Abstract:
The aim of the study was to investigate the effects of feed withdrawal and strain on laying
performance and egg quality of White and Brown Hy-line layers. Fifty four hens for each strain
(White Hy-Line and Brown Hy-line) aged 18 weeks (point of laying stage) were used in the
investigation. Feed withdrawal had no effect (P>0.05) on laying performance, mortality rate, egg
internal and external quality, but significantly affected (P<0.01) average feed intake, body
weight, small and extra-large eggs percentages. Hens under ad libitum consumed more feed
than hens under four hours and eight hours feed withdrawal. High body weight was observed on
ad libitum fed hens, intermediate on eight hours feed withdrawn hens and lower at four hours
feed withdrawn hens. High percentage of small graded eggs was observed on four hours feed
withdrawn hens, intermediate on eight hours feed withdrawn hens and lower on ad libitum fed
hens. High percentage of extra-large graded eggs was observed on ad libitum fed hens,
intermediate on eight hours feed withdrawn hens and lower four hours feed withdrawn hens.
Strain had a significant effect on average egg weight, median egg weight, albumen weight,
extra-small, small, medium and large graded eggs percentages (P<0.01) and on body weight,
egg height , egg width, average egg shell colour (P<0.05). Strain did not affect (P>0.05)
average feed intake, body weight change, egg output, feed conversion ratio, mortality rate, egg
shell breaking force, albumen height, yolk height, yolk weight, extra-large and jumbo graded
eggs percentage. Brown Hy-Line layers had high average egg weight, median egg weight, egg
height, egg width, and average egg shell colour and albumen weight than White Hy-Line layers.
Small sized eggs percentage and body weight were high on White Hy-Line layers compared to
Brown Hy-Line layers. Medium and large sized eggs were high on Brown Hy-Line layers than
White Hy-Lines. Feed withdrawal by strain interaction effect was observed on body weight,
average egg weight and median egg weight, albumen weight and egg height, percentage of
small, medium and large graded eggs (P<0.05). Brown Hy-Line hens under eight hours feed
withdrawal had high egg weight, median egg weight, egg height, albumen weight and under
eight hours feed withdrawn White Hy-Line hens had lower albumen height compared to other
interactions. In all interactions White Hy-Line had high percentage of small graded eggs
whereas Brown Hy-line had high percentage of large and medium graded eggs.
