Estimation of the genetic parameters of age at first egg, egg production, clutches, pause and broodiness in the turkey (Meleagris gallopavo)

Abstract

The objective of the current study was to estimate genetic and phenotypic parameters for age at first egg (AFE), egg number (EN), as well as clutch, lay pause and broodiness traits in turkeys. Clutch length (CL), maximum clutch length, pause length (PL), maximum pause length, and broodiness data for 5,671 hens in a commercial breeding program were analysed in this study. A broody period was defined as the average number of consecutive pause days between clutches that were higher than of the mean pause length for each hen (BR) and total mean of pause length. A multivariate animal model implementing restricted maximum likelihood methodology was applied to estimate heritability and genetic and phenotypic correlations for traits using DMU software. Heritability for AFE was estimated at 0.62 ± 0.03 and that for other traits analysed ranged from 0.14 to 0.29. Genetic correlations between AFE and EN and CL traits were negative (-0.52 ± 0.06 and -0.46 ± 0.08, respectively). However, our results show positive correlations between AFE and PL and BR traits; EN and CL increased and BR decreased with decreasing AFE. In addition, selection for EN is likely to increase CL substantially due to the positive genetic correlation while decreasing PL and BR. The correlation between BR and other selected traits is substantially different from unity. Therefore, our results suggest that inclusion of broodiness traits in turkey breeding programs could have a positive effect on overall production efficiency