Forage of beta-carotene-fortified orange-fleshed sweet potato is essential for alleviation cattle malnutrition. The study aims were to determine effects of supplementing sweet potato (SP) roots and sun dried forage on degradation of dietary legumes, intake and milk yield in dairy cattle. Mature SP roots were oven dried and forage vines and leaves (V&L) sun dried. Lactating dairy were supplied meals with total mixed ration (TMR) constituting varying levels of sweet potato forage and concentrate. The SP flour was rapidly and completely degraded In Sacco while degradability of V&L was comparable to that of Lucerne hay. Rumen degradation of Lucerne was reduced when the legume was incubated proximal to SP. Substitution of TMR with fresh SP forage and flour meal increased degradability of diets. Glucose post-feeding was increased (P<0.05) by SP roots but no change in milk yield. Orange-fleshed SP forage is recommended for improving energy supply in lactating cow diets / Agriculture and  Animal Health / M. Sc. (Agriculture)

Made available in DSpace on 2016-12-08T16:24:23Z (GMT). No. of bitstreams: 1 PGCV04MA001.pdf: 365827 bytes, checksum: 83549fc5b733303769d0838e07c56a4e (MD5) Previous issue date: 2004-12-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work the effects of the total and partial substitution of ground corn for dry rolled barley on the production and composition of milk was evaluated. Twenty-eight primiparous and multiparous Holsteins cows were used, with an average of 125 days in milk at the beginning of the experiment. The design of the experiment was a 4x4 latin square, each square being repeated seven times. Once a day, the diet was supplied in a totally mixed ration (TMR). Four levels of barley substitution for corn were tested, based on the dry matter of the concentrate (T1 - 0% barley; T2 - 33 % barley; T3 - 67% barley; and T4 - 100% barley). Diets were balanced according to the results of nutrient analysis of the feedstuffs. The ratio forageconcentrate, based on the dry matter intake (DMI), was of 55% to 45%. The experiment had a total duration of 105 days, including an initial adaptation period of 21 days and four periods of 21 days for treatment. The first 14 days of each treatment period were destined to the adaptation to the diet and the seven remaining days for data collection. The cows were milked twice a day (05:00 and 16:00 h), in a 4x4 milking parlour. The milk production was registred electronically measured. The contents of fat, protein, total solids of the milk, as well as the somatic cell count (SCC) were obtained on the 18th and 21rst day of each treatment period and the milk urea nitrogen (MUN) was determined at the end of each period. The body condition score (BCS) was evaluated at the beginning and end of each period. The mean values of dry matter intake (DMI), milk yield, production of 4% fat-corrected milk (FCM), and fat and protein contents, as well as their standard error of the mean were of 19.64±0.18kg, 26,95±0.12kg, 25.76±0.13kg, 3.72±0.02% and 3.23±0.01%, respectively. DMI decreased in a linear