Call number: LD2668 .T4 1955 P37 / Master of Science

Call number: LD2668 .T4 1962 T73

Call number: LD2668 .T4 1963 R34 / Master of Science

Call number: LD2668 .T4 1984 P44 / Master of Science

Call number: LD2668 .T4 1965 A13 / Master of Science

Thesis (MScAgric)--University of Stellenbosch, 2000. / ENGLISH ABSTRACT: Veal production is a specialised form of calf rearing in which calves were traditionally raised on all-liquid diets. The early weaning of calves onto concentrated diets provides an economically viable alternative rearing method with comparable calf performance. The emphasis in meat production has shifted to the production of lean meat, therefore the deposition of protein instead of fat has become a priority. The optimum level of dietary crude protein for growing calves is well established. Very little, however, is known about the influence of protein degradability in the diet of young ruminants. Recommendations by the NRC are derived from data obtained using lactating dairy cows. The aim was to obtain data on which recommendations for the level of degradable protein in starter and finisher diets for calves could be based. Two experiments were conducted to examine the effect of different levels of dietary crude protein degradability in starter and finisher calf diets on veal calf performance. In both experiments Holstein bull calves were 3 - 10 days of age at the onset, weaned at 4 weeks of age and slaughtered at 20 weeks of age for veal. In Experiment 1 calves were randomly assigned to one of three treatments: low (LO), medium (MD) and high (HO) rumen degradable protein. Calves received a starter diet up to 11 weeks of age and finisher diets from week 12 - 20. In Experiment 2 calves received a starter diet either high or low in rumen degradable protein up to 10 weeks of age. In the finishing period (week 11 - 20) both the low and high groups were again divided into a low and high group, resulting effectively in 4 treatments, viz. LL, LH, HL and HH. The diets in both experiments were formulated to be iso-nitrogenous and iso-caloric, differing only in rumen undegradable protein content within periods and. respective experiments. Body weight gain, feed intake and feed conversion efficiency data for the preweaning, starter, finishing and total experimental period was compared between treatments. There were no significant differences for feed intake, body weight gain or feed efficiency in the starter period of both experiments between treatments. In the finishing period of Experiment 1 the average daily gain for the LO treatment was significantly higher than for the HO treatment, with the MD treatment having an intermediate value. The feed conversion ratio (FCR) for the LO treatment was also significantly better than for the other two treatments. In Experiment 2 the FCR tended (P = 0.0984) to differ between treatments in the finishing period. Calves from the LL and HL treatments had a more favourable FCR than calves from the LH treatment. The HH treatment had an intermediate FCR. According to these results crude protein degradability appears to have an effect on the FCR in the finishing period. The lack of response to higher levels of undegradable dietary protein in calves younger than 10 weeks may be due to underdeveloped rumen functions and it seems possible for high degradable protein to escape degradation to a higher extent than at a later age. In a third experiment, Holstein bull calves and Holstein cows were used to determine and compare the dry matter and crude protein degradability of the four calf diets used in Experiment 2. Rumen VFA concentrations, pH level and NH3-N concentrations were measured for the cannulated Holstein calves to evaluate the level of rumen metabolic maturity of growing calves. Five Holstein bull calves were ruminally cannulated at 6 weeks of age. Dry matter and crude protein degradability were determined once weekly from week 8 - 20 by means of 24 h in sacco incubations. Three ruminally cannulated Holstein cows were used to determine the comparable values for mature ruminants. Dry matter and crude protein degradability differed significantly between the low and high degradable diets for both calves and cows. Dry matter and crude protein degradability in calves increased up to 11 and 12 weeks of age respectively, and then appeared to remain constant to week 20. Dry matter and crude protein degradability values of the starter diets were lower for the calves than for the cows, but values were similar for the finisher diets. Rumen VFA concentrations, pH level and NH3-N concentration showed some fluctuation between weeks, but were similar to literature values for mature animals. / AFRIKAANSE OPSOMMING: Titel: Die invloed van verskillende vlakke van proteïendegradeerbaarheid in aanvangs- en afrondingsdiëte op kalfprestasie in 'n kalfsvleisproduksiestelsel. Kalfsvleisproduksie is 'n gespesialiseerde grootmaakstelsel wat tradisioneel alleenlik op vloeistofdiëte gebaseer was. 