Morphological state of the digestive organs red-clawed crayfish (Cherax quadricarinatus) by the use of feed additives

Abstract

The morphological structure of the digestive system organs (stomach, intestines and digestive gland) of the Australian red-clawed crayfish (Cherax quadricarinatus) was studied when using alfalfa flour in feed as an alternative additive. Crayfish were kept in laboratory conditions, at a temperature of 24-26.5 °C and divided into 3 groups: control (11 individuals); crayfish that received experimental feed version No. 1 (10 individuals) and feed version No. 2 (10 individuals). The control group was fed with granular feed intended for sturgeon fish. In experimental feeds, fish meal was replaced by alfalfa flour by 10%. An enzyme preparation – natusim in the amount of 350 mg/kg of feed was added to the feed option No. 1. The experiment lasted 45 days. Feeding was carried out 2 times a day at the rate of 2-4% of body weight. No damage to the gastric mucosa was detected on histological preparations of control and experimental individuals. The thickness of the stomach wall from the muscle layer to the edge of the epithelium varied in a wide range – from 40 to 200 microns, regardless of the experimental group. There were no large accumulations of hemocytes in the mucous membrane, which indicates the absence of an inflammatory process. The thickness of the intestinal epithelial layer was 40-55 microns. A large number of goblet cells were observed, which may indicate an active digestion process. No pathological changes in the structure of the intestine were detected. The transverse size of the tubes of the digestive gland was in the range from 180 to 300 microns. On the cross-section, the proportion of the glandular part of the tubules reached 80-90%. Micro-preparations of the digestive gland of cancers receiving experimental feeds did not differ morphologically from the control group.