title: Implications of genetic selection on yolk proportion on the dry matter content of eggs in a White Leghorn population.
abstract: 1. The responses to genetic selection on yolk proportion as a technique for increasing egg dry matter content, an important criterion for the egg-product industry, was investigated in a pedigree flock of White Leghorn hens. 2. Parents were preselected on high and low yolk proportion from a base population. The absolute estimated breeding value for yolk proportion of both groups differed by 3%. The realised selection difference in dry matter content of eggs between groups was more than 1% in the analysed offspring population. 3. Heritability estimates were moderate and dry matter had a lower heritability (h(2) = 0.39) than yolk proportion (h(2) = 0.44). 4. The genetic correlation between yolk proportion and dry matter content was highly positive (rg = 0.91). Genetic correlations with egg weight were negative and would have to be compensated for in a breeding programme (rg = -0.76 with yolk proportion and rg = -0.64 with dry matter content). The genetic correlation between the laying performance and yolk proportion was rg = 0.28 and close to zero (rg = -0.05) for dry matter content. 5. Easy recording and lower undesirable correlations make yolk proportion more suitable for commercial selection compared with egg dry matter content in layer breeding.
authors.affiliation: a Lohmann Tierzucht GmbH , Cuxhaven , Germany.
authors.forename: W
authors.initials: W
authors.lastname: Icken
authors.forename: C
authors.initials: C
authors.lastname: Looft
authors.forename: K
authors.initials: K
authors.lastname: Schellander
authors.forename: D
authors.initials: D
authors.lastname: Cavero
authors.forename: A
authors.initials: A
authors.lastname: Blanco
authors.forename: M
authors.initials: M
authors.lastname: Schmutz
authors.forename: R
authors.initials: R
authors.lastname: Preisinger
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001947:Breeding; D002645:Chickens / Q000235:genetics* / Q000502:physiology; D004530:Egg Yolk; D004531:Eggs; D056726:Genetic Association Studies; D010641:Phenotype; D012641:Selection, Genetic