Factors affecting first lactation performance of Friesian cows in Syria.

摘要

The factors affecting milk production and milk fat percentage in pure Friesian cows under Syrian environmental conditions were studied. Records of 106 first lactations from one herd of cows raised in Zareth farm, Aleppo, Syria (1998-2000) were usedto determine the effects of sire, season of calving and age and weight of cow at calving on total milk yield (TMY), 305-day milk yield (305 d-MY) and milk fat percentage. Heritabilities as well as genetic and phenotypic correlations for all the traits studied were likewise evaluated. Sire had significant effect (P < 0.05) on 305 d-MY and non-significant effect on TMY and fat percentage. Differences due to season of calving were highly significant for fat percentage and non-significant for TMY and 305 d-MY. Age of cow at calving significantly affected TMY. Cow weight at calving had no significant effects on all traits studied. Heritabilities for TMY, 305 d-MY and fat percent were 0.21, 0.38 and 0.31, respectively. Genetic correlation among studied traits ranged from 0.74 to 0.99.