This study was conducted to examine the effect of fermented alcoholic feedstuff (FAF), sustained-release recombinant bovine somatotropin(rBST) on growth performance and body size of Korean native cattle, Hanwoo. The experiment was carried at the Livestock Breeding Station in Kangwon-do with fourteen bulls of two groups, control and treatment. Seven bulls per each group were allocateed. In control group, bulls were treated with total mixed ration(TMR) for the whole experimental periods. In treatment group, bulls were treated with TMR+FAF+rBST for the fattening period and TMR+FAF for the finishing period, respectively. The results are summarized as follows ; Average daily gains(ADG) of control and treatment groups were 0.86 and 1.11kg during the fattening period. ADG of treatment group were 29.1% higher than that of control group. For the whole experimental period, the fattening period and finishing period, ADG in control and treatment groups were 0.69 and 0.79kg, respectively, which shows 14.5% improvement of ADG in treatment group. Dry matter intake(DMI) was higher in treatment group than in control group during the finishing, fattening or whole experimental period. Feed conversion efficiencies in fattening period were 8.65 for control group and 6.93 for treatment group which shows improving 19.9% of feed conversion efficiency for treatment group, while 12.38 for control group and 14.48 for treatment group in finishing period. There were no significant differences between control and treatment group in feed conversion efficiency for the whole experimental period. Overall results indicate that the favorable feeding system to produce growth performance is TMR+FAF+rBST feeding during the fattening period and TMR+FAF feeding in treatment during the finishing period.

This study was performed to examine the effects of recombinant bovine somatotropin (rBST) and fermented alcoholic feedstuff(FAF) on blood metabolites, carcass characteristics and profitability. Sixteen Hanwoos(bulls; 8, steers; 8) with average 143㎏ of body weight were randomly assigned to bull control group(BC), steer control group(SC), bull group(BrA) treated with rBST and FAF, and steer group(SrA) treated with rBST and FAF. Sustained release rBST(0.03㎎/㎏/body weight) was administered biweekly and dose of rBST was adjusted monthly according to body weight increase. The blood glucose content was higher in the groups treated with rBST and FAF than control groups. The blood cholesterol contents tended to be lower in the treatment groups (BrA, 120.5 mg/dl; SrA, 104.0 mg/dl) than in the control groups (BC, 141.0 mg/dl; SC, 125.5 mg/dl). No significant difference between the groups of bulls and steers were found in the blood triglyceride concentrations as well as the albumin contents. The rib eye area of BC and BrA were 70 and 72 cm2, respectively, which are slightly larger than the area of SC and SrA. The treatment did not affect the backfat thickness both in bulls and steers. The marbling scores of BC and BrA appeared as No. 1 and No. 2, respectively, and No. 3 and No. 4 were obtained in SC and SrA. Lower non saturate fat concentrations were observed in the treatment groups (BrA, 64.30%; SrA, 59.59) than in control groups (BC, 58.98%; SC, 58.09%). Saturated fatty acids and amino acids contents were slightly more improved in the treatment than in the control. Average auction prices of BC and BrA were 7,900 and 8,089 wons per 1kg of carcass, respectively, whereas the prices of SC and SrA were 9407 and 9866 wons per 1kg of carcass, respectively. It is concluded that the treatment with rBST and FAF can improve the growth performance such as marbling scores and rib eye area and increase the auction prices.