rate of the carcasses, which in turn is affected by the level of carcass fatness. Carcass fatness increased with an increase in the number of days under feedlot conditions, resulting in a low 48h post mortem pH. A low 48h post mortem pH is accompanied by higher percentages of cooking and drip loss, as well as a high a*-colour reading for all three breeds. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die effek van voerkraalproduksie op die groeivermoë, karkaseienskappe, verspreiding van spier, been en vet, en vleiskwaliteit van Merino, Suid-Afrikaanse Vleismerino (SAVM) en Dorperlammers te bepaal. Die Merino en SAVM 2008 produksiegroepe het hoër (P<0.05) gemiddelde daaglikse toenames getoon as die SAVM 2007 en beide Dorper groepe, terwyl die Merino en beide SAVM produksiegroepe die beste voeromset verhoudings bereik het (P<0.05). Die hoogste persentasie A2 gegradeerde karkasse is na 42 dae in die voerkraal deur die Merino en beide Dorper produksiegroepe geproduseer, terwyl dit slegs 21 dae onder dieselfde toestande vir die SAVM groepe geneem het om dieselfde resultaat te lewer. Daar is ‘n betekenisvolle verhoging in slagmassa, karkasmassa en uitslagpersentasie vir al drie die rasse gevind met ‘n toename in die aantal dae in die voerkraal, terwyl ‘n afname in die persentasie kop, pote en haarslag gevind was. Die persentasie vetter groothandelsnitte (dikrib, dunrib, ribtjop en lendesnit) het toegeneem (P<0.05) met ‘n toename in die aantal dae in die voerkraal. ‘n Betekenisvolle afname in die persentasie van die maerder groothandelsnitte (blad en boude) is gevind met ‘n toename in die aantal produksie dae in die voerkraal. Die hoogste inkomste van ‘n lamkarkas is afkomstige van die ribtjop, lende snit en boude. ‘n Kombinasie van hierdie drie snitte was die hoogste vir die lammers van die Merino en beide Dorper groepe na 42 en 63 dae in die voerkraal onderskeidelik. Die laat volwasse SAVM lammers het die hoogste persentasie van hierdie drie snitte bereik na 63 en 84 dae in die voerkraal vir die SAVM 2007 en SAVM 2008 onderskeidelik. Die neerlegging van pensvet en niervet het voortdurend toegeneem deur die produksieperiode vir al drie rasse. Die Dorperlammers het die hoogste onderhuidse vetneerlegging getoon, maar het ook die swaarste en vetste karkasse geproduseer. Dorperlammers het die hoogste uitslagpersentasie en laagste onderhuidse vetneerlegging vir A2 gegradeerde karkasse gehad, gevolg deur die SAVM en Merino. ‘n Afname in die persentasie spier en been in karkasse is waargeneem namate die lammers langer in die voerkraal was, terwyl ‘n toename in die persentasie vet onder dieselfde omstandighede waargeneem is. Die 48h post mortem karkas pH affekteer die meeste vleiskwaliteit eienskappe. Hierdie pH waarde word weer deur die tempo van karkasafkoeling beϊnvloed, wat op sy beurt deur die vetheidsgraad van die karkas bepaal word. Die vetheid van karkasse het toegeneem met ‘n toename in die aantal dae in die voerkraal, wat ‘n lae pH waarde 48h post mortem tot gevolg gehad het. ‘n Lae 48h post mortem pH waarde het gelei tot hoër persentasies kook- en dripverliese en hoë a* kleurlesings vir al drie rasse.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: A total of 32 cattle were divided into four groups of eight each (A1-8, A9-16, A17-24, B1-B8) to be slaughtered on different days over a period of 45 days. All the cattle in Groups A were of Bonsmara type and those in Group B were of Charolais type. Three treatments, Tenderstretch (TS), Tendercut (TC) and Hock suspension (HS) were randomly allocated to each of the 48 sides from group A. Only two treatments (TC and HS) were implemented on the carcass sides in Group B alternating between the right and left sides. Two muscles from each side namely Gluteus medius and Longissimus dorsi were evaluated for purge, cooking loss, shear force and sarcomere length after 2, 4, 6, 10 and 14 days of aging. Paired t-Tests were performed for each pair of treatments and each day separately, on all variables accessed (Snedecor, 1980). The differences in purge and cooking loss between treatments were all found to be inconclusive for each day of aging. Although purge had significant differences between the treatments TC and TS for the GM and LD muscle after 14 days of aging (P = 0.0341 and P = 0.0348 respectively) these were found to be open to doubt as the treatment that delivers the most purge differs between muscles and that the two treatments delivered no differences compared to its HS values. Aging had a significant effect on purge as it doubles after 14 days of aging. Cooking loss values only differed significantly on day 2 for the LD muscle between treatments TC and HS. The differences in shear force were all smaller than 0.3205 kg/ 1.27cm and not consistent over all carcasses. A mean positive improvement in tenderness was calculated from high difference in mean values from some carcasses although some carcasses showed a decrease in tenderness when using TS and TC, which suggests that the treatments are of no relevance towards the industry. Although the differences in shear force become smaller as aging commences, it is not constant, a phenomenon most probably due to the variance between animals. Aging again had the most significant effect (P<.0001) on shear force. Correlations between sarcomere lengths and shear force were low for all the treatments on the GM muscle (HS = -0.453; TC = -0.401 and TS = -0.2) but in the LD muscle the TS method showed a higher correlation (TS = -0.665) than the other treatments (HS = 0.059 and TC = 0.059). / AFRIKAANSE OPSOMMING: `n Totaal van 32 beeste was opgedeel in vier groepe van agt elk (A1-8, A9-16, A17-24, B1-B8) wat geslag is op verskillende dae oor n periode van 45 dae. Beeste van die A groep was almal Bonsmara tipe en die van die B groep charolais tipe. Drie behandelings naamlik Tenderstretch (TS), Tendercut (TC) en Hak suspensie (HS) was ewekansig tot die 48 sye van die karkasse van groep A toegedeel. Groep B se 16 sye is net met TC en HS ewekansig tot die linker en regter sy toegedeel. Twee spiere naamlik Gluteus medius en Longissimus dorsi was geevalueer vir drup verlies, kook verlies, sarkomeer lengte en taaihied na 2, 4, 6, 10 en 14 dae se veroudering. Gepaarde t – toetse is gedoen vir elke paar behandelings vir elke dag van veroudering op al die veranderlikes genoem. Die verskil in drup verlies en kook verlies tussen behandelings was as nie betekeinisvol bestempel. Behalwe vir die feit dat drup verlies betekenisvolle verskille getoon het tussen die behandelings TC en TS vir die GM (P = 0.0341) en die LD (P = 0.0348) spiere na 14 dae se veroudering was dit bevind as nie betekenisvol juis oor dat die twee behandelings teenoor hul HS waardes geen verskille getoon het nie. Veroudering van die vleis het wel die grootste betekenisvolle verskil in drupverlies gemaak waar dit amper verdubbel soos die vleis verouder vir 14 dae. Kookverlies het net op dag twee n betekenisvolle verskil getoon in die LD spier vir die HS – TC kombinasie. Die verskil in taaiheid was almal kleiner as 0.3205 kg/ 1.27cm en nie kostant vir alle karkasse nie. n’ Positiewe gemiddelde verbetering in sagtheid is verkry deur die kalkulasie van hoë positiewe waardes en lae negatiewe waardes vir sommmige karkasse wat n laer sagtheid getoon het wanneer TS en TC gebruik is. Hierdie onkonsekwente verbeterings in sagtheid maak dat hierdie behandelings van min praktiese nut vir die bedryf is. Alhoewel hierdie verskille tussen behandelings kleiner raak tydens veroudering, is dit nie konstant nie, wat as gevolg van die variasies tussen diere kan wees. Veroudering het weereens die mees betekenisvolle effek op die vleis getoon (P< 0.001). Die korrelasie tussen sarkomeer lengte en WBSF taaiheid was laag vir alle behandelings in die GM spier (HS = -0.453; TC = -0.401 en TS = -0.2) behalwe vir die LD spier waar die TS behandeling n hoer korrelasie van TS = -0.665 as die ander twee behandelings (HS = 0.059 en TC = 0.059) opgelewer het.

