Macromineral requirements by beef cattle under pasture supplementation.

The objective of this work was to determine macromineral requirements by Zebu steers grazing Brachiaria decumbens supplemented with concentrate. It was used 24 non-castrated steers, at an average age of 7 months and at initial average weight 180 kg. Eight control animals were slaughtered for determining initial body composition. The 16 remaining animals were divided in four four-animal plots, in a complete random design. Each plot received mineral mixture or supplements at the levels 0.75; 1.50 or 2.25 kg/animal/day. The right half-carcass of eight animals, two per group, was dissected in muscle, fat and bones and all body constituents were weighted for determination of empty body weight and body composition. Net requirements of calcium and phosphorus for an animal at 400 kg body weight were 11.13 g and 5.40 g, respectively. To estimate dietary requirements of maintenance and after, sum them to dietary requirements for gain in order to obtain total dietary requirements, it was adopted endogenous losses and bioavailability present in literature for each mineral macroelement. Total dietary requirement for calcium, phosphorus, magnesium, sodium and potassium for a 400-kg BW animal with 1.0-kg daily weight gain were 34.59; 17.36; 7.82; 5.19 and 41.11 g/day, respectively. Macromineral requirements by beef cattle under pasture supplementation are similar to those recommended by BR-Corte for beef cattle in feedlots

THERMODYNAMIC ANALYSIS AND ECOLOGICAL EFFICIENCY OF A COMBINED CYCLE POWER PLANT

The purpose of this article is to through the analysis of the first law of thermodynamic for a combined cycle determines the ecological coefficient of the same. This system consists of two gas turbines, two heat recovery boilers and a steam turbine, having a total installed capacity of power generation of 500 MW. This plant will be installed in a small town located 180 km from São Paulo. This place was chosen based on technical aspects by present proximity to the pipeline and transmission line, water availability and other favorable environmental aspects of the project. The natural gas that will serve as the plant's fuel will come from the Field of Mexilhão, from the base of Caraguatatuba, and the water used for cooling will come from the Paraíba do Sul River

Ofertas de suplementos múltiplos em tourinhos anelorados na fase de recria, em pastagens durante o período da seca: produção e eficiência microbiana.

O uso de suplementos múltiplos para bovinos visa aumentar o aporte de nutrientes, para melhor atender às exigências nutricionais. Neste contexto, avaliou-se a digestibilidade em tourinhos anelorados em fase de recria, recebendo diferentes ofertas de suplementos em pastagem de Brachiaria decumbens. A área foi dividida em cinco piquetes de 2,0 ha cada. Foram utilizados 30 tourinhos, com peso e idade iniciais médios de 230,0 ±6,14 kg e 8,5 ±0,18 meses, em delineamento inteiramente casualizado, contendo cinco tratamentos, sendo quatro ofertas de suplementos, mais mistura mineral (MM) e seis repetições. Foram avaliados a MM (60g/animal) e suplementos múltiplos, formulados para atender diferentes níveis de suplementação diariamente nas quantidades de 0,5, 1,0, 1,5 e 2,0 kg/animal e suprir 300g/dia de PB. O consumo de suplemento aumentou (P<0,10) a produção de proteína microbiana (PMic), quando comparado com os animais do grupo controle. A produção de PMic apresentou comportamento quadrático com ponto de máxima produção de 404,47 gramas na quantidade de 1,34kg de suplemento. A eficiência de síntese microbiana (EFMic) não diferiu entre os animais do grupo controle e os suplementados. Contudo, observa-se um comportamento quadrático com máxima eficiência 160,38 g/kg de NDT para oferta de 1,18 kg de suplemento. Observa-se que o ponto (1,18 kg) onde ocorreu a máxima EFMic foi inferior ao valor (1,34 kg) em que ocorreu a máxima produção de PMic. Conclui-se que, o ponto ótimo entre produção e eficiência de síntese de proteína microbiana, está entre as ofertas de suplemento diárias de 1,18 e 1,34 kg/animal

Effects of supplements with different protein contents on nutritional performance of grazing cattle during the rainy season

