EFFECTS OF GnRH ANALOGUE AND VITAMIN AD3E ON INDUCTION OF CYCLICITY IN ANOESTRUS HEIFERS

Abstract

The purposes of this investigation were to determine the effects of different drugs such as GnRH analogue, vitamin AD₃E and combination of vitamins and minerals on induction of cyclicity followed by conception in crossbred anoestrus heifers. The effects of body condition score (BCS) and age at anoestrus heifers during treatment on induction of cyclicity and conception were also determined. Sixty crossbred anoestrus heifers having > 2.5 BCS at >24 months age at Potiya Upazilla of Chittagong district were used. The cyclicity of the cows was confirmed by using real time ultrasonography on the basis of presence or absence of corpus luteum. The anoestrus heifers were allotted for 1 to 4 different treatment groups with GnRH analogue, vitamin AD₃E and vitamin mineral solution including one no-treatment control group. AI was done in observed oestrus heifers and the conception was determined transrectally by using B-mode real time ultrasonography between 28-35 days post-Al. Heifers showed oestrus at higher (46.67%) proportion in treatment groups than that in no-treatment counterpart (6.67%) (P<0.05). The conception rate was 35.56% in treatment received heifers. The GnRH treated heifers showed the highest (60.00%) proportion of cyclicity and conception rate (46.67%) whereas vitamin mineral solution treated heifers showed the lowest cyclicity (33.33%) and conception rate (26.67%) (P<0.05). Heifers with BCS 3.5 had the highest (57.14%) rate of oestrus induction and (57.14%) rate of conception (P<0.05) whereas heifers with BCS 2.5 had the lowest (41.67%) rate of oestrus induction and (20.83%) rate of conception (P>0.05).  Heifer showed highest rate (50.00%) of cyclicity and (38.89%) rate of conception when their age ranges from 36 to 42 months where as heifer showed lowest (37.50%) rate cyclicity and (31.58%) rate conception when their age ranges from 24 to 29 months (P>0.05). In conclusion, treatment of crossbred anoestrus heifers with drugs has positive effect on induction of cyclicity followed by conception. GnRH may be the drug of choice among the drugs tested in this study. The BCS of heifers during treatment influences the treatment outcome with respect to induction of cyclicity followed by conception.