An experiment was conducted to evaluate the effects of supplementing feed additives of Barodon®, effective microorganism® (Bacillus (B.) subtilis), and Ampbio® on the growth performance, blood metabolites, stress, and reproductive hormone levels of Korean native heifers. A total of 48 Korean native heifers were assigned to four groups with 6 heifers in each group. The groups were control, Barodon (0.2%), beneficial microorganism (1%), and Ampbio (1%). Animals in all groups were fed a basal diet composed of selected feed additives and water ad libitum for 99 days. Results showed that there are significant changes in body weight and daily gain in the Ampbio-supplemented group as compared with the control and other feed additives groups (p < 0.05). The increased level of feed intake (7.30 ± 0.03 kg) and feed requirements (10.81 ± 0.52 kg) was observed in the Ampbio-fed group followed by the effective microorganism (EM), Barodon, and control groups. There were no significant changes in albumin, glucose, glutamic oxaloacetic transaminase (SGOT), serum pyruvic transaminase (SGPT), and total protein level, but the decreased levels of total cholesterol and triglycerides and the increased level of blood urea nitrogen were noted in the Ampbio-fed group as compared with the control and other feed additive groups. The reduced level of cortisol (p < 0.05) and elevated levels of progesterone and estradiol (p > 0.05) were noted in the Ampbio-fed group as compared to the other feed additive groups. It is therefore concluded that incorporation of Barodon, EM (B. subtilis), and Ampbio in the recommended diet improved the growth and health performance of Korean native heifers.
Keywords: Blood metabolites; Cortisol; Estradiol; Feed additives; Growth performance; Heifer.