The Systematic Study on the Effects of Adding Bile Acids and Zinc to Laying Hens' Diets: From Production Performance to Egg Quality, Trace Element Content, and Intestinal Microorganisms.

Abstract

This study systematically assessed the impact of bile acids and zinc on the production performance, egg quality, tissue trace element content, and intestinal microorganisms of laying hens, with an initial investigation into their potential interactions. Three hundred healthy 240-day-old Jingfen No. 8 laying hens were assigned into 4 groups, each group contains 75 hens with 5 replicates.The control group was fed with a standard diet, 500 mg/kg bile acids, 120 mg/kg zinc, and 500 mg/kg bile acids + 120 mg/kg zinc were added to the three experimental groups. The experimental procedure included a 7-day acclimation period followed by a 56-day formal trial. Supplementation with 500 mg/kg bile acids significantly increased average daily feed intake (ADFI), laying rate, and egg production, while decreasing both the feed-to-egg ratio (F/E) and Haugh unit values. On the other hand, supplementation with 120 mg/kg zinc notably boosted daily feed intake, egg weight, yolk color and eggshell weight, and elevated Zn²⁺ concentrations in the liver, yolk, and whole egg. Analysis of intestinal microorganisms revealed a high level of similarity between the groups, although not reaching statistical significance. However, when both supplements were combined at 500 mg/kg bile acids and 120 mg/kg zinc, a significant reduction in average egg weight compare to the control group was observed, with no significant variances in other measured parameters. Nonetheless, certain differences and similarities in the composition of intestinal microorganisms were noted. Interaction analysis revealed significant effects between bile acids and zinc on average egg weight, ADFI, laying rate, egg production, yolk color, and eggshell weight. The findings collectively indicate that the individual use of bile acids and zinc significantly enhances production performance, egg quality, tissue zinc content, and influences the composition of intestinal microorganisms in laying hens. Conversely, when these supplements are combined, antagonistic effect emerge, indicating a diminished effectiveness of the combined supplementation. These results offer empirical support for understanding the limitations in formulating feed additives.