Resumo: O objetivo deste trabalho foi quantificar as exigências nutricionais para a manutenção (NRm) e o crescimento (NRg), assim como o coeficiente de retenção (RC) de cálcio, fósforo, sódio, potássio e magnésio, de bezerros da raça Holandesa. As NRm foram de 87,8, 20,8, 4,36, 2,21 e 1,01 mg kg-1 da massa de corpo vazio para Ca, P, Na, K e Mg, respectivamente. O RC foi de 0,882, 0,473, 0,274, 0,088 e 0,052 para Ca, P, Na, K e Mg, respectivamente. As exigências nutricionais de Ca e P de bezerros da raça Holandesa são maiores do que aquelas estimadas para animais adultos.

Abstract: The objective of this work was to quantify the net requirements for the maintenance (NRm) and growth (NRg), as well as the retention coefficient (RC) of calcium, phosphorus, sodium, potassium and magnesium, of Holstein calves. The NRm were 87.8, 20.8, 4.36, 2.21, and 1.01 mg kg-1 of empty body weight for Ca, P, Na, K, and Mg, respectively. The RC was 0.882, 0.473, 0.274, 0.088, and 0.052 for Ca, P, Na, K, and Mg respectively. The requirements of Ca and P of Holstein calves are higher than those estimated for adult animals.

The objective of this study was to evaluate the in situ and in vitro degradation kinetics and to predict the digestible neutral detergent fiber (dNDF) from the incubation times; in situ and in vitro degradation kinetic parameters; and equations fitted for agricultural and agro-industrial byproducts. Byproducts from pineapple, cocoa, palm kernel, corn gluten meal, common bean, sunflower, guava, cassava bark, cassava stems, cassava foliage, papaya, mango, passion fruit and turnips were evaluated. There were differences between the byproducts as for the potentially neutral detergent fiber (NDF) fraction and the in situ NDF degradation rate in the final volume of the gases generated by fibrous carbohydrates (FC), for the lag time and for the in vitro fractional degradation rate of the FC. There was equivalence between the dNDF values predicted in situ and those observed in vivo; however, there was low precision of estimates. The degradability in the in vitro incubation times of 30 and 48 hours presented equivalence with the values observed, but also did not present precision in the estimates. The equations fitted without lignin were not precise and accurate to estimate the dNDF of agricultural and agro-industrial byproducts. The equation with lignin and with the digestion rate obtained by the in vitro method presented more precise estimates. Byproducts from common bean, cassava bark and papaya presented greater NDF availability, whereas those of guava had the lowest NDF availability. The digestible NDF fraction was best predicted with the in situ incubation time of 72 hours. The equation fitted utilizing in vitro or in situ digestion rates enables the prediction of the NDF availability of agricultural and agroindustrial byproducts.

O objetivo deste trabalho foi avaliar os efeitos de níveis de inclusão de glicerina bruta (GB), contendo 36,20% de glicerol, na dieta de cordeiros em terminação, sobre o consumo, digestibilidade dos componentes da dieta e desempenho produtivo e econômico. Utilizaram-se 35 cordeiros machos não castrados da raça Santa Inês, com peso médio inicial de 20±2,27 kg, distribuídos em delineamento inteiramente casualizado, com cinco tratamentos e seis repetições. Os tratamentos consistiram de níveis de inclusão da GB na dieta (0, 3, 6, 9 e 12% da matéria seca), em substituição ao milho. Após 10 dias de adaptação, cinco animais foram abatidos para se obter o rendimento de carcaça inicial. Após o período de adaptação, os 30 animais restantes foram alojados em baias individuais. Quando o grupo atingiu o peso médio de 35 kg, os animais foram abatidos. Houve efeito linear decrescente dos níveis de GB sobre o consumo de MS e ganho médio diário de peso, e efeito quadrático sobre o coeficiente de digestibilidade da fibra em detergente neutro corrigida para cinzas e proteínas. Houve efeito quadrático também sobre o peso corporal final dos animais e conversão alimentar (CA). A GB contendo 36,20% de glicerol pode ser incluída na dieta de cordeiros em terminação em até 6% da MS da dieta, com otimização da CA e aumento dos benefícios econômicos.

The objective of this work was to evaluate the effects of crude glycerin (CG) inclusion, with 36.20% of glicerol, on finishing lamb diets on intake, nutrients digestibility, and productive and economical performance. Thirty-five intact male lambs (Santa Inês), with 20±2.27 kg of initial average body weight were randomly assigned to five treatments, with six replicates. The treatments consisted of increasing crude glycerin levels on the diet: 0, 3, 6, 9 and 12% of diet dry matter. After ten days of adaptation, five animals were slaughtered to determine initial carcass dressing. After the adaptation period, 30 animals were housed in individual pens. When the group reached average body weight of 35 kg, animals were slaughtered. The CG levels had a negative linear effect on dry matter intake and average daily weight gain, and a quadratic effect on neutral fiber detergent digestibility corrected for ash and protein. Crude glycerin levels had also a quadratic effect on body weight at slaughter and feed-to-gain ratio (FGR). Crude glycerin with 36.20% of glycerol can be included in the diet of finishing lambs up to 6% of dry matter, optimizing the FGR and promoting economic benefits.