PSI-18 - Effects of heat treatment and multi-carbohydrase supplementation on the digestibility of phosphorus in field peas fed to growing pigs

Abstract: Most plant-based feed ingredients contain about two-thirds of their total P as phytate. Mineral elements are chelated to phytate or entrapped in plant cell walls, and microbial or enzymatic breakdown of cell walls may be able to release entrapped P, thus leading to improvement of the apparent total tract digestibility (ATTD) of P in pigs. Heat treatment is one of the processing methods that improve the digestibility of fiber in various feedstuffs for pigs. Therefore, this study aimed to determine the effects of heat treatment and multi-carbohydrase supplementation on the ATTD and standardized total tract digestibility (STTD) of P in peas fed to growing pigs. A total of 18 pigs (23.9 ± 1.3 kg) were assigned to 1 of 3 diets in a completely randomized design to give 6 replicates per diet. Three experimental diets were formulated: 1) non-heated or 2) heat-treated (pelleted) peas as the sole source of P, and 3) heat-treated peas with multi-carbohydrase supplementation. Pigs were individually housed in metabolism crates for 12 d, including 7 d for adaptation and 5 d for total collection of feces. Pigs were offered their daily ration at 2.8 times their maintenance energy requirement. Samples of ingredients, diets, and feces were analyzed for dry matter, Ca, and P. Fecal samples were analyzed for mixed bacterial mass (MBM) and volatile fatty acids (VFA) concentrations. Data were analyzed using the PROC MIXED of SAS. The statistical model included diet as fixed effect and replicate as random effect. An alpha level of 0.05 was used to determine statistical significance and P ≤ 0.10 was considered a trend. Pigs fed the diet that contained heat-treated peas with carbohydrase supplementation tended to have a higher (P < 0.10) ATTD and STTD of P than pigs fed the diet containing heat-treated peas without enzyme. The values of STTD of P were 54.4, 47.3, and 55.0% for diets containing raw peas, heat-treated peas, and heat-treated peas with carbohydrase supplementation, respectively. Heat treatment and enzyme supplementation did not affect the ATTD of Ca in peas fed to growing pigs. No significant differences were observed in fecal MBM-P and VFA concentrations. In conclusion, carbohydrase supplementation tended to increase the digestibility of P in heat-treated peas fed to growing pigs, however, there was no difference in P digestibility between raw and heat-treated peas. Heat treatment and carbohydrase supplementation did not affect fecal MBM-P and VFA concentrations in growing pigs.