Comparison of a wheat-based diet supplemented with purified β-glucans, with an oat-based diet on nutrient digestibility, nitrogen utilization, distal gastrointestinal tract composition, and manure odor and ammonia emissions from finishing pigs1

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It was hypothesized that supplementation of an oat-extracted mixed-linkage (1 → 3), (1 → 4)-β-d-glucan (β-glucans) to a wheat-based diet may beneficially mitigate manure odor and ammonia emissions associated with intensive pig production, without depressing nutrient digestibility as has been observed with oat-based diets. An experiment was conducted to investigate the effect of dietary β-glucan source and the inclusion of an enzyme composite containing β-glucanase on energy and nutrient digestibility, N utilization, distal gastrointestinal tract (GIT) fermentation, and manure emissions from finisher boars. Twenty-eight boars (BW = 74.2 ± 3.6 kg) were assigned to 1 of 4 dietary treatments (n = 7/treatment): 1) an oat-based diet (oat), 2) an oat diet + enzyme composite (OE), 3) a wheat-based diet + purified β-glucans (WG), and 4) a wheat-based diet + purified β-glucans + enzyme composite. The wheat-based diets containing purified β-glucans were formulated to contain concentrations of total β-glucans comparable with the oat-based diet. Consumption of the WG diet resulted in a greater digestibility of GE (P = 0.001) and an increase in the urine:feces N excretion ratio (P = 0.049) compared with the oat diet. In the distal GIT, pigs offered the WG diet contained fewer bifidobacteria (P = 0.027) and lactobacilli (P = 0.050) compared with the oat diet. Pigs offered the WG diet had increased manure odor emissions compared with the oat diet (P = 0.023). In conclusion, although supplementing wheat-based diets with extracted oat-β-glucan did not reduce nutrient digestibility, there was a negligible effect in beneficially influencing manure emissions from pigs when compared with a conventional oat formulation.