Effects of hydroxy methionine zinc on growth performance, immune response, antioxidant capacity, and intestinal microbiota of red claw crayfish (Procambarus clarkii).

This study aimed to evaluate the effects of varying zinc (Zn) levels on the growth performance, non-specific immune response, antioxidant capacity, and intestinal microbiota of red claw crayfish (Procambarus clarkii (P. clarkii)). Adopting hydroxy methionine zinc (Zn-MHA) as the Zn source, 180 healthy crayfish with an initial body mass of 6.50 ± 0.05 g were randomly divided into the following five groups: X1 (control group) and groups X2, X3, X4, and X5, which were fed the basal feed supplemented with Zn-MHA with 0, 15, 30, 60, and 90 mg kg-1, respectively. The results indicated that following the addition of various concentrations of Zn-MHA to the diet, the following was observed: Specific growth rate (SGR), weight gain rate (WGR), total protein (TP), total cholesterol (TC), the activities of alkaline phosphatase (AKP), phenoloxidase (PO), total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD) and catalase (CAT), the expression of CTL, GPX, and CuZn-SOD genes demonstrated a trend of rising and then declining-with a maximum value in group X4-which was significantly higher than that in group X1 (P < 0.05). Zn deposition in the intestine and hepatopancreas, the activity of GSH-PX, and the expression of GSH-PX were increased, exhibiting the highest value in group X5. The malonaldehyde (MDA) content was significantly reduced, with the lowest value in group X4, and the MDA content of the Zn-MHA addition groups were significantly lower than the control group (P < 0.05). In the analysis of the intestinal microbiota of P. clarkii, the number of operational taxonomic units in group X4 was the highest, and the richness and diversity indexes of groups X3 and X4 were significantly higher than those in group X1 (P < 0.05). Meanwhile, the dietary addition of Zn-MHA decreased and increased the relative abundance of Proteobacteria and Tenericutes, respectively. These findings indicate that supplementation of dietary Zn-MHA at an optimum dose of 60 mg kg-1 may effectively improve growth performance, immune response, antioxidant capacity, and intestinal microbiota richness and species diversity in crayfish.

Feasibility of Using Seaweed (Gracilaria coronopifolia) Synbiotic as a Bioactive Material for Intestinal Health.

The market contains only limited health care products that combine prebiotics and probiotics. In this study, we developed a seaweed-based Gracilaria coronopifolia synbiotic and verified the efficacy by small intestinal cells (Caco-2). We also developed a functional material that promotes intestinal health and prevents intestinal inflammation. G. coronopifolia was used as a red seaweed prebiotic, and Bifidobacterium bifidums, B. longum subsp. infantis, B. longum subsp. longum, Lactobacillus acidophilus, and L. delbrueckii subsp. bulgaricus were mixed for the seaweed's synbiotics. G. coronopifolia synbiotics were nontoxic to Caco-2 cells, and the survival rate was 101% to 117% for a multiplicative effect on cell survival. After cells were induced by H2O2, the levels of reactive oxygen species (ROS) increased to 151.5%, but after G. coronopifolia synbiotic treatment, decreased to a range between 101.8% and 109.6%. After cells were induced by tumor necrosis factor α, the ROS levels increased to 124.5%, but decreased to 57.7% with G. coronopifolia symbiotic treatment. G. coronopifolia synbiotics could effectively inhibit the production of ROS intestinal cells under oxidative stress (induced by H2O2 and tumor necrosis factor α (TNF-α)), which can reduce the damage of cells under oxidative stress. Functioning of intestinal cells could be improved by inhibiting the production of inflammatory factor substances (interleukin 8) with G. coronopifolia symbiotic treatment. Also, gastrointestinal diseases may be retarded by a synbiotic developed from G. coronopifolia to promote intestinal health and prevent intestinal inflammation.