Thesis (MScAgric)--University of Stellenbosch, 2002. / ENGLISH ABSTRACT: An experiment was conducted to determine the effect of the frequency of supplementary feeding on the production of South African Mutton Merino (SAMM) ewes grazing wheat stubble. One hundred and sixty ewes were randomly divided into two groups that consisted of four groups each. Eight camps were grazed for 138 days during which lambing occurred. Four groups of 25 ewes each grazed a 17 ha camp at a stocking density of 5.8 ewes/ha and four groups of 15 ewes each grazed a 12 ha camp at a stocking density of 5.0 ewes/ha. A combination energy/protein supplement was made available to the ewes as a lick. Two of the groups received no supplementary feed (control), two groups received 200 g/ewe/day, two groups received 400 g/ewe every second day and two groups received 600 g/ewe every third day. The smallest decrease in weight during the feeding period was observed in the ewe group that received supplementation every day as well as the ewe group that received supplementation every second day, but no significant differences were observed between these two groups. The smallest decrease in weight over the total feeding period was observed in the three ewe groups that received supplementation (P < 0.1), while the ewes that received none (control groups) lost the most weight during the same period. All supplemented groups performed significantly better than the unsupplemented control group in terms of the liveweight change over the feeding as well as the total period. No significant differences occurred in the lambing percentage, weaning percentage, birthweight, 42-day weight and survival rate of the lambs due to the different feeding regimes. It was concluded that supplementation to ewes every third day or every second day is an economically feasible option and will reduce labour and transport costs. In the second study the effect of stocking density on canola stubble composition and subsequently the production of SAMM ewes on this type of stubble was investigated. Forty-eight ewes were randomly divided into four groups that grazed canola stubble at a stocking density of approximately 1.5, 3.5, 5.5 and 7.5 ewes/ha for 152 days. The ewes did not receive any supplementation and were weighed every 14 days. Parturition occurred during the last week in March 1997 until the first week in May 1997, and the lambs were weighed at birth, and every 14 days thereafter. Stubble samples were collected from the paddocks during the first part of the trial (January and February) and at the end of the trial (April and May) by cutting ten replicate quadrates per paddock and were analysed for dry matter (DM), crude protein (CP), acid detergent fibre (ADF), neutral detergent fibre (NDF) and in vitro digestibility of organic matter (IVDOM). The live weight of the ewes at a stocking density of 5.5 ewes/ha decreased significantly, while the ewes at a stocking density of 1.5 ewes/ha gained weight. The ewes at a stocking density of 3.5 ewes/ha had the lowest weight loss (P = 0.01). Stocking density did not affect the birthweight of the lambs significantly. The CP concentration of the stubble decreased with an increase in stocking density, while the ADF and NDF concentration of samples were significantly higher at the higher stocking density. In the third study the supplementation of rumen inert fat or starch on the production of ewes grazing wheat stubble, was investigated. Fifty-six SAMM ewes were randomly divided into four groups of 14 ewes each, grazing the wheat stubble at a stocking density of 4.6 ewes/ha. Each group was supplemented with 250 gJewe daily for the last six weeks of pregnancy, which was increased to 360 gJewe during the first four weeks of lactation. Supplementation was supplied on Mondays, Wednesdays and Fridays for a 70-day period. The CP concentration of the supplement varied between 16.7 % and 19.6 %, while the total digestible nutrient (TDN) content varied between 52.0 % and 76.7 %. No significant difference (P > 0.05) occurred between the live weights of ewes during the last six weeks of pregnancy, the first four weeks of lactation, or the total feeding period. The ewes in the 50 % fat plus 50 % maizemeal group lost less weight (P :s; 0.08) during lactation than the ewes that received maizemeal as their main energy source. The study indicated that there was no significant advantage in the live weight change of the ewes during the experimental period, when compared to the group that received wheat bran (control group). In the fourth study the economic advantage of supplementation to SAMM ewes grazing wheat- or oat stubble were studied. Three hundred and sixteen ewes were divided into four flocks, of which two grazed oat stubble and two wheat stubble. Each of these four flocks was again subdivided into four subdivisions of which two subdivisions received supplementation and two none. Four subdivisions received 200 g/d for 83 days, and the other four subdivisions received 200 g/d for 44 days after which it was increased to 300 g/d for 37 days (81 days in total). The ewes were weighed monthly. The final bodyweight of the ewes that received supplementation was significantly higher than those that received none. Over the feeding period, the ewes that received supplementation had a significant lower weight loss in comparison to the ewes that did not receive supplementation. The 42-day weight of the lambs improved significantly due to supplementation, but no significant increase was indicated in the birthweight, weaning weight and survival rate of the lambs whose mothers received supplementation. In the fifth study the influence of supplementary feeding to ewes and creep feeding of their lambs on the production of both the ewes and lambs were studied. One hundred and sixty eight ewes were divided into two groups of 68 and 100 ewes that grazed a 12.9 and 18 ha camp respectively. Each of these ewe groups was subdivided into four groups of which two ewe groups received supplementation and two none. Within each ewe group two groups of lambs received creep feeding and two received none. A two (supplementation of ewes) by two (creep feeding of lambs) factorial design was used. Supplementation was supplied at 200 g/d for the first 69 days and 300 g/d for the next 120 days to ewes. Lambs received an average ofO.58 kg creep feed per day for 96 days. It was concluded that the live weight change (LWC) of the ewes during the experimental period was not affected significantly by creep feeding of their lambs. Ewes that received supplementation maintained higher live weights than their counterparts for most of the feeding period, although final weights at the end of the experimental period did not differ significantly. The average daily gain (ADG) of the lambs whose mothers received supplementation tended to be higher than that of mothers that received no supplementation, while the ADG of the lambs that received creep feeding was significantly higher than the lambs that received none. In the sixth study the carry-over effect of supplementation in the previous year on the production of the ewes in the following year was studied. Three hundred and sixteen ewes were divided into four flocks, of which two grazed oat stubble and two wheat stubble. Each of these four flocks was again subdivided into four subdivisions of which two subdivisions received supplementation and two none. Four subdivisions received 200 g/d for 83 days, and the other four subdivisions received 200 g/d for 44 days after which it was increased to 300 g/d for 37 days (81 days in total). The ewes were weighed monthly. Results indicated that birth status (lambs born per ewes mated) of lambs showed a tendency to increase in 1999 due to supplementation in 1998, while weaning status was not significantly affected. Due to multiple births in the supplemented groups, the birthweight and weaning weight of lambs was negatively affected by supplementation. The study concluded that supplementary feeding in the previous year did not have significant carry-over effects in the following year. However, the effect may have been influenced by the fact that mature animals were used in the study, while the pasture availability during the non-productive stage will also affect possible carry-over effects. / AFRIKAANSE OPSOMMING: 'n Eksperiment is uitgevoer om te bepaal wat die invloed van die frekwensie van byvoeding op die produksie van Suid-Afrikaanse Vleismerino (SAVM) ooie wat koringstoppel bewei, sal wees. Eenhonderd-en-sestig ooie is ewekansig in twee groepe verdeel wat bestaan het uit vier groepe elk. Die agt kampe is vir 138 dae bewei waartydens die ooie ook gelam het. Vier groepe bestaande uit 25 ooie het 'n 17 ha kamp teen 'n weidigtheid van 5.8 ooie/ha bewei en die ander vier groepe bestaande uit 15 ooie het 'n 12 ha kamp teen 'n weidigtheid van 5.0 ooie/ha bewei. 