Phenotypic and genetic trends of some reproductive traits in N'Dama herd at Fashola Stock Farm, Nigeria

Abstract

Age at first calving (AFC) and calving interval (CALINT) records of 1349 N’Dama dams reared at Fashola Stock Farm between 1947 and 1984 were analyzed. Estimated phenotypic trend was‘75±.02months/yr and -.003±07jdays/yr in AFC and CALINT respectively. Annual phenotypic mean increased from 27.47 to 78.51 months in AFC and 383.67 to 790.52 days in CALINT. Genetic trends were not linear. Sequential polynomial fitting of the data showed quadratic function would be adequate to describe the phenotypic trend while the genetic trends can be better fitted by the cubic function. The regression equations obtained for the phenotypic trend were: Y =21.98 + .09b1 + .01b2 for AFC, andY =325.01 + 2.48b1+ .001b2 for CALINT, While the genetic trend curve equations were: Y = -.04 + .001b1 - .77b2- .13b3for AFC, andY = -.01 + .002b1 + .lib 2 + .43b3 for CALINT.