Restricted feeding of broiler breeder pullets during the rearing period and its effect on productivity and breeding

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Abstract
A total of 2000 broiler breeder pullets was used for an experiment comparing two levels of restricted feeding from 6 to 20 weeks with three levels of low‐lysine feeding from o to 12 weeks of age. The object of the experiment was to obtain matching body weights at 20 weeks of age between the two levels of quantitative restriction and the highest and lowest levels of lysine feeding and to compare subsequent biological performance during lay. A control treatment was included in which birds were fed ad libitum at all stages. Both methods of nutrient restriction reduced intake to 20 weeks of age. From 1 d to 60 weeks of age total food intake was reduced in proportion to the degree of restriction applied during the growing stage. Sexual maturity was delayed by both methods of restriction, though low‐lysine diets produced a greater delay than quantitative restriction. Production of total eggs and of settable eggs was increased by both quantitative food restrictions and by the least severe of the lysine‐deficient diets. Following quantitative restriction egg size and fertility were both improved, but these advantages were not obtained by lysine restriction. Mortality and culling were mainly influenced by a high incidence of “rupture of the gastrocnemius tendon “ which occurred exclusively in pullets fed lysine‐deficient diets during rearing. It is concluded that quantitative restriction is to be preferred because of its advantageous effects on egg weight, rate of lay and fertility, and because it avoids the high mortality rate found with severe lysine restriction.