Influence of bull biostimulation on age at puberty and reproductive performance of Sahiwal heifers

Abstract

Present study was undertaken to compare the effect of biostimulation by exposing the heifers to fenceline bull contact and fenceline + direct contact on age at puberty and reproductive performance of Sahiwal heifers. Pre-pubertal heifers (24) were allotted to 3 groups (8 animals each), i.e. non-bull exposed (NBE), fenceline bull exposed (FBE) and FBE + direct bull exposed (DBE) on the basis of age and body weight. In NBE group, heifers were not exposed to bull; in FBE group, heifers were exposed to the bull through a fenceline contact (24 h) and in FBE+DBE group, heifers were housed in a fenceline contact (24 h) with bull along with direct contact for 6 h through another bull in the heifer shed. Heifers were considered to have attained puberty if progesterone concentration was >1 ng/ml. The mean age and body weight at puberty in FBE (19.33±0.36 months and 226.20±6.35 kg) and FBE+DBE (19.11±0.58 months and 224.19±4.54 kg) heifers were almost similar but significantly lower than NBE heifers (24.13±0.16 months and 262.50±8.50 kg). The average age at first service and first calving was similar in FBE (20.41±0.45 and 30.20±0.73 months) and FBE+DBE (20.78±0.36 and 29.90±0.44 months) heifers but significantly lower than NBE heifers (25.15±0.14 and 34.29±0.53 months). We conclude that biostimulation of heifers by fenceline contact with the bull is as effective as FBE + 6 h of daily direct bull contact in hastening the age at puberty and improving reproductive performance.