Effect of human chorionic gonadotrophin,gonodotrophin releasing hormone and prostaglandin F2 alpha in augmenting conception rate of repeat breeder cattle

Abstract

Repeat breeding in cattle especially due to ovulatory disturbances has become a frustrating problem under field conditions. The present study was aimed to formulate an effective and economic therapy for this problem. Hence three therapeutic approaches viz. human chorionic gonadotrophin, Gonadotrophin releasing hormone and prostaglandin F2 alpha were undertaken, and its efficacy and economic viability was compared. The material for the study consisted of repeat breeder cross-bred cows and heifers presented at Artificial insemination centre and bull station, attached to the Department of Animal Reproduction, College of Veterinary and Animal Sciences, Mannuthy, Thrissur. Occurrence of ovulatory disturbance were studied and white side test was done to exclude those with infection Overall occurrence of anovulation and delayed ovulation were 7.38 and 15.77 per cent.Anovualtion in cows and heifers were 5.21 and 17.82 and delayed ovulation was 14.7 and 8.8 per cent respectively. On study of . characteristics of cervical mucus, clear colour (93 per cent), thick consistency (43.47 per cent) and atypical crystallization (57.97 per cent) were found to be high in repeaters with ovulatory disturbances. Spinnbarkeit value varied significantly (t' = - 4.2779, P < 0.01) where as pH variation was non significant (t' = 2.37, P > 0.05) between normal and repeaters. Changes in the tubular tract such as vulval oedema, hyperaem ia of

vaginal mucosa and uterine tonicity were found to be medium and low in most of the repeat breeders. Repeat breeders with ovulatory disturbances were randomly allotted to three groups of twelve each group-A, group B and group C. Intramuscular administration of Human chorionic gonadotrophin (Chorulon, 1500.I.U),GnRH analogue (Buserelin acetate -Receptal, l Ougjand Prostaglandin F2 alpha analogue (Luprostiol - Prosolvin, 3 mg) were done immediately after insemination in group-A ,group B and group C respectively. There was a significant reduction in duration of oestrum in group A (50.17 to 38.08 hours) and group B (50.08 to 36.17 hours) and non significant in group C. Ovulatory response was 33.33, 75.00 and 66.66 per cent respectively in group A, Band C. Conception rate was 25,50,50 and 22.22 per cent respectively in group A, B, C and repeaters given double insemination at 24 hours interval. The cost for treatment per animal in rupees and amount required per conception in rupees was 220, 103,44, and 35 and 880, 206, 88 and 157.5 respectively in group A, B, C and those given double insemination. Hence it is inferred that PGFz alpha treatment immediately after insemination is preferred to treatment with GnRH or hCG or double insemination at 24 hour interval and that administration ofGnRH is found better than hCG in repeat breeding due to ovulatory disturbances in cattle.