Published research suggests that it might be beneficial to increase the amount of rumen undegradable protein (RUP) that passes out of the rumen, through manipulation of rumen fermentation to establish a lower rumen pH. To test this hypothesis, a study was conducted in which three ruminally cannulated Holstein cows, 722 kg ±25.6 kg fed three different diets (treatments) were used in a Latin square design experiment to determine effects of increasing levels of dietary concentrate on some rumen parameters and ruminal crude protein (CP) degradability. The in situ method was used to determine the ruminal protein degradability of sunflower oilcake, cottonseed oilcake and roasted soya. The three treatments differed in roughage:concentrate ratio, being 60:40 (Treatment UP 60), 45:55 (Treatment UP 45) and 30:70 (Treatment UP 30). Intake of dry matter (DM) (kg/day) did not differ between treatments. The mean rumen pH in cows receiving the three experimental diets differed and was 6.00, 6.27 and 6.44 for treatments UP 30, UP 45 and UP 60 respectively. The time (hours) below pH 5.8, which is considered to be the pH where fibre degradation is substantially negatively affected, was approximately 2.5 hours, but only on treatment UP 30. Mean rumen ammonia nitrogen (N) and total volatile fatty acid (VFA) concentrations did not differ among cows receiving different treatments but, cows fed treatment UP 30 had a lower ruminal acetic acid:propionic acid (A:P) ratio compared to the other treatments. There were no differences in ruminal CP degradation within the three feedstuffs when incubated in cows fed diets with different roughage:concentrate ratios. Results suggest that roughage:concentrate ratios ranging from 60:40 to 30:70, which resulted in mean pH values ranging from 6.4 to 6.0, did not affect ruminal CP degradation of sunflower oilcake, cottonseed oilcake and roasted soya. / Dissertation (MSc(Agric))--University of Pretoria, 2009. / Animal and Wildlife Sciences / unrestricted

Four multiparous Holstein cows, averaging 44 days in milk and previously fitted with rumina1 and duodenal cannulae, were utilized in a 4 x 4 Latin square design to evaluate effects of dietary nonfibrous carbohydrate (NFC) and rumen undegradable protein (RUP) on metabolic and lactational parameters. Diets were isonitrogenous (17.4% CP) and structured in a 2 x 2 factorial arrangement with levels of NFC at 41 or 47% of dietary OM and RUP at 27 or 41% of dietary CP with inclusion of corn gluten meal, fish meal, and feather meal to increase dietary RUP. When cows were fed diets containing 47% NFC, intake of DM, OM, NFC, and N increased (P ± .05) while those containing 41 % NFC increased (P±.01) intake of NDF and ADF. Ruminal digestibility coefficients were not affected leading to greater quantities of NFC digested resulting in suppressed pH (P ±.01) and acetate (P ±.05) and increased propionate (P ± .05), Diets containing 27% RUP increased (P ±.01) ruminal ammonia and plasma urea nitrogen (N) with 41 % NFC eliciting higher ammonia N concentrations at each RUP level. Bacterial yields (averaging 220 g/d) were slightly higher when 41% NFC diets were consumed with no dietary effects on efficiency. Flow of ammonia N to the small intestine (SI) increased (P ± .01) with 27% RUP. When compared to 41% NFC, diets containing 47% NFC increased (P ± .05) flow of methionine (38.6 vs. 32.5 g/d). Fifty percent of the essential amino acids entering the SI were of bacterial origin. Diets containing 41% RUP elicited lower total tract digestion of N while enhancing that of hemicellulose. Total tract digestion of NFC and ADF was greater when 41% NFC diets were consumed. Yields of milk (38.7 vs. 37.7 kg/d) and lactose (1.94 vs 1.88 kg/d) increased with 27% RUP. Efficiency of production was increased by both 41% NFC and 27% RUP. Total and whey N in milk increased (P 5 ±.05) while milk urea N decreased (P ± .01) with higher (41%) dietary RUP. Increased (P ± .05) absorption of N (490.4 vs. 461.6 g/d) at the SI occurred with the 47 vs. 41 % NFC diets, respectively, with no effects observed on that retained or excreted in the urine or milk. Although supply of methionine to and the absorption of N from the S1 was greater with the 47% NFC diets, no positive effects were observed on nitrogen balance or milk production. Rather, dietary RUP provided greater promise in that lower dietary RUP increased milk production and efficiency while increased RUP enhanced milk N content. Therefore, economics regarding feed costs as well as price for milk and milk components may largely dictate preferential dietary RUP content. Abbreviation key: ADC = apparent digestion coefficient, CGM corn gluten meal, CRN = carbon hydrogen nitrogen, CHO = carbohydrate, CNCPS = Cornell Net Carbohydrate and Protein System, MUN = milk urea nitrogen, N = nitrogen, NAN = nonammonia N, NANMN = nonammonia nonmicrobial N, NFC = nonfibrous carbohydrate, NPN = nonprotein N, PUN = plasma urea N, RDP = rumen degradable protein, RUP = rumen undegradable protein, SI = small intestine, TDC = true digestion coefficient, 41:27 = 41% NFC and 27% RlUP, 47:27 = 47% NFC and 27% RUP, 41:41 = 41% NFC and 31% RUP, 47:41 = 47% NFC and 41% RUP. / Ph. D.