'n Kombinasie energie/proteïen aanvulling in die vorm van 'n lek is aan die ooie beskikbaar gestel. Twee van die groepe het geen aanvullende voeding ontvang nie (kontrole), twee groepe het 200 g/dag/ooi ontvang, twee groepe het 400 glooi elke tweede dag ontvang en twee groepe het 600 glooi elke derde dag ontvang. Die kleinste daling in liggaamsgewig tydens die voerperiode is waargeneem in die ooie wat elke dag sowel as elke tweede dag byvoeding ontvang het, alhoewel geen betekenisvolle verskille tussen dié twee groepe waargeneem is nie. Die kleinste daling in gewig tydens die totale voerperiode is waargeneem in die drie groepe wat byvoeding ontvang het (P < 0.1) terwyl die groepe wat geen byvoeding ontvang het nie (kontrole) die meeste gewig tydens dieselfde periode verloor het. Al die groepe wat byvoeding ontvang het, se liggaamsmassa verandering oor die voerperiode asook die totale periode was betekenisvol beter as die kontrole groep Geen betekenisvolle verskille is gevind by lampersentasie, speenpersentasie, geboortegewig, 42-dae gewig en oorlewing van lammers nie. Daar is bevind dat die byvoeding aan ooie elke derde of elke tweede dag ekonomies geregverdig is en 'n moontlike afname in arbeid- en vervoerkostes mag meebring. In die tweede studie is die invloed van weidigtheid op die samestelling van kanolastoppel en die produksie van SAVM-ooie op hierdie tipe stoppelondersoek. Agt-en-veertig ooie is ewekansig in vier groepe verdeel en het kanolastoppel teen 'n weidigtheid van ongeveer 1.5, 3.5, 5.5 en 7.5 ooie/ha vir 152 dae bewei. Die ooie het geen byvoeding ontvang nie en is elke 14 dae geweeg. Die ooie het gelam vanaf die laaste week in Maart 1997 tot die eerste week in Mei 1997. Die lammers is met geboorte geweeg en daarna elke 14 dae. Stoppelmonsters van die kampe is versamel gedurende die eerste deel van die studie (Januarie en Februarie) asook aan die einde van die studie (April en Mei) deur tien kwadrate per kamp te sny en is daarna ontleed vir droë materiaal (DM), ruproteïen (RP), suur bestande vesel (SBV), neutraal bestande vesel (NBV) en in vitro verteerbaarheid van organiese materiaal (lVVOM). Die liggaamsgewig van die ooie teen 'n weidigtheid van 5.5 ooie/ha het betekenisvol afgeneem, terwyl die ooie teen die weidigtheid van 1.5 ooie/ha toegeneem het in massa. Die ooie teen 'n weidigtheid van 3.5 ooie/ha het die kleinste gewigsverlies getoon (P = 0.01). Die geboortegewig van die lammers is nie betekenisvol deur weidigtheid beïnvloed nie. Die RP-konsentrasie van die stoppel het afgeneem met 'n toename in weidigtheid, terwyl die SBV en NBV -konsentrasie van die monsters betekenisvol hoër was by die hoër weidigtheid. In die derde studie is die byvoeding van rumen inerte vet of stysel aan ome wat koringstoppel bewei ondersoek. Ses-en-vyftig SAVM ooie is ewekansig in vier groepe van 14 elk verdeel en het koringstoppel teen 'n weidigtheid van 4.6 ooielha bewei. Elke groep het daagliks byvoeding teen 250 glooi tydens die laaste ses weke van dragtigheid ontvang, waarna dit vermeerder is tot 360 glooi tydens die eerste vier weke van laktasie. Byvoeding is op Maandae, Woensdae en Vrydae vir 70 dae voorsien. Die RP-konsentrasie van die byvoeding het gevarieer tussen 16.7 % en 19.6 % terwyl die totale verteerbare voedingstof (TVV) konsentrasie gevarieer het tussen 52.0 % en 76.7 %. Daar was geen betekenisvolle verskille (P > 0.05) tussen die liggaamsmassa van die ooie gedurende die laaste ses weke van dragtigheid, die eerste vier weke van laktasie, of die totale voerperiode nie. Die ooie in die 50 % vet plus 50 % mieliemeel groep het minder gewig (P ~ 0.08) gedurende laktasie verloor as die ooie wat mieliemeel as hulle hoof energiebron ontvang het. Die studie het getoon dat daar geen betekenisvolle toename in die liggaamsgewig van die ooie tydens die eksperimentele periode was in vergelyking met die groep wat koringsemels (kontrole) ontvang het nie. In die vierde studie is die ekonomiese voordeel van byvoeding vir SAVM ooie wat koringof hawerstoppel bewei het ondersoek. Driehonderd-en-sestien ooie is in vier groepe verdeel,waarvan twee hawerstoppel en twee koringstoppel bewei het. Elk van hierdie vier groepe is herverdeel in vier subdivisies waarvan twee byvoeding ontvang het en twee geen. Vier subdivisies het 200 gld vir 83 dae ontvang, terwyl die ander vier subdivisies 200 gld vir 44 dae ontvang het, waarna dit verhoog is na 300 gld vir 37 dae ('n totaal van 81 dae). Die ooie is maandeliks geweeg. Die finale liggaamsgewig van die ooie wat byvoeding ontvang het betekenisvol hoër was as die ooie wat geen byvoeding ontvang het nie. Tydens die voerperiode het die ooie wat byvoeding ontvang het 'n betekenisvolle laer gewigsverlies getoon in vergelyking met die ooie wat geen byvoeding ontvang het nie. Die 42-dae gewig van die lammers het ook betekenisvol toegeneem, maar geen verskil is waargeneem in die geboortegewig, speengewig en oorlewingstempo van lammers wie se moeders byvoeding ontvang het nie. In die vyfde studie is die invloed van byvoeding aan ooie en kruipvoeding aan hulle lammers op die produksie van beide die ooie en lammers bestudeer. Eenhonderd-agt-en-sestig ooie is onderskeidelik in twee groepe van 68 en 100 verdeel wat twee kampe van 12.9 en 18 ha respektiewelik bewei het. Elkeen van hierdie groepe is onderverdeel in vier groepe waarvan twee groepe byvoeding ontvang het en twee groepe geen. Binne elke ooi groep het twee groepe lammers kruipvoeding ontvang en twee geen. 'n Twee (byvoeding aan ooie) by twee (kruipvoeding aan lammers) faktoriaal ontwerp is gebruik. Byvoeding aan die ooie is verskaf teen 200 gld vir die eerste 69 dae en 300 gld vir die volgende 120 dae. Lammers het 0.58 kg kruipvoer per dag vir 96 dae ontvang. Daar is bepaal dat die liggaamsgewig-verandering van die ooie gedurende die eksperimentele periode nie betekenisvol beïnvloed is deur kruipvoeding van die lammers nie. Ooie wat byvoeding ontvang het het 'n hoer liggaamsgewig vir die grootste deel van die voerperiode gehandhaaf, alhoewel die finale gewigte aan die einde van die eksperimentele periode nie betekenisvol verskil het nie. Die gemiddelde daaglikse toename (GDT) van die lammers wie se moeders byvoeding ontvang het, het geneig om hoër te wees as die lammers wie se moeders geen byvoeding ontvang het nie, terwyl die GDT van die lammers wat kruipvoeding ontvang het was betekenisvol hoër as die lammers wat geen kruipvoeding ontvang het nie. In die sesde studie is die oordrageffek van byvoeding in die vorige jaar op ooie se produksie in die opvolgende jaar ondersoek. Driehonderd-en-sestien ooie is in vier groepe verdeel,waarvan twee hawerstoppel en twee koringstoppel bewei het. Elk van hierdie vier groepe is herverdeel in vier subdivisies waarvan twee byvoeding ontvang het en twee geen. Vier subdivisies het 200 gld vir 83 dae ontvang, terwyl die ander vier subdivisies 200 gld vir 44 dae ontvang het, waarna dit verhoog is na 300 gld vir 37 dae ('n totaal van 81 dae). Die ooie is maandeliks geweeg. Resultate het aangedui dat die geboortestatus (lammers gebore/ ooie gepaar) van lammers 'n tendens getoon het om toe te neem in 1999 as gevolg van byvoeding in 1998, terwyl speenstatus nie betekenisvol beïnvloed is nie. Byvoeding in 1998 het die geboortegewig en speengewig van lammers verlaag omdat dit 'n groter aantal meerlinggeboortes veroorsaak het. Die studie het bevind dat byvoeding in die vorige jaar nie 'n betekenisvolle oordrageffek in die volgende jaar teweeg gebring het nie. Die resultate mag egter beïnvloed gewees het deurdat volwasse diere in die studie gebruik is, terwyl die beskikbaarheid van weiding tydens die stadium wanneer die ooie nie gereproduseer het nie ook die moontlike oordrageffek kon beïnvloed het.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The purpose of this study was to investigate the variation that exists between maize samples regarding particle size separation, in vitro fermentation kinetics and in vitro dry matter (DM) disappearance. A second objective was to quantify possible relationships between the Roff Milling Index (RMI) of maize and any of the measured in vitro parameters. Three trials were conducted: a particle size distribution trial, a gas production trial and an in vitro DM degradability and starch disappearance trial. Overall, nine maize samples, which differed in terms of cultivar and endosperm type, were collected from different origins for the study. The samples were selected in terms of their Milling Index (MI). Three of the nine samples had a high MI that ranged between 109 and 118, three had a low MI that ranged between 67 and 71 and the other three samples had a medium MI that ranged between 85 and 92. Although the MI is not a direct indication of the hardness or softness of the endosperm, it was believed to be indirectly associated with vitreousness. In the first trial, the different maize samples were milled through a 1 mm screen and sieved through a series of three sieves 150, 125 and 106 μm, respectively. It was found that RMI was not a reliable indicator to predict particle size distribution, especially in terms of the coarse (>150 μm) and very fine (<106 μm) particles. In the gas production trial, the nine different maize samples were subjected to a gas production system for a duration of 48 hours. Here gas production and rate of gas production of the different maize types in buffered rumen liquor were measured during incubation. After fitting the gas volume data to the respective models, the non-linear parameters b, c and L were subjected to a main effects ANOVA with the aid of Statistica, version 9 (2009). Main effects were treatment and repetition. Means were separated by means of a Scheffé test and significance was declared at P < 0.05. The results were compared to the RMI of the different maize types and it was concluded that RMI was not a reliable predictor of gas production or rate of gas production of different maize types. In the third trial, in vitro DM degradability and starch disappearance of the different maize types were measured. In vitro DM degradability was conducted in the Ankom DAISYII incubator apparatus and the incubation times were 0, 2, 4, 8, 12 and 24 hours. Starch disappearance was measured on residues of the samples incubated for 0, 2 and 4 hours. After fitting the DM disappearance data to the respective models, the non-linear parameters a, b, c and L were subjected to a main effects ANOVA with the aid of Statistica, version 9 (2009). Main effects were treatment and repetition. Means were separated by means of a Scheffé test and significance was declared at P<0.05. The results indicated variation between maize samples, especially in terms of the a-, b- and L-values. The RMI did not appear to be a reliable predictor of digestibility parameters. