Phenotypic and Genetic Effects on Feed Intake of Laying Hens in Different Years

Abstract

Feed intake from 21 to 40 wk and from 41 to 60 wk of age of brown egg layers was analyzed. The full model contained BW, egg mass (EM) output, BW change (BWCH), and age at first egg as covariates in addition to effects of plumage condition class, sire, and dam. A reduced model contained the covariates only. Between 90S and 1,161, and 880 and 1,119 hens were available in the first and second periods, respectively. Averaged over 6 yr the full model explained 84 and 77%, the reduced model 73 and 63%, respectively, of the variance in feed consumption in the two periods. Regression coefficients for BW showed only a small variation between years as well as between periods. Variation was larger for the coefficients of EM and of BWCH. Larger coefficients were observed in the first period for both traits. The sequence of entering the reduced equation in a stepwise procedure was always BW, EM output, then BWCH. Averaged over 6 yr, the relative contribution of BW by its own to the accuracy of the regression model, was 68 and 60% in the two periods. Egg mass output then added 25 and 39%, and BWCH 7 and 2% in the first and second periods, respectively. The predictive value of the covariates changed with increasing age of the hens. A high average heritability of .48 could be estimated for the residual feed intake in both periods. This suggested enhanced selection response for efficiency.

Genetic parameters of feed efficiency traits in laying period of chickens

“… 1994 ), and moderate estimated heritability (0.29) for RFI2 indicated the presence of sufficient genetic variability for the trait in the resource population. However, our findings diverged from those reported by Hagger ( 1991 ) and Katle and Kolstad ( 1991 ). The difference implied that longer test periods would result in more stable and higher heritability estimates (Luiting and Urff 1991b ).…”

Experimental comparison between selection for residual feed consumption and feed conversion ratio in Tribolium

“…The heritability estimates obtained in this study are in agreement with the values found in other species. The heritability estimated for residual feed consumption is generally moderate (W ing and N ordskog 1982, and T ixier ‐B oichard et al 1995, in laying hens; V an B ebber and M ercer 1994, in broilers; M rode and K ennedy 1993, in pigs; J ensen et al 1992, in beef cattle; K orver et al 1991, and van A rendonk et al 1991, in dairy cattle) or high (H agger 1991, L uiting and U rff 1991b, and S chulman et al 1994, in laying hens). The realized heritability was high too in the selection experiment reported by K atle and K olstad (1991) in laying hens.…”

“…Heritability of residual feed consumption has been estimated in poultry (W ing and N ordskog 1982; H agger 1991; L uiting and U rff 1991b; S chulman et al 1994; van B ebber and M ercer 1994; T ixier ‐B oichard et al 1995), pigs (M rode and K ennedy 1993), beef cattle (J ensen et al 1992), and dairy cattle (K orver et al 1991; van A rendonk et al 1991). K atle and K olstad (1991) selected two low lines and one high line in laying hens for percentage residual feed consumption during four generations.…”

Phenotypic and genetic relationships among feather scores, income minus food cost and food conversion ratio in laying hens

“…Substantial phenotypic differences in food intake between well-feathered hens and hens with extensive naked body areas have been found (Braastad and Katie, 1989;Hagger 1991). Luiting (1990) gives an overview on topics of feathering, food intake, heat loss and body insulation.…”