Effect of dietary lysine level on performance, egg quality and serum biochemical indices of laying pigeons

The objective of this study was to evaluate the effect of dietary lysine level on performance, egg quality and serum biochemical indices of laying pigeons, with the aim of discussing the lysine requirements of laying pigeons. A total of 2,400 healthy pigeons (average body weight: 583 +/- 77g) with the age of 40 wk were randomly allocated to 6 treatment groups of 5 replicates with 80 female pigeons each (housed 2 per cage). A 16L:8D light cycle was used. The control group fed the basal diet which was primarily composed of corn-soybean meal with a low lysine level of 0.64%. The lysine levels of the other 5 treatment groups were 0.68%, 0.72%, 0.76%, 0.80%, and 0.84% achieved by adding supplemental lysine to the basal diet. The study had lasted for 12 wk after a 1-wk adaptive phase. The results showed that laying rate and average egg weight of the entire experimental period were significantly influenced by dietary lysine level (P < 0.05), laying rate showed a significant quadratic response to increasing dietary lysine level (maximum response = 0.784), egg weight showed a significant linear response. Dietary lysine level had significant effects on eggshell thickness and yolk color (P < 0.05), both showing significant linear response. Eggshell thickness showed a downward trend while yolk color showed an opposite trend. Dietary lysine level had significant effects on the concentration of calcium (Ca), phosphorus (P), total cholesterol, and total protein (P < 0.05) in serum. The concentration of Ca and total cholesterol showed significant linear responses; Ca showed an upward trend, and total cholesterol showed the opposite trend. The content of P showed a significant quadratic response, and showed an upward trend in the range of dietary lysine levels. In conclusion, taking laying rate as the main assessment index and then considering egg quality and serum biochemical indices secondly, the optimal lysine level of dietary was 0.78% for laying pigeons.