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die variasie tussen mieliemonsters te ondersoek ten opsigte van die skeiding van partikelgroottes, in vitro-fermentasiekinetika en in vitro-droëmateriaalverdwyning. ‘n Tweede doel was om te bepaal of daar moontlike verwantskappe tussen die Roff Milling Index (RMI) van mielies en enige van die ander in vitro-parameters bestaan. Drie proewe is gedoen: verspreiding van partikelgrootte, ‘n gasproduksieproef en ‘n droëmateriaal degradeerbaarheid- en stysel verdwyningsproef. Nege mieliemonsters, wat van mekaar verskil ten opsigte van kultivar en endospermtipe, is van verskillende lokaliteite versamel. Die monsters is gekies in terme van hul maal-indeks (MI). Drie van die nege monsters het ‘n hoë MI gehad wat gewissel het tussen 109 en 118, drie het ‘n lae MI gehad wat gewissel het tussen 67 en 71 en die ander drie monsters het ‘n medium MI gehad wat gewissel het tussen 85 en 92. Alhoewel die MI waardes nie ‘n direkte indikasie van ‘n endosperm se hardheid- of sagtheidsgraad is nie, is dit aanvaar dat daar ‘n indirekte verwantskap tussen MI en glasagtigheid van die mielie bestaan. In die eerste proef is die nege verskillende mieliemonsters deur ‘n 1 mm sif gemaal en daarna deur ‘n reeks van drie siwwe met groottes van onderskeidelik 150, 125 en 106 μm gesif. Daar is bevind dat die RMI nie ‘n betroubare voorspeller is om partikelgrootte-verspreiding aan te dui nie, veral nie ten opsigte van growwe (> 150 μm) en baie fyn (< 106 μm) patikels nie. Tydens die gasproduksieproef is die nege mieliemonsters vir 48 ure blootgestel aan ‘n gasproduksiesisteem, waar gasdruk outomaties aangeteken is. Gasproduksie en tempo van gasproduksie van die verskillende mieliemonsters is gemeet en aangeteken gedurende inkubasie met ‘n gebufferde rumenvloeistofmedium. Nadat die gasvolumedata met behulp van relevante modelle gepas is, is die nie-linêre parameters b, c en L onderwerp aan ‘n hoof-effek ANOVA met die gebruik van Statistica weergawe 9 (2009). Hoof-effekte was behandeling en herhaling. Gemiddeldes is deur ‘n Scheffé-toets geskei en betekenisvolheid is verklaar by P<0.05. Die resultate verkry is vergelyk met die RMI van die verskillende mielietipes. Die gevolgtrekking is gemaak dat Roff MI nie ‘n betroubare voorspeller van totale gasproduksie of gasproduksietempo is nie. Tydens die derde proef is droëmateriaaldegradeerbaarheid en styselverdwyning van die verskillende mielietipes bepaal. In vitro droëmateriaal (DM) degradeerbaarheid is gedoen in die Ankom DAISYII inkubator met inkubasietye van 0, 2, 4, 8, 12 en 24 ure. Styselverdwyning is bepaal deur styselanalises op die residue van die monsters wat geïnkubeer is vir 0, 2 en 4 ure. Nadat die DM-degradeerbaarheid met behulp van relevante modelle gepas is, is die nie-lineêre parameters a, b, c en L onderwerp aan ‘n hoof-effek ANOVA met die gebruik van Statistica weergawe 9 (2009). Hoof-effekte was behandeling en herhaling. Gemiddeldes is deur ‘n Scheffé toets geskei en die betekenisvolheid is verklaar by P<0.05. Die resultate het aangedui dat daar groot variasie tussen mielies bestaan, veral ten opsigte van die a-, b- en L-waardes. Dit het verder geblyk dat die RMI van die verskillende mielietipes nie ‘n betroubare voorspeller van DM-degradeerbaarheid was nie.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The aim of this study was to determine the rate of transfer of melamine as fertilizer ingredient to kikuyu pastures and if melamine would be transferred from the fertilized pasture to cow’s milk. Three trials were conducted in the study, viz. a pilot pot plant trial, an applied pasture trial and a milk production trial. Melamine is a commercially available industrial chemical with a high nitrogen content. Large quantities of melamine waste can sometimes be incorporated into crop and pasture fertilizers due to the high N content. An initial pot plant trial with kikuyu was conducted to determine whether melamine would be absorbed as such from the soil to the plant material. The pots were fertilized in the form of melamine adulterated Chinese maize Gluten 60, at a rate equivalent to 8.8 kg of melamine/ha. Results indicated that melamine was indeed absorbed and 7 days after fertilization, the concentration of melamine in the grass was 228 mg/kg. An applied pasture trial was then conducted were three pastures of 0.3 ha each were used. One pasture served as a control and received N fertilization in the form of LAN at a rate of 40 kg N/ha. The other two pastures also received LAN, but with 10% (Treatment 1) and 20% (Treatment 2) of the LAN-N substituted with melamine-N. All three pastures also received P-fertilization in the form of Single Superphosphate at a rate of 20 kg P/ha and KCl fertilizer at a rate of 50 kg K/ha. Pasture samples were taken once a week for 10 weeks, each time at the exact same spot in each camp. Samples were dried and finely milled before analysis via LC-MS/MS for melamine content. The initial concentration of melamine in the grass of Treatment 2 was higher than that in the grass of Treatment 1. The rate at which melamine decayed in the plant material was found to be quite similar for the two melamine treatments. In this trial, melamine took around 10 weeks to reach undetectable levels in the grass. It was concluded that melamine was absorbed as such from the soil by pasture grass when included in a fertilizer. For the milk production study, eighteen lactating Holstein cows, 60 ± 5.1 (SE) DIM, with a daily milk production of 36.5 ± 2.0 (SE) kg/d and weighing 609 ± 12.8 (SE) kg, were stratified according to milk production and then randomly allocated to three groups of six cows. The groups were then randomly allocated to the three pastures used in the applied pasture trial. Cows were kept on the melamine fertilized pasture for 9 days, in which they were allowed to graze the pasture for approximately 10 hours each day. After the 9 day period, melamine was withdrawn by placing the cows on the control pasture that did not receive melamine contaminated fertilization for another 7 days. During these 16 days, milk was collected twice a day, viz. during the morning and afternoon milkings. Milk samples of each cow were sub-divided into two samples, one was preserved with potassium dichromate and analysed for milk composition and the other was frozen until analysed for melamine by LC-MS/MS. For the duration of the trial, melamine containing milk was destroyed in order to prevent it from contaminating milk collected from the rest of the herd. Results from the analysis for melamine confirmed that melamine was transferred from melamine fertilized pasture to milk. In this study, it took 6 days from melamine withdrawal for melamine to reach undetectable levels in the milk. It was also found that the melamine fertilized pasture did not have any significant effect on the average milk production and milk composition of the cows. The aim of the study was met and it was confirmed that melamine can be transferred from fertilizer to the soil, to the pasture and to the milk of cows grazing these pastures. