The response of four strains of White Leghorn layers to two levels of dietary phosphorus

The purpose of this experiment was to determine the response of four high producing strains of Single Comb White Leghorn-type hens to dietary phosphorus levels of 0.4 and 0.6 percent as measured by shell quality, egg production, egg weight, feed consumption, body weight and mortality. This study was conducted for 11 -- 28 day periods. Results were subjected to analysis of variance and when significance was determined (P ≤ 0.05) mean separation was performed using Duncan's Multiple Range test. The results showed no significant relationship between dietary phosphorus level and egg production, egg weight, feed per hen, feed per dozen or mortality. Dietary phosphorus level had a significant effect on egg shell quality and body weight in that the lower phosphorus diet resulted in significantly improved egg specific gravity but reduced final body weight and body weight gain. Egg shell quality declined with length of lay and responded to environmental temperature by improving during the final period which was much cooler than the previous periods. Significant differences between strains were observed for all parameters studied and a significant difference in strain response to the two diets was observed for egg production. One strain had significantly lower egg production on the 0.4 percent phosphorus diet whereas another strain improved egg production on the same diet. There appeared to be differences in strain response for mortality but these differences proved statistically nonsignificant.