Porcine In Vitro Degradation and Fermentation Characteristics of Oats

Study was conducted to determine porcine in vitro digestion and fermentation characteristics of hulled and hulless oat varieties that differed in crude fat content. Treatments were: hulless low-fat or high-fat oat; hulled low-fat or high-fat oat; and corn, which was included for comparison. Samples were digested with porcine pepsin and pancreatin. Undigested residues were subjected to porcine in vitro fermentation for 72 h. Gas production was measured and modeled to estimate kinetics of gas production using incubation time, maximum gas volume for t = ∞ and lag time before fermentation starts and fractional rate of degradation of substrate. Total VFA concentration in fermented solutions was also measured. Corn contained 7.66% CP on DM basis. In vitro digestibility of DM (IVDDM) for corn (66.7%) was lower (P < 0.05) than that of hulless oat (84.3%), but similar to that of hulled oat (70.1%). Hulless oat had greater (P < 0.05) IVDDM than hulled oat. IVDDM for high-fat hulless oat was greater (P < 0.05) than that for low-fat hulless oat (87.6 vs. 81.0 %), whereas IVDDM of hulled oat was unaffected by variety (70.5 vs. 69.7%). Total gas production for hydrolyzed residue of corn (249.5 mL/g DM) was greater (P < 0.05) than that of low-fat (160.1 mL/g DM) or high-fat (148.3 mL/g DM) varieties of hulless oat. Total gas production for hulless oat varieties was greater (P < 0.05) than that of low-fat (42.3 mL/g DM) or high-fat (42.4 mL/g DM) varieties of hulled oat. Total gas production for high-fat oat was similar to that of low-fat oat regardless of hull type. Per unit weight of feedstuff, total VFA production for corn was greater (P < 0.05) than that for hulless or hulled oats. Hulless oat had greater (P < 0.05) VFA production than hulled oat (0.57 vs. 0.31 mmol/g DM of feedstuff). Total VFA production for low-fat hulless oat was greater (P = 0.003) than that for high-fat hulless oat (0.71 vs. 0.41 mmol/g DM of feedstuff); there was no effect of variety on VFA of hulled oats. In conclusion, hulless oat is better source of nutrients for pigs than hulled oat. Grain fat level may influence digestibility and fermentability of hulless oat, but not of hulled oat.

Analyzed composition of oats (DM basis)
Item, %	Hulless		Hulled
	Low-fat	High-fat	Low-fat	High-fat
Crude protein	15.73	16.29	12.98	12.57
Ether extract	6.66	8.67	6.51	8.06
β-glucan	5.44	5.08	5.68	4.82