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die tempo van oordrag van melamien as bemestingstof na Kikuyu weiding te bepaal, asook om te bepaal of melamien oorgedra sal word vanaf die bemeste weiding na melk. Drie proewe is uitgevoer wat ‘n potplant loodsproef, ‘n toegepaste weidings proef en ‘n melkproduksie proef ingesluit het. Melamien is ʼn kommersieël-beskikbare industriële chemikalieë met ʼn hoë stikstof inhoud. Groot hoeveelhede van melamien-afval kan soms in kunsmis ingesluit word vir die bemesting van gewasse en weidings, weens die hoë stikstof inhoud van melamien. ʼn Potplant loodsproef met Kikuyu is uitgevoer om te bepaal of melamien vanaf die grond deur die plantmateriaal geabsorbeer word. Melamienbemesting is in die vorm van vervalste Chinese mieliegluten 60 toegedien teen ʼn hoeveelheid gelykstaande aan 8.8 kg melamien/ha. Die resultate van hierdie proef het getoon dat melamien wel deur die plantmateriaal geabsorbeer is en 7 dae nadat bemesting toegedien is, was die konsentrasie van melamien in die gras 228 of mg/kg. ʼn Toegepaste weidingstudie is uitgevoer waar drie kampe van 0.3 ha elk gebruik is. Een van die kampe het as ʼn kontrole gedien en het stikstof bemesting in die vorm van KAN teen 40 kg N/ha ontvang. Die ander twee kampe het KAN bemesting ontvang waar 10% (Behandeling 1) en 20% (Behandeling 2) van die KAN-N deur melamien-N vervang is. Al drie kampe het ook fosfaatbemesting in die vorm van Enkel Superfosfaat ontvang teen 20 kg P/ha, asook KCl kunsmis teen 50 kg K/ha. Weidingmonsters is eenmaal per week op dieselfde plek in elke kamp geneem vir 10 weke nadat bemesting toegedien is geneem. Monsters is gedroog en daarna fyngemaal voordat dit vir melamieninhoud geanaliseer is met behulp van LC-MS/MS. Die aanvanklike melamienkonsentrasie in die gras van Behandeling 2 was hoër as die in die gras van Behandeling 1. Die tempo waarteen die melamienkonsentrasie in die plant materiaal afgeneem het, was baie dieselfde vir Behandelings 1 en Behandeling 2. Dit het ongeveer 10 weke geneem voordat die melamien in die gras nie-waarneembare vlakke bereik het. Die gevolgtrekking is gemaak dat melamien wat in die vorm van kunsmis toegedien word, as sodanig uit die grond geabsorbeer word deur die gras. Vir die melkproduksiestudie is agtien lakterede Holsteinkoeie, 60 ± 5.1 (SE) dae in melk, met ‘n daaglikse melkproduksie van 36.5 ± 2.0 (SE) kg/dag en ‘n liggaamsmassa van 609 ± 12.8 (SE) kg, volgens hul melkproduksie gerangskik en ewekansig in drie groepe van ses koeie elk ingedeel. Die groepe is daarna ewekansig aan die drie kampe, wat in die toegepaste weidingstudie gebruik is toegedien. Die koeie is vir 9 dae op die melamienbemeste weidings gehou, waartydens hulle toegelaat is om vir ongeveer 10 ure elke dag te wei. Na die tydperk van 9 d, is die koeie vanaf die melamienbemeste weidings onttrek deur hulle op die kontroleweiding te plaas vir ʼn verdere 7 dae. Gedurende hierdie 16 dae is melkmonsters tweekeer per dag geneem, tydens die oggend- en die middagmelkings. Die melkmonsters van elke koei is vervolgens onderverdeel in twee monsters, waarvan een met kaliumdichromaat gepreserveer is vir die beplaing van melksamestelling, terwyl die ander een gevries is totdat dit later vir melamien inhoud ontleed is met behulp van LC-MS/MS. Melk van die koeie wat op die melamienweidings gewei het, is weggegooi om te voorkom dat melk van die res van die kudde gekontamineer kon word. Die resultate van die melamienanalises het getoon dat melamien oorgedra word vanaf die melamienbemeste weiding na die melk. Tydens hierdie studie het dit 6 dae geneem vandat koeie vanaf die melamienbemeste weidings onttrek is, totdat die melkmelamien nie-bepaalbare vlakke bereik het. Daar is bevind dat melamienbemeste weidings geen betekenisvolle uitwerking op die gemiddelde produksie en samestelling van die melk gehad het nie. Die doel van hierdie studie is bereik en daar is getoon dat melamien vanaf kunsmis na die grond, na die gras en na die melk oorgedra kan word wanneer koeie op weidings geplaas word wat melamienbemeste kunsmis ontvang het.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: In recent years, the aim of the production of broilers became more focused on the increase of the performance of the birds in order to increase profit. To obtain an increased performance with broiler chicks, it is necessary to look at the development of their gastrointestinal tract, the feed requirements and the ability to digest certain nutrients in the period post hatch. Research have shown clear evidence of increased performance of chicks by the inclusion of certain carbohydrate and protein sources in the prestarter diets, but in contrast to this there are also some research that found no significant effects on the performance of broilers when certain carbohydrate and protein sources were included in the pre-starter diet. Therefore, the purpose of this study was to investigate the effect that a product containing specific carbohydrate and protein sources, included in the pre-starter diets of broiler chicks, would have on their performance. It was believed that the products to be tested would result in increased performance of the chicks in the following growth phases. Special emphasis was placed on the average daily gain (ADG), feed intake, cumulative feed intake, feed conversion ratio (FCR), European production efficiency factor (EPEF) and the protein efficiency ratio. Different inclusion levels of the different raw materials were investigated in the first trial. Three raw materials and a control were compared using a summit dilution process at 100:0, 66:34, 50:50, 34:66 and 0:100. Specific production parameters such as ADG total live weight gain, feed intake per week, cumulative feed intake, FCR, EPEF and PER were measured and calculated in order to determine if there were any significant differences between the treatments with the different raw material inclusions on the performance of the chicks. No significant differences (P>0.05) were found between the 13 treatments for the ADG, total live weight gain, feed intake per week, cumulative feed intake, FCR, EPEF and PER. The results therefore indicated that there were no significant differences between the different inclusion levels of the different raw materials and no significant differences for the production parameters for animals receiving diets with various levels of the three raw materials. It is thus concluded that these raw materials can be successfully utilised in pre-starter diets of broiler chicks. The effect of the contribution of sugar to the metabolisable energy (ME) of the raw materials was tested in a commercial grower trial. The three raw materials had inclusion levels leading to supply of either 12% or 18% of the ME in the form of sugar. No significant differences were found between the seven treatments for ADG, total live weight gain, feed intake per week, cumulative feed intake, FCR, EPEF or the PER. It was concluded that the percentage in contribution of sugars between 12 and 18% to the ME of the prestarter diets had no significant effects on the production parameters tested. / AFRIKAANSE OPSOMMING: Met die produksie van braaikuikens word daar deesdae al hoe meer klem gelê op die verhoging van die produksie van die kuikens om dan dus ‘n verhoging in die wins te bewerkstellig. Om hierdie verhoogde produksie by braaikuikens te kan bereik, is dit nodig om na eienskappe van die kuiken soos die ontwikkeling van die spysvertering stelsel, die nutrient- behoeftes van die kuiken en die vermoë om sekere nutriënte te kan verteer in die periode na uitbroei. Sommige navorsing het gewys dat die insluiting van sekere koolhidraat – en proteïen bronne in die voor-aanvangs diëete van braaikuikens, lei tot ‘n positiewe effek op die produksie van die kuikens, waar ander navorsing geen effek gevind het nie. Daarom was die doel van die huidige navorsing gewees om te toets wat die effek van die insluiting in die voor-aanvangs dieet van braaikuikens ‘n sekere produk met ‘n spesifieke koolhidraat –en proteïen bron samestelling op die produksie van die kuikens sal wees in die daaropvolgende fases. Dit was verwag dat die insluiting van hierdie produkte in die voor-aanvangs diëte van braaikuikens ‘n positiewe effek sou hê op die produksie van die kuikens. Spesiale klem was gelê op die parameters soos gemiddelde daaglikse toename (GDT) voer inname, kumulatiewe voer inname, voeromset verhoudings (VOV) Europese produksie doeltreffendheids- faktor (EPEF) en die proteïen doeltreffendheids faktor (PER). Verskillende insluitings vlakke van die verskillende produkte wat getoets is, is in die eerste proef ondersoek. Die drie produkte is deur middel van ‘n piek verdunnings proses by verhoudings van 100:0, 66:34, 50:50, 34:66 en 0:100 met mekaar vergelyk. Spesifieke produksie- parameters soos die GDT, lewende massa, weeklikse voer- inname, kumulatiewe voer- inname, VOV, EPEF en die PER is gemeet. Geen betekenisvolle verskille (P>0.05) was vir die 13 behandelings verkry nie. Die resultate het derhalwe getoon dat daar geen betekenisvolle verskille tussen die verskillende insluitings vlakke van die onderskeie produkte was nie en dat daar geen betekenisvolle tussen die produksieparameters van die kuikens wat die diëte met die verskillende insluitingspeile van die drie roumateriale ontvand het, was nie. Daarom is tot die slotsom gekom dat hierdie roumateriale suksesvol in die vooraanvangsdieet van braaikuikens aangewend kan word. Die effek van die bydrae van die suiker tot die metaboliseerbare energie (ME) van die produkte was in ‘n kommersiële groei proef getoets. Die drie rou materiale was by beide 12- en 18% ingesluit. Geen betekenisvolle verskille (P>0.05) was vir die sewe behandelings vir GDT, lewende massa, weeklikse voer- inname, kumulatiewe voer- inname, VOV, EPEF en PEF verkry nie.

