摘要：
Tadpole cultivation is a crucial step in the artificial production of bullfrogs ( Lithobates catesbeiana ), but its feed nutrition is poorly understood. This study examined how dietary lipid and protein levels affect metamorphosis, growth and intestinal health of tadpole. Six groups of tadpoles were fed six diets with two lipid levels (7% and 10%) and three protein levels (36%, 40% and 44%) for 70 days. The results showed that at 7% lipid level, increasing protein enhanced metamorphosis rate and mean weight of tadpoles, reaching the optimal value at 40% protein ( P < 0.05). At 10% lipid level, increasing protein also improved mean weight, peaking at 40% protein. Dietary nutrition also influenced liver amino acid and lipid metabolism directly. At 7% lipid level, increasing protein significantly increased the activities of hepatic enzymes GLS, PDH, ALT, AST, etc. ( P < 0.05), and up -regulated the expression of hepatic genes fas , accb , fadd6 and cpt1a involved in lipid metabolism ( P < 0.05). At 10% lipid level, increasing protein also up -regulated fadd6 and cpt1a genes ( P < 0.05), but downregulated acadl gene. Meanwhile, increasing dietary lipid level elevated TG and T-CHO levels in liver. Increasing dietary protein enhanced gut microbiota richness, while increasing lipid reduced it. Moreover, different gut microbiota groups had distinct biomarkers, such as Rikenellaceae , Desulfovibrionaceae , Burkholderiales and Bacteroidales, which were related to amino acid or lipid metabolism. In summary, under the test conditions, 7% lipid and 40% protein in diet are suitable levels, which can promote metamorphosis, growth and metabolism of tadpoles, and are more economical than high -lipid and high -protein diets.
摘要：
An investigation into the possible substitution of Clostridium autoethanogenum protein (CAP) for soybean meal (SBM) in the diet of grass carp (Ctenopharyngodon idellus) was carried out. During a 56-day feeding trial, 750 grass carp were fed five experimental diets with different levels of CAP: SBM (control group), CAP25, CAP50, CAP75, and CAP100, corresponding to dietary SBM replacements levels of 0%, 25%, 50%, 75%, and 100%. The results showed that dietary CAP significantly increased FW, WGR, and PER in CAP25 group (P < 0.05), but complete substitution showed the opposite trend (P < 0.05). The liver antioxidant capacity was improved in CAP25 group manifested by the enhanced SOD, GPx and CAT activities, reduced ROS, and MDA contents, and the up-regulated cuznsod, mnsod, gpx1, gpx4, gsto and gr transcript levels mediated by Keap1-Nrf2 signaling pathway (P < 0.05). The intestinal inflammation was relieved in CAP25 group evidenced by the down-regulated il-beta, il-6 and tnf-alpha expressive abundance through NF-kappa B pathway (P < 0.05). Additionally, the intestinal mucosal barrier function was enhanced by the upregulation of tight junction proteins (occludin, zo-1 and zo-2) in the CAP25 group. Whereas the intestinal folds showed varying degrees of breakage in CAP100 group. The increased amylase and lipase activities, intestinal folds height, and goblet cell numbers were found in CAP25 group (P < 0.05). The gut microbiota revealed no significant differences in the alpha diversity indices across treatments (P > 0.05). Besides, the abundance of Bacteroides in the CAP25 group was increased, while the abundance of Erysipelatoclosridium in the CAP100 group was increased. Summarily, CAP could replace 25% of SBM with positive influences on growth, antioxidant capacity, immunity and intestinal microbiota for juvenile grass carp. Conversely, high levels of CAP impaired intestinal physical barrier and caused intestinal microbiota disturbance, resulting in negatively affect the growth performance.
