Effect of dietary fat and available phosphorus on performance and egg quality parameters of hens subjected to high environmental temperature

Abstract

Two experiments were conducted to study the relationship between dietary fat and available phosphorus (AP), and their impact on the performance and egg quality parameters of laying hens subjected to high environmental temperature. One hundred and ninety two Single Comb White Leghorn layers of the Babcock strain were used in a 2x2x4 factorial arrangement in a complete randomized design (CRD) There were 2 heat regimens, ambient temperature (AT) at 13-18?C and constant high temperature (CHT) at 33?C in experiment 1. In experiment 2, cyclic high temperature (CYHT) varying from 20-34-20?C was applied . The dietary levels were 0 and 4% fat and 0.15, 0 25, 0.35 and 0.45% available phosphorus (AP). The 8 isocaloric (ME = 2806 kcal/Kg) and isonitrogenous (18.5% CP) dietary treatments were fed individually to hens for an experimental period of 84 days. Body weight change (BWC), feed intake (FI), egg production (EP) and feed conversion (FC) were recorded every 14 days. Egg weight (EW), Haugh unit score (HU), yolk color (YC) and shell thickness (ST) were determined on all eggs collected during the last 3 days of each 14 day period. All interaction terms among the 3 main factors were not significant in both trials except for a significant interaction between fat and temperature for HU in the second study.