Chemical composition and porcine in vitro disappearance of heat-pretreated and multi-enzyme-supplemented soybean hulls

Soybean hulls are poorly digested by pigs. Heat-pretreatment or the use of fiber-degrading enzyme supplementation of soybean hulls can potentially improve the digestibility of soybean hulls. Thus, study was conducted to determine the effects of heat pretreating (at 160 degrees C and 70 psi for 20 min) and supplementing soybean hulls with the multienzyme product, Superzyme-OM (Canadian Bio-Systems, Alberta, Calgary, AB, Canada), which was in liquid form in was dosed at 3 mg/g of sample, which supplied 5100 U of cellulase, 3300 U of pectinase, 720 U of mannanase, 90 U of galactanase, 3600 U of xylanase, 1080 U of glucanase, 4500 U of amylase, and 360 U of protease per kilogram of feedstuff on porcine in vitro nutrient disappearance. The samples were subjected to in vitro enzymatic hydrolysis using pepsin and pancreatin. The samples were incubated in a buffer solution with fresh pig feces as inocula for 72 h to measure gas production. Concentration of volatile fatty acids (VFA) per gram of dry matter (DM) of samples was measured in fermented solutions. On a DM basis, untreated and pretreated soybean hulls contained 10.4 and 10.6 % crude protein. Heat pretreatment reduced total non-starch polysaccharides content of soybean hulls from 71.5 to 64.2%. Heat pretreatment and multi-enzyme supplementation did not interact on coefficient of in vitro disappearance of dry matter (IVDDM). Heat pretreatment increased (P < 0.01) the coefficient of IVDDM of soybean hulls by a mean of 45.5 % whereas multi-enzyme supplementation tended to increase (P = 0.055) the coefficient of IVDDM of soybean hulls by 3%. Heat pretreatment and multi-enzyme interacted (P < 0.05) on fractional rate of degradation and half time such that the fraction rate of degradation for soybean hulls increased (P < 0.01) and the half time for soybean hulls decreased (P < 0.05) when both heat-pretreated and multi-enzyme supplemented. Cumulative gas volume for heat-pretreated soybean hulls at 8, 12, 18, 24, 36, and 48 h after the commencement of incubation was greater (P < 0.01) than that of untreated soybean hulls. Heat pretreatment of soybean hulls increased (P < 0.05) the VFA production per gram of DM of feedstuff. In conclusion, heat-pretreatment and multi-enzyme supplementation increased IVDDM of soybean hulls, implying that the heat pretreatment used in the current study can be used to enhance the nutrient utilization of soybean hulls for pigs.

Automated summary

Heat-pretreatment and multi-enzyme supplementation were found to increase the in vitro digestibility of soybean hulls for pigs, suggesting potential benefits in nutrient utilization.