Genetic Analyses for Milk Yield, Lactation Period and Fat Percentage in Brown Swiss Cattle


JOURNAL OF ANIMAL AND VETERINARY ADVANCES, vol.8, no.5, pp.857-862, 2009 (SCI-Expanded) identifier identifier


In this study, a total of 733 milk yield records of Brown Swiss cows raised at Konuklar State Farm in Konya Province in Turkey were used for estimation of phenotypic and genetic parameters for milk yield, lactation period and fat percentage. The Phenotypic and genetic parameters were estimated by the MTDFREML program using Multiple Trait Animal Model. The model included individual, permanent environment and errors as random effects, year and season of calving, parity, year and age as fixed effects and days in milk as a covariate for milk yield; milk yield as a covariate for lactation period and milk yield and lactation period as covariate for fat percentage. Genetic parameters and breeding value of cow, sire and dam for milk yield in kg, for lactation period in days and for fat percentage in percent were estimated. Cow breeding values ranged from -3006-1724 kg for milk yield, from 10.81-14.22 days for lactation period and from -1.48-0.97% for fat percentage. Likewise, dam breeding values ranged from -1628-862 kg, from -5.69-7.74 days and from -0.76-0.48% for the same traits, respectively. Sire breeding value ranged between -1129 and 862 kg, -8.63 and 5.73 days and -0.68 and 0.83% for the above mentioned traits, respectively. Estimates of heritability were 0.33, 0.11 and 0.39 for milk yield, lactation period and fat percentage, respectively. The genetic correlation between milk yield and fat percentage was positive and high (0.95), whereas the genetic correlation between lactation period and milk yield and between lactation period and fat percentage was negative, -0.49 and -0.73, respectively. Repeatability estimates were 0.34, 0.47 and 0.54 for the same traits, respectively.