A 3 x 3 treatment arrangement varying in dietary protein and TSAA:Lys was used to
evaluate the effect of low-protein diets fed to Hy-Line W-98 laying hens. Phase I
was 20 to 43 wk of age with 18.9, 17.0, and 14.4 g of protein/hen per day and 0.97,
0.85, and 0.82 TSAA:Lys, whereas phase II was 44 to 63 wk of age with 16.3, 14.6,
and 13.8 g of protein/hen per day and 0.92, 0.82, and 0.72 TSAA:Lys. Egg production
and feed consumption decreased from 83.7 to 82.2% and 98.8 to 95.6 g, respectively.
Feed efficiency improved from 1.680 to 1.645 g of feed/g of egg mass with decreasing
dietary protein. Body weight gain was similar for hens fed high or medium protein
diets. In phase II, hens consuming 13.8 g of protein/day had significantly reduced
egg weight compared with hens consuming 14.6 or 16.3 g of protein/day. Wet and dry
albumen percentage, albumen solids, and albumen and yolk protein percentages were
significantly decreased with feeding low-protein diets. Yolk protein percentage was
increased from 14.85 to 15.11% when decreasing the ratio from 0.97 to 0.82. Hens consuming
a low-protein diet produced eggs with the lowest specific gravity. An interaction
was observed for protein retention during phase I, feeding 14.4 g of protein/day or
a ratio of 0.97 improved protein retention by 9 and 16%, respectively. Overall, hens
consuming 16.3 or 14.6 g of protein/hen per day performed similar to hens consuming
18.9 and 17.0 g of protein/hen per day during P1 and P2, respectively. Also, hens
consuming diets containing 0.97 and 0.92 TSAA:Lys produced eggs with improved shell
quality as compared with other ratios during P1 and P2, respectively.