• Journal of Animal Science and Technology
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• v.45 no.6
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• pp.975-986
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• 2003

Present study was conducted to investigate the effect of the level of concentrates and pasture grazing in 36 autumn born Hanwoo heifers(initial body weight, 119.7${\pm}$25.6kg) for 426d including 195d for a pasture stage. The animals were fed commercial concentrates at a rate of 0.5%(T1), 1.0%(T2), 1.5%(T3) and 2.0%(T4) of body weight, respectively, for pre- and post-pasture. 1. Mean daily gains by treatments were 0.348, 0.403, 0.450 and 0.501kg for T1, T2, T3 and T4, respectively, indicating that increases in concentrates intake was associated with the daily gain of grazing Hanwoo heifers. However, the mean daily gain was the highest for T2 during the pasture stage. 2. TDN intakes per 1kg gain were, on average, 8.61kg for the entire experimental period and 9.22kg for the pasture stage, respectively. In addition, the rate of roughage to concentrate during the entire experimental period was 49.6 to 68.2%(mean 58.5%). 3. Age reached 225 and 250kg of body weight was, on an average, 15.1mo. and 17.6mo., respectively, indicating that increasing the level of concentrates feeding(by 0.5% of body weight) reduced the first pregnancy by 0.9 mo. Ages and body weight for first service were 19.5mo. and 272.2 kg, respectively. Mean pregnant rate of total heads was approximately 52.8%, but appeared to 66.6% for T3 and T4. Therefore, it may be concluded that the optimum level of concentrates for autumn born Hanwoo heifers is 1.8% of body weight for indoor feeding on rice straw-based diet and 1.5% of body weight for a pasture stage, respectively.