Effects of dietary butyrate supplementation on intestinal integrity of heat‐stressed cockerels
Heat stress (HS) impairs poultry performance, increases mortality and results in significant economic losses (St‐Pierre et al., 2003). Many physiological parameters of various systems (e.g. the digestive system) are disturbed when the ambient temperature exceeds the thermoneutral zone (Quinteiro‐Filho et al., 2012; Abdelqader and Al‐Fataftah, 2014). The single cell layer of the intestinal epithelium plays key roles in nutrient digestion and absorption and forms the most important barrier against the external environment (Söderholm and Perdue, 2006). Also, HS can impair the integrity of the gut barrier by damaging the intestinal epithelial cells (Pearce et al., 2013), increase intestinal permeability (Lambert, 2009) and induce intestinal inflammation (Quinteiro‐Filho et al., 2012). The poor outcome of the intestines as a result of HS enhances the infiltration of endotoxins into the blood circulation, which could result in further systemic inflammatory responses and multi‐organ dysfunction (Bouchama and Knochel, 2002). Moreover, reports from our laboratory and others have shown that HS causes imbalance in the intestinal microflora (Al‐Fataftah and Abdelqader, 2014; Song et al., 2014). Butyrate was found to be effective in preventing intestinal injury and enhancing epithelial repair mechanisms (Qiao et al., 2015). Under thermoneutral conditions, butyrate works as a growth promoter for chickens' gut wall (Antongiovanni et al., 2009), enhances villi growth (Levy et al., 2015) and controls intestinal pathogenic bacteria (Namkung et al., 2011). In heat‐stressed broilers, it reduces intestinal epithelia damage and enhances intestinal recovery (Abdelqader and Al‐Fataftah, 2016). However, broilers are intensively selected for high growth rates which are associated with high metabolic heat production (Havenstein et al., 2003). Recent genetic improvement of broilers, laying hens and breeders for high production leads to high susceptibility to HS (Havenstein et al., 2003; Gous, 2010). Given that layer cockerels are not producing animals, they were used as a model in this experiment to investigate the true effect of butyrate on intestinal integrity. The current study aimed to investigate the potential of butyrate to reduce intestinal injury and to improve intestinal integrity in heat‐stressed chickens.