Growing and finishing crossbred feedlot ewe lambs fed with increasing levels of concentrate in the diet

Abstract

To maximize economic gain in sheep production systems it is critical to adjust feedlot diets to maximize performance while minimizing feed, and especially concentrate, waste. Little information is available on ideal diets for crossbred ewe lambs. Therefore, this study aimed to evaluate the performance of feedlot crossbred ewe lambs, and the digestibility of diets, with increasing levels of concentrate during the growing and finishing phases. Twenty-four crossbred Texel × Pantaneira Texel ewe lambs were confined and fed Tifton hay with increasing levels of concentrate in the diet (20, 40, 60 and 80%) for individual evaluation of dry matter intake (DMI), digestibility of diets, average daily gain (ADG) and feed efficiency (FE). Animals were slaughtered at 47 kg. In the growing phase, the inclusion of concentrate in the diets (1176 g.kg -1 ) did not change DMI (p > 0.05). Concentrate levels had a quadratic effect (p < 0.05) on the dry matter digestibility coefficient (DMDC) and on total digestible nutrients (TDN) during the growing phase. In the finishing phase, there was a negative linear effect of concentrate levels on DMI (p < 0.05), but TDN intake was similar among the experimental diets (p > 0.05). DMDC and TDN values displayed a quadratic behavior (p < 0.05), plateauing at 60% concentrate. ADG and FE increased as concentrate was added to the diet in the growing phase (p < 0.05). During the finishing phase, lamb performance was similar (p > 0.05) for different diets. Thus, the use of 60% concentrate in the confined crossbred ewe lamb diet during growing and 20% concentrate during finishing is recommended. Key words: Feedlot. Digestibility coefficient. Intake. Weight gainh. ResumoPara maximizar o ganho econômico em sistemas de produção de ovinos é fundamental ajustar as dietas de confinamento para aumentar o desempenho e minimizar os custos e desperdícios com alimentação, especialmente com concentrado. Existem poucas informações sobre avaliação de dietas ideais para cordeiras mestiças. Objetivou-se avaliar o desempenho de cordeiras mestiças confinadas e a digestibilidade de dietas com níveis crescentes de concentrado durante as fases de recria e terminação. Foram confinadas 24 fêmeas mestiças Texel (1/2 Pantaneira x 1/2 Texel) alimentadas com feno de capim-Tifton e níveis crescentes de concentrado na dieta (20, 40, 60 e 80%) para avaliação individual do consumo de matéria seca (CMS), digestibilidade dos nutrientes das dietas, ganho médio diário (GMD) e eficiência alimentar (EA). Os animais foram abatidos com 47 kg. Na fase de recria, o CMS não foi alterado (p > 0,05) pela inclusão de concentrado nas dietas (1176 g kg -1 ). Foi observado efeito quadrático dos níveis de concentrado (p < 0,05) sobre os coeficientes de digestibilidade de matéria seca (CDMS) e nutrientes digestíveis totais (NDT) durante a recria. Na fase de terminação, houve efeito linear negativo dos níveis de concentrado sobre o CMS (p < 0,05), porém a ingestão de NDT foi similar entre as dietas experimentais (p > 0,05). O CDMS e o valor...