Effect of Chlorella pyrenoidosa meal and Sinotaia quadrata viscera as diets on growth, digestive enzyme activities, antithrombin activity, and gut morphology of Whitmania pigra

The experiment aimed to evaluate the effects of varying amounts of Chlorella pyrenoidosa meal as a supplementary diet and Sinotaia quadrata viscera on the growth, digestive enzyme activities, antithrombin activity, and gut morphology of Whitmania pigra. W. pigra (1.27 ± 0.01 g) were randomly assigned to four groups with triplicates each. The groups were fed with live S. quadrata (Snail group), live S. quadrata and 0.125 g/L C. pyrenoidosa meal (Snail + LA group), live S. quadrata and 0.250 g/L C. pyrenoidosa meal (Snail + HA group), as well as S. quadrata viscera (Snail viscera group). The feeding trial lasted for 30 days. The results showed that the final weight of Snail + HA group was significantly higher than that of Snail and Snail viscera groups, and it was significantly higher in Snail group than in Snail viscera group (P < 0.05). The trends in weight gains followed the same pattern as the body weights observed. The specific growth rate (SGR) values of Snail viscera group on days 0–15 and 0–30 were significantly lower than those of the other three groups (P < 0.05). Feed intake of the Snail + LA group was significantly higher than that of the other groups during days 0–30 (P < 0.05). The feed conversion ratio (FCR) of the Snail viscera group was inferior to that of the other three groups at both days 0–15 and 0–30 (P < 0.05). The activities of antithrombin, lipase and protease in the Snail + LA and Snail + HA groups exhibited a significant increase compared to the remaining two groups (P < 0.05). Additionally, the gene expression levels of Protease (PT) and Superoxide dismutase (SOD) in the Snail + LA and Snail + HA groups were significantly higher than those in the Snail group (P < 0.05). Moreover, the gut cell junction of the Snail visceral group appeared relatively loose, characterized by the presence of more cell vacuoles within the epithelial tissue and the occurrence of black substances in certain cells. In conclusion, both 0.125 and 0.250 g/L C. pyrenoidosa meal, when used as a supplementary diet in combination with live S. quadrata, improved the growth performance and increased antithrombin, lipase and protease activities in W. pigra. However, feeding prepared S. quadrata viscera to W. pigra adversely affected the growth and gut morphology.