Effects of butyrate on the insulin homeostasis of chickens kept on maize- or wheat-based diets

Abstract

The aim of the present study was to investigate the effects of butyrate as a feed supplement on the expression of insulin signalling proteins as potent regulators of metabolism and growth in Ross 308 broiler chickens fed maize-or wheatbased diets. Both diets were supplemented with non-protected butyrate (1.5 and 3.0 g/kg of diet, respectively) or with protected butyrate (0.2 g/kg of diet); the diet of the control groups was prepared without any additives (control). On day 42 of life, systemic blood samples were drawn for analyses of glucose and insulin concentrations, and tissue samples (liver, gastrocnemius muscle and subcutaneous adipose tissue) were taken for Western blotting examinations. The expression of key insulin signalling proteins (IRβ, PKCζ and mTOR) was assessed by semiquantitative Western blotting from the tissues mentioned. The type of diet had a remarkable influence on the insulin homeostasis of chickens. The wheat-based diet significantly increased IRβ and mTOR expression in the liver as well as mTOR and PKCζ expression in the adipose tissue when compared to animals kept on a maize-based diet. IRβ expression in the liver was stimulated by the lower dose of non-protected butyrate as well, suggesting the potential of butyrate as a feed additive to affect insulin sensitivity. Based on the results obtained, the present study shows new aspects of nutritional factors by comparing the special effects of butyrate as a feed additive and those of the cereal type, presumably in association with dietary non-starch polysaccharide-(NSP-) driven enteric shortchain fatty acid release including butyrate, influencing insulin homeostasis in chickens. As the tissues of chickens have physiologically lower insulin sensitivity compared to mammals, diet-associated induction of the insulin signalling pathway can be of special importance in improving growth and metabolic health.

Modulation of Hepatic Insulin and Glucagon Signaling by Nutritional Factors in Broiler Chicken

“…The hypothesis of our study was that, similar to other observations, [ 6 ] exogenous- (feed additive sodium [n-]butyrate) and endogenously produced (anaerobe microbial fermentation product of NSP) butyrate might affect the metabolism of chicken differently—primarily through insulin and glucagon signaling—or have a different action when applied in combination.…”

“…Butyrate can be used as feed supplement (exogenous origin), or produced endogenously by anaerobe microbial fermentation of carbohydrates in the ceca of broilers [ 3 ]. The formation of SCFA can be enhanced by the application of ingredients with an elevated ratio of soluble non-starch polysaccharides (NSP) in the feedstuff, such as rye or wheat [ 4 , 5 ], the latter containing more NSP compared to maize [ 4 , 6 ], mostly arabinoxylans [ 7 ]. The molar ratio of acetate, propionate and butyrate in the ceca varies from approximately 75:15:10 to 40:40:20 in a healthy chicken [ 8 ].…”

“…Orally administered butyrate proved to affect the insulin signaling of broilers on a tissue-dependent manner as a daily oral bolus [ 22 ]. The potential of a fiber-rich diet to influence insulin homeostasis has also been declared in different species [ 6 , 23 , 24 ].…”

Effects of dietary butyrate supplementation and crude protein level on carcass traits and meat composition of broiler chickens

“…Dietary supplementation of protected butyrate provides butyrate release in more distal sections of the intestines, while unprotected butyrate is rapidly absorbed from the proximal section of the gastrointestinal tract (Kulcsár et al, 2017). These different kinetic properties of protected butyrate products should deliver better butyrate exposure for the intestinal microflora, and the prolonged absorption may also have differing effects on various extraintestinal tissues compared to the action of unprotected butyrate (Kulcsár et al, 2016(Kulcsár et al, , 2017Petrilla et al, 2018).…”

“…Beside these intestinal effects, butyrate as an epigenetically active molecule can cause histone hyperacetylation, described in the liver of chickens after oral butyrate ingestion (Mátis et al, 2013), modulating the expression of certain genes and thus possibly leading to metabolic alterations. For instance, butyrate can affect insulin homeostasis, modifying the abundance of key insulin signaling proteins in a tissue-dependent manner (Mátis et al, 2015;Kulcsár et al, 2016).…”