Impact of Calves Gender Birth Weights on Predicting the Future Performance of Friesian Cattle under Farm Conditions
2023
Shereen K. Genena | Samah Z. Ebrahim
A total of 4913 Friesian cows at Sakha Experimental Farm were analyzed between 1975 and 2020 to determine the effects of gender calf birth weight (CBW) on the future performance of their dams. The fixed effects of CBW classified into five groups: < 25, 26-30, 31-35, 36-40 and >40kg on lactation period, total (TMY) and 305- day (305MY) milk yield, age at first calving (AFC), gestation length (GL), days open (DO), and calving interval (CI), as well as their genetic (rG) and phenotypic correlations with CBW, were estimated using BLUPF90 software. Increased CBW had a highly significant (P<0.001) effect on milk productivity; the maximum TMY was obtained at >36 kg for males, but at > 31 kg for females in 305MY. Until >40 kg, CBW had a linear effect on AFC and CI (P< 0.001). High positive rG estimates were obtained between CBW categories with TMY and 305MY, ranging from 0.48 to 0.89 and 0.23 to 0.87, respectively. Moderate to high positive rG estimates were obtained between CBW and reproductive traits, ranging from 0.24 to 0.76 for dams. Selection for intermediate CBWs combined under appropriate management conditions should be beneficial for maximizing milk production, controlling fertility, with delivering healthy calves without dystocia.
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