The objective of this study was to evaluate the effects of supplements with different crude protein (CP) contents on grazing cattle intake, digestibility, ruminal fermentation pattern, and nitrogen (N) metabolism characteristics during the rainy season. Five ruminal and abomasal cannulated Holstein×Zebu steers (296 kg body weight, BW) were used in a 5×5 Latin square design. The animals grazed five signal grass paddocks (0.34 ha). The five treatments evaluated were: Control (no supplement) and 1.0 g of supplement/kg BW with 0, 330, 660, and 1,000 g of CP/kg as-fed. The supplement was composed of starch, soybean meal, urea, and ammonium sulphate. There was a positive linear effect (p≤0.033) of the CP content in the supplements on the organic matter (OM), CP, and digested OM intakes. The provision of supplements did not increase (p≥0.158), on average, total and ruminal digestibilities of OM and CP. However, the increase in CP content in the supplements caused a positive linear effect (p≤0.018) on ruminal digestibilities of OM and CP. Additionally, a quadratic effect of the CP contents of the supplements were observed (p = 0.041) for the ruminal digestibility of neutral detergent fiber corrected for ash and protein, with the highest estimate obtained with the CP content of 670 g/kg. The supply of supplements increased (p<0.001) the ruminal ammonia N concentration, which also changed linearly and positively (p<0.001) according to increase in CP content in the supplements. The apparent N balance and relative N balance (g/g N intake) were not, on average, changed (p≥0.164) by the supplements supply. However, both showed a tendency of a linear increase (p≤0.099) with increasing supplement CP content. The supplements increased (p = 0.007) microbial N production in the rumen, which also changed linearly and positively (p = 0.016) with increasing supplement CP content. In conclusion, protein supplementation in grazing cattle during the rainy season, while stimulating voluntary forage intake, results in higher efficiency of N utilization when compared to energy supplementation. This is a possible response to increased microbial protein synthesis in the rumen and improved N status in the animal body

Supplementation levels for growing beef cattle grazing in the dry-rainy transition season.

The objective of this experiment was to study the effects of different levels of supplementation on the performance, intake, digestibility, pH and rumen ammonia concentration in growing bulls grazing Brachiaria decumbens Stapf. pasture, during the dry-rainy transition season. For evaluation of performance, intake and digestibility, it was used 25 non-castrated steers at 11 months of age and initial average body weight of 270 kg, grouped in five plots of five animals each, following a completely randomized design. Each plot received one of the following feeding treatments: mineral mixture and supplement at the proportion of 0.5, 1.0, 1.5 and 2.0 kg/animal/day, corresponding to 0.18, 0.36, 0.54 and 0.72% of the average body weight of the animals. The area designated for the animals was constituted of five 2.0-ha paddocks. For the evaluation of the pH and rumen ammonia concentration, five crossbred non-castrated steers were used, with average body weight of 240 kg, fistulated in the esophagus, rumen and abomasum, disposed in a 5 × 5 Latin square, with five treatments and five experimental periods. Animal performance behaved in a positive linear manner according to the supplementation levels, responding with an increase of more than 80% on weight gains of the animals. Intakes of total and pasture dry matter (DM), organic matter and neutral detergent fiber were not influenced by supplementation. Intakes of crude protein, nonfibrous carbohydrates, ether extract and total digestible nutrients as well as nutrient digestibility and rumen ammonia concentration showed a positive linear pattern in response to supplementation levels. Increasing levels of concentrate supplementation influence positively the performance of bulls growing on pastures during the dry-rainy transition season

Ofertas de suplementos múltiplos para tourinhos Nelore na fase de recria em pastagens durante o período da seca: desempenho produtivo e características nutricionais.

