Marlou W. Bosch

Effects of Dietary Non-Digestible Oligosaccharides on Microbial Characteristics of Ileal Chyme and Faeces in Weaner Pigs

Fructooligosaccharides (FOS) and transgalactooligosaccharides (TOS), which are non-digestible oligosaccharides (NDO), were included at 10 and 40g/kg in an NDO-free control diet at the expense of purified cellulose. Each of the 5 diets was fed to 4 weaner pigs and microbial characteristics of their ileal chyme and faeces were assessed. The NDO-pigs had lower ileal pH than the control pigs. Dietary NDO did not affect the ileal volatile fatty acid concentration, though FOS-pigs had a higher concentration of lactic acid and relatively more iso-valeric acid and less acetic acid than TOS-pigs. The NDO-pigs had lower ileal aerobic bacterial counts than the control pigs, whilst the FOS-pigs had a larger ileal anaerobic bacterial counts than the TOS-pigs. The NDO-pigs had an higher faecal pH and their faecal volatile fatty acid pool contained relatively more iso-butyric acid and iso-valeric acid than the control pigs. The TOS-pigs tended to have higher faecal anaerobic bacterial counts and had a smaller concentration of faecal volatile fatty acid than the FOS-pigs. We concluded that whilst effects at the faecal level may have been partly due to a reduced intake of cellulose, dietary NDO can exert precaecal prebiotic effects in weaner pigs.

Quantifying Resistant Starch Using Novel, In Vivo Methodology and the Energetic Utilization of Fermented Starch in Pigs

To quantify the energy value of fermentable starch, 10 groups of 14 pigs were assigned to one of two dietary treatments comprising diets containing 45% of either pregelatinized (P) or retrograded (R) corn starch. In both diets, a contrast in natural ¹³C enrichment between the starch and nonstarch components of the diet was created to partition between enzymatic digestion and fermentation of the corn starch. Energy and protein retention were measured using indirect calorimetry after adapting the pigs to the diets for 3 wk. Fecal ¹³C enrichment was higher in the R-fed pigs (P < 0.001) and 43% of the R resisted enzymatic digestion. Energy retained as protein was unaffected and energy retained as fat was 29% lower than in P-fed pigs (P < 0.01). Prior to the morning meal, end products of fermentation substantially contributed to substrate oxidation in the R-fed pigs. During the 3-4 h following both meals, heat production was higher (P < 0.05) in P-fed pigs, but this was not preferentially fueled by glucose from corn starch. Digestible energy intake, metabolizable energy intake, and energy retention were reduced (P < 0.05) in R-fed pigs compared with P-fed pigs by 92, 54, and 33 kJ/(kg⁰·⁷⁵ · d), respectively. Therefore, the energy values of fermented resistant starch were 53, 73, and 83% of the digestible, metabolizable, and net energy values of enzymatically degradable starch, respectively. Creating a contrast in natural ¹³C enrichment between starch and nonstarch dietary components provides a promising, noninvasive, in vivo method for estimating the proportion of dietary starch fermented in the gastrointestinal tract.

Dietary fructooligosaccharides and transgalactooligosaccharides can affect fermentation characteristics in gut contents and portal plasma of growing pigs

We studied whether dietary non-digestible oligosaccharides (NDOs) affected pH and volatile fatty acids (VFAs) in gastrointestinal contents and in portal plasma of young pigs. Five groups of five 57-day-old pigs received for 44 days either a corn-based control diet or this diet with 7.5 or 15 g/kg fructooligosaccharides (FOSs, Raftilose P95?) or the control diet with 10 or 20 g/kg transgalactooligosaccharides (TOSs, Oligostroop?). The pigs weighed on average 45.5±1.3 kg during dissection, which took place 3 h after feeding. Dietary NDOs tended to lower the pH of the stomach content from 4.5 to 4.2 (P=0.06). Pigs fed the high TOS diet had more caecal VFAs than the control pigs (30.4 vs. 15.6 mmol, P<0.05). Compared to TOS-fed pigs, FOS-fed pigs had a higher proximal colon pH (6.5 vs. 6.2, P<0.01), lower proximal colon VFA concentration (131 vs. 166 mmol/l, P<0.01) and lower portal VFA concentration (0.9 vs. 1.6 mmol/l, P<0.05), with the control pigs being intermediate. However, the amount of colonic VFAs was similar across diets (~40 mmol). The results support the view that dietary FOSs and TOSs may have different effects on fermentation characteristics of gut contents of pigs.

Dietary carbohydrates with different rates of fermentation affect fermentation end-product profiles in different sites of gastro-intestinal tract of weaning piglet

An in vivo experiment was conducted to examine changes in fermentation end-products in the gastro-intestinal tract (GIT) of weaning piglets by the inclusion of fermentable carbohydrates in the diet. The experiment was repeated in three replicates of 36 piglets. Piglets were raised free of antibiotics and creep feeding prior to weaning at 4 weeks of age. Each replicate was conducted over a period of 10 days. The piglets were offered one of two dietary treatments: control diet (CON), and fermentable carbohydrate enriched diet (CHO); and were subjected to one of the two fasting treatments (i) fasting for 2 days in the beginning of the experimental period and (ii) non-fasting. Piglets were slaughtered on the 1st, 4th and 10th day of each period. Digesta samples were collected from: first half of small intestine, second half of small intestine, caecum, and colon. The dry matter, volatile fatty acid (VFA) profile, and ammonia concentrations were analysed. Food intake, growth and food conversion ratio were also recorded. There were no differences in production performances such as growth and food conversion ratio (FCR) between the treatment groups. Concentrations of VFA were significantly higher, while ammonia concentration was significantly lower in the CHO group compared to the CON group in different fermentation sites within the GIT (P<0·001), and on different slaughtering days (P<0·05). Fasting had no effect on fermentation end-products. This study concludes that the addition of fermentable carbohydrates of varying fermentabilities stimulated carbohydrate fermentation, with reduction in protein fermentation along the different parts of GIT studied, in weaning piglets