Largemouth bass (Micropterus salmoides) exhibited better growth potential after adaptation to dietary cottonseed protein concentrate inclusion but experienced higher inflammatory risk during bacterial infection

Abstract

Cottonseed protein concentrate (CPC) has been proven to partially replace fishmeal without adverse effects on fish growth performance, while little information is known about the effects on liver health during bacterial infection. In the present study, 15% CPC was included into the diet of juvenile largemouth bass (32.12 ± 0.09g) to replace fishmeal for 8 weeks, with fish growth potential and hepatic inflammatory responses during Nocardia seriolae (N. seriolae) infection systemically evaluated. After adaptation to dietary CPC inclusion, largemouth bass even exhibited better growth potential with higher SGR and WGR during the last three weeks of whole feeding trial, which was accompanied with higher phosphorylation level of TOR signaling and higher mRNA expression level of myogenin (myog). At the end of 8-weeks feeding trial, the histological structure of largemouth bass liver was not significantly affected by dietary CPC inclusion, accompanied with the similar expression level of genes involved in innate and adaptive immunity and comparable abundance of T cells in bass liver. N.seriolae infection induced the pathological changes of bass liver, while such hepatic changes were more serious in CPC group than that in FM group. Additionally, RT-qPCR results also suggested that largemouth bass fed with CPC experienced much higher inflammatory potential both in liver and gill during N. seriolae infection, which was accompanied with higher expression level of genes involved in pyroptosis. Therefore, this study demonstrated that the application of CPC in largemouth bass diet should be careful, which may induce higher inflammatory potential during N. seriolae infection.

Liver Injury and Metabolic Dysregulation in Largemouth Bass (Micropterus salmoides) after Ammonia Exposure

“…In the normal fish liver, hepatocytes were double-layered and radially arranged around the central vein in bundles, with the vascular (sinusoids) and biliary (canaliculi) network distributed in the lacunae among hepatocytes. This is consistent with normal largemouth bass liver morphology reported in our previous study [ 25 ] and other studies [ 30 ]. Ammonia exposure has been reported to impair the histological features of Nile tilapia liver tissue [ 31 ].…”

“…Water parameters in the circulating water system were kept constant with the flow at 0.5 L/min and temperature at 26 ± 2 °C. Fish were fed with a diet (crude protein of 47.35%) reported in our previous study [ 25 ]. The water pH was maintained at 7.6 ± 0.2, and the dissolved oxygen was maintained at 7.5 ± 0.3 mg/L.…”

Effects of Replacing Fish Meal with Enzymatic Cottonseed Protein on the Growth Performance, Immunity, Antioxidation, and Intestinal Health of Chinese Soft-Shelled Turtle (Pelodiscus sinensis)

“…[ 70 ]. Mengya et al [ 71 ] showed that adding cottonseed protein to the diet of largemouth bass increased the risk of inflammation. Li et al [ 72 ] showed that adding soybean meal to a turbot diet caused intestinal damage.…”

IFN-γ enhances protective efficacy against Nocardia seriolae infection in largemouth bass (Micropterus salmoides)

“…Largemouth bass ( Micropterus salmoides ) is globally recognized as one of the most economically significant fish species in aquaculture ( 1 ). It was introduced into China in the 1980s and has expanded to become a significant economic fish in China’s freshwater aquaculture industry ( 2 ).…”