Efeito dos níveis de concentrado sobre o desempenho de ovinos Morada Nova em confinamento Effect of concentrate level on performance of feedlot Morada Nova sheep

Avaliaram-se o desempenho e a digestibilidade dos nutrientes em 32 ovinos Morada Nova, castrados, em confinamento alimentados com dietas contendo 20, 40, 60 e 80% de concentrado. Os animais tinham 8,11 &plusmn; 1,15 meses de idade, peso inicial de 19,67 &plusmn; 2,97 kg e peso ao abate de 30,0 kg. Utilizou-se delineamento experimental em blocos casualizados, com quatro tratamentos e oito repetições. Houve efeito linear decrescente dos níveis de concentrado sobre o número de dias em confinamento, que variou de 123,37 a 52,50 para as dietas com 20 e 80% de concentrado. O consumo diário de MS aumentou linearmente com a redução da proporção volumoso:concentrado, que variou de 0,925 a 1,124 kg. O ganho de peso, a conversão e a eficiência alimentar melhoraram com aumento do nível de concentrado na dieta. Os consumos de MO, PB, EE, NDT, EM, carboidratos totais (CT) e carboidratos não-fibrosos (CNF) elevaram, enquanto os de FDN e FDA decresceram com a inclusão do concentrado. Os coeficientes de digestibilidade de MS, MO e dos CT foram crescentes, enquanto a digestibilidade do EE e dos CNF sofreram efeito quadrático e as digestibilidades de PB, FDN e FDA não foram influenciadas pelo aumento de concentrado na dieta. Níveis de concentrado acima de 60% elevaram os ganhos de peso e anteciparam a idade ao abate dos ovinos Morada Nova. Dietas com níveis superiores a 40% de concentrado melhoraram os índices de digestibilidade aparente dos nutrientes. A raça Morada Nova tem potencial para produção de carne em confinamento.<br>The objective of this trial was to evaluate performance and nutrient intake and digestibility in feedlot Morada Nova hair sheep fed increasing levels of dietary concentrate. Thirty-two castratated Morada Nova sheep averaging 8.11 &plusmn; 1.15 months of age and 19.67 &plusmn; 2.97 kg of body weight (BW) at the beginning of the study were used in this trial. Animals were slaughtered with 30.0 kg of BW and fed diets with the following concentrate levels: 20, 40, 60 or 80%. A completely randomized block design with eight replicates per treatment was used. There was a significant linear reduction in feedlot days from 123.37 to 52.50 when the concentrate levels increased from 20 to 80% in the diet. Conversely, dry matter intake increasead linearly from 0.925 to 1.124 kg/day by reducing the forage:concentrate ratio of the diet. The daily weight gain and feed conversion and efficiency improved with increasing the levels concentrate in the diet. Intakes of organic matter, crude protein, ether extract, total digestible nutrients, metabolizable energy, total carbohydrates, and nonfiber carbohydrates all increasead with concentrate levels in the diet, while the opposite was observed for intakes of neutral detergent fiber and acid detergent fiber. Total tract apparent digestibility of dry matter, organic matter, and total carbohydrates increased when the concentrate levels was increased in the diet. Significant quadratic effects were observed for the the digestibility of ether extract and nonfiber carbohydrates while that of crude protein, neutral detergent fiber and acid detergent fibers was not affected by the dietary levels of concentrate. Dietary concentrate levels greater than 60% improved performance of feedlot Morada Nova sheep by increasing daily weight gain and decreasing slaughter feedlot time. Diets with concentrate levels higher than 40% increasead digestibility coefficients of nutrients.