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Productive performance of crossbreds Nellore beef heifers, in the growing stage receiving different supplement levels for three months grazing Brachiaria decumbens pasture were evaluated. The area was divided in five paddocks of 2.5 ha, with dry matter availability and potentially of dry matter digestible of 3.85 and 2.12 t/ha, respectively. Forty beef heifers of 191 ± 3.99 kg initial weight and 8.5 ± 0.15 months of age were assigned in a completely randomized experimental design with five treatments, and four supplementation levels. Mineral mixture (MM) (60 g/day) and multiple supplements, formulated to supply different supplementation levels in the amounts of 0.5, 1.0, 1.5 and 2.0 kg/animal more MM (60 g/day) were evaluated. The supplement had 300 g of crude protein/kg. Animals not responded significantly (P > 0.05) to the use of multiples supplements to final body weight. However, the heifers than received supplement won more weight (P £ 0.01) (372 g vs. 92g of average daily gain), in addition to highers (P £ 0.01) serum N-urea levels (20.14 vs. 12.09 mg/dL), when compared with heifers fed diets supplied only with mineral mixture. In conclusion, increasing the amount of protein supplement during the dry season, increased of performance of beef heifers. However, despite increase productive performance and intake of energy during dry season, additional higher levels of supplementation resulted in lower increment in growth.

The objective of this study was to estimate requirements of energy, protein and macrominerals of young Nellore/Holstein crossbreds bulls supplemented on pastures of Brachiaria decumbens Stapf. Thirty-five young bulls, at 8.53±0.18 months of age and with initial body weight of 230.6±6.1 kg were used. Ten animals were slaughtered as reference, in different weight range, and the other animals were slaughtered at the end of the experimental period. For estimate of net energy requirements for weight, a regression equation between log of retained energy (RE) and log of empty body weight gain (EBWG) was constructed. Net requirements of Ca, P, Mg, Na and K were determined by the equation Y' = a.b.Xb-1, in which a and b represent the intercept and the coefficient of equation of prediction of macrominerals in body content, respectively. Requirements of metabolizable energy for maintenance (MEm) were obtained from retained energy in function of metabolizable energy intake (MEI). The requirements of MEm of Nellore/Holstein crossbreds young bulls on pasture was 125 kcal/EBW0.75/day. The efficiency of ME utilization for maintenance (km) of grazing Nellore/Holstein crossbred young bulls was 0.58 and 0.24 for gain. The total metabolizable protein requirements for an animal with 400 kg and with average daily gain of 1.0 kg, were 638.36 g/day. The dietetic requirements of Ca and P for an animal with 400 kg BW were 0.49 and 0.21% of DM, respectively. Daily metabolizable energy requirement for maintenance of grazing Nellore/Holstein crossbred young bulls was 11.6% greater than the values found for cattle in feedlot in Brazil (112 kcal/kg EBW0.75).

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, non-fibrous 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. Objetivou-se estudar os efeitos de diferentes níveis de suplementação sobre o desempenho, o consumo, a digestibilidade, o pH e a concentração de amônia ruminal em bovinos recriados em pastagem de Brachiaria decumbens Stapf. durante o período de transição seca-águas. Para avaliação do desempenho, do consumo e da digestibilidade, foram utilizados 25 novilhos não-castrados com idade e peso médio iniciais de 11 meses e 270 kg, divididos em cinco lotes de cinco animais, segundo um delineamento inteiramente casualizado. Cada lote recebeu um dos seguintes complementos alimentares: mistura mineral; e suplemento na proporção de 0,5; 1,0; 1,5 e 2,0 kg/animal/dia, correspondentes a 0,18; 0,36; 0,54 e 0,72% do peso corporal médio dos animais. A área destinada aos animais foi constituída de cinco piquetes de 2,0 ha. Para a avaliação do pH e da concentração ruminal de amônia, foram utilizados cinco novilhos mestiços não-castrados, com peso médio de 240 kg, fistulados no esôfago, rúmen e abomaso, dispostos em quadrado latino 5 × 5, com cinco tratamentos e cinco períodos experimentais. O desempenho dos animais comportou-se de forma linear positiva de acordo com os níveis de suplementação, refletindo em aumento de mais de 80% no ganho de peso dos animais. Os consumos de matéria seca (MS) total e do pasto, de matéria orgânica e de fibra em detergente neutro não foram influenciados pela suplementação. Os consumos de proteína bruta, carboidratos não fibrosos, extrato etéreo e nutrientes digestíveis totais, assim como a digestibilidade dos nutrientes e a concentração de amônia ruminal, apresentaram comportamento linear positivo em resposta aos níveis de suplementação. Níveis crescentes de suplementação concentrada influenciam positivamente o desempenho de bovinos recriados em pastejo no período de transição seca-águas.

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.

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.

