This study evaluated the biomass flow of massai grass in regrowth subjected to different nitrogen levels (control - no fertilization; 400; 800; and 1200 N kg ha-1year-1) and under rotational stocking with sheep, in a completely randomized design with repeated measures over time. The leaf elongation rate increased with increasing nitrogen levels (N) and the fourth grazing cycle presented a lower value compared with the others. The stem elongation rate responded linearly with increasing levels of N, but it was not influenced by grazing cycles. The senescence rate of leaves remaining before grazing and after grazing were not influenced by the nitrogen fertilization or amended with successive grazing cycles. The phyllochron was influenced only by the nitrogen fertilization, with a decreasing linear response with nitrogen levels. Quadratic response was observed for the average length of leaves with increasing N levels and the grazing cycle 4 presented the lowest value for this variable. For each kilogram N ha-1 year-1, increases of 0.161 and 0.1604 kg ha-1 day-1 were verified in the herbage growth and accumulation rates, respectively. Nitrogen fertilization favors the biomass flow of massai grass, promoting an expressive increase in the production and accumulation of forage.

Objetivou-se avaliar a influência de quatro níveis de substituição (0; 33; 67 e 100%) do farelo de soja pela torta de mamona destoxificada em rações sobre o desempenho produtivo e as características de carcaça de ovinos mestiços de Morada Nova. Utilizaram-se 20 machos não-castrados, com peso vivo médio de 18,7 kg, em delineamento de blocos ao acaso com cinco repetições. Foram avaliados o desempenho, o peso, o rendimento e a composição regional das carcaças. A substituição do farelo de soja pela torta de mamona destoxificada não teve efeito sobre o peso vivo ao abate e o ganho de peso total durante o confinamento, entretanto teve efeito linear decrescente sobre o ganho médio diário e a conversão alimentar dos animais. Não foi observado efeito dos níveis de substituição do farelo de soja pela torta de mamona destoxificada sobre o peso vivo final, o peso vivo ao abate em jejum, o peso corporal vazio, o peso da carcaça quente e o peso da carcaça fria. O rendimento de carcaça quente foi afetado pelos níveis de substituição do farelo de soja pela torta de mamona, mesmo comportamento observado para o rendimento de carcaça fria. O peso da costela e os rendimentos da costela e da paleta também foram influenciados pelos níveis de substituição do farelo de soja pela torta de mamona destoxificada. O peso e o rendimento das demais regiões, no entanto, não apresentaram diferenças entre níveis de substituição. A torta de mamona destoxificada pode ser utilizada em níveis de até 67% de substituição ao farelo de soja em dietas para ovinos.

The objective of this study was to evaluate the influence of four substitution levels (0; 33; 67 and 100%) of soybean meal by detoxified castor cake on performance and carcass characteristics of 20 non-castrated male crossbred Morada Nova lambs, with mean body weight of 18.7 kg, in a randomized blocks design with four treatments and five replicates. Performance, carcass weight, carcass yield and relative composition of the commercial cuts were evaluated. The substitution levels of soybean meal by detoxified castor cake had no effect on final live weight or total weight gain in feedlot, but it caused decreasing linear effect on average daily gain and feed conversion ratio was observed. There was no effect of the substitution levels of soybean meal by detoxified castor cake on final body weight, live weight at fasting, empty body weight, hot carcass weight or cold carcass weight. The hot carcass yield was affected by substitution levels; the same behavior was observed for cold carcass yield. Rib weight and yield and shoulders yield had linear decrease of substitution levels of soybean meal by detoxified castor cake, whereas weight and yield of other regions did not present any effect for the substitution levels. Detoxified castor cake can be utilized in levels of up to 67% in substitution of the soybean meal in sheep diets.

Objetivou-se avaliar a influência de rações que continham torta de mamona em características de carcaça e componentes não carcaça de ovinos. Foram distribuídos 20 ovinos Morada Nova (peso inicial de 18,7±1,18kg) em blocos ao acaso, de acordo com o sexo (machos inteiros e fêmeas), com cinco tratamentos (torta de mamona não tratada, tratada com calcário calcítico, ureia, fosfato monobicálcico e autoclavada) e quatro repetições. Não houve diferença no consumo de matéria seca, ganho de peso total e peso ao abate entre tratamentos e, consequentemente, não ocorreu na maioria das variáveis analisadas entre tratamentos. No entanto, animais alimentados com torta autoclavada e torta tratada com fosfato monobicálcico foram superiores aos alimentados com torta de mamona não tratada. Quanto à perda ao jejum, houve diferença entre animais alimentados com torta autoclavada e com ureia, o que resultou em diferença no percentual de peso de corpo vazio. Animais alimentados com torta tratada com fosfato monobicálcico apresentaram maior peso de rúmen retículo em relação aos animais do tratamento ureia. A área de olho de lombo foi melhor nos animais alimentados com torta de mamona autoclavada seguido pelos animais que ingeriram torta tratada com fosfato monobicálcico. Em geral, a torta de mamona não tratada não prejudica as características de carcaça e seus não componentes.

To evaluate the effects of rations containing castor cake on sheep carcass and non carcass components characteristics, this research was undertaken. Twenty Morada Nova sheep (initial weight of 18,7±1,18kg) were assigned to a complete randomized block design according to sex (whole males and females), with five treatments (castor cake untreated, castor cake treated with limestone, urea, phosphate monodicalcium and autoclaved) and four repetitions. There wasn't difference in dry matter intake, total weight gain and weight of slaughter between treatments and therefore didn't occur in most variables between treatments. However, animals fed with rations containing castor cake autoclaved and castor cake treated with phosphate monodicalcium were higher than those fed untreated castor cake. The loss in fast, there was difference between animals fed with rations containing castor cake autoclaved and animals fed with castor cake treated with urea, resulting also in difference in the percentage empty body weight. Animals fed with rations containing treated with phosphate monodicalcium had higher weight of rumen-reticulum in relation to the animals fed with ration containing castor cake treated with urea. The rib eye area was greater on animals fed castor cake autoclaved and treated with phosphate monodicalcium. In general, the castor cake untreated not affect carcass and non carcass components.

This study was carried out to estimate efficiencies of the utilization of metabolizable energy for maintenance (k m) and weight gain (k g) and to evaluate the Small Ruminant Nutrition System (SRNS) model in predicting dry matter intake and average daily gain of growing Santa Ines sheep. Twenty-four non-castrated Santa Ines sheep, at 50 days of age and with average body weight of 13.00 ± 0.56 kg, respectively, were used. After a 10-day adaptation period, four animals were slaughtered to be used as reference for estimating initial empty body weight and body composition of the other animals. The remaining animals were distributed in a random block design, with the treatments consisting of diets containing different levels of metabolizable energy (2.08, 2.28, 2.47 and 2.69 Mcal/kg of DM), with five replicates. The metabolizable energy use efficiencies for maintenance and for weight gain were calculated from the relationship between the dietary net energy for maintenance and gain and ME concentration in the diets. Evaluation of the SRNS model was performed by adjustment of simple linear regression model between the predicted (independent variable) and observed (dependent variable) values. The estimated energy use efficiency for maintenance (k m) was 0.70; and for gain weight (kg) it showed to be inversely proportional to the increase of metabolizable energy concentration in the diet. The dry matter intake predicted by the SRNS model did not statistically differ from that observed, but the model overestimated the average daily gain by 5.18%. Those results can contribute to the construction of a database, which could be condensed into several others in a predictive model of performance and feed planning for sheep reared in Brazil.