Temperature and dietary lysine levels for laying broiler breeder hens

Al-Saffar, Abdulameer (2001). Temperature and dietary lysine levels for laying broiler breeder hens. PhD thesis The Open University.

DOI: https://doi.org/10.21954/ou.ro.0000fd1c

Abstract

The specific objectives of this project were; to examine and explain the response of laying broiler breeders to different constant and cycling ambient temperatures, to different dietary concentrations of lysine and the temperature x dietary lysine interactions. A quantitative literature review indicated that there was a curvilinear (P<0.001) response in most egg production variable by egg-laying strains kept in different ambient temperatures. A second quantitative evaluation of literature indicated that increases in dietary amino acid concentrations given to egg-laying strains of hens gave small increases (P<0.001) in egg laying performance until an asymptote was reached. Little information is available on these responses in laying meat-line (broiler breeds) hens. Four feeding experiments were performed to examine and explain the response of laying broiler brœders to different constant and cycling temperatures, to different dietary concentrations of lysine and the temperature x lysine interactions. Two experiments used small flocks of floor-housed breeders in which egg production and egg composition, hatchability and chick quality variables were examined. Two further experiments were conducted in which breeder hens were caged individually and egg production, egg composition, blood physiology and carcass composition variables were examined. The egg production (egg mass output and egg weight) response of broiler breeds hens to different ambient temperatures was similar to that previously demonstrated for egg-laying strain birds, but there were no (P>0.05) effects on hatchability or chick quality. Increasing dietary lysine concentrations tended (P<0.1) to give a curvilinear response in egg mass outputs although the shape of the response curve was different to that of egg-laying strains. Different dietary lysine concentrations did not affect (P>0.05) hatchability or chick quality. Increasing dietary lysine increased (P=0.044) blood lysine concentration and increased (P=0.026) blood haematocrit values in birds kept at 21°C but not in those kept at 32°C. There was a similar temperature x lysine interaction (P= 0.031) in carcass protein composition and a trend (P<0.1) for this same interaction in body weight change of the hens in two experiments.