Soybean meal is considered the main alternative to replace fish meal in aquaculture diets. However, due to imbalanced amino acids, lower phosphorus availability, and some antinutritional factors, soybean meal has not been able to completely replace fish meal.
Previous studies have shown that fermentation and proteolysis increase the crude protein content and decrease crude fiber, antinutritional factors, and toxins.
Compared to conventional soybean meal, proteolytic soybean meal contains a large number of small peptides, which have better physical and chemical properties and increase digestibility.
Scientists from Shanghai Ocean University, Shanghai Collaborative Innovation Center for Cultivating Elite Breeds and Green-Culture of Aquaculture Animals, National Demonstration Center for Experimental Fisheries Science Education, and Beijing Dabeinong Technology Group Co., Ltd., conducted a feeding trial to investigate the effects of proteolytic soybean meal on the growth, immunity-related genes, and resistance against Vibrio alginolyticus in Litopenaeus vannamei shrimp.
They used six levels of inclusion of proteolytic soybean meal in the diet: 0, 35, 45, 55, and 65 g/kg, added to a base diet.
Proteolytic soybean meal
The fermentation process can improve the availability of vitamins, protein solubility, amino acid profiles, and palatability of soybean meal. Proteolysis, on the other hand, is used to generate various protein hydrolysates that can reduce antinutritional factors and increase peptide content.
Proteolytic soybean meal is soybean meal treated with an enzyme complex, containing 48% crude protein and 0.9% crude lipids.
According to the study results, the used proteolytic soybean meal has substantially high levels of small peptides.
Inclusion level of proteolytic soybean meal
“The results showed that juvenile shrimp fed with more than 45 g/kg of proteolytic soybean meal exhibited significantly better growth compared to the control,” the scientists report.
Likewise, the treatments supplemented with proteolytic soybean meal showed significantly better performance in terms of feed conversion ratio, protein efficiency ratio, and protein deposition rate.
The scientists report that processing soybean meal into proteolytic soybean meal can remove lectin and trypsin inhibitors, which also contributes to increased growth in the proteolytic soybean meal treatments.
“Our results indicated that shrimp fed with proteolytic soybean meal showed higher superoxide dismutase (SOD) activity and lower malondialdehyde (MDA) levels than shrimp fed with conventional soybean meal. This finding supports that proteolysis can reduce the adverse effects of soybean on the oxidative status of white shrimp.”
According to the study results, shrimp fed a diet supplemented with 65 g/kg of proteolytic soybean meal showed significantly lower cumulative mortality compared to the control group after challenge with Vibrio alginolyticus.
“The current study showed that shrimp fed with proteolytic soybean meal were less susceptible to V. alginolyticus infection, especially in the treatment with a level of 65 g/kg. The results were consistent with the change in serum lysozyme and antioxidant capacity parameters,” they highlighted.
“The current study demonstrated that replacing an appropriate dose of soybean meal with proteolytic soybean meal in a low fish meal diet could result in better growth and immunological status of L. vannamei,” they concluded.
The study was funded by the Shanghai Agriculture Applied Technology Development Program, China, and the Shanghai Collaborative Innovation Center for Cultivating Elite Breeds and Green-culture of Aquaculture Animals.
Centre for Research on Environmental Ecology and Fish Nutrition
Ministry of Agriculture and Rural Affairs
Shanghai Ocean University, China
Reference (open access)
Weilong Wang, Detian Jiang, Ganfeng Yi, Xuxiong Huang, “An Evaluation of Replacing Soybean Meal with Proteolytic Soybean Meal in Low-Fish-Meal Diet on Growth Performance, Expression of Immune-Related Genes, and Resistance against Vibrio alginolyticus in White Shrimp (Litopenaeus vannamei)“, Aquaculture Nutrition, vol. 2022, Article ID 8384917, 9 pages, 2022. https://doi.org/10.1155/2022/8384917