Effect of sire of foetus on current and subsequent milk yield of the dam

Abstract The influence of the sire of foetus and the birth weight of the calf on the dam's current and subsequent milk production was investigated in Simmental cows. The study was based on milk yields of 19 339 primiparous and 53 942 multiparous dams carrying foetuses from 260 sires of 5 different Red Holstein × Simmental breed groups. The foetal-sire effect on milk production was calculated as the correlation between the record of the dam, corrected for various factors, and the genotype of the sire of foetus. These correlations were small for the subsequent as well as for the current lactation, and ranged from 0.04 to 0.11. The milk yields of multiparous cows were affected by the breed of sire of foetus. This was, however, only occasionally the case in primiparous cows. Significant but small effects of calf birth weight were found only in multiparous cows. Although the sire of foetus has a significant effect on the milk yield of the dam, genetic implications seem unimportant in sire evaluation, since the largest difference between sire of foetus averaged only 40 kg for the standard lactation in primiparous cows. These effects are somewhat larger for the 100-day milk yield (90 kg).