'n Stelsel waar kalwers vroeg gespeen word en 'n volledige aanvangs- en afrondingsrantsoen ontvang, bied 'n alternatiewe metode wat ekonomies lewensvatbaar is en vergelykbare kalfprestasie tot gevolg het. Die klem in vleisproduksie het verskuif na die produksie van maervleis. Die neerlegging van proteïen in plaas van vet het dus 'n prioriteit geword. Die optimale vlak van dieetproteïen vir groeiende kalwers is deeglik nagevors. Baie min is egter bekend oor die invloed van proteïendegradeerbaarheid in die dieet van jong herkouende diere. Aanbevelings deur die NRC is afkomstig van data verkry van studies met melkproduserende koeie. Die doel was om data te bekom waarop aanbevelings vir die vlak van degradeerbare proteïen in aanvangs- en afrondingsdiëte vir kalwers gegrond kan word. Twee eksperimente is uitgevoer om die invloed van verskillende vlakke van proteïendegradeerbaarheid in aanvangs- en afrondingsdiëte op kalfprestasie in 'n kalfsvleisproduksiestelsel te ondersoek. Holstein bulkalwers was 3 - 10 dae oud met die aanvang van beide eksperimente, is gespeen op 4 weke ouderdom en op 20 weke ouderdom vir kalfsvleis geslag. In Eksperiment 1 is kalwers ewekansig aan een van drie behandelings toegewys: lae (LO), medium (MD) en hoë (HO) rumen degradeerbare proteïen. Kalwers het tot op 11 weke ouderdom aanvangsdiëte ontvang, terwyl afrondingsdiëte vanaf 12 - 20 weke ouderdom aangebied is. In Eksperiment 2 het kalwers tot op 10 weke ouderdom "n dieet wat óf hoog óf laag in rumen degradeerbare proteïen was, ontvang. In die afrondingsperiode (week 11 - 20) is die lae en hoë groepe elk vervolgens in "n lae en hoë groep verdeel wat effektief tot 4 behandelings gelei het, nl. LL, LH, HL en HH. Die diëte in albei eksperimente was geformuleer om iso-nitrogenies en iso-kalories te wees. Slegs die rumen degradeerbare proteïeninhoud het tussen die onderskeie diëte binne "n bepaalde periode en eksperiment verskil. Gewigstoename, voerinname en voeromsettingsdoeltreffendheid vir die voorspeense-, aanvangs-, afrondings- en totale eksperimentele periode is tussen behandelings vergelyk. In beide eksperimente is geen betekenisvolle verskille gedurende die aanvangsperiode waargeneem t.o.v. voerinname, massatoename en voeromsettingsdoeltreffendheid (VOD) nie. In die afrondingsperiode van Eksperiment 1 was die gemiddelde daaglikse massatoename van die LO behandeling betekenisvol hoër as dié van die HO behandeling, terwyl die MD behandeling "n intermediêre waarde gehad het. Die VOD vir die LO behandeling was ook betekenisvol beter as vir die ander twee behandelings. Die VOD in die afrondingsperiode van Eksperiment 2 het geneig (P = 0.0984) om te verskil tussen behandelings en kalwers van die LL en HL behandelings het "n meer gunstige VOD as kalwers van die LH behandeling gehad. Die HH behandeling het "n intermediêre VOD gehad. Volgens die resultate van hierdie eksperimente het proteïendegradeerbaarheid in kalfrantsoene waarskynlik "n invloed op VOD in die afrondingsperiode. Die gebrek aan respons as gevolg van hoër insluitingsvlakke van nie-degradeerbare proteïen in die rantsoen by kalwers jonger as 10 weke kan moontlik toegeskryf word aan onderontwikkelde rumenfunksies. Dit blyk moontlik te wees dat die hoë degradeerbare proteïenfraksie by jonger kalwers rumendegradering in "n hoër mate as op "n latere ouderdom vrygespring het. In "n derde eksperiment is Holstein bulkalwers en Holstein koeie gebruik om die droëmateriaal- en proteïendegradeerbaarheid van die vier diëte wat in Eksperiment 2 gebruik is, te bepaal en te vergelyk. Rumen WS-konsentrasies, pH-vlak en NH3-Nkonsentrasies is vir die kalwers gemeet om die vlak van metaboliese rumen volwassenheid van groeiende kalwers te evalueer. Vyf Holstein kalwers is op 6 weke ouderdom ruminaal gekannuleer. Droëmateriaal- en proteïen-degradeerbaarheid is een maal per week vanaf week 8 - 20 deur middel van 24 h in sacco inkubasies bepaal. Drie rumen-gekannuleerde Holstein koeie is gebruik om die vergelykbare waardes van volwasse herkouers te bepaal. Droëmateriaal- en proteïendegradeerbaarheid het betekenisvol tussen die lae en hoë degradeerbare diëte vir beide die kalwers en koeie verskil. Droëmateriaal- en proteïendegradeerbaarheid by die kalwers het tot op 11 en 12 weke ouderdom, onderskeidelik, verhoog en daarna tot week 20 relatief konstant gebly. Die droëmateriaal- en proteïendegradeerbaarheidswaardes van die aanvangsdiëte was laer vir die kalwers as vir die koeie, maar die waardes vir die afrondingsdiëte was eenders. Rumen WS-konsentrasies, pH-vlak en NH3-N-konsentrasies het In mate van fluktuasie tussen weke getoon, maar was soortgelyk aan literatuurwaardes vir volwasse diere.

