Performance of Zebu Crossbred Dairy Heifers Fed Monensin Around Puberty

Eight KF heifers were randomly divided into two groups. Group I heifers were fed concentrate mixture and green fodder to meet the requirements on the basis of body weight. Group II were fed the same control diet as above for first 20 days (adaptation phase), followed by monensin supplementation @ 200 mg/day/head for next 3 5 days (experimental phase). After that the supplementation was withdrawn and the heifers were followed for another 20 days on control diet (post experimental phase). Body weights were monitored every week on two consecutive days and averaged. Average weight gain was 17.59% higher in Group II than Group I. DMI averaged 3.24% less in Group II. Feed required per kg gain was also reduced by 11.63% due to feeding of monensin. BCS did not alter significantly (P>0.05) upon monensin feeding. The supplementation had a beneficial effect on attainment of puberty. While the response was 100% for Group II, it was 50% for Group I. The heifers in Group II attained puberty with in 25.25 ± 6.51 days (range 12–43 days) after initiation of the monensin supplementation. Average age and body weight at the commencement of puberty in supplemented heifers was 764.0 ±12.59 days and 300.00 ± 21.76 kg respectively.