Dietary fiber sources for gestation sows: Evaluations based on combined in vitro and in vivo methodology

Abstract

An in vitro-in vivo methodology was used to evaluate the potential value of different sources of fiber for gestation sows. Soluble and insoluble dietary fiber of 9 feed ingredients were isolated and fermented in vitro with sow faecal inoculum, using the cumulative gas production technique, to examine the kinetics, end-products and microbiota of fermentation after 72 h. It was shown that all fermentation kinetics parameters of gas production varied among feed ingredients. The production of short chain fatty acids (SCFA), branched-chain fatty acids (BCFA) and ammonia (NH3) were greater for wheat grain and maize compared to other feed ingredients on insoluble dietary fiber (IDF) fermentation for 36 h, and higher for maize compared to other feedstuffs on IDF fermentation for 72 h. However, SCFA, BCFA and NH3 were the highest of sorghum grain compared to other feedstuffs on soluble dietary fiber (SDF) fermentation for 36 and 72 h. The capacity of SCFA, BCFA and NH3 produced by SDF were significantly greater than that of IDF from different ingredients. IDF and SDF of beet pulp exhibited lower pH, higher Bacteroidetes and lower Firmicutes phylum after fermentation. The observed species and Shannon index in the beet pulp IDF and SDF were significantly lower than others. In genus level, Parabacteroides and unidentified_Prevotellaceae were higher but unidentified_Lachnospiraceae was lower in SDF fermentation compared to IDF fermentation. Further, a total of 75 multiparous gestation sows (Landrace × Yorkshire) were randomly assigned three fiber-rich diets provided by beet pulp (BP), soybean hull (SH), and wheat bran (WB) after mating. The sows were fed with three different fiber diets during gestation, but all the sows were similarly fed ad libitum during lactation. Sows fed BP diets farrowed a greater number of total (+1.7 pigs, P<0.05) and alive (+1.1 pigs, P<0.1) piglets compared with sows fed SH diets. In summary, beet pulp, irrespective of fiber type maybe have a better potential to be used in sow nutrition to manipulate the fermentation activity, microbiota and a greater litter size. Moreover, IDF and SDF from different feed ingredients, as well as the same feedstuff IDF and SDF, due to differences in fiber structure and composition may affect microbiota composition and ultimately affect the level of fermentation metabolites produced.