Thesis (MPhil (Agrisciences)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: In South Africa quail do not have the same status as an agricultural produce as do other livestock species. As quail has mostly been judged as a cute little bird seen on shows, very few people have paid attention to the commercial value of this bird specie. In South Africa quail farming is done on a very limited scale, but competition regarding this very unique market is already challenging. If it is to be a viable project it is of utmost importance to limit the costs to the minimum and, by doing so, increasing the profitability of the project. In this study the economic aspects of a quail production unit was researched to assess whether any improvements in profitability could be made. Quails from a production unit outside Stellenbosch were used to describe the growth curves of these birds under three different diet regimes. 300 Birds were used and then divided into groups of a hundred. The first treatment was fed the standard starter (22% protein) then after five weeks a finisher (19% protein). The second treatment was fed a starter ration containing 40% Soya oil cake and 60% of the standard starter (27.2% protein). The same finisher as in treatment one was fed to treatment two after five weeks. Treatment three was fed a newly formulated starter ration (28% protein). The same finisher was fed to treatment three after five weeks as with the first two treatments. It was found that treatments one and two differed significantly from treatment three, but not from each other. It was expected that treatment three would result in better growth than treatment one, but contrariwise, treatment three did the worst. In accordance with literature it was found that under commercial conditions quail could be fed lower concentrations of protein than prescribed by literature. / AFRIKAANSE OPSOMMING: As 'n landbouproduk het kwartels in Suid-Afrika nie dieselfde status as ander lewende hawe nie. Omdat kwartels merendeels gesien is as 'n oulike klein voeltjie op skoue, het weinig mense enige aandag gegee aan die kommersiele waarde van kwartels. Alhoewel kwartelboerdery in Suid-Afrika huidiglik slegs op 'n baie klein skaal bedryf word, is kompetisie in hierdie nismark reeds kompeterend en uitdagend. Om so 'n boerdery ekonomies vatbaar te maak en hoe profyt marges te handhaaf, is dit van wesenlike belang om insetkostes tot die minimum te beperk. In hierdie studie is ekonomiese aspekte van 'n kwartel produksie eenheid nagevors om sodoende te kon bepaal op watter aspekte, indien enige, gekonsentreer kan word om wins marges te verhoog. Kwartels van 'n produksie eenheid buite Stellenbosch is gebruik. Hierdie kwartels is op drie verskillende diete geplaas en afsonderlik ge-evalueer om die groeikurwes op elke dieet te bepaal. Driehonderd kwartels is in groepe van honderd elk verdeel. Die eerste groep se dieet het bestaan uit die standaard beginners groeimeel wat deur Meadows vervaardig word (22% proteren), en is na vyf weke afgerond na 'n afrondings dieet (19% proteren). Die tweede groep se dieet was dieselfde beginners dieet as in groep een wat met 40% Soya oliekoek gemeng is (totale proteren inhoud van 27.2%). Daar is na vyf weke oorgeslaan na dieselfde afrondings dieet as in groep een. Die derde dieet het bestaan uit 'n nuut geformuleerde beginners dieet (28% proteren). Weereens is daar na vyf weke oorgeslaan na dieselfde afrondings dieet as in die vorige twee groepe. Daar is gevind dat die groeikurwes van diete een en twee beduidend verskil het van dieet drie, maar daar was nie 'n beduidende verskil tussen groepe een en twee nie. Alhoewel daar verwag is dat dieet drie 'n beter groeikurwe sou toon as dieet een, was dit egter nie die geval nie. Dieet drie het egter die swakste groeikurwe getoon. Daar is dus gevind dat kwartels onder kommersiele toestande laer konsentrasies proteren gevoer kan word as wat algemeen voorgeskryf word.