摘要：
<jats:p>A low metamorphosis rate of amphibian larvae, commonly known as tadpoles, limits the farming production of bullfrogs (Lithobates catesbeiana). This study aimed to examine the effects of processed thyroid powder as a feed additive on tadpole metamorphosis, lipid metabolism, and gut microbiota. Five groups of tadpoles were fed with diets containing 0 g/kg (TH0), 1.5 g/kg (TH1.5), 3 g/kg (TH3), 4.5 g/kg (TH4.5), and 6 g/kg (TH6) thyroid powder for 70 days. The results showed that TH increased the average weight of tadpoles during metamorphosis, with the TH6 group having the highest values. The TH4.5 group had the highest metamorphosis rate (p < 0.05). Biochemical tests and Oil Red O staining showed that the lipid (triglyceride) content in the liver decreased after TH supplementation, especially at doses higher than 1.5 g/kg. RT-qPCR revealed that TH at doses higher than 4.5 g/kg significantly up-regulated the transcriptional expression of the pparα, accb, fas, fadd6, acadl, and lcat genes, which are related to lipid metabolism (p < 0.05). These results showed that TH seems to simultaneously promote the synthesis and decomposition of lipid and fatty acids, but ultimately show a decrease in lipids. As for the gut microbiota, it is noteworthy that Verrucomicrobia increased significantly in the TH4.5 and TH6 groups, and the Akkermansia (classified as Verrucomicrobia) was the corresponding genus, which is related to lipid metabolism. Specifically, the metabolic pathways of the gut microbiota were mainly enriched in metabolic-related functions (such as lipid metabolism), and there were significant differences in metabolic and immune pathways between the TH4.5 and TH0 groups (p < 0.05). In summary, TH may enhance lipid metabolism by modulating the gut microbiota (especially Akkermansia), thereby promoting the growth of tadpoles. Consequently, a supplementation of 4.5 g/kg or 6 g/kg of TH is recommended for promoting the metamorphosis and growth of tadpoles.</jats:p>
摘要：
Cottonseed meal and rapeseed meal exhibit a potential for fishmeal substitute in grass carp feed, while their excessive use contribute to growth decline and weakening immunity of aquatic animals. Clostridium butyricum metabolites (CBM) was recognized as a functional additive due to its antioxidant properties and maintenance of intestinal microbiota balance. CBM was added to a high of cottonseed and rapeseed meal diet to determine its effects on growth, immunity, and intestinal microbiota alterations of grass carp (Ctenopharyngodon idella) over 56 days. Eight hundred grass carp (mean weight, around 50g) were randomized to five treatments and fed with the basic diet (CON), CBM0 diet (28% cottonseed and 27% rapeseed meal), and CBM diets (CBM0.5, CBM1, and CBM2, namely CBM0 diet supplemented with 500, 1000, and 2000mgkg(-1) CBM). The results indicated that compared to CBM0, The ingestion of 1000mgkg(-1) CBM diet by grass carp significantly promoted growth as measured by intestinal lipase activity, villus height, and muscle thickness. Moreover, accompanied by a decrease in intestine MDA content, and enhance antioxidant capacity by activating Keap1/Nrf2 signaling pathway to increase enzyme activities (SOD, CAT and T-AOC) and corresponding gene expression (mnsod, cat, gsto and gpx1) in the intestine of grass crap fed CBM1 diet. The dietary CBM1 diet increased serum levels of C3 and IgM, increased ACP activity and expression of the corresponding anti-inflammatory factors (tgf-β1 and il-15), and suppressed the expression of pro-inflammatory factors (tnf-α and il-12β), resulting in enhanced immunity. The dietary CBM1 diet up-regulates gene expression of tight junction proteins (zo-1, occludin, occludin7a and occludin-c), coupled with the decreases in DAO and D-lactate contents, implying that the decreased mucosal permeability could be observed in the gut. The dietary CBM1 diet largely altered the intestinal microbial community, especially reducing the relative abundance of intestinal pathogenic bacteria (Streptococcus and Actinomyces). And it significantly increased the content of short-chain fatty acids (acetic acid, butyric acid, isobutyric acid, propionic acid and isovaleric acid). Taken above, dietary CBM supplementation improved growth in grass carp and attenuated the intestinal oxidative stress, inflammation and microflora dysbacteriosis caused by high proportions of cottonseed and rapeseed meal diets.
