Energy and Protein Requirements of Growing Lambs in Colombian Highlands

Simple Summary Determination of nutrient requirements in sheep is essential to generate appropriate recommendations for dietary formulation, promoting sustainable systems. However, there is limited information regarding the energy and protein requirements of growing lambs in the Colombian highlands. Twenty-two growing lambs were enrolled in this experiment. Four lambs were slaughtered at the beginning of the experiment to determine the lambs' energy and protein baseline concentration. The remaining lambs received different amounts of feed and were slaughtered to determine the energy and protein accumulation during the evaluation period. The maintenance energy was 82.3 kcal/kg BW0.75, while maintenance and gain energy efficiencies were 0.72 and 0.29, respectively. In addition, the crude protein requirement for maintenance was 1.78 g/kg BW0.75, and the nitrogen efficiency for maintenance and gain protein was 0.41 and 0.27, respectively. The maintenance requirement of energy was greater, while protein was similar to values reported in the literature; however, the efficiency of energy and protein use was lower in growing lambs. These results suggested that estimating energy and nitrogen requirements for growing lambs must be adjusted in Colombian highland conditions.Abstract Determining the nutritional requirements of lambs is necessary to formulate balanced rations and contribute to sustainable sheep production systems. However, limited information is available regarding the nutritional requirements of growing lambs in the Colombian highlands. Twenty-two Romney Marsh males were used. Initially, four lambs were slaughtered at 20 kg body weight (BW). The remaining 18 lambs were distributed into two groups, according to BW (light: 20 BW and heavy: 30 kg BW). Lambs were randomly allocated into one of three different nutritional schemes, according to voluntary intake (no restriction, and 25 and 50% restriction). All the animals received a totally mixed ration. When a voluntary-fed lamb gained 10 kg BW, the two other lambs restricted to 25 and 50% were slaughtered and dissected into components to determine protein and gross energy concentration. Energy and protein accumulation were analyzed through regression analysis. The net energy for maintenance was 82.3 kcal/kg BW0.75, while the energy efficiencies for maintenance and gain were 0.72 and 0.29, respectively. Crude protein for maintenance was 1.78 g/kg BW0.75, and the nitrogen efficiencies for maintenance and gain were 0.41 and 0.27, respectively. The maintenance requirement of energy was greater, while protein was similarly related to values reported in the literature; however, the efficiency of energy and protein use was lower in growing lambs. These results suggested that estimating energy and nitrogen requirements for growing lambs must be adjusted in Colombian highland conditions.