Effects of Periplaneta americana residue on the growth performance and intestinal health of laying hens during the prebreeding period
Residue extracted from Periplaneta americana contain substantial quantities of protein, lipids, and various bioactive compounds. This study aimed to investigate the impact of these residue on the nutritional and physiological parameters of prebreeding laying hens. A total of 450 one_month_old Nandan Yao chickens were allocated randomly into six groups (each with five replicates and 15 chickens per replicate). The control group (Group A) was provided a standard diet, whereas the experimental groups (Groups B through F) received diets in which a proportion of the soybean meal was replaced with 10%, 20%, 30%, 40%, or 50% P. americana residue, respectively, over an 11_week experimental period. Research has focused on investigating the influence of various concentrations of P americana on the growth performance, intestinal immunoglobulins, cytokines, pH, morphology, flora, and transcriptome of hens. These findings indicate that the supplementation of P. americana did not result in a statistically significant modification in the average daily gain or feed consumption of the laying hens (p > 0.05). Nevertheless, certain experimental groups exhibited enhanced average daily gains and feed conversion ratios when compared to the control group. In terms of intestinal immunoglobulins, the addition of P. americana residue significantly increased the concentrations of immunoglobulin A (IgA) in both the duodenum and jejunum (p < 0.05), as well as the levels of immunoglobulin M (IgM) and IgG in the ileum, demonstrating a quadratic increment trend (p < 0.05). This suggests a positive impact on the intestinal immune function of the hens. morphological examination of the intestinal tract revealed no statistically significant differences in villus height, width, crypt depth, or the villus_crypt ratio across all treatment groups (p > 0.05). However, there was a notable increase in villus height and the villus_crypt ratio in the ileum within specific experimental groups (p < 0.05), indicating potential enhancements in intestinal absorption. Additionally, a significant reduction in intestinal pH was observed in the ileum and jejunum with increasing proportions of P. americana residue (p < 0.05), suggesting a regulatory effect on the intestinal environment that could optimize the digestive and absorptive functions of hens.The diversity of the intestinal microbiota remained largely unaltered among the various treatment groups. Gene expression analysis illuminated the molecular mechanisms by which P. americana residue may influence intestinal health, including pathways related to RNA biosynthesis, DNA repair, immune response, and metabolic regulation. In conclusion, the incorporation of P. americana residue as a feed additive marginally improved the growth performance and intestinal health of laying hens. These residues could be utilized as effective substitutes for soybean meal in poultry diets, with a replacement ratio of 30% to 50% appearing to be optimal. This approach not only alleviates the pressure on protein resources but also provides a scientific basis for the utilization of insects and other waste products in animal nutrition.