Submitted by Claudia Rocha (claudia.rocha@udesc.br) on 2018-03-15T17:08:18Z No. of bitstreams: 1 PGCA17MA214.pdf: 1462448 bytes, checksum: d0c357a0a70e666c70e6a3ccf065d2f6 (MD5) / Made available in DSpace on 2018-03-15T17:08:18Z (GMT). No. of bitstreams: 1 PGCA17MA214.pdf: 1462448 bytes, checksum: d0c357a0a70e666c70e6a3ccf065d2f6 (MD5) Previous issue date: 2017-03-23 / Capes / Energy is the most limiting nutrient to dairy cows at pasture, especially at tropical pastures. However when energy supplementation is offered, other nutrients may become limiting, as the protein under forms of Rumen Degradable Protein (RDP) or Rumen Undegradable Protein (RUP). The objective of this study was evaluate the effects of supplementation with energetic or energetic-proteic concentrate with protein sources of high or low rumen degradability to high producing Jersey cows grazing tropical grasses. Thirty Jersey cows (DIM 58.2 ± 44.4, milk yield 21.0± 4.4 kg and body weight 345.5 ± 32.1 kg at the beginning of the experiment) were assigned to one of three continuous treatments in a 12-wk trial (1 for adaptation and 11 experimental) from October to December, which consisted of three concentrate supplements: energetic, 14% of crude protein (CP), energy-protein 20% of CP with high RDP and a energy-protein 20% of CP with high RUP, offered at 7 kg/ cow/ day,, twice after milking. Concentrates were composed by ground corn, soybean hulls, solvent soybean meal or treated soybean meal (Soypass BR®), minerals and vitamins. The cows grazed a fertilized pasture with predominance of giant-missionary grass (Axonopus catharinensis), under intermittent stocking. Milk yield was taken daily, milk composition and body condition score (BCS), were taken weekly. Body weight was taken at begin and end of experiment. After experimental period, the cows received the same management and feed supply by 11 weeks for evaluation of carryover effects. The milk yield increased at 2 kg/cow/day, as the fat, protein and lactose yields were greater for cows receiving RUP supplementation. Live weight gain and dry matter intake also were increased by RUP supplementation. At post experimental period, the cows that had received RUP produced more milk and protein. Supplementation of RUP to cows at tropical pasture increased the milk, milk components yield and weight gain, with carryover effects along lactation. Supplementation with RDP did not increase milk or milk components yield when compared with energy supplementation / A energia é o nutriente mais limitante para vacas leiteiras em pastagens, especialmente em pastagens tropicais, no entanto quando é oferecida suplementação energética outros nutrientes podem se tornar limitantes como a proteína sob as formas de Proteína Degradável no Rúmen (PDR) ou Proteína Não Degradável no Rúmen (PNDR). O objetivo deste estudo foi avaliar os efeitos da suplementação concentrada energética ou energético-proteica com fontes de proteína de alta ou baixa degradabilidade ruminal para vacas Jersey de alta produção mantidas em pastagem tropical. Trinta vacas Jersey (DEL 58.2 ± 44.4, produção de leite 21.0± 4.4 kg e peso vivo 345.5 ± 32.1 kg no início do experimento) foram alocadas em um dos três tratamentos contínuos em um experimento de 12 semanas (1 para adaptação e 11 experimentais) de outubro a dezembro que consistiram de três suplementos concentrados: energético com 14% de Proteína Bruta (PB), energético-proteico com 20% de PB com alta PDR e energético-proteico com 20% de PB com alta PNDR, oferecidos na taxa de 7 kg/vaca/dia em duas vezes após as ordenhas. Os concentrados foram compostos por milho moído, casca de soja, farelo de soja ou farelo de soja tratado (Soypass BR®), minerais e vitaminas. As vacas foram mantidas em uma pastagem fertilizada com predominância de missioneira gigante (Axonopus catharinensis), sob lotação intermitente. A produção de leite foi medida diariamente, a composição do leite e o escore de condição corporal (ECC) foram avaliados semanalmente. O peso vivo foi mensurado no início e final do período experimental. Após o período experimental, as vacas receberam o mesmo manejo e alimentação por 11 semanas para avaliação de efeitos residuais dos tratamentos. A produção de leite aumentou em 2 kg/vaca/dia, e também as produções diárias de gordura, proteína e lactose foram maiores para as vacas recebendo suplementação com PNDR. O peso vivo e o consumo de matéria seca foram aumentados pela suplementação com PNDR. No período pós-experimental, as vacas que tinham recebido PNDR produziram mais leite e proteína. A suplementação com PNDR para vacas em pastagem tropical aumentou a produção de leite, de componentes do leite e o ganho de peso das vacas, com efeitos residuais ao longo da lactação. A suplementação com PDR não aumentou a produção de leite ou de componentes quando comparado com a suplementação energética