fashion when barley substituted for corn in the diet. The intake of crude protein (CP), neutral fiber detergent (NDF) and acid fiber detergent (ADF) however were not affected when substituting corn by barley. Linear reduction was observed in milk yield, FCM production and fat and protein contents of the milk as a function of the level of corn substitution by barley, while the protein percentages increased in a linear manner. No effect was registered concerning the levels of substitution on the protein production, total solids of the milk, SCC, MUN and on the conversion efficiency / O objetivo deste trabalho foi avaliar os efeitos da substituição total e parcial de grãos de milho moídos por grãos de cevada laminados sobre a produção e composição do leite, bem como, verificar quais os níveis de substituição são mais adequados. Foram utilizadas 28 vacas Holandesas, primíparas e ,multíparas, com média de 125 dias de lactação ao início do experimento, em um delineamento do tipo Quadrado Latino 4x4, sendo cada quadrado repetido 7 vezes. A dieta foi fornecida na forma de dieta totalmente misturada (DTM), 1 vez ao dia. Foram testados 4 níveis de substituição de milho por cevada, com base na matéria seca do concentrado (T1 0% cevada; T2 33 % cevada; T3 66% cevada; e T4 - 100% cevada). As dietas foram balanceadas com base na análise bromatológica dos alimentos utilizados. A relação volumoso:concentrado, baseada na ingestão de matéria seca (IMS), foi de 55%:45%. O experimento teve uma duração total de 105 dias, constituído de um período de adaptação de 21 dias e 4 períodos de 21 dias por tratamento, sendo os 14 primeiros dias de cada período para adaptação à nova dieta e os 7 dias restantes para a coleta de dados. As ordenhas foram feitas 2 vezes ao dia (05:00 e 16:00 hs), em sala de ordenha 4x4, sendo que a medição do leite foi feita eletronicamente. A percentagem de gordura, proteína e extrato seco total do leite, bem como a contagem de células somáticas foram determinadas 2 vezes nos dias 18 e 21 de cada período e a determinação do nitrogênio ureíco no leite (NUL) foi efetuada ao final de cada período. A avaliação do escore da condição corporal (ECC) foi feita no início e no fim de cada período. Os valores médios de IMS, produção de leite, produção de leite corrigido para 4% (LCG), e percentagens de gordura e proteína , bem como seus erros-padrão foram de 19,64±0,18 kg, 26,95±0,12 kg, 25,76±0,13 kg, 3,72±0,02% e 3,23±0,01%, respectivamente. A IMS decresceu linearmente quando a cevada substituiu o milho na dieta. Porém a ingestão de proteína bruta (PB), fibra em detergente ácido (FDA) e fibra em detergente neutro (FDN) não foram afetadas pela substituição do milho pela cevada. Foi observada redução linear na produção de leite, LCG, produção e na percentagem de gordura do leite em função do nível de substituição de milho por cevada, enquanto a percentagem de proteína aumentou linearmente. Não houve efeito do nível de substituição sobre a produção de proteína, extrato seco total (EST), contagem de células somáticas (CCS), NUL e na eficiência alimentar (EA)