关键词：
Cottonseed protein concentrate;Antioxidant capacity;Immunity;Intestinal health;Ctenopharyngodon idellus
摘要：
An investigation into the replacement of soybean meal (SBM) with cottonseed protein concentrate (CPC) in the diet of grass carp feed (Ctenopharyngodon idellus) was carried out. During a 56-day feeding trial, 750 grass carp were fed five experimental diets (isonitrogenous and isolipidic) with different levels of CPC: SBM (control group), CPC25, CPC50, CPC75, and CPC100, corresponding to dietary SBM replacements levels of 0%, 25%, 50%, 75%, and 100%. The results showed that dietary CPC inclusion significantly increased FW, WGR, and PER (P < 0.05) except CPC100 groups, which did not differ with SBM group (P > 0.05). FCR was remarkably increased when SBM replacement levels reached up to 100% (P < 0.05). Based on broken-line regression analysis of WGR against the dietary replacement of SBM with CPC, the optimal replacement level of SBM with CPC was estimated to be 75.11% for juvenile grass carp. Muscle texture parameters hardness, gumminess and chewiness were apparently elevated (P < 0.05), demonstrated an improved flesh quality followed CPC added. The CPC inclusion groups showed significantly higher serum IgM, C3 amd C4 contents, as well as ACP and AKP activities than SBM group except CPC100 groups (P < 0.05). The hepatic antioxidant capacity was enhanced followed CPC inclusion verified at enzymatic and transcriptional levels (P < 0.05). The intestinal inflammation was relieved evidenced by the down-regulated il-beta, il-6 and tnf-alpha expressive abundance mediated through NF-kappa B pathway (P < 0.05). Additionally, the intestinal mucosal barrier function was enhanced by the up-regulation of tight junction proteins (occludin, claudin12, zo-1, and zo-2). The intestinal lipase and trypsin activities in CPC50 and CPC75 and intestinal folds height in CPC25, CPC50 and CPC75 were advanced (P < 0.05). The gut microbiota revealed no significant differences in the alpha diversity indices across treatments (P > 0.05). While the key bacteria of Aeromonas in the CPC100 group was increased leading intestinal dysbacteriosis. Besides, the ME1 of the microbial network has a negative correlation with pro-inflammatory gens and a positive correlation with antioxidant gens and tight linking proteins (P < 0.05). Summarily, CPC could partially replace SBM with positive influences on growth, antioxidant capacity, immunity, and intestinal microbiota in grass carp.
摘要：
In pursuit of sustainable aquaculture, this study was performed to evaluate chicken meal as a substitute for fishmeal in bullfrog diets. Three experimental groups were established: a control group (FM) with 20% fishmeal, a CM50 group with 50% replacement (10% fishmeal), and a CM100 group with 100% replacement (0 fishmeal). Bullfrogs were fed for 56 days. The CM50 group exhibited significant increases in total weight gain and survival rate and a notable decrease in feed coefficient (p < 0.05). However, the CM100 group showed contrary effects. Increasing chicken meal substitution correlated with decreased amino acid content in muscle. Notably, the CM50 group demonstrated enhanced activities of antioxidant enzymes (CAT, T-AOC) and elevated gene expression levels (cat, sod, gst, etc.) in muscle and the intestine (p < 0.05), improved intestinal morphology, enhanced digestive enzyme activities (amylase, lipase), and reduced expression of inflammatory factors (il-1β, il-8, il-17, etc.). Conversely, the CM100 group's indicators regressed to levels similar to or worse than those of the FM group. Therefore, a 50% substitution of fishmeal with chicken meal effectively promoted bullfrog survival, protected the intestines, and enhanced antioxidant capacity, supporting its potential as a fishmeal alternative. However, the adverse outcomes of the CM100 strategy, including growth retardation and reduced amino acid content in muscle, indicate that complete replacement is unsuitable.
摘要：
The present study was to investigate the effects of Methylococcus capsulatus protein (MCP) replacing fish meal on the growth performance, immunity, and intestinal health of Chinese soft-shelled turtle ( Pelodiscus sinensis ). Four isonitrogenous (47.00% crude protein) and isolipidic (6.00% crude lipid) diets were formulated for an 8-week feeding trial. The fish meal group (FM) contained 55% fish meal. MCP was used to replace 10%, 15%, and 20% of the fish meal in the FM group to create MCP10, MCP15, and MCP20 treatment groups. No significant differences were observed in the weight gain, feed conversion efficiency, physical indicators, or muscle amino acid composition among all diet treatments ( P > 0.05). The MCP15 group showed the best growth performance. There were no significant differences in serum biochemistry among the groups ( P > 0.05), except for aspartate aminotransferase, which exhibited a significant linear increase trend with the increase of MCP replacement level ( P = 0.049). In the MCP20 group, the complement C3 content, immunoglobulin M content, and lysozyme activity in serum were significantly lower than those in the FM, MCP10, and MCP15 groups ( P < 0.05), showing a quadratic relationship characterized by an initial increase followed by a decrease as the MCP level in the feed increased ( P < 0.05). The intestinal morphology in all treatment groups appeared normal and the expression levels of intestinal inflammatory cytokines showed no significant differences ( P > 0.05). The community structure of the intestinal microbiota, as well as the phylum and genus composition underwent significant alterations in response to the MCP supplementation. The recommended practice for Chinese softshell turtle diet involves substituting 15% MCP for fish meal, which enhances growth, boosts immune response, and does not adversely affect serum biochemistry, amino acid composition, or intestinal health.
作者机构：
[邵闯; 秦守旺; 朱波; 张俊智; 戴济鸿; 戴振炎; 胡毅; 陈开健] Hunan Engineering Technology Research Center of Featured Aquatic Resources Utilization, Hunan Agricultural University, Changsha, 410128, China
