Field data for the period 1976 to 1998 from South African and Namibian Afrikaner, Drakensberger, SA Angus and Simmentaler beef cattle breeds was used to investigate two fertility traits, calving rate (CR) and calving success (CS). Calving rate, a lifetime reproduction trait of the dam, was defined as number of calves produced by the dam divided by the age of the dam in years. For CS, a score of one was allocated for successful calvings and zero for failure to calve. All variances were estimated using REML procedures. The heritability estimate for CR was low (0.04) and that for CS was zero for all four breeds. After analysing CS using GFCAT (sire model) a heritability of 0.27 was estimated for the Afrikaner, suggesting that additive genetic variance does exist for CS in southern African beef cattle populations.
"Experientia docet" - Experience is the best teacher