Abstract
ABSTRACT The present study was conducted on pair aged commercial laying breeder strains (Hy-Line Brown and Hy-Line W-36) to evaluate genetic differences of eggshell and bone quality. In addition, egg production performance, mortality rate, internal organs and reproductive measurements were determined. Correlation coefficients among some eggshell and bone traits were calculated. White layer breeder hens had significantly higher percentages of hen-day and hen-housed egg production compared to the brown one. Brown Hy-Line layer breeder strain had better eggshell quality compared to W-36 Hy-Line layer breeder strain. The white layer breeder strain had a significantly higher relative oviduct weight compared to the brown one. Brown layer breeder strain recorded the higher humerus width in comparison with the white one. Tibia bone weight of brown layer breeder strain was significantly heavier by 22.87% as compared to the white strain. Moreover, the brown breeder strain recorded the higher figure of tibia width, thickness, and strength. In conclusion, at the end of the laying cycle, brown Hy-Line layer breeder strain exhibited better eggshell quality, body weight and tibia bone quality than those of W-36 breeder strain. Positive correlation coefficients were detected between humerus bone strength and both eggshell thickness and strength in brown and white strains.
Highlights
There has been increased interest from the scientific community and poultry industry regarding eggshell and bone quality of laying breeder strains
Modern commercial layer breeder hens produce more than 260 hatching eggs during a production period, and the amount of calcium for eggshell formation corresponds to such numbers of eggs during that time, with the advancing of layer breeder hen’s age in late stages of egg production
The lower mortality rate of Hy-Line W-36 layer breeder strain indicated a better adaptation to the prevailing environmental conditions compared to Brown strain
Summary
There has been increased interest from the scientific community and poultry industry regarding eggshell and bone quality of laying breeder strains. It is hard to imagine how this rather small animal can cope with this effort, which requires a high ability to process feed for eggs and high eggshell quality. Another problem that occurrs on commercial laying breeder hens is the loss of bone strength at the end of the laying season. Modern laying breeder hens face a major physiological challenge when they must produce large quantities of hatching eggs and maintain the strength of their skeleton. Egg production is a dependent variable and is influence by several factors like the strain of chicken, feeding, mortality, culling, health, and management practices, peak lay and persistency of lay. The higher mortality rate has been stated to harmfully affect production performance of layer eRBCA-2020-1250
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