Intake of tropical grass forages alone is generally insufficient to avoid nutrition imbalances and reduced animal performance; therefore, supplementation is often recommended. The hypothesis of the present study is that when combined with fat, soybean hulls (SH) could replace corn as a source of energy, reducing methane production without affecting animal performance. This study evaluated the effects of starch-based supplementation level combined with oil on intake, digestibility, performance, and methane emissions of growing Nellore bulls (P = 44; initial BW = 250.69 ± 27 kg) fed cv. Xaraés during the rainy season. There were no interactions between starch level and oil supplementation with regard to intake of DM (P = 0.67), forage DM (P = 0.55), supplement DM (P = 0.14), OM (P = 0.66), CP (P = 0.74), NDF (P = 0.50), ether extract (EE; = 0.47), and GE ( P= 0.68). The intake of EE was greater for animals supplemented with oil than those fed supplements without oil (P < 0.01). There were no interactions between starch level and oil supplementation on digestibility of DM (P= 0.18), OM (P = 0.11), NDF (P= 0.42), and EE (P = 0.14). Moreover, there was interaction between starch and oil supplementation on GE (P < 0.01). Independent of starch level used, the addition of oil decreased the digestibility of OM (P = 0.04) and NDF (P = 0.03). There were no main effects of starch level, oil, or interaction between starch and oil for initial BW (P = 0.10), final BW (P = 0.94), ADG (P = 0.40), feed efficiency (P= 0.37), and carcass gain (P = 0.38). There was no interaction between starch-based supplementation level and oil on methane emissions when expressed in grams per day (P = 0.77), kilograms per year (P = 0.77), grams per kilogram DMI (P = 0.53), and grams per kilogram carcass gain (P= 0.31). There was, however, an interaction (P = 0.04) between starch level and oil on methane emissions when corrected for NDF intake. Additionally, oil decreased enteric methane emission for intake of GE (P = 0.04) and EE (P < 0.01) of animals fed with starch level. Soybean hulls have an estimated feeding value similar to that of corn. The use of oil supplementation may be effective to reduce enteric methane emission of Nellore bulls raised on pasture.

O objetivo deste experimento foi determinar a qualidade e o valor nutritivo de silagens do subproduto da pupunha, produzidas com aditivos, conforme os tratamentos: T1 - Testemunha (sem aditivo); T2 - Adição de 2,5% de açúcar; T3 - Adição de 10,0% de polpa cítrica e T4 - Adição de 10,0% de milho moído, base da matéria natural. Verificou-se que a adição 10% de polpa cítrica (PC) ou milho moído (MM) elevou o teor de matéria seca da massa a ser ensilada, bem como da silagem, em 6,5 e 8,0 unidades percentuais, respectivamente. Silagens com aditivos apresentaram menores valores de nitrogênio amoniacal (N-NH3 / NT) e pH. O consumo de matéria seca foi maior para as silagens feitas com PC ou MM, atingindo 85 g/kg PV0,75 ou 2,1% do PV, contra 44,7 g/kgPV0,75 ou 1,12%, para as silagens sem aditivo ou com 2,5% de açúcar. O coeficiente de digestibilidade aparente da matéria seca, também foi superior para as silagens contendo 10% de PC ou MM (65,0%) em relação à média das demais (52,0%). A digestibilidade da parede celular não mostrou tendência definida em função dos tratamentos. A silagem de subproduto da pupunha feita com a adição de 10% de polpa cítrica ou milho moído, apresentou valor nutritivo semelhante às silagens de forrageiras convencionais.

RESUMO -O objetivo do trabalho foi avaliar comparativamente as características de carcaça e a composição corporal de machos jovens da raça Nelore não-castrados, filhos de touros com diferencial positivo (Linhagem Seleção) ou nulo (Linhagem Controle) para ganho de peso aos 378 dias de idade. Utilizaram-se informações de 92 zebuínos Nelore, com peso de abate médio de 456,00 kg, sendo 51 animais pertencentes à Linhagem Seleção e 41 animais da Linhagem Controle, foram criados em pastagens cultivadas até os 18 meses, quando foram alocados nos dois sistemas de terminação, de forma a compor grupos homogêneos quanto ao peso e filiação. Os animais de confinamento receberam, em baias individuais, ração para possibilitar ganhos de 1,0 kg/cab/dia. Antes do abate, os animais foram submetidos a jejum e pesados, quando se obteve o peso de abate. Após o armazenamento das carcaças em câmara fria, obteve-se a seção da 9 a -10 a -11 a costelas. Não houve efeito significativo de linhagem para nenhuma das características analisadas, exceto para a porcentagem de ossos, sendo que os animais da Linhagem Seleção superaram os animais da Linhagem Controle. O regime de terminação apresentou efeito significativo para a quase totalidade das características estudadas, com exceção para as características de composição corporal. Não houve efeito significativo de interação entre linhagem e terminação. As classes de idade apresentaram efeito significativo para as características peso de abate, peso de carcaça quente, peso da gordura renal-pélvica-ingüinal, porcentagem de músculo, gordura e osso.Palavras-chave: bovino de corte, produção de carne, qualidade da carne, seleção, zebuínos Carcass Traits and Body Composition of Young Nellore Bulls Finished at DifferentFeeding Regime ABSTRACT -The objective of this work was to evaluate comparatively the carcass traits and body composition of young Nellore breed intact male, sons of bulls with differentials positive (Selection Lineage) or null (Control Lineage) at weight gain at 378 days of age. Data from 92 Nellore cattle, with 456.00 kg of slaughter weight, being 51 animals of Selection Lineage and 41 animals of Control Lineage. They were raised in cultivated pastures until 18 months of age, when were designated in two finishing systems, to arrange homogeneous groups to weight and filiation. The animals were fed, in individual pens, with ration for gains of 1.0 kg/day. Before slaughter, the animals were fasted and weighed, when the slaughter weight was obtained. After carcass storage in cold chamber, the section of 9 th -10 th -11 th ribs was obtained. There were no significant effects of lineage were for neither traits studied, except for the bone percentage, and the animals of Selection Lineage were superior than the animals of Control Lineage. The finishing system showed significant effects for all traits studied, except for the body composition. There were no significant effects of interaction between lineage and finishing system. The classes of age showed significant effects for the traits slaughte...

