Barley and oat cultivars with diverse carbohydrate composition alter ileal and total tract nutrient digestibility and fermentation metabolites in weaned piglets

Abstract

An experiment was conducted to evaluate the effects of cereal carbohydrate form (isolated v. cereal matrix) and level, especially mixed-linked b-glucan (hereafter referred to as b-glucan) and starch amylase/amylopectin ratio on nutrient digestibility and fermentation parameters in the intestines of weaned pigs. Four hulless barley cultivars containing varying b-glucan levels (41 to 84 g/kg) were compared with hulled barley, supplemented or not with a b-glucan concentrate (BBG; 270 g/kg b-glucan) and two oat cultivars for digestibility and fermentation metabolites. Seventy-two weaned piglets (BW 5 12.8 6 1.9 kg) were assigned to one of nine diets composed of 815 g/kg cereal, 60 g/kg whey, 90 g/kg soy protein isolate and 35 g/kg minerals. After 15 days, the pigs were killed, and digesta collected from ileum and colon were analyzed for proximate nutrients, short-chain fatty acids (SCFAs), lactic acid (LA) and ammonia. Ileal and total tract digestibility of proximate nutrients and non-starch polysaccharides (NSPs) were determined using HCl-insoluble ash as a marker. Organic matter (OM) ileal digestibility was greater (P , 0.05) for diets based on hulless barley (77% 6 1.1% on average), as compared with hulled barley (64% 6 1.4%) and oat (58% 6 1.5%). Similar trends were found for total tract OM digestibility, varying from 90% 6 0.3% for hulless barley to 67% 6 0.4% for oat, on average. NSP digestibility differed (P , 0.05) within and between cereal types, ranging from 20% (hulled barley plus 163 g/kg BBG or , 40 g/kg b-glucan) to 51% (SB94893 hulless barley cultivar with high b-glucan and high amylose ratio) at the ileum and from 44% (hulled barley) to 84% (SB94893 cultivar) at the total tract level. No dietary effect (P . 0.05) was found for SCFA concentration in ileal contents, whereas in colonic contents, SCFA was lower in pigs fed oat (P , 0.001). LA concentration was greater (P , 0.001) in the colon of pigs fed hulless barley than in pigs fed hulled barley and oat. Expressed per kg carbohydrate (NSP 1 starch) fermented, the ammonia concentration at the colon was lowest for hulled barley diets (supplemented with b-glucan) and the highest for oat diets. In conclusion, the interaction of both form and level of b-glucan impacted nutrient digestibility and fermentation. Hulless barleys with high soluble NSP such as b-glucan and resistant starch yielded, in general higher SCFA and LA and lower ammonia. Hulless barleys may, therefore, have potential for use in feeding strategies designed to improve gut health in pigs.

Standardized ileal digestibility of amino acids in eight genotypes of barley fed to growing pigs

“…Among the NSP fraction, the major components in barley are β-glucan and AX; β-glucan is confined to the aleurone layer and the endosperm, whereas AX is present in endosperm, aleurone but also in the hull layer (Holtekjølen et al, 2006). In the present study, mean β-glucan content was 1.1% units greater than reported values for hulled barley but still within the range of values for hulless barley (Jha et al, 2010). There is evidence from studies in broilers (Bedford and Classen, 1992) and weaned pigs (Yin et al, 2001b) that β-glucan may contribute to a decrease in digestibility of AA due to increasing digesta viscosity, but only SID of few AA in the present genotypes decreased with increasing content of total β-glucan or soluble β-glucan.…”

Feed ingredients differing in fermentable fibre and indigestible protein content affect fermentation metabolites and faecal nitrogen excretion in growing pigs

“…Celite R (Celite 545, Celite Corporation, Lompoc, CA, USA) was incorporated into the diet (6 g/kg dry matter; DM) as a source of acid-insoluble ash (AIA), as an indigestible marker to measure the apparent total tract digestibility (ATTD). Chromic oxide (Cr 2 O 3 ) was used as a marker to measure the apparent ileal digestibility (AID) because Cr 2 O 3 is a preferred marker at the ileum level than AIA (Van Leeuwen et al, 1996;Jha et al, 2010). The Cr 2 O 3 was added to the diet (3 g/kg DM) directly before feeding from day 13 of the start of the experiment for 3 consecutive days.…”

“…However, most of these beneficial effects have been observed with isolated fibres. A finding from a recent study (Jha et al, 2010) suggests that the fermentation characteristics of DF depend on how they are present in the diet: in the isolated form or embedded as an integrated part of grain matrix. Moreover, adding DF just for its fermentative properties is an economical nonsense.…”

“…A more pragmatic approach would involve using feed ingredients that present desirable benefits of DF on gut environments of pig. By choosing barley varieties according to the properties of their fibre fraction, it is, for example, possible to enhance SCFA and reduce NH 3 production in the pig intestines (Jha et al, 2010 and2011a), which in turn supports the growth of beneficial bacteria such as Lactobacilli (Pieper et al, 2008).…”

In vitro digestion and fermentation characteristics of canola co-products simulate their digestion in the pig intestine

“…Specifically, butyrate is the most interesting of the VFA, because butyrate is an important energy source for the colonic epithelium and regulates cell growth and differentiation (Calabrò et al, 2013). Fermentation characteristics in the pig intestine vary widely among feedstuffs (Jha et al, 2010;Jha and Leterme, 2012) and it is important to understand their contribution toward energy needs and gut health of pigs. However, information about fermentation characteristics of canola co-products in the pig intestine is minimal.…”