Estimate of Direct and Maternal Genetic Parameters for some Production and Reproduction Traits in Friesian COWS through Sire and Animal Models

Abstract

This research papper was carried out to assessment variance components, genetic parameters and breeding value for some productive traits such as: milk yield (MY), lacation period (LP) and dry period ( DP), and reproductive traits such as: days open (DO) and calving interval (CI), for a herd of Friesian cows, belong to Shobratana Animal Production Society, Tanta city in Egypt. Data were covered the period from 1985 to 2003. A total records were 2302 of 755 cows were sired by 45 bulls were analyzed using LSMLMW and MTDFREML programes. Unadjusted means of MY, LP, DP, DO and CI were 4875 kg, 333 d, 72 d, 119 d and 405d, respectively. Sire heritability were 0.43, 0.28, 0.30, 0.26 and 0.24 for MY, LP, DP, DO and CI, respectively. In this respect, direct and maternal heritabilities for the same traits were 0.34, 0.17, 0.13, 0.15 and 0.17, and 0.11, 0.15, 0.14 0.23 and 0.10, respectively. For sire model, genetic correlations among productive traits ranged from -0.30 (LP and DP) to 0.76 (MY and LP), while between reproductive and productive traits were postive and high (0.86 to 0.93) except DP and each of DO and CI were low and positive (0.13 and 0.09), respectively. The same trend as in the sire model was obtained also in the direct genetic correlations (ra1a2) among the same previous traits. Likewise estimates of maternal genetic correlations (rm1m2) were the similar the direct genetic correlations. Accuracy of decled breeding value, ranged from 35 to 88, 72 to 89 and 37 to 87 for sires, cows and dams, respectively, for different studied traits. This indicte that genetic improvement should be preferable realized through cows which the minimum of acurrecy was highest comparing to sires or dams. The present high estimates of genetic correlations between MY, LP and reproductive traits (DO and CI) that offer the possibility genetic improvement if selection for MY avaiable. Also the actual estimate of maternal heritability suggested that the maternal effects take into account in the analysis models and selection for productive and reproductive traits in Friesian cows cows in Egypt.