Variations in composition and disappearance of nutrients in dairy cattle feeds are dictated by ingredients, methods of processing, storage while milk production levels depend on the animal, environmental factors and largely on pools of available carbohydrates, proteins, vitamins and minerals in the concentrate feeds. There is a wide variety of concentrates for dairy cattle on the formal and informal markets and dairy farmers need to be astute in selecting feeds appropriate for specific production periods and animals to sustain their businesses. Composition of nutrients displayed on concentrate containers is however inadequate for in-depth assessment of products. This study determined nutrient composition, rumen dry matter disappearance and microbial colonization on residual substrate on commercial concentrate feeds and simulated total mixed rations for dairy calves, heifers, lactating and dry cows based on common feeding guidelines. Equivalent feeds for each herd group were obtained from three suppliers in the formal markets in Gauteng province of South Africa, making a total of twelve. An analysis of the data on container labels for the herd groups displayed similar feed values, as also reflected on the recommendation Tables of Act 36: Feeds and Fertilizer bill 1947 of South Africa. / Agriculture, Animal Health and Human Ecology / M.Sc. (Agriculture)

Master of Science

South African dairy farmers have generally used kikuyu pasture to tide them over from one ryegrass season to the next, and as a result of its resilient nature, have assumed careful management of it to be unnecessary. This has resulted in its mismanagement which is unaffordable in current times where the profitability of dairy farming is increasingly dependent on low input, pasture-based systems. Kikuyu pasture may play a larger role in supplying nutrients to dairy cattle over the summer months in future as the alternative home produced feed sources such as silage and perennial ryegrass become increasingly unaffordable. Improving animal production from kikuyu is difficult as there is little information relating kikuyu pasture management to dairy cow performance. Efficient utilization and quality of temperate pasture have been more comprehensibly researched. The relations discovered between the chemical compounds in temperate grass species have been applied to tropical pastures such as kikuyu with limited success and often confusing results. For example, crude fibre in kikuyu was found to be positively related to digestibility. In South Africa, much research has been done on the use of kikuyu in beef production systems. This information has been applied to dairy farming systems with limited success, owing to the higher metabolic demands of dairy animals. Pasture farming needs to become more precise to improve pasture quality and hence milk yields as research trials focussing on stocking rate and grazing system comparisons have yielded results that are too general with little application at the farming level. A need for integrated and flexible management of animals and pastures has been recognised. The grazing interval is a key aspect in improving pasture and animal performance and fixed rotation lengths and stocking rates have been identified as being detrimental to performance. The relation between growth stage and pasture quality has lead researchers to identify plant growth characteristics, such as pasture height and leaf stage, as signs of grazing readiness. At the four and a half leaves per tiller stage of regrowth, the chemical composition ofthe kikuyu plant is more in line with the requirements ofthe dairy cow, with the leaf to stem ratio at its highest. The primary limitation of kikuyu pasture is a lack of energy, particularly readily fermentable carbohydrate, which makes the fermentation of structural carbohydrates difficult and dry matter intakes are reduced. Other limitations to animal performance include high cell wall constituents, low calcium, magnesium and sodium content and antinutritional factors such as nitrate and insoluble oxalate. These deficiencies and antinutritional factors are in some cases unique to 5 kikuyu pasture, meaning that kikuyu specific supplementation may be the key to improving performance from dairy cattle grazing kikuyu pasture. The objectives are to evaluate current kikuyu management systems in South Africa and their impact on dairy cow performance and to evaluate the use of pasture height and burning as quality control tools. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2007.

This study investigated the effects of Brevibacillus laterosporus and live yeast (LY) on rumen fermentation, nutrient digestibility and microbial protein synthesis. The basal diet was a total mixed ration formulated to fulfil the minimum nutrient requirement of early lactating 600 kg Holstein cow producing 40kg of milk with 3.5 % fat and 3.3 % protein using CPM-dairy software (NRC, 2001). Treatments were: T1 (Control: basal diet with no additive), T2 (Basal diet + Brevibacillus laterosporus), T3 (Basal diet + Live yeast), and T4 (Basal diet + Brevibacillus laterosporus + Live yeast). In situ degradation, in vitro batch fermentation were performed. Data obtained were subjected to analysis of variance (ANOVA) using PROC GLM (SAS Institute, 2009). The effective dry matter (DM) degradability evaluated at low (0.02) and medium (0.05) ruminal passage rate (ED1 and ED2) were higher (p<0.05) in T1 compared to T2 and T3, but did not differ (p>0.05) between T2, T3 and T4, and between T1 and T4. When evaluated at fast passage rate (0.08) the effective DM degradability (ED3) was higher (p<0.05) in T1 compared to T3 and T4, but did not differ (p>0.05) between T1 and T2. The difference in ammonia nitrogen production was observed only between T1 and T2, and was higher (p<0.05) in T1. The total VFA’s concentration was higher (p<0.05) in T3 compared to the control. All additives decreased the molar percentage of acetate (P<0.05). The concentration of acetate was lower (p<0.05) in T3 and T4 compared to control. Propionate concentration was higher (p<0.05) in T3 and T4 compared to other treatments and lower (p<0.05) in the control compared to the rest of treatments. Butyrate concentration was higher (p<0.05) in T2 and T4 compared to the rest of the treatments, and lower (p<0.05) in T3 than other treatments. The microbial protein synthesis measured as purine derivate done on residues was higher (p<0.05) for T3 compared to T1 and T2, but did not differ between T1, T2 and T4, and between T3 and T4. These results showed that the two additives have different individual effects on DM and CP degradability, but also associative effects in some fermentation parameters such as propionate production. / Agriculture, Animal Health and Human Ecology / M. Sc. (Agriculture)