Effect of norgestamet and prostaglandinfalpha in crossbred heifers for augmenting fertility

Abstract

With the objective of studying the effect of norgestamet-oestradiol and PGF2a treatment on oestrus synchronisation and to enhance the fertility rate in crossbred heifers at fixed time double insemination, forty-five cycling heifers, selected from Kerala Agricultural University Livestock Farms, were randomly allotted to three treatment groups, Group I, Il and Ill. Fifteen heifers of Group I were given 3 mg norgestamet implant kept in situ for nine days and an injection containing a combination of 3 mg norgestamet and 5 mg oestradiol valerate on the day of insertion of implant. While the fifteen heifers of Group Il were given double dose regimen of 15 mg PGF2a (luprostiol) at 11 days apart. Group III consisted of fifteen heifers that were kept as control. In both Groups I and Il, 14 heifers (93.33 per cent) each responded to the treatments. The time taken for the induction of oestrus in the Group I was 50.1 ± 4.58 hours as against 69.50 ± 1.34 hours in the Group 11. There was significant difference on the time of induction of oestrus between Group I and Group n. The duration of oestrus in the Group I was 27.8 ± l.09 hours, as against 28 ± 1.07 and 19 ± 0.33 hours respectively in Group II and Group III. Though analysis of variance showed no significant difference between Group I and Group Il, pairwise comparison showed no significant difference between Group I and Group Il. A higher percentage of heifers in Group I and II showed medium to high intensity of oestrus than Group Ill. The cervicovaginal mucus examination revealed an increase in typical fern pattern in Group I and II than Group Ill.

The first, second and third service pregnancy rate in Group I were 21.42, 28.57 and 14.28 per cent respectively at fixed time artificial insemination, 48 and 72 hours after the removal of the implant, as against 42.86, 21.43 and 14.28 per cent at fixed time artificial insemination, 72 and 96 hour after the second injection of PGF2a in Group II. In Group III heifers 20 per cent each required one and three inseminations and 13.44 per cent required two inseminations to effect pregnancy. The overall pregnancy rate obtained for Group I, II and III were 64.27, 78.57 and 53.33 per cent respectively. The AI indices for Group I and II were 1.72 and 1.63 as against 2.13 of Group Ill. The present study reveals that though norgestamet- oestradiol and PGF2a could be effectively used for synchronisation of oestrus, use of PGF 2a is the better alternative for augmenting fertility in crossbred heifers.