Resumo - O estudo foi conduzido em um sistema agrissilvipastoril na Embrapa Caprinos em Sobral - CE, Brasil, no período de 1999 a 2001. Objetivou-se determinar o efeito do sistema de produção agrissilvipastoril sobre o desempenho produtivo de ovelhas Crioulas, na região semi-árida do Nordeste brasileiro. Nos sistemas agrissilvipastoril e tradicional foram utilizadas matrizes ovinas Crioulas e reprodutores Santa Inês. Com relação às matrizes foram monitorados os pesos ao pós-parto e à desmama, a fertilidade ao parto, a prolificidade e a distribuição estacional dos partos. Os resultados mostraram que o peso vivo médio (PVM) das matrizes ao pós-parto não foi influenciado pelo sistema de produção e pela estação do ano, porém registrou-se o efeito de ano, e que o PVM à desmama não foi influenciado por nenhuma das fontes de variação estudadas. Os valores dos parâmetros reprodutivos avaliados, fertilidade ao parto e prolificidade, foram elevados para o sistema agrissilvipastoril e normais para o tradicional, comparados aos obtidos na região. No sistema agrissilvipastoril, apesar de não ter havido diferença no desempenho das matrizes, é possível a obtenção de três partos em dois anos, mais bem distribuídos, sem comprometimento do desempenho dos animais, desde que haja suplementação no período seco. ABSTRACT: A study was conducted at Embrapa Caprinos in Sobral, Ceara, Brazil, during 1999 ? 2001, to determine the effect of an agrosilvipastoral production system on the productive performance of Creole ewes in the semi-arid region of Northeastern Brazil. Creole ewes and Santa Inês rams were used in the agrosilvipastoral and traditional systems. Ewe weight at post-partum and weaning, fertility at birth, prolificacy rate and seasonal birth distribution were monitored. The results showed that medium alive weight (MAW) of ewes at postpartum was not influenced by the production system and season; however, year effect was recorded and MAW at weaning was not influenced by any of the variation sources studied. The values of the reproductive parameters fertility at birth and prolificacy were high for the agrosilvipastoral system and normal for the traditional system, compared to those obtained in the semi-arid region of Northeastern Brazil. Although no differences were found in the performance of the ewes, three better distributed births are likely to occur in two years in the agrosilvipastoral systemwithout compromising animal performance, provided feed supplement is available during the dry period.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2014-02-26T17:20:00Z No. of bitstreams: 1 WOS000076957700021.pdf: 28803 bytes, checksum: 1b7edf9c540e59a9f45c4a843131a9c8 (MD5) Made available in DSpace on 2014-02-26T17:20:00Z (GMT). No. of bitstreams: 1 WOS000076957700021.pdf: 28803 bytes, checksum: 1b7edf9c540e59a9f45c4a843131a9c8 (MD5) Previous issue date: 1998-07-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T15:24:23Z No. of bitstreams: 1 WOS000076957700021.pdf: 28803 bytes, checksum: 1b7edf9c540e59a9f45c4a843131a9c8 (MD5) Made available in DSpace on 2014-05-20T15:24:23Z (GMT). No. of bitstreams: 1 WOS000076957700021.pdf: 28803 bytes, checksum: 1b7edf9c540e59a9f45c4a843131a9c8 (MD5) Previous issue date: 1998-07-01 This research was conducted to evaluate the productive performance (live weight gain and carcass weight gain and gain efficiency) of animals from four zebu breed slaughtered in three maturity stages. Thirty-six bulls from Gyr, Guzera, Mocho Tabapua and Nellore with twenty-four months of average age and average initial live weight of 357.6, 362.0, 368.6 and 376.4 kg, respectively, were used. The bulls, from each breed, were randomly assigned to individual pens and were full-fed a diet containing 50% concentrate (DM basis) and distributed to three category (1, 2 and 3) of slaughter weights. The bulls from category 1, 2 and 3 were slaughtered when reached the individual live weight of 405, 450 and 500 kg, respectively. At slaughter the empty body weight was determined. The Nellore breed bulls showed greater average empty body weight gain and carcass gain in relation to the other breeds, which did not differ among themselves. There were no differences among breeds regarding to feed efficiency (empty body weight gain efficiency and carcass gain efficiency per unit of metabolizable energy intake). The slaughter weight did not influence the empty body weight gain and carcass gain, but animals slaughtered at higher slaughter weights showed lower gain efficiency and spent more time in feedlot. DPEA, UNESP, BR-18618000 Botucatu, SP, Brazil UENF, BR-28015620 Campos, RJ, Brazil UFV, Dept Zootecn, Vicosa, MG, Brazil UFV, Bolsista Iniciacao Cient, Vicosa, MG, Brazil DPEA, UNESP, BR-18618000 Botucatu, SP, Brazil