Heritabilities of Adjusted and Unadjusted Feed and Abdominal Fat Traits in a Broiler Dam Population

Abstract

Data from five generations of selected and control strains of a pedigreed synthetic broiler dam population were analyzed to estimate heritabilities for production traits. The population was composed of one selected strain with two replicates and one control strain in each generation. Eight production traits were measured. Growth rate traits included body weights at 28 (BW28) and 42 days (BW42) and weight gain (WG) during Days 28 to 42. Feed traits included feed consumption (FC) and feed efficiency (FE) during 28 to 42 days. Carcass traits included carcass weight (CWT), abdominal fat weight (AFW), and abdominal fat percentage (AFP) of carcass weight at 47 days.Realized heritability estimates for the two selected traits, BW28 and FE, were .32 and .14, respectively. Heritability estimates based on sire variance components were .38 for BW28, .41 for BW42, .30 for WG, .35 for FC,. 16 for FE, .43 for CWT, .53 for AFW, and .53 for AFP. Heritability estimates for feed traits adjusted for BW28 and BW42 as covariates and AFW and AFP adjusted for 47-day CWT as a covariate were averaged after weighting. Heritabilities for adjusted FC, FE, AFW, and AFP were .27, .26, .48, and .49, respectively.When either FC or FE and either BW or WG are both being selected, the feed traits should be corrected for differences in growth rate during test. The need for adjustment is evident from the differences in heritability estimates for feed traits before and after correction for growth differences as well as the absence of correlation between adjusted feed traits and growth rate.