Cereal β-glucan alters nutrient digestibility and microbial activity in the intestinal tract of pigs, and lower manure ammonia emission: A meta-analysis

Abstract

Cereal β-glucan may be detrimental in pig production because of negative effects on nutrient digestibility, but they may act as functional ingredients by stimulating the intestinal microbiota. This study primarily aimed to investigate relations between dietary β-glucan and nutrient digestibility, intestinal fermentation, and manure NH3 emission in weaned, growing, and finishing pigs. Effects of dietary xylose, NDF, and CP, and pig BW on animal responses were also evaluated. A meta-analytical approach, accounting for inter- and intraexperiment variations, was used to compute prediction models. Data from 26 studies including 107 different dietary treatments with appropriate dietary and physiological measurements were used to parameterize these models. Dietary β-glucan inclusion ranged from 0 to 6.7%. Increasing dietary β-glucan reduced apparent ileal (AID) and total tract digestibility (ATTD) of CP and energy (R(2) = 0.12 to 0.29; P < 0.05), whereas the ATTD of DM was reduced by 10% up to a threshold β-glucan of 3.5%, above which the response became asymptotic (R(2) = 0.34; P < 0.01). Increasing dietary NDF content decreased ATTD of DM and energy, and increasing xylose concentration reduced ATTD of energy and CP (R(2) = 0.24 to 0.85; P < 0.05). Broken-line model indicated that cecal total VFA and butyrate concentrations increased up to a threshold of 2.5 and 1.4% β-glucan in the diet, respectively, above which these responses became asymptotic (R(2) = 0.77 to 0.96; P < 0.05). Ileal butyrate was negatively and colonic iso-butyrate was positively linked to increasing β-glucan concentration (R(2) = 0.17 to 0.41; P < 0.05). Greater β-glucan concentration were negatively related (R(2) = 0.86; P < 0.01) to NH3 emission, indicating a reduction in NH3 emission by one-half with 6% β-glucan. Backward elimination analysis indicated that greater BW of pigs counteracted (P < 0.05) the negative effect of β-glucan on AID of CP and energy and ATTD of DM and CP. Pig BW also enhanced effects of β-glucan on cecal total VFA, colonic iso-butyrate, ileal butyrate, and NH3 emission (P < 0.05). Dietary CP potentiated (P < 0.01) the β-glucan effects on cecal total VFA, cecal butyrate, and colonic iso-butyrate. In conclusion, this study indicates that β-glucan can stimulate cecal butyrate and ameliorate manure NH3 emission, thereby decreasing nutrient digestibility. Because greater BW ameliorates β-glucan effects, finishing diets may be formulated to contain more β-glucan than weaner diets.

Modulation of resistant starch and nutrient composition of barley grain using organic acids and thermal cycling treatments

“…D). The observed decrease of the ash content after acid treatments might be the result of a greater solubility of minerals, which is supported by previous findings . Besides potassium (about 10 g/kg), P is the main mineral in barley.…”

“…Thus, promotion of the hydrolysis of phytate and a decrease of its content in barley by chemical treatments is highly desired. Further research is warranted to differentiate mineral composition and also evaluate whether CA promotes the hydrolysis of phytate at the same rate as LA, reported previously .…”

“…F). This could be an indicator for an increased recovery of NDSF such as β‐glucans and pectic substances, which are reported to have positive health effects in humans and animals . Future research is needed to further evaluate the OR fraction and also validate these findings both in in vitro and in in vivo experimental conditions.…”

“…Thus, a decrease of the ash content is likely related to an enhanced degradation and hydrolysis of this mineral too, which in cereals is mostly in the form of phytate [50]. In fact, in a previous work, we observed that treating barley grain with LA significantly decreased the ash content, and this effect was associated with a greater hydrolysis of phytate in barley [50]. Phytate lowers the availability of dietary P and other cations, being therefore considered an antinutritional factor in nutrition.…”

Treatments with organic acids and pullulanase differently affect resistant starch and fiber composition in flour of various barley genotypes (Hordeum vulgare L.)

“…With increasing the consumption of starch, the intake of fiber has been reduced significantly in western countries . Health‐promoting effects of dietary fiber are long known in humans , and similar results have also been recently reported in pigs and rabbits . Whole barley is a good source of dietary fiber.…”