Present study was conducted to investigate the optimal feeding levels for producing the high quality meat on the basis of the information deriving from the comparison of the growth performance and carcass characteristics among breeds (Holstein vs F1, Holstein♀ × Hanwoo ), sex ♂ (steer vs heifer) and interaction between breed and sex. Thirty two animals on 4 treatments (i.e. eight head each) were used for 540 days from seven to 24 months of age.The results obtained are summarized as follows; the range of average daily gains was 0.733 to 1.018, 0.994 to 1.255, 0.947 to 1.259 and 0.736 to 0.824 kg for the growing, the early-fattening, the midfattening and the finishing periods, respectively. The range of average daily gains for the entire period was 0.882 to 1.061 kg. The gains were higher for Holstein(7.3%) and the steers(10.5%) than F1 and the heifers, respectively. Concentrates and total digestible nutrients intakes per kg gain were higher for Holstein and the heifers than F1 and the steers, respectively. These findings may indicate that feed utilization is higher for Holstein than F1, and higher for the steers than the heifers.In carcass characteristics, back fat thickness was thicker for Holstein than F1, and rib-eye area was smaller for Holstein than F1. The rib-eye area per kg carcass weight was larger for F1 and the heifers than Holstein and the steers, respectively. Meat color was better for Holstein than F1, but the sex distinction did not show any differences. In physicochemical properties of longissimus dorsi, shear force, cooking loss, water holding capacity and the panel test scores of juiciness, tenderness and flavor for F1 and the heifers were better than those for Holstein and the steers, respectively. According to the above results, we may conclude that F1 and heifers rather than Holstein and steers are recommended for high quality meat production. In steers and heifers of Holstein and F1, the optimal feeding levels may be 1.9% of apparent body weight for concentrates and 25% of concentrates intake for rice straw.

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Twenty four Holstein steers fed commercial concentrates with rice straw (T1), mixed grass hay (T2), or wet brewer's grains based TMR ad libitum (T3) were used to investigate the effects of roughage feeding type during the growing and early-fattening periods on growth performance, feed efficiency and carcass characteristics. Growth performance and feed efficiency were investigated during the feeding trial conducted from 6 to 23 mo of age, and carcass characteristics were investigated after slaughter. Body weight at slaughter and daily gains were 751 to 802 kg (mean 782 kg) and 1.064 to 1.159 kg/d (mean 1.122 kg/d), respectively, showing that those for T2 were highest followed by T3. Compared with T1, the daily gain for T2 was improved by 8.9%. The TDN intakes per kg gain were 6.87, 7.17 and 7.15 kg for T1, T3 and T2, respectively, indicating that feed efficiency for T2 was improved (approx. 5%) compared with T1. The feeding treatments did not change dressing percentage (mean 60.8%), back fat thickness (6.68 mm) and rib-eye area (84.0 cm 2 ). Neither meat quality characteristics nor physicochemical properties were significantly different among the treatments. However, economic analysis accounting for 882.8, 991.7 and 943.8 thousand won per head for T1, T2 and T3, respectively, indicated that T2 and T3 increased (7~12%) total net income compared with T1. Therefore, it may be concluded that high quality meat of Holstein steers can be produced if they are fattened until 23 mo of age and that feeding mixed grass hay as roughage or TMR containing mainly wet brewer's grains during the growing and early-fattening periods can improve growth performance compared with feeding rice straw.

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