본 연구는 성성숙 전 한우 암송아지의 일일 유지 단백질(CPm) 요구량을 구하기 위하여 평균체중 143.1 kg (실험 1)과 257 kg (실험 2)의 각 6두씩을 3수준의 단백질을 급여하는 two 3 ${ imes}$ 3 latin square design에 공시하였다. 실험 1에서는 기초사료로서 timothy 건초를 2.8 kg/d/head를 급여(LCP)하면서 분쇄옥수수와 corn gluten meal을 각각 250 g과 150 g (MCP) 그리고 500 g과 300 g (HCP) 보충 급여하였다. 실험 2에서는 기초사료로서 timothy 건초를 4.8kg/d/head를 급여(LCP)하면서 분쇄옥수수와 corn gluten meal을 각각 350g과 250g (MCP) 그리고 700g과 500g (HCP) 보충 급여하였다. 실험 1에서의 CP 섭취량은 LCP, MCP, HCP구에서 각각 236.6, 340.1, 459.8g/d 이었고, 대사체중당 조단백질 균형은 각각 0.51, 1.87, 3.20g 이었다. 실험 2에서의 CP 섭취량은 LCP, MCP, HCP구에서 각각 415.2, 606.9, 793.0g/d 이었고, 대사체중당 조단백질 균형은 각각 0.67, 1.03, 2.99g 이었다. 실험 1과 2에서 얻은 CPm 요구량은 각각 4.58과 5.02/$BW^{0.75}$ 이었고 한우 사양표준(농림부, 2007)에서 채택하고 있는 5.56g CP/$BW^{0.75}$ 보다 낮았다.
Two trials at different body weights of Hanwoo heifers (average body weight of 143 and 257 kg, respectively) were conducted to determine crude protein requirements for maintenance (CPm). Six Hanwoo heifers in each trial were used in two 3 ${ imes}$ 3 Latin square design with three diets containing three levels of CP, 14 days in each period. In trial 1, the diets were based on 2.8 kg fresh wt./day/heifer timothy hay (LCP) with supplements of either 250 g ground corn and 150 g corn gluten meal (MCP) or 500 g ground corn and 300 g corn gluten meal (HCP). In trial 2, the diets were based on 4.8 kg fresh wt./day/heifer timothy hay (LCP) with supplements of either 350 g ground corn and 250 g corn gluten meal (MCP) or 700 g ground corn and 500 g corn gluten meal (HCP). In trial 1, CP intakes were 236.6, 340.1, and 459.8 g/d for LCP, MCP, and HCP, respectively. Crude protein balances were 0.51, 1.87 and 3.20g/$BW^{0.75}$/d for LCP, MCP, and HCP, respectively. In trial 2, CP intakes were 415.2, 606.9 and 793.0g/d for LCP, MCP and HCP, respectively. Crude protein balances were 0.67, 1.03, 2.99 g/$BW^{0.75}$/d for LCP, MCP, and HCP, respectively. The maintenance requirements for CP from the regression equation between CP intake and CP balance were 4.58g/$BW^{0.75}$/d (trial 1) and 5.02 g/$BW^{0.75}$/d (trial 2) and lower than the value (5.56 g/$BW^{0.75}$/d) adopted by Korean Feeding Standards for Hanwoo (2007).
