Previous studies demonstrate that maternal supplementation of the circulating metabolite of vitamin D3 (D3), 25-hydroxycholecalciferol (25OHD3), enhances the immunocompetence of broiler chick offspring. To assess the effect of combining maternal (MD) and post-hatch (PD) dietary 25OHD3 inclusion on duodenal (DUO) crypt cell proliferation and local innate immunity of young broiler chickens, a randomized complete block design experiment with a 2 × 2 factorial treatment structure was conducted. All diets were formulated to provide 5,000 IU of vitamin D. From 25 to 41 wk-of-age, broiler breeder hens were fed 1 of 2 MD: 5,000 IU D3 per kg of feed (MCTL) or 2,240 IU of D3 + 2,760 IU of 25OHD3 per kg of feed (M25OHD3). Male broiler offspring (n = 480) hatched from eggs collected from 41-wk-old hens were fed 1 of 2 starter PD: 5,000 IU D3 per kg of feed (PCTL) or 2,240 IU D3 + 2,760 IU 25OHD3 (P25OHD3). DUO samples (n = 12 birds per treatment per day) were collected on d 3, 6, 9, 12, 15, 18, and 21 for cryohistological and immunofluorescence analysis to facilitate the enumeration of total macrophages, CD80+ macrophages (pro-inflammatory macrophages), and mitotically active cells (BrdU+) to calculate the proportion of proliferating cells per duodenal crypt (PPC). Broilers from the M25OHD3:PCTL group had higher PPC than MCTL:PCTL on d 3 (P = 0.002). On d 9, MCTL:P25OHD3 broilers had more proliferating, proinflammatory macrophages compared with those from the M25OHD3:P25OHD3 treatment (32 vs. 17 cells per mm2; P = 0.023). M25OHD3:PCTL broilers had more total proliferating macrophages than M25OHD3:P25OHD3 birds (89 vs. 56 cells per mm2; P = 0.033). At d 21, a MD × PD interaction was observed, where birds from the M25OHD3:P25OHD3 treatment had more proliferating macrophages than M25OHD3:PCTL broilers (P = 0.029). In conclusion, these results indicate that combined MD and PD 25OHD3 supplementation may alter early post-hatch duodenal development and local intestinal innate immunity parameters.
Key Words: 25-hydroxycholecalciferol, vitamin D, intestinal development, intestinal macrophages.
Presented at the 9th Symposium on Gut Health in Production of Food Animals, St. Louis, USA, 2021. For information on the next edition, click here.