Estimating total lysine requirement for optimised egg production of broiler breeder hens during the early-laying period.

ABSTRACT

The production performance of broiler breeder hens in response to different levels of total lysine during the early laying period was investigated. A total of 126 Ross 308 parent stock hens were offered one of seven dietary treatments formulating elevated contents of total lysine ranging from 0.55% to 0.79% (0.04 scale; 133 g of feed) from 23 to 29 weeks of age. Each treatment had six replicates with three birds per pen. Body weight was recorded triweekly and eggs were collected and weighted at 900 am daily. One hen from each pen was euthanized to collect blood samples and visceral organs were harvested and weighed. Egg production, egg weight and egg mass were lower (p < 0.05) in hens offered a diet containing 0.55% total lysine compared to those fed the diet containing higher total lysine. Hens offered a diet containing 0.71%, 0.75%, and 0.79% total lysine had greater (p = 0.008) egg production rate compared to those offered a diet containing lysine less than 0.71%. The number of total eggs produced tended to be greater (p = 0.083) in hens offered a diet containing 0.71 and 0.75% total lysine compared to the other treatments. The number of settable egg production was higher (p < 0.001) in hens offered a diet contacting 0.79% total lysine compared to those fed the diet containing lower levels of total lysine. The relative weights of oviduct and ovary were lower (p < 0.05) in hens offered a diet containing 0.59% total lysine compared to the other treatments. No difference found in body weight, the number of total eggs, double-yolk eggs and abnormal shell eggs among the treatments. The urea nitrogen, estradiol-17 beta and progesterone in plasma were not affected by treatments. Based on linear- and quadratic-plateau models, total lysine requirements for egg production, settable egg production and egg mass at the early laying period were to be 0.73%, 0.77%, and 0.71%, respectively. Modern broiler breeder hens likely require higher total lysine than NRC recommendation in a diet for enhancing productivity during the early-laying period.