Protein requirements for maintenance and growth of Corriedale lambs

The protein requirements of lambs for growth and fiber production can be breed specific. The Corriedale is a dual-purpose lamb breed, suitable for fleece and meat production; however, there is no information regarding the specific protein requirements for its growth and maintenance. In this study, we aimed to determine the protein requirements of castrated Corriedale lambs for maintenance, weight gain, and wool growth. Purebred Corriedale lambs with average body weights (BW) of 28, 33, and 38 kg were distributed into three respective trial groups. Their requirements of net protein for maintenance (NPm), metabolizable protein for maintenance (MPm), net protein for weight gain (NPg), net protein for wool growth (NPw), metabolizable protein for weight gain (MPg), metabolizable protein for wool growth (MPw), and their efficiencies for metabolizable protein use were determined. The NPm and MPm of the Corriedale lambs with 28-38 kg BW were 1.44 +/- 0.58 g/d/kg(0.75) and 3.07 +/- 1.28 g/d/kg(0.75) of their fasting BW, respectively, and the MP efficiency use for maintenance was 0.47. The NPg and NPw increased with the lambs' weight gain (from 100 to 250 g/day) and ranged from 9.53 +/- 0.001-21.8 +/- 0.003 and 7.13 +/- 0.038-24.4 +/- 0.079 g/d, respectively, in the lambs with 28-38 kg BW. The partial MP efficiencies for the maintenance use of a fleece-free body and wool protein retention were 0.72 and 0.27, respectively. The MPg and MPw ranged from 13.2 +/- 0.002-30.3 +/- 0.004 g/d and 26.4 +/- 0.14-90.4 +/- 0.29 g/d, respectively, in the lambs with 28-38 kg BW and an average daily weight gain of 100-250 g. The findings of this study can help feeding systems to improve their protein requirement recommendations for Corriedale sheep in the future.