living animals, was used to fatten steers at the finishing period for examining the effects on the body weight gain and the meat quality. Ten Holstein steers in NODAI's Fuji Experiment Farm were divided into two groups, and each group was further divided into two lots, the experimental and the control. In both groups, body weight and traits of carcass were measured.Blood properties after the fattening were also measured in one group. In Group I, the average daily gains were 1.17kg and 0.95kg in the lot of V. E and control, respectively.In Group II, they were 1.08kg and 1.06kg. The differences were not significant.Carcass weight, marbling, quality of meat, rib eye area and grading of the carcass were a little better in the lot of V. E than in control.Dressing percentage, price at the market and appearance of them were similar in both lots. The changes of erythrocyte, leucocyte, Hematocrit, total protein, cholesterol, calcium, inorganic phosphorus and uric acid during the experimental period of one month were not distinguished between both lots. Jpn. J. Zootech. Sci., 56 (10) In connection with fat, V. E prevents the disturbance of lipid peroxide, which arises from a peroxidation of fatty acid, while V. E itself is easily oxidized4). As the result, in a normal route, fatty acids in the body produceIn this papers, the accelerating effect of V. E on metabolism in tissues was focussed, and the effect on body weight gain and meat quality of Holstein steers was examined when it was given per os in the latter period of fattening. Materials and MethodsTen Holstein steers in NODAI's Fuji Experiment Farm that were fed for beef from 12 months of age were divided into two groups (Table I). Four steers of 20 months and 614-692kg in body weight were included in Group I, and two of them were given V. E mixed with grain ration for the last one month before slaughtering at the dose of 1g per head (1.54-1.64mg per kg of body weight). Other six steers of 18.5 months and 580-631kg were included in Group II, and three of them were Jpn. J. Zootech.Sci., 56 (10): 802-806 802 1985

agonist, clenbuterol (CL), on growth and muscle composition were examined in broiler chicks treated with or without thyroxine (T4). Fourteen day-old chicks were divided into 6 groups of 6 birds each and fed experimental diets incorporating T4 (0 or 1.2ppm) and CL (0, 1 or 2ppm) for 12 days. CL treatments decreased (P<0 .05) body