ABSTRACT. The objective of this work was to evaluate the chemical composition and rumen disappearance rate of dry matter of corn silages with inoculants combining L. buchneri strain LN40177 in different strata of the silo. The experimental design was a 3x2 randomized complete block design, with three treatments: Control: corn silage without inoculant; 11CFT: corn silage with inoculant which combines L. buchneri strain LN40177 (1.1 x 1011 CFU g-1) with L. casei (1.1 x 1011 CFU g-1); and 11C33: corn silage with inoculant which combines L. buchneri strain LN40177 (1.1 x 1011 CFU g-1) with L. plantarum (1.1 x 1011 CFU g-1) and Enterococcus faecium (1 x 1010 CFU g-1), associated with two strata of the silo (lower and upper). The silage inoculated with 11C33 presented higher contents of crude protein and NDF and lower hemicellulose content in relation to the control treatment and 11CFT. The use of both inoculants resulted in silages with higher concentrations of soluble nutrients. Lower stratum silage had a higher rumen disappearance rate of dry matter compared to the upper stratum. In general, the combinations of L. buchneri promoted nutritional improvements in corn silage, but in presence of L. casei, there were more outstanding improvements.

RESUMO. As enzimas podem ser aditivos interessantes em dietas de alta energia para gado em confinamento. No entanto, a literatura é inconsistente para este assunto. Assim, este trabalho foi realizado para avaliar o desempenho de touros em confinamento com dietas de alta densidade energética, composto apenas de uma mistura de 85% de grãos de milho inteiros e 15% de núcleo proteico-vitamínico-mineral, com ou sem inclusão de enzimas à base de xilanase. Os tratamentos foram CON - dieta sem enzimas (controle) e ENZ - dieta com enzimas (5 g animal dia-1). Foram utilizados 32 touros, com idade média de 11 ( 2, peso inicial médio de 365 kg ( 5 e terminados por 119 dias. O delineamento experimental foi inteiramente casualizado, consistindo em dois tratamentos e oito repetições, em que cada repetição foi representada por uma baia com dois animais. ENZ aumentou o ganho de peso (1,69 vs. 1,33 kg dia-1) e melhorou a conversão alimentar (4,60 vs. 6,03 kg-1) na fase de adaptação dos animais em confinamento. Os animais que receberam ENZ aumentaram 1,65% do rendimento de carcaça e foram 7,57% mais eficientes na transformação da matéria seca consumida no ganho de carcaça em relação ao CON. As características de carcaça de touros terminados em confinamento não foram alteradas em função da inclusão de enzimas. O complexo de xilanase pode aumentar eficiência de touros de confinamento.

ABSTRACT. Enzymes can be an interesting additive in high energy diets for feedlot cattle. However, literature is inconsistent on this subject. Thus, this study was conducted to evaluate animal performance of feedlot bulls receiving high energy diet, composed of a mixture of 85% whole corn grain and 15% protein-mineral-vitamin nucleus, without or with xylanase included in the diets. Diets consisted of: CON - diet without enzymes (Control) and ENZ - diet with enzymes (5 g animal day-1). Thirty-two bulls were used, with an average age of 11 ( 2 months, average initial weight of 365 ( 5 kg, and finished for 119 days in feedlot. The experimental design was completely randomized, consisting of two treatments and eight replications, where each replication was represented by a stall with two animals. ENZ increased the weight gain (1.69 vs. 1.33 kg day-1) and improved the feed conversion (4.60 vs. 6.03 kg-1) in the adaptation period of the animals. Animals receiving ENZ increased 1.65% of carcass yield and were 7.57% more efficient in the conversion of dry matter consumed into carcass gain in relation to CON. Carcass traits of feedlot-finished bulls were not altered by inclusion of enzymes. Xylanase-complex could increase efficiency in feedlot bulls.

ABSTRACT The objective of this study was to evaluate the production performance and carcass traits of feedlot steers fed a high-energy diet supplemented with doses of an enzyme complex (0, 2.5, 5.0, and, 7.5 g animal−1 day−1). Thirty-two ½ Angus ½ Nellore crossbred steers at an average age of 12 months and an average initial weight of 422 kg, were kept in a feedlot for 77 days. The roughage-free diet was composed of a mixture of whole corn grain and a protein-mineral-vitamin mix at a constant ratio of 85:15, on a dry matter basis. A completely randomized block design was adopted, consisting of four treatments and four replicates, in which each replicate was represented by a stall with two animals. Each gram of product added to the diet led to a decrease of 0.0818 kg in daily dry matter intake (DMI), whereas fat thickness at the ribs and at the hindquarter increased by 0.3850 and 0.080 mm, respectively. Feed efficiency increased by 0.0054 kg BW kg DMI−1 per gram of enzyme added. Apparent dry matter digestibility had a quadratic response, with maximum digestion manifested at the dose of 4.78 g animal−1 day−1. The gradual inclusion of enzyme complex reduces the DMI but increases feed efficiency and carcass fat cover of feedlot steers.