Effects of Reducing Dietary Crude Protein with Amino Acids Supplementation on Performance of Commercial White Leghorn Layers during Late Production Period

Several strategies are being developed to minimize nitrogen (N) pollution from poultry waste in areas with high concentrations of commercial poultry operations. This study focus on the effect of feeding reduced protein (CP) diets on laying hens housed under commercial conditions. The experiment was carried out using 144 Hy-Line W-36 hens which were randomly assigned to one of four dietary treatment groups. Corn-soy based diets varying in dietary crude protein (CP) levels supplemented with commercially amino acids as follows: [1] 17% CP + Met, [2] 16% CP + Met & Lys, [3] 15% CP + Met & Lys, and [4] 14% CP + Met, Lys & Thr, were fed to layers from 53 to 64 weeks of age. Cage was considered the experimental unit (4 hens/cage), and each treatment was replicated 9 times. Using final body weights (BW), feed consumption (FC), protein intake (PI) and feed conversion ratio (FCR), egg production (EP), egg weights (EW), egg mass (EM) and egg components and solids data as growth and productive parameters during the studied period (11 weeks), one slope, broken-line regression models were employed to estimate the break point for each parameter due to reducing CP in Commercial White Leghorn hens diets. Mean differences in BW, FC and FCR among dietary CP levels were not significantly different. However, PI data showed that reducing dietary CP levels resulted in a significant (P ≤ 0.001) PI linear reduction in hens fed the 14% CP consuming the lowest PI 13.10 g/ hen as compared to all other dietary CP treatments. Estimating PI break point, hens fed the 16.78% CP consumed 16.01 g/ hen which was similar (P ≤ 0.001) to 17% CP and higher than hens fed 14, 15 or 16% CP, respectively. Numerically higher EP was recorded for hens fed on the 17% CP diet (84.74%), and heavier EW was recorded for the 16% CP (63.34 g). Albumen solids were reduced