Long-term effects of a 72-hour post hatch feed delay on intestinal development in broiler chickens
Date
2021
Authors
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Publisher
University of Delaware
Abstract
Intestinal development is sensitive to stress, which could lead to long term dysfunctions. Delayed post-hatch feeding is a common stressor in poultry production which negatively impacts performance and health. The objective of this study was to evaluate the impact of delayed feeding in broilers on later life intestinal development and barrier function. Ross 308 birds were hatched and allotted into either delayed feeding (DF, no feed until ~72hr post-hatching) or normal feeding groups (NF, immediate access to feed). DF and NF chicks were co-housed and had ad libitum access to the same commercial diet until d42 of age. Body weight (BW) and feed conversion ratio (FCR) were recorded weekly. At d21 and d42 of age, oral FITC-dextran (FD4) gavage was conducted to evaluate permeability of the whole GI tract. Mid-jejunal and distal ileal tissues were collected at d21 and d42. Intestinal region-specific barrier function was evaluated on Ussing Chambers via transepithelial resistance (TER) and FD4 flux measurements. Small intestinal morphology, goblet cells and Paneth cells quantification were analyzed on d21 and d42. Gene expression of intestinal barrier markers (tight junction proteins, mucin protein) and immune markers (cytokines and lysozyme) were measured via qRT-PCR. Delayed feeding resulted in suppressed BW (P<0.05) until d28. Interestingly, the feed efficiency was improved (P<0.05) in DF birds at the last week of the experiment. Compared with age-matched NF birds, the whole GI tract was constantly leakier to FD4 at d21 and d42 (P<0.05) in DF birds. Specifically, DF birds exhibited reduced TER (P<0.05) and increased FD4 permeability (P<0.1) in the jejunum. At d21, the DF group showed increased expression of pro-inflammatory TNFa (P<0.05) in jejunum, and increased expression of tight junction Claudin-2 (CLDN2) (P<0.1) in ileum. In DF chickens, the MUC2 expression was decreased (P<0.1) in jejunum while was increased (P<0.1) in ileum. Expression of Paneth cell marker (LYZc) was decreased (P<0.1) in ileum. Quantification of goblet cells and Paneth cells was in line with the gene expression data. The d21 jejunal villus width (VW) (P<0.1) and villus height (VH):crypt depth (CD) ratio (P<0.05) were reduced, while the CD was increased (P<0.1) in DF chickens. At d21, VH and villi surface area of ileum were decreased (P<0.05), while that of jejunum were increased at d42. Interestingly, the thickness of jejunal smooth muscle was increased (P<0.05) on d21. Together, the results indicated that early feed delay induced a lasting detrimental effect on intestinal barrier function, which may lead to suppressed growth performance and health in broiler chickens.
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Keywords
Gut health, Intestinal barrier, Intestinal permeability, Intestine