Genetic and phenotypic evaluation of growth traits in selection experiment performed in synthesized Benha chickens

الملخص EN

-A selection program for four generations (base and three selected generations) was started in 2011 at Benha University, Egypt to improve growth traits in a synthetic line named Benha chickens.

A total of 18 cockerels and 180 pullets were selected according to their BLUP values for egg number during 90 days of laying from Benha base population (control).

Data of 4916 chicks produced by 69 sires and 484 dams were used to estimate heritabiliets, genetic and phenotypic correlations and BLUP estimates for body weight at 0 (BW0), 4 (BW4), 8 (BW8), 12 (BW12) and 16 (BW16) weeks of age along with daily gains during 0-4 weeks (DG4), 4-8 weeks (DG8), 8-12 weeks (DG12) and 12-16 weeks (DG16).

The selection effects, correlated responses and the genetic and phenotypic trends for body weights and daily gains across generations were quantified or clarified applying the updated approach of the animal model program of BLUPF90.

Heritability estimates were moderate or high; being 0.52, 0.28, 0.27, 0.33 and 0.31 for BW0, BW4, BW8, BW12 and BW16, respectively.

Genetic correlations for growth traits at different ages were positive and ranged from 0.64 to 0.88 among body weights, and from 0.14 to 0.65 among daily gain traits.

The ranges in BLUP of most body weights and gains in the control generation were higher than those in the selected generations.

Accuracies of BLUP estimates for growth traits in all generations (control and selected) were moderate or high.

The three selected generations were superior (P <0.05) in most body weights and daily gains than the base generation and the contrasts among estimates of these generations were significant (P<0.05).The phenotypic trend increased from 33 to 34 g, 234 to 256 g, 532 to 650 g, 962 to 1123 g and 1458 to 1635 g for BW0, BW4, BW8, BW12 and BW16, respectively.

the genetic trends across the generations clarifying that the initial BLUP estimates for BW0, BW4, BW8, BW12 and BW16 were 0, 1.0, 1.0, 1.4 and 0.1 g in the base population then gradually increased as the generation advanced till reached 0.1, 3.0, 9.5, 11 and 5.1 g in the first selected generation, 0.2, 5.0, 18, 20 and 9 g in the second selected generation, and 0.3, 7.0, 25, 29 and 13 g in the third selected generation, respectively.

The accumulative correlated selection responses were 84 g for BW8, 123.6 g for BW12 and 123.6 g for BW16