Cohousing-mediated microbiota transfer promotes bone health and modulates gut integrity, and immunity in young broiler chickens

Abstract

The intestine hosts a complex microbiota, which plays a crucial role in health and development. This study investigated the impact of cohousing day-old broilers with 14-day-old (CH14) or 42-day-old (CH42) broiler chickens and their fecal material for a week, compared to a non-cohoused control group. Birds were raised for 42 days, and bone traits, gut integrity and microbiota, cytokine and antimicrobial peptide profiles, and T cell immunity subsets were assessed at days 14 and 42. Production parameters were recorded weekly, and mortality daily. Both treatment groups exhibited significantly improved tibial bone length, cortical bone volume, and mineral density, with reduced pore volume and diameter. These effects were more pronounced in CH42 birds at day 14. Pro-inflammatory (IL-6, IL-17, IL-1β, IL-2, AvBD-4, AvBD-7) and anti-inflammatory (IL-10, TGF-β) markers were monitored, with CH42 birds showing significantly higher levels of both IL-10 and TGF-β at day 42. CH42 birds had higher CD4+CD25+ T regulatory cells and lower CD4+ T cells, while CD8+ T cells remained unchanged. Gut integrity markers (Claudin-2, Occludin, ZO-1, JAM-2) were improved in both groups. CH42 birds showed increased microbiota alpha and beta diversity and Firmicutes dominance by day 42. Cohousing and fecal material transfer improved bone development, gut integrity and microbiota, and immune homeostasis, highlighting the potential of older birds' microbiota and inspiring the development of microbiota-based approaches to enhance poultry health, welfare, and management.

Keywords: Bone health; Broiler; Cohousing; Gut integrity; Immunity.

Fig. 1

Effects of cohousing with day 14 and day 42 broilers on body weight (A), feed intake (B) and feed conversion ratio (C) of broiler chickens raised for 42 days. Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. The bars represent mean values ± SEM (n = 8).

Fig. 2

Effects of cohousing with day 14 and day 42 broilers on tibial bone length (A) and tibial bone mineral content (B) of broiler chickens at day-14 and day-42 of age. Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abDifferent letters mean significant differences among groups (P < 0.05) at days 14 and 42 and bars represent mean ± SEM (n = 8).

Fig. 3

Effects of cohousing with day 14 and day 42 broilers on tibial bone area (A), pore volume (B), pore diameter (C) and ability to stand in warm water (latency to lie test) (D) of broiler chickens at day-14 and day-42 of age. Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abDifferent letters mean significant differences among groups (P < 0.05) at days 14 and 42 and bars represent mean ± SEM (n = 8).

Fig. 4

Effects of cohousing with day 14 and day 42 broilers on cecal tonsil’s CD4⁺ (A), CD8⁺ (B) and CD4⁺CD25⁺(C) T cells of broiler chickens raised for 42 days. Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abDifferent letters mean significant differences among groups (P < 0.05) at days 14 and 42 and bars represent mean ± SEM (n = 8).

Fig. 5

Effects of cohousing mediated fecal microbiota transfer on cecal pro-inflammatory profile of cytokines and anti-microbial peptides in broiler chickens at day 14. Bar plots in panels present expression level of IL-6 (A), IL-17 (B), IL-1β (C), IL-2 (D), AvBD-4 (E) and AvBD-7 (F). Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abcDifferent letters mean significant differences among groups (P < 0.05) at day 14 and bars represent mean ± SEM (n = 8).

Fig. 6

Effects of cohousing mediated fecal microbiota transfer on cecal pro-inflammatory profile of cytokines and anti-microbial peptides in broiler chickens at day 42. Bar plots in panels present expression level of IL-6 (A), IL-17 (B), IL-1β (C), IL-2 (D), AvBD-4 (E) and AvBD-7 (F). Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abcDifferent letters mean significant differences among groups (P < 0.05) at day 42 and bars represent mean ± SEM (n = 8).

Fig. 7

Effects of cohousing mediated fecal microbiota transfer on cecal anti-inflammatory profile of cytokines in broiler chickens at days 14 and 42. Bar plots in panels present expression level of IL-10 (A) and TGF-β (C) at day 14 and IL-10 (B) TGF-β (D) at day 42. Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abDifferent letters mean significant differences among groups (P < 0.05) at days 14 and 42 and bars represent mean ± SEM (n = 8).

Fig. 8

Effects of cohousing mediated fecal microbiota transfer on expression of gut integrity related genes in broiler chickens at day 14. Bar plots in panels present expression level of Claudin 2 (A), JAM-2 (B), Occludin (C), and ZO-1 (D). Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abDifferent letters mean significant differences among groups (P < 0.05) at day 14 and bars represent mean ± SEM (n = 8).

Fig. 9

Effects of cohousing mediated fecal microbiota transfer on expression of gut integrity related genes in broiler chickens at day 42. Bar plots in panels present expression level of Claudin 2 (A), JAM-2 (B), Occludin (C), and ZO-1 (D). Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. ^abDifferent letters mean significant differences among groups (P < 0.05) at day 42 and bars represent mean ± SEM (n = 8).

Fig. 10

Effects of cohousing mediated fecal microbiota transfer on diversity and composition of cecal microbiota of broiler chickens at day 42. Boxes in panels present alpha (A (OTU’s), B (Pielou metric) and C (Shannon metric)) and beta (D (Weighted UniFrac metric)) diversity while bars in panel E showing relative frequency of the microbial taxonomic composition at phylum level. Cages for CH14 or CH42 groups received 100 g of fecal material per day, and one-day old chicks were cohoused with a single older chick from donor birds aged 14 days or 42 days for one week. In contrast, control chicks (Control) were neither exposed to fecal material nor cohoused with older birds. Boxes in panels A to D show the medians/quartiles of treatment samples, and the error bars extend to the most extreme values within the 1.5 interquartile ranges (n = 8). ^abcDifferent letters mean significant differences among groups (P < 0.05).