Nutritional improvement of copra meal for swine feed

Abstract

Copra meal as a feed ingredient in swine is limited due to the high content of non-starch polysaccharides (NSPs), and enhancing it in a batch setting limits enzyme activity because of high water-substrate absorption. Thus, optimum hydrolysis conditions for improving copra meal using mannanase from Bacillus circulans NT 6.7 in fed-batch setting were investigated using response surface methodology. The experimental results and expected responses were in good agreement after model validation. The effects of simulated swine gastrointestinal (GI) digestion of hydrolyzed copra meal (HCM) from fed-batch and conventional copra meal (CM) were also studied. Batch hydrolysis yielded an experimental value of reducing sugar of 13.05 ± 0.12 mg/mL and a total oligosaccharide 18.44 mg/mL. A higher reducing sugar of 25.74 ± 0.13 mg/mL and a total oligosaccharide of 30.95 mg/mL were obtained using fed-batch hydrolysis under optimal conditions (substrate concentration of 25 g, start time of 1 h, and number of times of 3 once), enzyme concentration of 18 U/mL, and hydrolysis at 50 °C for 6 h. Proximate analyses revealed that 50% of neutral detergent fiber (NDF) and acid detergent fiber (ADF), 37.29% cellulose, 47.5% hemicellulose and almost all lignin were reduced by mannanase. As evidenced by SEM images of copra meal and hydrolyzed copra meal (HCM), significant degradation of copra meal microfibrils occurred. The simulated digestion revealed that HCM was digested more easily than CM, resulting in lower dry weight and more oligosaccharide released. This work outlined the optimum conditions to improve the functionality of copra meal in a fed-batch setting.