Avaliaram-se o desempenho produtivo e as características nutricionais em tourinhos Nelore em fase de recria, não-castrados, recebendo diferentes ofertas de suplementos em pastagem de Brachiaria decumbens, de julho a setembro de 2006. A área foi dividida em cinco piquetes de 2,0 ha, com disponibilidade média de matéria seca (MS) e matéria seca potencialmente digestível (MSpd) de 3,88 e 2,22 t/ha, respectivamente. Foram utilizados 30 bezerros com peso e idade iniciais médios de 230,0 ± 6,14 kg e 8,5 ± 0,18 meses, em delineamento inteiramente casualizado contendo cinco tratamentos: quatro ofertas de suplementos em comparação a mistura mineral (MM). Foram avaliados a MM (60 g/animal) e suplementos múltiplos, fornecidos diariamente nas quantidades de 0,5; 1,0; 1,5 e 2,0 kg/animal para suprir 300 g/dia de PB. Os animais responderam ao uso de suplementos múltiplos, ganhando mais peso (88,72%) e apresentaram maiores níveis séricos de N-ureia (19,95 vs. 9,66) em comparação àqueles que receberam mistura mineral. Os animais sob suplementação apresentaram maiores consumos de MS, MO, EE, FDN, CNF e NDT e esses consumos aumentaram com os níveis de oferta de suplemento. A suplementação aumentou o coeficiente de digestão da maioria das variáveis avaliadas, independentemente do nível de suplemento fornecido. Os níveis mais moderados (0,5 kg) de suplementos múltiplos podem ser fornecidos aos tourinhos em fase de recria durante o período da seca para estimular o consumo de pasto, porém a máxima produção microbiana é obtida com oferta de 1,34 kg de suplemento. As melhores respostas de desempenho e características nutricionais podem ser obtidas com o fornecimento diário de suplemento em níveis de 0,5 a 1,34 kg/animal

Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage

Citation: Batista, E. D., Detmann, E., Titgemeyer, E. C., Valadares, S. C., Valadares, R. F. D., Prates, L. L., . . . Paulino, M. F. (2016). Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage. Journal of Animal Science, 94(1), 201-216. doi:10.2527/jas2015-9493Effects of supplemental RDP and RUP on nutrient digestion, N metabolism, urea kinetics, and muscle protein degradation were evaluated in Nellore heifers (Bos indicus) consuming low-quality signal grass hay (5% CP and 80% NDF, DM basis). Five ruminally and abomasally cannulated Nellore heifers (248 +/- 9 kg) were used in a 5 x 5 Latin square. Treatments were the control (no supplement) and RDP supplementation to meet 100% of the RDP requirement plus RUP provision to supply 0, 50, 100, or 150% of the RUP requirement. Supplemental RDP (casein plus NPN) was ruminally dosed twice daily, and RUP supply (casein) was continuously infused abomasally. Jugular infusion of [(NN)-N-15-N-15]-urea with measurement of enrichment in urine was used to evaluate urea kinetics. The ratio of urinary 3-methylhistidine to creatinine was used to estimate skeletal muscle protein degradation. Forage NDF intake (2.48 kg/d) was not affected (P >= 0.37) by supplementation, but supplementation did increase ruminal NDF digestion (P < 0.01). Total N intake (by design) and N retention increased (P < 0.001) with supplementation and also linearly increased with RUP provision. Urea entry rate and gastrointestinal entry rate of urea were increased by supplementation (P < 0.001). Supplementation with RUP linearly increased (P = 0.02) urea entry rate and tended (P = 0.07) to linearly increase gastrointestinal entry rate of urea. Urea use for anabolic purposes tended (P = 0.07) to be increased by supplementation, and RUP provision also tended (P = 0.08) to linearly increase the amount of urea used for anabolism. The fraction of recycled urea N incorporated into microbial N was greater (P < 0.001) for control (22%) than for supplemented (9%) heifers. Urinary 3-methylhistidine: creatinine of control heifers was more than double that of supplemented heifers (P < 0.001). Control heifers reabsorbed a greater (P < 0.001) fraction of urea from the renal tubule than did supplemented heifers. Overall, unsupplemented heifers had greater mobilization of AA from myofibrillar protein, which provided N for urea synthesis and subsequent recycling. Supplemental RUP, when RDP was supplied, not only increased N retention but also supported increased urea N recycling and increased ruminal microbial protein synthesis