Effects of Dietary Lentinus edodes Fermentation Supplementation on Digestive Enzyme Activity, Antioxidant Capacity and Morphology of the Liver and Intestine in Largemouth Bass (Micropterus salmoides) Fed High Plant Protein Diets

Abstract

This study evaluated the effect of Lentinus edodes fermentation (LEF) on digestive enzyme activity, antioxidant capacity and morphology of the liver and intestine in largemouth bass (Micropterus salmoides) fed high plant protein diets (HPPD). LEF was supplemented in HPPD with 0 g kg−1 (LEF0), 10 g kg−1 (LEF1), 20 g kg−1 (LEF2), 30 g kg−1 (LEF3), 40 g kg−1 (LEF4), 50 g kg−1 (LEF5), respectively, and then the six diets were fed to largemouth bass with a body weight of 28.8 ± 0.05 g for eight weeks. Juvenile fish were randomized into 6 groups and each group had 4 replicates with 40 fish. Dietary LEF supplementation alleviated the liver inflammatory reaction of largemouth bass caused by HPPD and improved liver morphology. Goblet cells multiplied and the gut muscle layer thickened after LEF supplementation. The LEF significantly increased amylase activity in the liver and intestine of largemouth bass in individual experimental groups. The LEF could increase the activity of catalase in the liver and intestine of largemouth bass (p < 0.05). The content of malondialdehyde was significantly lower than that in the control group (p < 0.05). Dietary LEF supplementation had no significant effect on the intestinal flora of largemouth bass. These findings imply that LEF supplementation can reduce liver inflammation, enhance intestinal tissue morphology, and eventually benefit largemouth bass health.

Growth Performance, Feed Utilisation, Digestive and Metabolic Enzyme Activity, and Liver Morphohistology in Hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus) Juveniles Fed with the Inclusion of Chitosan in Their Diet

“…The liver samples after neutral formalin immersion were dehydrated in a graded ethanol series from 70 to 100%; next, the sample slices were embedded in paraffin, and the samples were sectioned at 5 µm on a rotating microtome (Leica RM, San Diego, CA, USA). Then, they were stained with hematoxylin and eosin (H&E) and observed under the light of an optical microscope (Olympus, New York, NY, USA) using a colour digital camera attached to the microscope and a computer equipped with the software Image Scion 4.0.2 (National Institute of Health, Bethesda, MD, USA) [26]. The areas of the hepatocytes, nuclei, and cytoplasm of the liver tissues were measured: twenty values were randomly measured in each section, and the average value was taken as the measurement result [27,28].…”