Thesis (MPhil (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: The proximate composition of food products, and more importantly fat content and fatty acid composition, is of growing concern to consumers. It is also of concern to fish processors because of the effects that various levels of proteins, lipids, water and ash have on the cold storage potential and texture of fish. A total of 17 Seriola lalandi (yellowtail) were harvested from a net cage production unit off the coast of Port Elizabeth. Proximate, fatty acid and mineral analysis were conducted on five areas on the fillet, as well as on the whole fillet as a control. Differences (P < 0.05) were found in the water and fat content between dorsal and ventral samples. The highest amount (% wet weight) of moisture (71.5 ± 0.4%) was observed in the caudal region of the fish. This region was also found to contain the lowest levels of fat (4.3 ± 0.23%). Protein levels did not differ (P > 0.05) between sample regions. The total fat content (g/100 g wet tissue) of the whole fillet (A; control) was 5.3 ± 0.11 of which saturated fatty acids (SFA) accounted for 35.5 ± 1.13%, monounsaturated fatty acids (MUFA) for 25.7 ± 0.51% and polyunsaturated fatty acids (PUFA) for 38.2±0.88%. The most predominant saturated fatty acid was palmitic acid (hexadecanoic acid, C16:0) with levels reaching 24.2 ± 1.25% in the mid belly area, sample section E (mid ventral). The data shows that one could use either section B (anterior dorsal), section D (mid dorsal) or section F (dorsal and ventral posterior sections combined) as a representative sample of the whole fillet when doing proximate analysis. The belly sections of the fish differed significantly (P < 0.05) to the whole fillet. There was too much variation between samples with regards to the mineral and fatty acid analysis to identify a section that is representative of the whole fillet. The edible portion of the farmed yellowtail examined in this study contained eicosapentonic acid (EPA) and docosahexaenoic acid (DHA) levels of 0.24% and 10.90% respectively which is notably lower than other marine fish species. However, this could be linked to the feed that these specific yellowtail were fed, as the lipid profile of the diet has been shown to have an effect on the lipid profile of the fish. / AFRIKAANSE OPSOMMING: Die algemene samestelling van voedsel produkte, asook die vet inhoud en vetsuur samestelling daarvan, wek deesdae al meer besorgdheid by verbruikers. Dit is ook belangrik vir vis verwerkers as gevolg van die effek wat verskillende vlakke van proteïene, lipiede, water en minerale het op die tekstuur van vis asook die potensiaal om vis in verkoelers te stoor. ‘n Totaal van 17 Seriola lalandi (geelstert) is geöes vanuit ‘n net-hok eenheid op die kus van Port Elizabeth. Proksimale, vetsuur en mineraal analises was uitgevoer op vyf areas van die filet sowel as op die heel filet as ‘n kontrole. Verskille (P < 0.05) is opgemerk in die water en vet inhoud tussen die dorsale en ventrale monsters. Die hoogste voginhoud (71.5 ± 0.4%) was opgemerk in die stert gedeelte van die vis en hierdie gedeelte het ook die laagste vetinhoud gehad (4.3 ± 0.23%). Proteïen vlakke het nie verskil tussen enige van die monsters nie (P < 0.05). Die totale vetinhoud (g/100 g nat weefsel) van die heel filet (A, kontrole) was 5.3 ± 0.11 waarvan versadigde vetsure (SFA) 35.5 ± 1.13%, monoönversadigde vetsure (MUFA) 25.7 ± 0.51%, en polionversadigde vetsure (PUFA) 38.2 ± 0.88% uitgemaak het. Die oorheersende versadigde vetsuur was palmitiese suur (heksadekanoïese suur, C16:0) wat vlakke van 24.2 ± 1.25% bereik het in seksie E (middel ventraal). Die data wys dat seksie B (voorste dorsaal), seksie D (middel dorsaal) of seksie F (agterste ventraal en dorsaal) gebruik kan word as verteenwoordigende monsters van die heel filet wanneer proksimale analise uitgevoer word. Die maag gedeeltes van die vis het beduidend verskil (P < 0.05) van die heel filet. Die resultate van die mineraal en vetsuur analises het te veel gevarieer en daarom kon geen verteenwoordigende seksie van die heel filet geïdentifiseer word nie. Die eetbare dele van akwakultuur geelstert wat in hierdie studie ondersoek is, bevat 0.24% EPA en 10.90% DHA wat heelwat laer is as die van ander marine vis spesies. Hierdie verskil kan moontlik toegeskryf word aan die voer wat aan die geelstert gegee is aangesien dit voorheen bewys is dat die lipied profiel van die dieet ‘n uitwerking het op die lipied profiel van vis.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: A study was conducted to characterize the three ostrich breeds available as genetic resource in South Africa, namely the South African Black (SAB), Zimbabwean Blue (ZB) and the Kenyan Redneck (KR), and their respective crosses. Growth, slaughter traits and reproduction of these ostriches were recorded at Oudtshoorn Research Farm in the Western Cape of South Africa. Individual non-linear regressions (Gompertz) were fitted to the data of 390 purebred and 41 crossbred ostriches, using the SAS NLIN function. Heterosis was estimated for each parameter of the Gompertz model. The estimated adult weight (Aparameter) of the ZB (147 kg) and the KR breeds (148 kg) were higher than that of the SAB breed (129 kg). The overall growth rate (B-parameter) of the ZB breed (0.0075) and the SAB breed (0.0080) was lower than that of the KR (0.0150). The age at maximum weight gain (C-parameter) was higher for the ZB breed (226 days) compared to the SAB (198 days) and the KR (194 days). Heterosis for the A-parameter was estimated at -6.2% and at -12% for the C-parameter. The slaughter traits studied were slaughter weight (SLW), carcass weight (CW), dressing percentage (DP), fan fillet weight (FFW), pH0, pH24, drip loss % (DL%), cooking loss % (CL%), tenderness and meat colour traits. Differences were observed between the means for SLW of the SAB (86.5 kg) and ZB (93.9 kg). Mean DP of the KR breed (52.5%) was increased relative to the low DP of their SAB contemporaries (48.8%). The sire lines (ZB and KR) and crosses were heavier than the SAB (dam line), whereas the crosses resembled the dam line for meat quality traits. Means for pH24 also differed, with higher values for the sire lines (ZB – 6.36; KR – 6.4) relative to the SAB (5.85). The instrumental b* colour value also differed between the SAB (9.4) and KR (6.9). Records used for assessing the reproduction and body measurements of purebred and crossbred dams were 428 in total. Traits analyzed were, total egg production (TEP), the number of fertile eggs, number dead in shell chicks, hatchability and chick production (CP), the time to lay, live weight, front chest circumferences as well as tail circumference. The ZB and KR were heavier in live weight and of larger body measurements than the SAB, whereas the SAB exhibited superior reproduction performance in comparison with the ZB and KR breeds. Derived heterosis estimates amounted to 2.2% for tail circumference, 12% for TEP, 12% for hatchability and 19% for CP. Genetic variation between and within the breeds were determined utilizing 19 microsatellite markers. Significant molecular genetic differences were observed between the three breeds. The SAB and ZB (Fst = 0.10 and Nei = 0.49) were genetically most similar, whereas the genetic distance between the KR and ZB breeds were furthest (Fst = 0.13 and Nei = 0.61). The SAB breed exhibited the highest heterozygosity within its population and the ZB the lowest heterozygosity. These results contribute to a better understanding of the utilization of the distinct ostrich breeds for commercial production. / AFRIKAANSE OPSOMMING: Die doel van hierdie studie was om die verskille tussen drie volstruisrasse wat tans in Suid Afrika mee geboer word te karakteriseer, naamlik die “South African Black” (SAB), “Zimbabwean Blue” (ZB) en die “Kenyan Redneck” (KR) en hulle onderskeie kruisse. Rekords van die groei-, slag- en reproduksie eienskappe van die volstruise was by Oudtshoorn Navorsingsplaas in die Wes-Kaap aangeteken. Individuele nie-lineêre regressies (Gompertz) is op die data van 390 suiwerras en 42 kruisgeteelde volstruise gepas, met die gebruik van die “NLIN” prosedure van SAS, (2006). Heterose is beraam vir elke parameter van die Gompertz model. Die beraamde volwasse gewig (A-parameter) van die ZB (147 kg) en die KR ras (148 kg) was hoër as die van die SAB ras (129 kg). Die totale groeitempo (B-parameter) van die ZB ras (0.0075) en die SAB ras (0.0080) was laer as die van die KR (0.0150). Die ouderdom by maksimum groei (C-parameter) was hoër vir die ZB ras (226 dae) in vergelyking met die SAB (198 dae) en die KR (194 dae). Heterose vir die A-parameter was beraam teen -6.2% en teen -12% vir die C-parameter. Die slageienskappe wat ondersoek was, was slagmassa (SLW), karkasmassa (CW), uitslag persentasie (DP), “fan fillet” massa (FFW), pH0, pH24, drupverlies % (DL%), kookverlies % (CL%), sagtheid en