Effects of alcohol extract of defatted soybean meal on growth performance and digestive physiology of yellowtail Seriola quinqueradiata

Effects of feeding a fish meal-free soy protein concentrate-based diet on the growth performance and nutrient utilization of red sea bream (Pagrus major )

“…Low‐lipid digestibility has been previously reported when SBM was included in the diets of rainbow trout (Watanabe, Pongmaneerat, Sato, & Takeuchi, ) and yellowtail (Nguyen et al, ). Alcohol‐soluble components in soy products affect lipid digestibility (Olli, Hjelmeland, & Krogdahl, ), and the removal of these components increases their digestibility in rainbow trout (Yamamoto et al, ) and yellowtail (Nguyen et al, ). Despite the fact that SPC is generally manufactured using aqueous alcohol extraction (Peisker, ), reduced lipid digestibility has still been reported when the level of SPC in feeds is increased (Mambrini, Roem, Carvedi, Lalles, & Kaushik, ; Ustaoglu & Rennert, ).…”

“…Pancreatic lipase requires the presence of bile salts, which act as emulsifiers, to be completely activated in the digestive tract (Gjellesvik, Raae, & Walther, ), and lipase activity decreased significantly when an external emulsifier, sodium deoxycholate, is absent in an in vitro enzyme assay (Nguyen et al, ), suggesting that insufficient bile salts in the gut could also reduce lipase activity in vivo. Reduction in bile salt levels in the intestinal digesta of SBM‐fed fish has been reported in rainbow trout (Romarheim et al, ), red sea bream (Amano, Suzuki, Yamamoto, & Matsunari, ) and yellowtail (Nguyen et al, ). Moreover, Matsunari et al () found a significantly lower bile salt concentration in the intestinal digesta of red sea bream fed SPC or an alcohol‐treated soy protein isolate.…”

“…Low-lipid digestibility has been previously reported when SBM was included in the diets of rainbow trout (Watanabe, Pongmaneerat, Sato, & Takeuchi, 1993) and yellowtail (Nguyen et al, 2017). Alcohol-soluble components in soy products affect lipid digestibility (Olli, Hjelmeland, & Krogdahl, 1994), and the removal of these components increases their digestibility in rainbow trout (Yamamoto et al, 2008) and yellowtail (Nguyen et al, 2017).…”

“…Despite the significant reduction in fat accumulation in the SPC group fish, lipase activity in the hepatopancreas was not significantly different from that in the FM‐pair and FM‐sat groups. Nguyen et al () also reported lower lipid digestibility in fish fed with feed containing SBM compared with those fed a control FM feed, although lipase activity was not appreciably different between the two groups. One possible reason for the low lipid utilization in the SPC group fish is the reduction of lipase activity in the digestive tract itself due to an insufficient amount of bile salts.…”

“…In this study, however, there were no significant differences among the groups in terms of the lipase activity of the hepatopancreas where the enzyme is synthesized and stored. Nguyen et al () reported that lipase activity in the intestinal digesta of SBM‐fed yellowtail was significantly lower than that of FM‐fed yellowtail despite there being no significant difference between the two treatments in terms of enzyme levels in the pyloric caeca where the enzyme is stored. Thus, it is possible that the lipid digestion and absorption capacities of the SPC group were lower than those of the FM‐sat and FM‐pair groups, although lipid digestibility was not measured in our study.…”