ABSTRACT This study aimed to evaluate the effects of diets containing elephant grass genotypes silages as exclusive roughage on leg tissue composition, and physicochemical characteristics of meat of lambs. Twenty-four crossbred male lambs with an average initial body weight of 20.29±2.66kg were distributed in a complete randomized design with three treatments and eight replicates. The treatments consisted of three silages of elephant grass genotypes (IRI-381, Elephant B or Mott), without additives or wilting, as the only roughage. The diets did not affect (P>0.05) the dry matter (898.70±60.10 g/day), crude protein (128.93±6.91g/day), total digestible nutrients (690.20±91.82g/day) intakes, body weight at slaughter (24.83±2.79kg), and carcass yields (P>0.05). The tissue composition of the leg did not differ significantly between silages of elephant grass genotypes (P>0.05). No difference (P>0.05) for the physicochemical characteristics of meat from lambs fed diets tested was observed. Therefore, our results indicate that diets containing 50% elephant grass genotypes silages (IRI-381, Elephant B or Mott), harvested at 60 days of growth, have potential for use in lambs feeding.

RESUMO Este estudo teve como objetivo avaliar os efeitos de dietas contendo silagens de genótipos de capim-elefante como volumoso exclusivo sobre a composição tecidual da perna e nas características físico-químicas da carne de cordeiros. Vinte e quatro cordeiros machos mestiços, com peso corporal inicial médio de 20,29±2,66kg, foram distribuídos em delineamento inteiramente ao acaso, com três tratamentos e oito repetições. Os tratamentos consistiram de três silagens de genótipos de capim-elefante (IRI-381, Elephant B ou Mott), sem aditivos ou emurchecimento, como único volumoso. As dietas não afetaram (P>0,05) os consumos de matéria seca (898,70 ± 60,10g/dia), proteína bruta (128,93±6,91g/dia) e nutrientes digestíveis totais (690,20±91,82g/dia), peso corporal ao abate (24,83±2,79kg) e rendimentos de carcaça (P>0,05). A composição tecidual da perna não diferiu significativamente entre as silagens dos genótipos de capim-elefante (P>0,05). Não foi observada diferença (P>0,05) para as características físico-químicas da carne dos cordeiros alimentados com as dietas testadas. Portanto, os resultados indicam que dietas contendo 50% de silagens de genótipos de capim-elefante (IRI-381, Elephant B ou Mott), colhidos aos 60 dias de crescimento, têm potencial para uso na alimentação de cordeiros.

It was hypothesized that maize steep liquor, which is high in crude protein, could replace soybean meal in supplementation strategies in lamb production systems. Therefore, the effects of replacing soybean meal with maize steep liquor at 0%, 33%, 66% and 100% on a dry matter (DM) basis on growth performance, nutrient digestibility and carcass characteristics were assessed in feedlot lambs. Thirty-two Santa Inés intact male lambs, with an average initial weight of 21.0 ± 2.3 kg, were assigned to a completely randomized block design with four treatments and eight replicates. Intake of DM, organic matter, ether extract, neutral detergent fibre and total digestible nutrients were not affected by the diets. However, the intake of crude protein (CP) was reduced by 0.2 g/day for each 1% increase in the replacement level of soybean meal with maize steep liquor. Replacement of soybean meal with maize steep liquor in the diets did not affect the apparent digestibility of nutrients with the exception of CP, which decreased by 14.1 g/kg DM for each 1% increase in the replacement level of soybean meal. Similar trends were observed for average daily gain, hot carcass weight, cold carcass weight, hot carcass yield and cold carcass yield. From these results, soybean meal could be replaced by up to 100% with maize steep liquor in finishing diets for feedlot lambs.