SUMMARYThe use of diets with increasing proportions of concentrate to fibre can ensure appropriate energy levels and result in greater efficiency in Nellore feedlot steers. It was hypothesized that higher proportions of concentrate in the diet of these Nellore steers may affect ruminal fermentation and microbiota as a consequence of ruminal pH reduction. The present study was conducted to evaluate the effect of diets with four different roughage (hay Tifton 85) : concentrate ratios on intake, digestibility, rumen fermentation and rumen microbiota of Nellore feedlot steers. Higher proportions of concentrate in the diet did not affect intake and digestibility of dry and organic matter. The concentration of N-NH3, total rumen volatile fatty acid, acetic (C2), butyric (C4), isobutyric, valeric and isovaleric acids, and microbial nitrogen did not differ among diets. However, increasing proportions of concentrate in the diet resulted in a linear reduction in average rumen pH and increased propionic acid (C3) concentration, resulting in lower relative C2 : C3. Bacterial population of Fibrobacter succinogenes, Ruminococus flavefaciens and Ruminococcus albus decreased in the rumen. However, bacteria that are consumers of lactic acid (Selenomonas ruminantium and Megasphaera elsdenii) and producers of lactic acid (Lactobacillus sp. and Streptococcus bovis) increased when animals were fed with high-concentrate diets. The total number of protozoa was similar for the different roughage : concentrate ratios. Protozoan counts were only influenced by diet for the genus Dasytricha. The findings point to diets with increasing concentrate to Tifton 85 hay ratios as inhibiting the growth of some cellulolytic bacteria and reducing fibre digestibility, and indicate Tifton 85 hay as a possible modulated rumen fermentation in the Nellore steer feedlot.

The objective of this experiment was to determine the effect of crude glycerin combined with soybean oil on the performance and fatty acid composition of the longissimus muscle in Nellore bulls. Twenty-eight Nellore young bulls, each with an initial body weight (BW) of 408 ± 29 kg (age 20 ± 2 months), were used in a completely randomized design over a period of 84 days in a 2 × 2 factorial arrangement. The treatments were diets with crude glycerin at 100 g/kg DM (CG+) or without crude glycerin (CG−); diet with inclusion of soybean oil at 60 g/kg DM (Oil+) or without soybean oil inclusion (Oil−). All diets were composed of corn silage (400 g/kg DM), used as the only source of roughage, and concentrate (600 g/kg DM). The intake of the dry matter (g/kg of body weight), neutral detergent fiber (aNDF) and crude protein decreased with soybean oil inclusion, independent of crude glycerin addition. The aNDF digestibility decreased in diets with soybean oil and without crude glycerin. The DM and organic matter (OM) were most digestible in diets that added crude glycerin but excluded soybean oil. Animals fed soybean oil without crude glycerin exhibited higher intake of linoleic acids, total unsaturated fatty acids (UFA), and total polyunsaturated fatty acids (PUFA) than those fed other diets. There were no effects of oil or crude glycerin feeding on final body weight, average daily gain (ADG), hot carcass weight, subcutaneous fat thickness, or loin eye area (P > 0.05). Animals fed soybean oil incorporate into the muscle 40% more conjugated linoleic acids (CLA) and 32% more linoleic acids compared to other diets. The addition of crude glycerin decreased the elongase index (P = 0.04) in the longissimus muscle. The combination of crude glycerin and soybean oil did not effectively increase performance or unsaturated fatty acid deposition in meat. However, the addition of soybean oil at 60 g/kg DM optimized feed efficiency and did not alter ADG.