|ELLESTAD, LAURA - University Of Georgia|
|KAHL, STANISLAW - Retired ARS Employee|
|DARWISH, NADIA - Oak Ridge Institute For Science And Education (ORISE)|
|CAMPOS, PHILLIP - Oak Ridge Institute For Science And Education (ORISE)|
Submitted to: BMC Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/17/2022
Publication Date: 8/24/2022
Citation: Proszkowiec-Wegla, M.K., Miska, K.B., Ellestad, L.E., Schreier, L.L., Kahl, S., Darwish, N., Campos, P.M., Shao, J.Y. 2022. Delayed access to feed early post-hatch affects the development and maturation of gastrointestinal tract microbiota in broiler chickens. BMC Microbiology. 22:206. https://doi.org/10.1186/s12866-022-02619-6.
Interpretive Summary: In the current broiler production systems, chicks are deprived of food and water for up to 72 hours due to uneven hatching times, hatchery procedures such as sexing, sorting, selection and vaccination, and transportation time to destination farms. Lack of access to feed during the first 48-72 hours results in lower body and organ weight, higher feed conversion ratio (amount of feed required for 1 kg of body weight gain) and mortality, delayed growth rate and gastrointestinal tract development. Little is known about the effects of early neonatal development and delayed feeding immediately post-hatch on microbiota development in chicken. Microbiota plays an important role in health, nutrition, growth and development of the animal’s gastrointestinal tract and can be influenced by many physiological, environmental and dietary factors. Therefore, the aim of the present study was to investigate changes in the microbiota in broiler chickens early post-hatch and the effect of delayed access to feed on the microbiota. To mimic commercial settings, newly hatched chicks were subjected to 48 hours delay in feeding or fed immediately after hatch. We have determined that during delayed access to feed immediately post-hatch: 1) luminal (bacteria present in digesta) and mucosal (bacteria attached to the epithelial cells that line the intestinal tract) bacterial populations of ileum and ceca respond differently to lack of access to feed, 2) development of microbiota is affected by the lack of feed early post-hatch, and 3) developmental effect (the effect of age) is more pronounced in comparison to the effect of delayed access to feed.
Technical Abstract: Background: The first two weeks of post-hatch (PH) development in broilers (meat-type birds) are critical for gut development and microbiota colonization. In the current broiler production system, chicks may not receive feed and water for 24 to 72 h due to variations in hatching time and hatchery management. PH feed delay affects body weight, feed efficiency, mortality, and gut development. The goal of this study was to investigate changes in the microbiome in broiler chickens early PH and the effect of delayed access to feed on the microbiota. Results: Chicks either received feed and water immediately after hatch or access to feed was delayed for 48 h to mimic commercial hatchery settings (treatment, TRT). Both groups were sampled (n=6) at -48, 0, 4 h, and 1 (24 h), 2 (48 h), 3 (72 h), 4 (96 h), 6 (144 h), 8 (192 h), 10 (240 h), 12 (288 h) and 14 (336 h) days PH. Ileal (IL) and cecal (CE) epithelial scrapings (mucosal bacteria, M) and digesta (luminal bacteria, L) were collected for microbiota analysis. Microbiota was determined by sequencing the V3-V4 region of bacterial 16S rRNA and analyzed using QIIME2. The microbiota of early ileal and cecal samples were characterized by high abundance of unclassified bacteria. Among four bacterial populations (IL-L, IL-M, CE-L, CE-M), IL-M was the least affected by delayed access to feed early PH. Both alpha and beta diversities were affected by delayed access to feed PH in IL-L, CE-M and CE-L. However, the development effect was more pronounced. In all four bacterial populations, significant changes due to developmental effect (time relative to hatch) was observed in taxonomic composition, with transient changes of bacterial taxa during the first two weeks PH. Delayed access to feed has limited influence on bacterial composition with only a few genera and species affected in all four bacterial populations. Predicted function based on 16S rRNA was also affected by delayed access to feed PH with most changes in metabolic pathway richness observed in IL-L, CE-L and CE-M. Conclusions: These results show transient changes in chicken microbiota biodiversity during the first two weeks PH and indicate that delayed access to feed affects microbiota development. Moreover, significant differences in response to delayed access to feed PH between luminal and mucosal bacterial populations strongly suggests the need for separate analysis of these two populations.