Urea was applied uniformly inside alfalfa hay bales at baling or on top of bales subjected to rain and weather damage. Hay temperature, color, mold retardation and chemical composition were measured. Also, 24 lactating cows were used to test acceptability of the urea-treated hays. Cows were blocked for 14 d pre-treatment milk production and randomly assigned to one of six treated hays for 3 wk (4 cows/group). Cows were then reassigned at random to another hay for an additional 3 wk. Addition of 1% or more urea to high moisture alfalfa hay resulted in higher nutritional quality through reducing bale temperatures, non-enzymatic browning, and moldiness, compared to high moisture untreated hay. Urea treatment of high moisture hay decreased ADF and NDF content, while increasing digestibility of their fiber components. Urea treated hays were readily eaten by cows with no significant differences (P>.05) between treatments in DM intake, milk production, milk composition, or DM, ADF, and NDF digestion coefficients. Five types of alfalfa hay varying in % ADF were fed to 40 lactating cows. Cows were divided into 10 groups of 4 each based on 14-d pre-treatment milk. Each hay was mixed in TMR diets with 50 or 65% concentrate. In vivo and in situ trials were conducted to determine DM, ADF and NDF digestion. Results indicated that DMI, 3.5% FCM, cows body weight, body score, rectal temperature, and milk composition except milk fat were not affected by type of hay or level of concentrate. Milk fat was affected by level of concentrate (P<.16) while milk production was affected by type of hay (P<.01). Dry matter digestion coefficients for the complete rations showed no change with increased ADF in hay. Large decreases were noted in in situ DM, ADF, and NDF digestion as hay ADF increased. In another experiment, 32 mid to late lactation cows were used in a 41 d production trial. Cows were fed 2 levels of concentrate (25 vs. 50%) with alfalfa hay. Data indicated that DMI, milk yield, 3.5% FCM, milk composition, and other parameters did not differ between treatments. This might be due to the lack of response to higher concentrate level.

Liver glutathione peroxidase activity is affected by changes in selenium (Se) status. To investigate the effect of Se status on GSH-Px protein we prepared antibodies against rat liver GSH-Px and used them in an ELISA. The immunoreactivity of the anti-GSH-Px antibodies against GSH-Px was both tissue and species specific. When rats were depleted of Se, liver GSH-Px activity decreased exponentially to zero with a half-life of 2.8 d. Liver GSH-Px protein also decreased exponentially, but not to zero, with a longer half-life of 5.2 d. Dietary repletion of Se-deficient rats with 0.5 mg Se/kg diet increased GSH-Px protein and activity after 1 d. After 14 d of repletion the levels of GSH-Px protein and activity had plateaued at the levels present in Se-adequate rats. When Se-deficient rats were injected with 15 or 60 ug Se, only rats injected with 60 ug Se and killed 24 h later showed an increase in GSH-Px protein and activity. These results suggest that when Se is limiting, GSH-Px protein and GSH-Px activity are coordinately regulated by the available Se, but in Se-adequacy homeostatic processes control the level of GSH-Px.

The effects of dietary methionine (Met) on the utilization of selenium (Se) from stored tissue Se and dietary selenomethionine (SeMet) for glutathione peroxidase (GSH-Px) synthesis were studied in male rats. Plasma, liver and muscle Se significantly increased when rats were fed 0.5 mg Se/kg diet as SeMet in a Met-deficient diet for 21 d, whereas tissue GSH-Px activities decreased 43-50% during the SeMet supplementation period, suggesting that Se is deposited as SeMet in general body proteins. By calculation, a significant lower percentage of Se was associated with GSH-Px in Met-deficient as compared to Met-supplemented rats. Dietary Met supplementation increased the incorporation of 75Se from 75SeMet into specific rat selenoproteins in addition to liver GSH-Px. Overall, these results suggest that intact SeMet is preferentially incorporated non-specifically into general body proteins in Met-deficient rats, whereas with supplemental Met, more SeMet is degraded and the released Se used for specific selenoprotein synthesis. (Abstract shortened with permission of author.)