Effect of polyphosphates on productivity and physiological characteristics in laying hens.

Polyphosphates play a crucial role in enhancing nutrient absorption, energy metabolism, stress response, and cellular function and growth. However, the effects of polyphosphates on the laying performance and gut microbiota of laying hens are not known. This study assessed the effects of polyphosphate supplementation on laying performance, egg quality, blood, organ, tibia and cecal characteristics, and cecal microbiota in laying hens. A total of 100 Lohman Brown laying hens (51 weeks old) were distributed into four dietary treatments in a completely randomized design, each consisting of five replicates with four birds. Treatment groups were designated as corn-soybean meal basal diet (control), basal diet + 0.1% short-chain polyphosphate (P3), basal diet + 0.1% medium-chain polyphosphate (P14), and 0.1% long-chain polyphosphate (P130). Egg productivity rate and egg mass increased in the control and P3 group compared to the P130 group (p < 0.05). There was no significant effect of polyphosphate supplementation on egg weight, feed intake, FCR, Haugh unit, eggshell thickness, and eggshell weight. There were no significant differences in tibia strength among the groups. All polyphosphate groups (P3, P14, and P130) showed decreased crypt depth in the ileum and the P130 group showed an increased ratio of villus height to crypt depth (VH/CD) in the ileum (p < 0.05). P130 supplementation significantly increased bacterial diversity (ASVs and Chao1 index) in the cecal contents (p < 0.05), although there were no significant differences between groups in beta diversity and cecal microbiota composition. In conclusion, supplementation with P130 had a greater effect on the VH/CD ratio and cecal bacterial diversity while not positively affecting egg productivity, suggesting potential benefits for nutrient absorption and gut health in laying hens.