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

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

Genetic parameters for clutch and broodiness traits in turkeys (Meleagris Gallopavo) and their relationship with body weight and egg production

The objective of this study was to estimate phenotypic and genetic parameters for clutch and broodiness (BR) traits in turkeys and their relationship with body weight and egg production. Data on dam line hens was available and included: body weight at 18 wk of age (BW18), body weight at lighting (BWL, 29 to 33 wk), age at first egg (AFE), egg number (EN), rate of lay (RL), clutch length (CL), maximum clutch length (MCL), pause length (PL), maximum PL (MPL) and BR. BR was defined as the average number of consecutive pause days between clutches that was higher than the average PL per hen. Heritability estimates for BW18 and BWL were 0.50 and 0.53, respectively. The heritability for egg production, clutch, and pause traits varied from low (MPL = 0.15; BR = 0.15) to moderate (AFE = 0.22; EN = 0.28; RL = 0.29; CL = 0.21; MCL = 0.27; PL = 0.25). Genetic correlations were negative between body weight traits and EN (rg (BW18, EN) = −0.27; rg(BWL, EN) = −0.33) and CL (rg(BW18, CL) = −0.40; rg(BWL, CL) = −0.33). BR was negatively genetically correlated with EN (rg(BR, EN) = −0.85) and CL (rg(BR, CL) = −0.30), and positively genetically correlated with PL (rg(BR, PL) = 0.93) and AFE (rg(BR, AFE) = 0.21). EN had a positive (0.73) and a negative (−0.84) genetic correlation with CL and PL, respectively. Overall, the results of this study confirmed the negative (unfavorable) correlations between egg production and body weight. Despite unfavorable genetic and phenotypic correlations between egg production traits and those relating to BR, the inclusion of BR in a selection program through incorporation of clutch length traits and pause length traits is feasible. Integration of either clutch length traits or pause length traits in a selection index is likely to increase egg number while decreasing broodiness

Genetic parameters for clutch and broodiness traits in turkeys (Meleagris Gallopavo) and their relationship with body weight and egg production

The objective of this study was to estimate phenotypic and genetic parameters for clutch and broodiness (BR) traits in turkeys and their relationship with body weight and egg production. Data on dam line hens was available and included: body weight at 18 wk of age (BW18), body weight at lighting (BWL, 29 to 33 wk), age at first egg (AFE), egg number (EN), rate of lay (RL), clutch length (CL), maximum clutch length (MCL), pause length (PL), maximum PL (MPL) and BR. BR was defined as the average number of consecutive pause days between clutches that was higher than the average PL per hen. Heritability estimates for BW18 and BWL were 0.50 and 0.53, respectively. The heritability for egg production, clutch, and pause traits varied from low (MPL = 0.15; BR = 0.15) to moderate (AFE = 0.22; EN = 0.28; RL = 0.29; CL = 0.21; MCL = 0.27; PL = 0.25). Genetic correlations were negative between body weight traits and EN (rg (BW18, EN) = −0.27; rg(BWL, EN) = −0.33) and CL (rg(BW18, CL) = −0.40; rg(BWL, CL) = −0.33). BR was negatively genetically correlated with EN (rg(BR, EN) = −0.85) and CL (rg(BR, CL) = −0.30), and positively genetically correlated with PL (rg(BR, PL) = 0.93) and AFE (rg(BR, AFE) = 0.21). EN had a positive (0.73) and a negative (−0.84) genetic correlation with CL and PL, respectively. Overall, the results of this study confirmed the negative (unfavorable) correlations between egg production and body weight. Despite unfavorable genetic and phenotypic correlations between egg production traits and those relating to BR, the inclusion of BR in a selection program through incorporation of clutch length traits and pause length traits is feasible. Integration of either clutch length traits or pause length traits in a selection index is likely to increase egg number while decreasing broodiness