Effect of breed and age of buck and season of breeding on reproduction

Abstract

The reproductive performance in does has been found to be affected by several genetic and non-genetic factors, e.g. breed, season of breeding, parity and age and weight at service, but information on the effect of breed of buck on female reproduction has not been reported in the literature on tropical goats. This paper reports a study on the effect of breed of the buck, its age and season of breeding on some economically important reproductive traits, viz. conception rate, kidding rate and gestation length in Sirohi goats.Data on 913 service records of Sirohi does maintained at the Institute for a period of two years (1978 and 1979) covering three seasons of breeding, viz. spring (February to March), summer (May to June) and autumn (September to October) have been utilised for this analysis. After heat detection the does were allotted to Beetal and Sirohi bucks for natural service. The bucks used belonged to two age groups, young (one to three years) and adult (more than three years).The arithmetic means along with SEs for conception rate, kidding rate and gestation length in Sirohi does mated to the bucks in different seasons of breeding are given in Table I.An analysis of variance was carried out on the data on conception rate, kidding rate and gestation length, values for the first two traits being subjected to arcsin transformation. The effect of breed of the buck was non-significant (P > 0-05) on conception rate and kidding rate but significantly (P<0-01) on gestation length. Season of breeding significantly (P< 0"01) affected all these three traits..The conception and kidding rates were highest in summer followed by autumn and spring whereas the gestation length was shortest in autumn followed by summer and spring.Although the Beetal is a breed of high prolificacy 49-2% of multiple births having been reported (Singh, Balaine, Singh and Rathi, 1975) as compared to 4.3% in Numbers in parentheses indicate the number of bucks used for service. Means with dissimilar superscripts differ significantly at P < 0"01. TABLE I Mean and SEs in Sirohi does mated to Beetal and Sirohi bucks in different seasons Season 13