No abstract available / Thesis (PhD)--University of Pretoria, 1953. / Original thesis in typescript / Includes bibliographical references. / Production Animal Studies / PhD / Unrestricted

Includes bibliographical references (leaves [259]-290) Investigates nitrogen assimilation and metabolism in rumen bacteria with the object of understanding the basic process and their controls.

Includes bibliographical references (leaves 196-220) Studies the growth, body composition, feed intake of grazing animals, the use of anabolic agents, fatty acid composition of ruminants fats; and, the effect of saturated fat on human health.

Includes bibliographical references (leaves [259]-290) / xxviii, 290 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Investigates nitrogen assimilation and metabolism in rumen bacteria with the object of understanding the basic process and their controls. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Sciences, 1991

Bibliography: leaves 102-114. This study evaluates the difference in the nutritive value of rice straw varieties using chemical composition and digestibility measurements. It assesses several methods for improving the nutritive value of rice straw and the effect of urea treatment and rice straw quality on the colonisation of ruminal fungi and the characteristics of stem tissue structure.

Data is limited evaluating infrequent supplementation of urea or biuret to ruminants consuming low-quality forage (<6% crude protein). Therefore, a series of experiments were designed to compare the effects of daily (D) and alternate day (2D) supplementation of two non-protein nitrogen (NPN) sources (urea or biuret) to ruminants consuming low-quality forage. Experiment 1 was a N balance study using five wethers in an incomplete 5 x 4 Latin square design (five treatments; four 24-d periods) with a 2 x 2 factorial arrangement of treatments (two sources of NPN and two supplementation frequencies) and an unsupplemented control. Supplements, consisting of urea or biuret mixed with ground soy hulls and dried molasses, were isonitrogenous (approximately 26% crude protein; dry matter basis) and offered D or 2D. The 2D supplemented lambs received double the quantity of supplemental N on their supplementation day compared with D lambs; therefore, all D and 2D treatments received the same amount of supplemental N over a 2-d period. Experiment 2 was a 70-d cow performance study using 80 spring-calving cows during the last third of gestation. Cows were stratified by age, body condition score, and expected calving date, and assigned randomly within stratification to one of the five treatments described in Experiment 1 above. They were then sorted by treatment and randomly assigned to 1 of 20 pens (4 cows/pen, 4 pens/treatment). Experiment 3 was a site of digestion study using five ruminally and duodenally fistulated steers to compare D and 2D supplementation of urea or biuret on forage intake, ruminal fermentation, site and extent of nutrient digestion, and rumen microbial efficiency. Five ruminally and duodenally fistulated steers were used in an incomplete 5 x 4 Latin square design with the same treatments described in Experiment 1. The results for Experiment 1 reported that DM, OM, and N intake, DM, OM, and N digestibility, N balance, and digested N retained were greater (P<0.03) for supplemented wethers compared with CON with no difference (P>0.05) because of NPN source or SF. Supplemented lambs had increased plasma urea N (PUN) compared with CON (P<0.01) and urea treatments had greater PUN compared with biuret (P<0.01). Also, PUN was increased (P=0.02) for D compared with 2D treatments. In addition, data suggest that PUN exhibited less fluctuation on the day of a supplementation event for biuret compared with urea. Experiment 2 demonstrated that pre- and post- calving (within 14 d and 24 h of calving, respectively) cow weight and body condition score changes were more positive (P<0.05) for supplemented groups compared with the CON. In Experiment 3, forage OM intake and OM digestibility were not affected (P>0.05) by NPN supplementation, NPN source, or SF. However, total OM and N intake were increased (P<0.01) with supplementation. Duodenal flow of OM tended (P=0.08) to increase with NPN supplementation while N flow was greater (P=0.04) with NPN supplementation compared with the control. In addition, duodenal bacterial N flow was increased with NPN supplementation (P=0.04) and for biuret compared with urea (P<0.01). Bacterial efficiency (g bacterial N/kg OM truly digested in the rumen) was greater for the control compared with NPN treatments (P<0.01) while biuret had greater true N disappearance compared with urea (P=0.01). Intestinal disappearance (% of duodenal flow) of OM and N was not affected by NPN supplementation, NPN source, or SF. However, apparent total tract N digestibility was increased with NPN supplementation (P<0.01) and not affected by NPN source or SF. In addition, ruminal NH���-N increased (P<0.04) on the day all supplements were provided and the day only daily supplement were provided with supplemental NPN. However, an NPN source x SF interaction (P=0.03) on the day all supplements were provided indicated NH���-N increased at a greater rate for urea as SF decreased compared with biuret. Ruminal NH���-N on the day only daily supplements were provided was greater for D compared with 2D (P=0.02). This data suggests that ruminal degradation of biuret to NH���-N was more moderate and prolonged compared with urea, possibly improving use by ruminal microflora. On the day all supplements were provided, D treatments had increased (P=0.05) ruminal indigestible acid detergent fiber passage rate and ruminal liquid volume compared with 2D treatments. Overall, NPN supplementation when feeding low-quality forage (<6% CP) was more beneficial than compared to a negative control, for increasing efficiency of forage digestion, N use, and animal performance. While at the same time indicating that the infrequent supplementation of urea or biuret was not detrimental to forage nutrient utilization, N efficiency or cow performance. This research will provide researchers and ruminant livestock producers with original information that can be used in designing winter supplementation strategies that decrease supplementation costs. Keywords: Urea, Biuret, Forage, Non-Protein Nitrogen, Supplementation, Frequency / Graduation date: 2003

No description available.

