Energy requirements for growth in Santa Inés sheep

Abstract

The growth potential, digestible energy requirement (DE) and dry matter consumption (DM) in weaned Santa Inés lambs were established under subtropical conditions. Twenty-four lambs were subjected to three energy levels, offering a concentrated supplement based on whole cassava root with 18% crude protein (CP) and 3.6 Mcal DE / kg DM as 40, 60 and 80% of the total requirement of MS. The basal diet was Brachiaria decumbens forage, mowed and chopped before flowering. During 90 days the maximum growth rate was 130 g / d with a consumption of 1780 kcal ED, concentrated in 584 g of DM, which represented 3.5% of the live weight; the minimum growth (P <.05) was 55 g / d with a contribution of 1160 kcal ED, concentrated in 417 g of DM, which represented 3.2% of body weight. The equation Y = 8.66 + 12.85 PM + 0.44 CED - 1.35 CMS (PM = metabolic weight; CED = ED consumption; CMS = DM consumption), explained 81% of the variation in growth speed (Y) and the extrapolating to zero gain, the ED requirement for maintenance per metabolic unit was estimated at 172 kcal. The energy requirement was 4.4 kcal DE per unit of increase (g).