SELECTION INDEXES OF SOME ECONOMIC TRAITS ON FRIESIAN CATTLE IN EGYPT

Abstract

An evaluation for cow productivity traits of Holstein Friesian cattle kept at Dalla farm was carried at on 3096 first lactation records including 291 sires during the period from 1987 to 1994. Yields of 60 day milk yield (60 dMY), 305 day milk yield (305 dMY), lactation period (LP), days open (DO) and age at first calving (AFC) were the traits examined. Analysis was carried out using a mixed model with a month and year of calving as a fixed effects, days open and age at first calving as a covariate and sire as a random effect.

The results obtained from the analysis of the data can be summarized as:

1- 'Least squares analysis of variance showed that, the effect of month and year of calving on different traits studied were significant (P<O.O1) except for the effect of month of calving on 305 dMY.

2- Estimates of partial linear and quadratic regression coefficients of different traits studied on DO and AFC were significant (P<0.01) except the linear regression coefficients regression ofLP on AFC and 60 dMY on DO.

3- The sire of the heifers had a significant effect on different traits studied.

4- Heritabilities were 0.45±0.07, 0.52±0.06, 0.14±0.04, 0.001+0.03 and 0.57 ± 0.09 for 60 dMY, 305 dMY, LP, DO and AFC, respectively.

5- Genetic and phenotypic correlations were positive and significant (P<O.O1) except the genetic correlations between DO and different traits studied.