Effects of dietary phosphorus deficiency on the growth performance, hepatic lipid metabolism, and antioxidant capacity of Yellow River Carp Cyprinus carpio haematopterus.

OBJECTIVE: The study aimed to evaluate the effects of phosphorus (P) deficiency in diets on growth performance, hepatic lipid metabolism, and antioxidant capacity in Yellow River Carp Cyprinus carpio haematopterus. METHODS: In this study, 72 healthy experimental fish (initial weight = 12.0 ± 0.1 g [mean ± SE]) were randomly selected and distributed to two groups, with three replicates in each group. The groups were fed either a P-sufficient diet or a P-deficient diet for 8 weeks. RESULT: The P-deficient feed significantly decreased the specific growth rate, feed efficiency, and condition factor of Yellow River Carp. Fish that were fed the P-deficient feed demonstrated higher contents of triglyceride, total cholesterol (T-CHO), and low-density lipoprotein cholesterol in the plasma and a higher T-CHO content in the liver compared to the P-sufficient diet group. In addition, the P-deficient diet significantly reduced the catalase activity level, decreased the glutathione content, and increased the malondialdehyde content in the liver and in the plasma. Furthermore, P deficiency in the diet significantly downregulated the messenger RNA expression of nuclear erythroid 2-related factor 2 and peroxisome proliferator-activated receptor α, whereas it upregulated the messenger RNA expression of tumor necrosis factor α and fatty acid synthase in the liver. CONCLUSION: Dietary P deficiency reduced fish growth performance, induced fat deposition and oxidative stress, and impaired liver health.

Dietary sodium butyrate supplementation attenuates intestinal inflammatory response and improves gut microbiota composition in largemouth bass (Micropterus salmoides) fed with a high soybean meal diet.

The study aimed to investigate the effects of dietary sodium butyrate (NaBT) supplementation on the gut health of largemouth bass (Micropterus salmoides) fed with a high soybean meal diet. Three isonitrogenous and isolipidic diets were formulated: a high fishmeal group (Control); a high soybean meal group (SBM), in which the 30% fishmeal protein in the Control diet was replaced by soy protein; and an NaBT group, in which 0.2% NaBT was added to the SBM diet. Each diet was fed to triplicate tanks (20 fish in each tank). After 8 weeks of feeding trial, the distal intestine and intestinal digesta of the fish in each treatment were sampled. The results showed that fishmeal replacement and NaBT supplementation did not affect fish growth performance. Dietary 0.2% NaBT supplementation improved intestinal morphology, increasing the villus width and villus height and reducing the width of lamina propria. The distal intestine of fish in the control and NaBT groups demonstrated lower activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) and a lower malondialdehyde (MDA) content, compared with the fish in the SBM group. Moreover, the addition of 0.2% NaBT in the feed significantly decreased the expression of tumor necrosis factor α (TNF-α) and interleukin 1ß (IL-1ß) compared to the SBM diet. PCoA and UPGMA analyses based on weighted UniFrac distances demonstrated that intestinal microbial communities in the NaBT group were closer to those in the control group than to those in the SBM group. In addition, dietary 0.2% NaBT supplementation significantly increased the abundance of Firmicutes and Bacteroidetes and decreased the abundance of Tenericutes at the phylum level. Furthermore, the abundance of Bacteroides, Lachnospiraceae_unclassified, and Lachnospiraceae_uncultured was significantly increased, while that of Mycoplasma was significantly decreased in fish intestine at NaBT group at the genus level. In conclusion, dietary NaBT supplementation had beneficial roles in protecting the gut health of largemouth bass from the impairments caused by soybean meal.