No abstract

The cholesterol-lowering effect of barley β-glucan has been proposed to be the result of a pleiotropic effect, which involves several biological mechanisms such as gut fermentation, inhibition of intestinal cholesterol absorption and increased bile acid excretion and its synthesis. However, one of the recent studies from our laboratory indicated that increased bile acid excretion and subsequent increase in its synthesis, but not the inhibition of cholesterol absorption or synthesis might be responsible for the cholesterol-lowering effect of barley β-glucan. Accordingly, the primary objective of the present study was to investigate the concentration of bile acids (BA), neutral sterols (NS) and short chain fatty acids (SCFA) excreted through the feces by mildly hypercholesterolemic subjects who consumed diets containing barley β-glucan with varying molecular weights (MW) and concentrations. In a controlled, four phase, crossover trial, 30 mildly hypercholesterolemic but otherwise healthy subjects were randomly assigned to receive breakfast containing 3 g high MW (HMW), 5 g low MW (LMW), 3 g LMW barley β-glucan or a control diet for 5 weeks. The concentrations of BA, NS and SCFA in the feces were measured at the end of each treatment phase. Compared to the other treatment groups, 3 g day-1 HMW barley β-glucan consumption resulted in increased lithocholic acid (LCA) excretion (P < 0.001) but not LMW β-glucan, even at the high dose of 5 g day-1. Increased fermentability of fibre was also evident from a significant increase in fecal total SCFA concentrations in response to the 3 g HMW β-glucan diet compared to the 3 g LMW barley β-glucan and control diet (P = 0.0015). In summary, the current results validate our previous report on the role of fecal bile acid excretion in cholesterol lowering through the consumption of barley β-glucan. In addition, increased SCFA concentrations indicate that an increase in β-glucan molecular weight promotes hindgut fermentation, which might also be playing a role in attenuating cholesterol levels.

An experiment was conducted to determine the effects of including canola meal (CM) in nursery pig diets on growth performance, immune response, fecal microbial composition, and gut integrity. A total of 200 nursery pigs (initial body weight = 7.00 kg) were obtained in 2 batches of 100 pigs each. Pigs in each batch were housed in 25 pens (4 pigs/pen) and fed 5 diets in a randomized complete block design. The 5 diets were corn-soybean meal (SBM)-based basal diets with 0, 10, 20, 30, or 40% of CM. The diets were fed in 3 phases; Phase 1: d 0 to 7, Phase 2: d 7 to 21, and Phase 3: d 21 to 42. Diets in each phase were formulated to similar net energy, Ca, and digestible P and amino acid contents. Feed intake and body weight were measured by phase. Immune response and gut integrity parameters were measured for at the end of Phases 1 and 2. Fecal microbial composition for diets with 0 or 20% CM was determined at the end of Phase 2. Overall average daily gain (ADG) responded quadratically (P &lt; 0.05) to increasing dietary level of CM such that ADG was increased by 17% due to an increase in dietary level of CM from 0 to 20%, and was reduced by 16% due to an increase in dietary level of CM from 20 to 40%. Pigs fed diets with 0 or 40% CM did not differ in overall ADG. Dietary CM tended to quadratically decrease (P = 0.09) serum IgA level at the end of Phase 2 such that serum IgA level tended to reduce with an increase in dietary CM from 0 to 20%, and to increase with an increase in dietary CM from 20 to 40%. Dietary CM at 20% decreased (P &lt; 0.05) relative abundance of Bacteroidetes phylum and tended to increase (P = 0.07) relative abundance of Firmicutes phylum. Dietary CM linearly increased (P &lt; 0.05) the lactulose to mannitol ratio in the urine by 47 and 49% at the end of Phases 1 and 2, respectively; and tended to linearly decrease (P &lt; 0.10) ileal trans-epithelial electrical resistance at the end of Phase 1 by 64%. In conclusion, CM fed in the current study could be included in corn-SBM-based diets for nursery pigs 20% to improve growth performance and gut microbial composition, and reduce immune response. Also, the CM used in the current study could be included in corn-SBM-based diets for nursery pigs at 30 or 40% without compromising growth performance. Dietary CM increased gut permeability, implying that dietary CM at 20% improves growth performance of weaned pigs through mechanisms other than reducing gut permeability.

The present study was conducted to determine the effect of flaxseed meal and oat hulls supplementation on growth performance, apparent total tract digestibility (ATTD) of fat, serum lipids, and concentrations of VFA, bile acids (BA), and neutral sterols (NS) in digesta and feces in growing pigs. Forty-eight Genesus [(Duroc boar × Yorkshire-Landrace sows] barrows (25.0 ± 0.32 kg initial BW) were housed in pairs. Pigs were assigned to 1 of the 3 corn-soybean meal-based diets-a basal corn-soybean meal-containing diet (control), a flaxseed meal-containing diet (FM), or an oat hulls-containing diet (OH)-in a completely randomized design. All diets were formulated to be isoenergetic and to contain similar standardized ileal digestible AA contents and meet other nutrient requirements for growing pigs. The experiment lasted for 28 d. Average daily feed intake; ADG; G:F; ATTD of fat, serum lipids, and digesta; and fecal VFA, BA, and NS concentrations were determined. Pigs fed the control or OH had greater final BW ( < 0.001), ADFI ( = 0.005), and ADG ( < 0.001) than FM-fed pigs. The ATTD of fat in the FM was lowest at 70.1% followed by 79.2% in OH and was greatest at 92.4% in the control ( = 0.020). Total serum cholesterol content was 2.25 and 1.99 mmol/L and lower ( < 0.001) in pigs fed FM and OH, respectively, than the 2.36 mmol/L in pigs fed the control. Pigs fed the FM and OH had greater ileal and cecal total VFA ( < 0.001), ileal deoxycholic acid ( < 0.01), and cecal ( < 0.001) and fecal cholesterol ( = 0.002) concentrations than those fed the control. Pigs fed the FM excreted more fecal lithocholic acid ( = 0.002) and ursodeoxycholic acid ( = 0.001) compared with those that consumed the control and OH. The concentrations of coprostanol in cecal digesta ( < 0.001) and feces ( = 0.011) were higher in pigs fed the FM and OH than in pigs fed the control. In conclusion, feeding flaxseed meal and oat hulls induced intestinal fermentation; however, the former depressed growth performance whereas the latter did not have any effect. Addition of flaxseed meal and oat hulls in growing pig diets reduced fat digestibility and serum cholesterol and stimulated malabsorption of primary BA and excretion of secondary BA and NS.