PSX-11 Effects of lamb’s breed and energy concentration of diet on nutrient digestibility and growth performance

Abstract

Abstract The accumulation of subcutaneous adipose deposits occurs in many genotypes of animals adapted to tropical arid conditions. In sheep, good adaptation of fat-tailed sheep breeds, as Rabo Largo, to arid environmental conditions and food shortages can also undergo digestive and metabolic adaptation, including a greater capacity for digestion of poor roughage. Forty lambs (18±3 kg initial BW) were assigned in a randomized completely block design with a 2x2 factorial arrangement of treatments, with 2 breeds – B (Santa Inês- SI and Rabo Largo-RL) and 2 diets – D (low and high energy), resulting in four treatments: SILE, SIHE, RLLE and RLHE. Lambs (20 SI and 20 RL) were individually penned during 43 d and fed 1 of 2 diets with different concentrate: roughage ratio: low energy-LE (with 70% hay and 10.7% CP, DM basis) and high energy-HE (70% concentrate and 12.7% CP, DM basis). At the end of performance period, the intake was recorded and total feces collected for 5 d. Data were analyzed by ANOVA and when a significant effect (P < 0.05) was found, means were compared using Tukey’s method. The G:F ratio had effect only for D (0.12, 0.22, 0.10 and 0.24 for SILE, SIHE, RLLE and RLHE, respectively). There was observed an effect of D and B (P < 0.05) for all variables related to growth and digestibility, with higher means for SI and HE, except for NDF intake (495, 322, 340 and 268 g/d for SILE, SIHE, RLLE and RLHE, respectively) and NDF digestibility (63, 58, 59 and 45% for SILE, SIHE, RLLE and RLHE). It was observed an interaction D x B on CP intake, NDF intake and NDF digestibility. Breed and diets affected the performance and digestibility of lambs. However, RLLE increased the NDF digestibility, but decreased the ADG, suggesting higher fat depots accumulation.