kleureienskappe. Beduidendende verskille is waargeneem tussen die gemiddeldes vir SLW vir die SAB (86.5 kg) en ZB (93.9 kg). Gemiddelde DP van die KR ras (52.5%) was beter as die van die SAB ras (48.8%). Die mannetjielyne (ZB en KR) en die kruisse was swaarder as die SAB (wyfielyn), en die kruise was vergelykbaar met die wyfielyn vir vleiskwaliteit eienskappe. Gemiddeldes vir die pH24 het verskil, met hoër waardes vir die vaar lyne (ZB – 6.36; KR – 6.4) relatief tot die SAB (5.85). Die instrumentale b* kleurwaarde het ook verskil tussen die SAB (9.4) en KR (6.9). ‘n Totaal van 428 rekords is gebruik om reproduksie en liggaamsmetings van die suiwer en kruisteelwyfies te ondersoek. Reproduksie eienskappe ge-analiseer was: die aantal broeisels, totale eierproduksie (TEP), die aantal vrugbare eiers, die aantal kuikens dood in dop, uitbroeibaarheid, kuiken produksie (CP), tyd tot produksie van die eerste eier, volwasse gewig, voorbors omtrek, sowel as, kruisomtrek. Die ZB en KR rasse was swaarder as die SAB, en het groter liggaamsmetings gehad. Die SAB het beter reproduksie in vergelyking met die ZB- en KR rasse gehad. Heterose beramings was 2.2% vir kruisomtrek, 12% vir TEP, 12% vir uitbroeibaarheid en 19% vir CP. Genetiese variasie tussen en binne die rasse was vasgestel deur die gebruik van 19 mikrosatelliete merkers. Beduidende genetiese verskille op ‘n molekulêre vlak was waargeneem tussen die drie rasse. Die SAB en ZB (Fst = 0.10 en Nei = 0.49) was geneties meer gelyk terwyl die KR en ZB genetiese verder verwyder is (Fst = 0.13 en Nei = 0.61). Die SAB ras het die hoogste heterosigositeit binne populasie getoon, en die ZB die laagste. Hierdie resultate dra by tot ‘n beter begrip van die gebruik van die drie rasse in kommersïele produksie.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: The objective of this study was to evaluate the use of Musca domestica (common house fly) larvae meal, as protein source, for broiler production. This was done by investigating the nutritive value of house fly larvae meal together with its total tract digestibility, potential toxicity and carcass characteristics of the broilers supplemented with house fly larvae meal. The proximate analysis of house fly larvae meal show that it contained, on a dry matter basis, a gross energy value of 20.10 MJ/kg, 60.38% crude protein, 14.08% crude fat and 10.68% ash and that the house fly pupae contained a gross energy of 20.42 MJ/kg, 76.23% crude protein, 14.39% crude fat and 7.73% ash. House fly pupae meal had the closest match of amino acid profile when compared with the ideal amino acid profile required by broilers and it has arginine relative to the lysine content closer to the ideal amino acid profile than the house fly larvae meal. The essential fatty acid, linoleic acid, was found at levels of 26.25 and 36.27% of the total fats for the house fly larvae and pupae meal respectively. House fly larvae meal supplementation did not induce gizzard erosion or showed toxicity (regarding the gastro intestinal tract, immune system and organ stress) in broilers. Results revealed that house fly pupae meal had higher total tract digestibilities for most nutrients than of the house fly larvae meal. House fly larvae meal had a crude protein total tract digestibility of 69% and that of pupae meal was 79%. Both larvae and pupae meal had high amino acid total tract digestibilities of all the amino acids analysed. The house fly larvae and pupae meal had an apparent metabolizable energy (AME) value of 14.23MJ/kg and 15.15MJ/kg respectively. The larvae meal total tract crude fat and crude fibre digestibilities were 94% and 62% respectively. The pupae meal total tract crude fat and crude fibre digestibilities were 98% and 58% respectively. House fly larvae meal supplementation in a three phase feeding system significantly increased average broiler live weights at slaughter, total feed intake, cumulative feed intake as well as average daily gain (ADG) when compared to commercial maize: soya oil cake meal diet. In direct comparison of larvae inclusion levels with fishmeal in isonitrogenous and isoenergetic diet, no significant differences were observed between a 10% house fly larvae and a 10% fish meal diets regarding performance characteristic. The 25% house fly larvae meal diet yielded significantly better average broiler live weights at slaughter, total feed intake, cumulative feed intake (from the second week until slaughter) as well as average daily gain when compared to the 25% fish meal diet in the growth phases. Carcass characteristics of the 10% larvae, 10% fishmeal and commercial diets were compared. Chicks that received either the 10% house fly larvae meal or 10% fish meal supplementation produced significantly heavier carcasses and breast muscle portions than the chicks that received the commercial maize: soya oil cake meal. No treatment differences were found regarding breast and thigh muscle colour or pH. This study showed that house fly larvae meal can be regarded as a safe protein source that can be used to replace other protein sources and that has the ability to promote broiler performance without having any detrimental effects on carcass characteristics. / AFRIKAANSE OPSOMMING: Die doel van die studie was om die effek van Musca domestica (gewone huisvlieg) larwe meel, as ‘n protein bron, in braaikuikens te evalueer. Dit was gedoen deur die nutrient waarde van huisvlieg larwe meel saam met die totale spysvertering verteerbaarheid, moontlike toksiesiteit en karkas-eienskappe van braai kuikens te evalueer. Laboratoruim analiese toon dat huisvlieg larwe meel 20.10 MJ/kg bruto energie, 60.38% ru- protein, 14.08% ru- vet en 10.68% as bevat en huisvlieg papie meel 20.42 MJ/kg bruto energie, 76.23% ru- protein, 14.39% ru- vet en 7.73% as bevat. Huisvlieg papie meel stem die meeste ooreen met die idiale amino suur profiel soos wat benodig word deur braaikuikens en dit het ‘n arginien tot lisien verhouding wat die meeste ooreenstem met die idiale amino suur profiel in vergelyking met huis vlieg larwe meel. Die essensiele vet suur, linolien suur, was geanaliseer teen vlakke van 26.25- en 36.27% van die totale vette onderskeidelik vir huisvlieg larwe- en papie meel. Huisvlieg larwe meel vervanging het nie spiermaag erosie of enige ander toksiese effekte te veroorsaak nie. Resultate het getoon dat huisvlieg papie meel, in vergelyking met larwe meel, het ‘n hoër totale spysvertering verteerbaarheid vir meeste van die nutrient. Die huisvlieg larwe meel het ‘n totale ru- protein spysvertering verteerbaarheid van 69% en die van papie meel van 79%. Beide larwe en papie meel het hoë amino suur spysvertering verteerbaarheid. Larwe meel en papie meel het skynbare metaboliseerbare energie waardes van 14.23MJ/kg en 15.15%MJ/kg onderskeidelik. Die larwe meel het ‘n ru-vet en ru- vesel spysvertering verteerbaarheid van 94% en 62% onderskeidelik, waar die papies ‘n ru-vet en ru- vesel spysvertering verteerbaarheid van onderskeidelik 98% en 58% het. Huisvlieg larwe meel vervanging in ‘n drie fase voer stelsel het getoon om die gemiddelde braaikuiken lewende gewigte by slag, totale voer iname, sowel as die gemiddelde daaglikse toename te verhoog waneer dit vergelyk word met ‘n kommersiele mielie- soya olie koek dieet. Geen mekwaardige verskille was waargeneem toe die 10% larwe meel dieet direk met die 10% vismeel diet vergelyk was rakende enige produksie einskappe gemeet nie. Die 25% larwe meel dieet het merkwaardig beter gemiddelde braaikuiken lewende gewigte by slag, totale voer iname, sowel as die gemiddelde daaglikse toename getoon wanneer vergelyk word met die 25% vismeel dieet gedurende die verskeie groei fases. Karkas eienskappe van die 10% larwe meel, 10% vismeel en die kommersiele diete was gevergelyk. Kuikens wat 10% larwe meel en 10% vismeel in die diete ontvang het, het swaarder karkasse gelewer met swaarder borsie massas wanneer vergelyk word met die kommersiele mielie- soya olie koek dieet. Geen behandelings verskille was gevind rakende die borsie- en dy spier kleure of pH nie. Die studie toon dat huisvlieg larwe meel as ‘n veillige protein bron kan beskou word, wat gebruik kan word om ander protein bronne te vervang. Huisvlieg larwe meel het ook die vermoë om braaikuiken produksie te verhoog sonder om enige negitiewe effekte rakende die karkas eienskappe te toon nie.

