Abstract
Simple SummaryDiseases of crayfish (Procambarus clarkia) are closely related to intestinal health. Therefore, it is important for crayfish aquaculture to keep intestinal health in an optimum condition. As a beneficial fungus, Saccharomyces cerevisiae can effectively compete to inhibit the reproduction of pathogenic bacteria, regulate the intestinal microecosystem, and promote animal growth and disease resistance. This study aimed to assess the effects of S. cerevisiae YFI-SC2 on the growth, immunity, and intestinal health of crayfish. The results demonstrated that the addition of S. cerevisiae to the feed could improve the growth performance, the immune response, the intestinal morphology, the structure of intestinal microbiota, and the resistance to pathogens of crayfish. Therefore, S. cerevisiae can be used as a potential probiotic in crayfish farming. The present study aimed to evaluate the effect of the dietary supplementation of Saccharomyces cerevisiae YFI-SC2 on the growth performance, intestinal morphology, immune parameters, intestinal microbiota, and disease resistance of crayfish (Procambarus clarkia). Crayfish were randomly assigned to six different boxes and two different groups in triplicate. The control group received a basal diet and the treatment group received a diet containing S. cerevisiae at 107 CFU/g. After feeding for 28 days, crayfish of the treatment group exhibited a significantly better weight gain ratio (WGR) and a specific growth rate (SGR) (p < 0.05) than crayfish of the control group. Compared to the treatment group, the control group intestines showed an oedema connective tissue layer and a weak muscle layer. For immune-related genes, Crustin2 expression was similar between the groups, whereas Lysozyme and prophenoloxidase from treatment group expression levels were upregulated significantly (p < 0.05) after 14 and 28 days of feeding. Prophenoloxidase showed the highest expression, with 10.5- and 8.2-fold higher expression than in the control group at 14 and 28 days, respectively. The intestinal microbiota community structure was markedly different between the two groups. After 14 and 28 days of feeding, the relative abundance of Cetobacterium and Lactobacillus increased, whereas Citrobacter and Bacteroides decreased in the treatment group compared with that of the control group. The challenge test showed that crayfish of the treatment group had a significantly enhanced resistance against Citrobacter freundii (p < 0.05). Our results suggest that a S. cerevisiae-containing diet positively influenced the health status, immune parameters, intestinal microbiota composition, and disease resistance of crayfish.
Highlights
Crayfish belong to the subphylum Crustacea, the order Decapoda, and the family Cambaridae [1]
After 14 days and 28 days of feeding, the survival rates of the two groups of crayfish were above 90% (Table 2), and there was no significant difference between the groups
Compared with that in the control group, growth tended to be improved in the treatment group after 14 days of feeding
Summary
Crayfish belong to the subphylum Crustacea, the order Decapoda, and the family Cambaridae [1]. Crayfish is native to eastern North America. It was first introduced to Japan in. 1918, and entered China in the 1930s [2]. Its bright color and delicious taste mean that crayfish are loved by consumers, and they have recently become a commercially important freshwater species in China [3]. In 2018, world production of crayfish was 1.71 million tons [4], and it was 1.64 million tons in China [5]. Comparing with that in 2018, China’s total production of crayfish reached 2.09 million tons, with an increase of 27.52% in 2019 [5]
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