15 Effects of post-MSC DDGS inclusion in gestation diets compared with other fiber sources on in vitro gas and volatile fatty acid production

Abstract

Abstract In vitro fermentation has been used to characterize hindgut fermentation of fibrous ingredients fed to grower pigs. However, there is little to no work investigating hindgut fermentation of fibrous feedtuffs in gestating sows, who have greater fermentative capacity compared with grower pigs. The objective of this study was to characterize hindgut gas production and volatile fatty acids (VFA) following in vitro fermentation using fecal inoculum collected from the sows when fed either post-protein separation dried-distiller’s grains with solubles (post-MSC DDGS), soyhulls, or sugar beet pulp. Pregnant sows (n = 22; parity 0 to 1; body weigh = 190 ± 10 kg) were allocated to 1 of 6 dietary treatments in a crossover design with two collection periods (period 1 from d 40-59 of gestation and period 2 from d 60-79 of gestation) to attain at least 7 observations per treatment. Two of the six diets were practical corn-soybean meal-based gestation diets with either soyhulls (17.5% inclusion) or post-MSC DDGS (15% inclusion). The remaining four diets included a corn-basal diet and the basal diet plus 30% inclusion of post-MSC DDGS, soyhulls, or sugar beet pulp. Sows were fed experimental diets (2.2 kg/d in a single feeding) in two 20 d collection periods. For in vitro fermentation, fresh fecal samples were collected on d 16 of each collection period, prepared as inoculum, and subjected to the gas production measurement technique through in vitro fermentation. Supernatant residue from the in vitro fermentation was subjected to VFA analysis by gas chromatography. Data were analyzed with ANOVA and fixed to a mixed linear model using treatment as the main effect and collection period as a random variable. Total gas production of the practical diet containing post-MSC DDGS diet was 132 ml/g less (P = 0.03) than the practical soyhull diet. While the total concentration of total VFA did not differ between practical diets, the concentration of isovalerate tended to be greater for the post-MSC DDGS diet compared with the soyhull diet (P = 0.09). Total gas production was 140 and 375 mg/L less for the post-MSC DDGS than soyhulls and sugar beet pulp, respectively (P < 0.01). The concentrations of butyrate and isovalerate (relative to total VFA) were approximately 7 and 2%, respectively, greater for the post-MSC DDGS than in the soyhulls or sugar beet pulp fermentation residues (P < 0.05). Concentrations of other VFA relative to total VFA did not differ between fiber sources. In conclusion, post-MSC DDGS can contribute to sustainable swine production when fed to gestating by lowering total gas production and being a source of volatile fatty acids.