Thesis (MScAgric (Animal Sciences))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Forages are the main feed components in ruminant production systems for the reason that they are often the major source of energy available to the animal. However, only 10 to 35% of energy intake is available as net energy because the digestion of plant cell walls is not complete. This can significantly affect livestock performance and profits in production systems that use forages as a major source of nutrients of the diet. As a result of low and variable nutritive values of forage feedstuffs, attempts to improve ruminal fibre degradability have been an ongoing research topic. The use of exogenous fibrolytic enzymes (EFE) has been proposed as means to improve forage digestibility. Positive results with regard to rumen forage digestibility and other animal production traits have consequently been obtained due to increased rumen microbial activity following EFE addition in ruminant diets. Two EFE (Abo 374 and EFE 2) and one commercial yeast preparation were firstly identified and selected for their potential to improve the cumulative gas production (GP) at 24 hours of a range of feed substrates using the in vitro GP system as a screening step to identify the superior EFE products. The different feed substrates were lucerne hay, wheat straw, wheat straw treated with urea and a commercial concentrate diet. An in vitro experiment was undertaken on these four different substrates in order to evaluate the two EFE and the yeast preparation. This was to identify the most promising EFE capable of producing a significant effect on feed digestibility using organic matter digestibility (in vitro true digestibility) and fermentation characteristics (in vitro GP system). Results from the in vitro evaluation showed that EFE significantly enhanced in vitro DM degradability and GP profiles (P < 0.05). Abo 374 enzyme showed potential to increase in vitro microbial protein synthesis (MPS) of GP residues of the concentrate diet. In addition, no correlation was found between the in vitro MPS and the 48 hours cumulative GP of all the tested substrates (P < 0.05; R2 < 0.30). Treatments were found to increase in vitro MPS, feed degradability and the cumulative GP of different quality forages and the concentrate diet, with Abo 374 being the best treatment (P < 0.05). However in vitro responses of EFE were variable depending on the energy concentration and chemical composition of different substrates. Variation in MPS was mostly due to the low recovery of purine derivates with the purine laboratory analysis. On the basis of these results, Abo 374 was selected and consequently further tested in another in vitro and in situ trial using a mixed substrate of lucerne hay and wheat straw. Abo 374 significantly improved the cumulative GP, in vitro DM and NDF disappearance of the mixed substrate (P < 0.05). In addition, no correlation was found between the in vitro MPS and the cumulative GP at 48 hours (P = 0.68; R2 < 0.25). The in situ disappearance of feed nutrients (DM, NDF and CP) with Abo 374 was similar to the control. The lack of significance of disappearance was probably due to the small number of sheep used in the study and the relatively high coefficient of variation associated with measuring ruminal digestion. Abo 374 significantly increased the in situ MPS (P = 0.0088) of the mixed substrate of lucerne hay and wheat straw. Evidence of the increased MPS and both in vitro and in situ disappearance of DM and NDF resulted from the Abo 374 activity during either the pre-treatment or the digestion process. The addition of Abo 374 to the mixed substrate of lucerne hay and wheat straw appeared to have been beneficial for microbial colonization of feed particles as a result of the increased rumen activity. It could be speculated that the primary microbial colonization was thus initiated, leading to the release of digestion products that attract in return additional bacteria to the site of digestion. This EFE may be efficient to produce some beneficial depolymerisations of the surface structure of the plant material and the hydrolytic capacity of the rumen to improve microbial attachment and the feed digestibility thereafter. Therefore, the mechanism of action by which Abo 374 improved the feed digestion can be attributed to the increased microbial attachment, stimulation of the rumen microbial population and synergistic effects with hydrolases of ruminal micro-organisms. With regard to these findings, the addition of EFE in ruminant systems can improve the ruminal digestion of DM, NDF and CP to subsequently enhance the supply of the metabolizable protein to the small intestine. Key words: crude protein (CP), exogenous fibrolytic enzymes (EFE), dry matter (DM), gas production (GP), neutral detergent fibre (NDF), microbial protein synthesis (MPS). / AFRIKAANSE OPSOMMING: Ruvoere is die hoof-voerkomponent in herkouer produksiesisteme aangesien dit dikwels die vernaamstebron van energie aan herkouer is. Slegs 10 tot 35% van die energie-inname is beskikbaar as netto-enrgie, omdat die vertering van selwande onvolledig is. Dit kan die prestasie en profyt in produksiesisteme drasties beïnvloed waar ruvoere as ’n hoofbron van nutriënte in die dieet gebruik word. Aangesien die nutriëntwaarde van ruvoere laag is en baie varieer, is navorsing vir verbeterde ruminale veselvertering steeds ’n voorgesette onderwerp. Dit is voorgestel dat eksogeniese fibrolitese ensieme (EFE) gebruik kan word vir verbeterde ruvoervertering. Positiewe resultate in ruminale ruvoerverterig en ander diereproduksie-eienskappe, is verkry as gevolg van toenemende rumen mikrobiese aktiwiteit na EFE aanvulling in herkouerdiëte. Twee EFE’s (Abo 374 en EFE 2) en `n gisproduk is geïdentifiseer en geselekteer vir hul potensiaal om die kumulatiewe gasproduksie (GP) na 24 uur met ’n reeks voersubstrate te verbeter met die gebruik van die in vitro GP sisteem as seleksiemetode om die superieure EFE produkte te identifiseer. Die verskillende ruvoersubstrate was lusernhooi, koringstrooi, ureumbehandelde koringstrooi en ’n kommersiële konsentraatdieet. ’n In vitro eksperiment was onderneem om die vier verskillende substrate te gebruik om die twee EFE’s en gisproduk te evalueer. Hierdeur sou die belowendste EFE’s identifiseer kon word wat ’n betekenisvolle effek op ruvoervertering het. Die vertering van ruvoer sal bepaal word deur organiese materiaal vertering (in vitro ware vertering), asook fermentasie-eienskappe (in vitro GP sisteem). Resultate van die in vitro evaluering het getoon dat EFE’s in vitro DM degradering en GP profiele verbeter. Dit blyk dat die Abo 374 ensiem ’n potensiële toemame in in vitro mikrobiese proteïensintese (MPS), soos bepaal deur die GP oorblyfsels van konsentraat diëte, tot gevolg gehad het. Daar was geen korrelasie tussen die in vitro GP en MPS van al die proefsubstrate nie. Dit blyk dat die behandelings ’n toename in in vitro GP, MPS en ruvoerdegradeerbaarheid van lae kwaliteit ruvoer- en konsentraatdiëte gehad het, waar Abo 374 die beste behandeling was. Die in vitro reaksies van die EFE’s was egter wisselend, afhangende van die energiekonsentrasie en die chemiese samestelling van die verskillende substrate. Variasie van MPS was meestal as gevolg van die lae herwinning van purienderivate tydens die purienanalise. Op grond van dié resultate, is Abo 374 geselekteer om verdere toetse in ander in vitro en in situ proewe te doen. Die substraat wat gebruik is, was ’n 1:1 mengsel van lusernhooi en koringstrooi. Abo 374 het die kumulatiewe RP, in vitro DM en NBV verdwyning van die gemengde substraat verbeter. Boonop is geen korrelasie tussen die MPS en in vitro GP gevind nie. In situ verdwyning van DM, NBV en RP was hoër vir Abo 374, maar nie betekenisvol nie. Die gebrek aan betekenisvolle verdwynings mag die gevolg wees van die klein hoeveelheid skape wat in die proef gebruik is, asook die relatiewe hoë koëffisient van variasie wat gepaard gaan met die bepaling van ruminale vertering. Abo 374 het die in situ MPS betekenisvol verhoog. Verhoogde MPS en in vitro en in situ verdwyning van DM en NBV is waargeneemwaarskynlik as gevolg van die aktiwiteit van Abo 374 gedurende die voorafbehandeling óf die verterings proses. Die byvoeging van Abo 374 tot die gemengde substraat van lusernhooi en koringstrooi blyk om voordelig te wees vir mikrobiese kolonisering van voerpartikels as gevolg van ’n toename in rumenaktiwiteit. Die primêre mikrobiese kolonisering het waaarskynlik gelei tot die vrystelling van verteringsprodukte wat addisionele bakterieë na die plek van vertering lok. Die EFE mag geskik wees vir voordelige depolimerisasie op die oppervlakstruktuur van die plantmateriaal, asook verbeterde hidrolitiese kapasiteit van die rumen om sodoende mikrobiese aanhegting, asook ruvoervertering te verbeter. Dus, Abo 374 se meganisme van aksie wat verbeterde ruvoervertering tot gevolg het, kan toegeskryf word aan `n verhoogde mikrobiese aanhegting, stimulering van die rumen mikrobiese populasie en die sinergistiese effek met hidrolases van rumen mikroörganismes. Ten opsigte van die bevindings, kan die byvoeging van EFE in herkouersisteme ruminale vertering van DM, NBV en RP verbeter, wat dan daaropvolgend die dunderm met meer metaboliseerbare proteïn sal voorsien. Sleutelwoorde: eksogene fibrolitiese ensieme (EFE), droëmaterial (DM), ruproteïen (RP), neutraal bestande vesel (NBV), mikrobiese proteïensintese (MPS), gasproduksie (GP).