Estimates of genetic parameters for monthly egg production traits in a commercial broiler female line

Abstract

In this study, genetic parameters for monthly records of egg production, collected from weeks 24 to 55 on 16,830 hens during nine generations from a pedigreed commercial broiler female line, were estimated with single-trait, multipletrait and repeated records animal models, using restricted maximum likelihood procedures. With and without age at sexual maturity as a covariate, two models were fitted to the data for each analysis. From the weekly productions, eight monthly records on a 28-day basis were created. The estimate of heritability from single-trait analysis for the first month's record was relatively high (0.428), decreased to 0.150 and 0.092 in the second and third months, respectively, and then, with minor fluctuations, remained constant. Age at sexual maturity had a substantial influence only on heritability of the first month (0.192) and, to some extent, of the second month (0.103). Estimates of heritability and repeatability decreased from 0.067 and 0.379 to 0.029 and 0.251, respectively, owing to age at sexual maturity. Genetic correlations were generally positive, being relatively high to very high between adjacent monthly records, ranging from 0.725 (between the first and second month) to 0.986 (between the fourth and fifth month). These estimates between monthly records decreased as the time interval of the ages increased. The effect of age at sexual maturity on reduction of heritability of the first month's record and of its genetic correlations with all other monthly records suggests that it is essentially necessary to be included in the model or that the analysis is carried out without the first month's record.

Genetic parameters for eggshell traits in ostriches

“…Cloete et al (2006) observed comparable medium-tohigh repeatability coefficients for eggshell parameters (ranging from 0Á43 for pore count to 0Á72-0Á73 for shell thickness), but their study did not support the partitioning of animal effects into direct and maternal genetic components. Farzin et al (2006) reported a heritability estimate for shell thickness of 0Á68 in laying hens. This coincides with the results from the present study, but both estimates are higher than the heritability of 0Á33 reported by Johansson et al (1996).…”

Genetics and genomics of egg production traits in poultry species

“…In the study of Koerhuis and McKay (1996), heritability of hen housed production (HHP: 0.14) was similar to heritability of hen day production percent (0.1) but, as in layers, they reported a higher estimate of heritability for age at first egg (0.34). Farzin et al (2011) analyzed monthly egg production records in a commercial female line and noted higher heritability in the first month (0.43) than in the second (0.15) and third month (0.09). Adjusting for age at first egg reduced heritability in the first month to 0.19.…”

Seleção para a produção de ovos em períodos parciais e acumulados em linhagem de frango de corte comercial

“…Estudos têm relatado que os primeiros meses apresentam baixa correlação genética com os meses do meio e do final da postura (Wolc et al, 2007;Nurgiartiningsih et al, 2005), enquanto que, entre os meses do meio e do final de produção, essa correlação é elevada (Nurgiartiningsih et al, 2004;Wolc e Szwaczkowski, 2009;Farzin et al, 2011). As correlações genéticas entre meses consecutivos são elevadas e diminuem com o aumento da distância entre estes (Anang et al, 2000b;Farzin et al, 2010;Wolc e Szwaczkowski, 2009).…”