Influence of β-galacto-oligosaccharide on growth performance and components of intestinal barrier in broilers during heat stress

This study aimed to investigate the influence of β-galacto-oligosaccharides (β-GOS) on growth performance, organ development and intestinal microarchitecture of broilers during heat stress. Day-old chicks (n = 125) were divided into five groups. The control or thermoneutral zone group (TNZ) was raised under standard management until the 35th day. Four groups were exposed to cyclic heat stress (35 °C 8 h/d) from the 22nd to the 35th day. The TNZ and heat stress control (HSCT) groups were fed a corn-based diet and HS + 0.1% β-GOS; HS + 0.2% β-GOS; and HS + 0.5% β-GOS were fed a corn-based diet supplemented with β-GOS (0.1%, 0.2%, and 0.5%), respectively. Exposure to heat stress reduced feed consumption, feed efficiency and the relative weight of the liver, bursa of Fabricius, and small intestine, compared with the TNZ group. Morphometric evaluation of the small intestine revealed reduced villus surface area, villus height to crypt depth ratio (VH : CD) and intraepithelial lymphocytes (IELs) in all segments, and reduced acidic goblet cells (AGCs) in the ileum of the HSCT group compared with the TNZ group. Compared with the HSCT group, dietary β-GOS (0.2% and 0.5%) improved the feed efficiency and relative weight of the small intestine. Furthermore, dietary β-GOS (0.1%) increased villus surface area in the duodenum and IEL count in the small intestine compared with the HSCT group. Dietary β-GOS 0.5% increased villi surface area (VSA) in the jejunum and ileum, whereas the IEL count in the small intestine and acidic goblet cells (AGCs) in the jejunum and ileum were reduced compared with the HSCT group. In conclusion, dietary supplementation of β-GOS (0.2% and 0.5%) improved the growth performance and intestinal microarchitecture of broilers during heat exposure, along with partial immune stimulation. Keywords: Feed efficiency, goblet cell, intraepithelial lymphocytes, mucosal architecture, prebiotics, poultry, villus morphometry