Genetic and phenotypic trends of milk yield and reproductive traits for friesian herd raised in mid-delta
Abstract: Milk production records (12736) of 5632 cows daughters of 407 sires and 3192 dams kept at Sakha and Alkarda Experimental Farms belonging to Animal Production Research Institute, Egypt were analyzed to estimate genetic and phenotypic trends for the 305-day milk yield (M305), calving interval (Cl) and age at first calving (AFC) over the period from 1960 to 2005. Fixed effect model was used to test the non-genetic effects on the considered traits. Farm, parity and year of calving affected the studied traits significantly. Season affected only age at first calving. Multiple-trait derivative-free restricted maximum likelihood (DF-REML) with animal model analysis was used to estimate (co)variance components, genetic parameters and breeding values.
Estimates of heritability for M305, Cl and AFC were 0.19, 0.04 and 0.13 respectively. Genetic correlations between M305 and each of Cl and AFC were 0.38 and 0.24, respectively, while the genetic correlation between CI and AFC was 0.20. Phenotypic correlations between M305 and Cl and AFC were 0.10 and 0.20, respectively, while the phenotypic correlation between CI and AFC was -0.02. Repeatability estimates for M305 and Cl were 0.33 and 0.07 respectively. Predicted breeding values for M305 ranged from -610.0 to + 1142 kg, from -21.5 to 28.76 days for CI and for AFC ranged from -62.9 to 57.7 days. The estimated genetic trend for M305 was insignificant (P>0.68) and in the tavorable direction as 0.27 ± 0.66 kg while the phenotypic trend was significant (P<0.00) and estimated as 25.84 ± 5.20 kg. The estimated genetic trend for CI was insignificant (P>0.27), and in the unfavorable direction as 0.03 ± 0.03 days while the phenotypic trend was negative, insignificant (P>0.62) and estimated as-0.09 ± 0.17 days. The estimated genetic trend for AFC was insignificant (P>0.47) and in the favorable direction as -0.04 ± 0.06 days while the phenotypic trend was posirive, significant (P<0.00) and estimated as 2.26 ± 0.54 days. In conclusion. an efficient breeding program and selection indices that incorporate reproductive traits with milk production trait would be effective for genetic progress.
Publication year 2008
Pages 1-14
Availability location معهد بحوث الانتاج الحيوانى- شارع نادى الصيد- الدقى - الجيزة
Availability number
Organization Name
serial title Egyptian Journal of Applied Science
ISSN 1110-1571
Author(s) from ARC
Agris Categories Animal husbandry
AGROVOC
TERMS		 Breeding value. Cows. Genetic parameters. Herds. Milk production. Milk yield. Reproductive performance.
Publication Type Journal
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