Made available in DSpace on 2014-06-11T19:33:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-12-17Bitstream added on 2014-06-13T21:06:39Z : No. of bitstreams: 1 silva_tls_dr_botfmvz.pdf: 469730 bytes, checksum: fef540eada210b35cbd086f20dc1bed2 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / O objetivo do presente estudo foi avaliar a qualidade da carne de cordeiros mestiços Santa Inês alimentados com levedura (Saccharomyces cerevisiae) inativa da cana-de-açúcar em substituição ao farelo de soja. Foram ofertadas dietas com quatro níveis de substituição (0, 33, 66 e 100%) de levedura aos animais que foram abatidos com 35 kg de peso vivo. Foram realizadas as análises físicas e a determinação de umidade, proteínas, cinzas, gordura e colesterol no músculo Longissimus dorsi. Os níveis de substituição de 33 e 100% influenciaram a composição protéica da carne e os valores de lipídio não apresentaram diferença entre os tratamentos (P>0,05). O teor de colesterol foi menor para os animais que receberam dietas contendo levedura. O índice de fragmentação miofibrilar apresentou diferença entre os níveis de substituição. A maciez, quando analisado pelo método físico, foi satisfatória em carnes do tratamento 33% de substituição / This study aimed to evaluate Santa Inês lambs meat wich was fed with inactive yeast (Saccharomyces cerevisiae) instead of soy meal. The treatments offer were four levels (0, 33, 66 e 100%) of yeast to animals until the weight average 35 kg and they were slaughtered. The analyses were physical and humidity determination, protein, ash, fat cholesterol and in Longissimus dorsi muscle. The inclusion levels influenced in the protein composition of meat. The lipid values were similar (p> 0,05) between the treatments. The values of the tenderness fragmentation index showed variation between treatments. When the softness was analyzed by a physical method it confirmed that the meat has a satisfactory level of tenderness and cholesterol is similar to animals fed with yeast

Orientador: André Mendes Jorge / Coorientador: José Teodorico de Araújo Filho / Banca: Cledson Augusto Garcia / Banca: Paulo Roberto Meirelles / Banca: Cristiana Andrighetto / Banca: Janaina Haddich Conte / Resumo: O objetivo do presente estudo foi avaliar a qualidade da carne de cordeiros mestiços Santa Inês alimentados com levedura (Saccharomyces cerevisiae) inativa da cana-de-açúcar em substituição ao farelo de soja. Foram ofertadas dietas com quatro níveis de substituição (0, 33, 66 e 100%) de levedura aos animais que foram abatidos com 35 kg de peso vivo. Foram realizadas as análises físicas e a determinação de umidade, proteínas, cinzas, gordura e colesterol no músculo Longissimus dorsi. Os níveis de substituição de 33 e 100% influenciaram a composição protéica da carne e os valores de lipídio não apresentaram diferença entre os tratamentos (P>0,05). O teor de colesterol foi menor para os animais que receberam dietas contendo levedura. O índice de fragmentação miofibrilar apresentou diferença entre os níveis de substituição. A maciez, quando analisado pelo método físico, foi satisfatória em carnes do tratamento 33% de substituição / Abstract : This study aimed to evaluate Santa Inês lambs meat wich was fed with inactive yeast (Saccharomyces cerevisiae) instead of soy meal. The treatments offer were four levels (0, 33, 66 e 100%) of yeast to animals until the weight average 35 kg and they were slaughtered. The analyses were physical and humidity determination, protein, ash, fat cholesterol and in Longissimus dorsi muscle. The inclusion levels influenced in the protein composition of meat. The lipid values were similar (p> 0,05) between the treatments. The values of the tenderness fragmentation index showed variation between treatments. When the softness was analyzed by a physical method it confirmed that the meat has a satisfactory level of tenderness and cholesterol is similar to animals fed with yeast / Doutor

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Resource Conservation Biology. Johannesburg, 29 May 2017. / An understanding of animal foraging behaviour is key to proper management strategies that ensure the survival and species persistence within nature reserves. Here the foraging behaviour of ruminant (hartebeest and wildebeest) and non-ruminant (zebra) grazers were observed and compared between two areas with distinctively different vegetation structure, the natural vegetation (NL) and previously cultivated land (PCL), in Telperion and Ezemvelo Nature Reserves (TENR). Natural vegetation was dominated by tall grass of low greenness with patches of short to very short grass, while the PCL was dominated by areas of very short to short grass (grazing lawns) with patches of medium to tall grass. Step rate (SR) and foraging time spent per feeding station (FTFS) were used as indices of foraging behaviour. I also measured the characteristics of the grass sward (grass height and greenness) grazed on by the three species. Both ruminants had high SR and low FTFS. Despite having similar SR and FTFS, ruminants grazed on grass of different height. Hartebeest preferred tall grass with low greenness content (0-10%), while wildebeest preferred short to very short grass and were significantly selective of areas with relative high greenness (11-50%) on PCL, more so than any other species. Compared to ruminant grazers the non-ruminant (zebra) had low SR and high FTFS and like hartebeest they grazed on medium to tall grass of very low greenness content (0 10%). This study did not reveal any difference in feeding behaviour within species between the two study sites. The finding of this study confirms that ruminant and non-ruminant species have different foraging behaviour, and habitat heterogeneity is necessary for the reserve to support different grazing species. Key words: digestive physiology, feeding station, step rate, wildebeest, hartebeest, zebra / GR2018