Effect of different levels of monensin on growth performance and rumen volatile fatty acid in weaning Holstein male calves

The aim of this study was to evaluate the effect of different levels of monensin on growth performance, body weight gain, feed efficiency and rumen volatile fatty acid in weaning Holstein male calves. This study were conducted using 66 weaning male calves (average body weight 103 ± 5 kg and average age 90 ± 5 days) that received experimental diets including A) control without monensin, B) control with 70 mg/d monensin and C) control with 140 mg/d monensin in a complete randomized design with periods of 90 days (days of 90 to 180). The effect of treatments was significant on dry matter intake (P= 0.01). Daily Feed intake was 5.99, 5.82 and 4.04 Kg respectively for 1 to 3 treatment that highest in 70 mg monensin and lowest in control group. Feed conversion ratio (FCR) improved in month 5 in calves fed monensin as compared with control group (P= 0.05). The results indicated that monensin increased final weight in calves fed monensin as compared with control group. Body weight in 70 mg monensin was highest as compared with others (P≤ 0.05). Average daily gain in month 5 was significant (P≤ 0.05) that highest in 140 mg monensin group. Average height gain was significantly different between experimental treatments that highest in 140 mg monensin group (12.65 am). Monensin had significant effect on propionate that highest in 70 mg monensin group.