Protective effect of chlorogenic acid on liver injury in heat-stressed meat rabbits.

This study investigated the protective effects of chlorogenic acid (CGA) on production performance and liver function of rabbits under heat stress (HS) condition. A total of 120 healthy New Zealand weaned rabbits with similar initial body weight, were randomly divided into 3 treatments with 20 replicates per treatment and 2 weaned rabbits per replicate: control (CON) group (rabbits were housed at 25 ± 1°C and fed a basal diet), HS group (rabbits were housed at 35 ± 1°C and fed a basal diet), and HS + CGA group (rabbits were housed at 35 ± 1°C and fed a basal diet supplemented with 800 mg/kg CGA). The trial lasted for 28 days. The results showed that HS challenge decreased (p < 0.05) growth performance, induced oxidative stress and hepatic apoptosis, and caused liver damage in rabbits. However, dietary CGA supplementation increased (p < 0.05) body weight gain and feed efficiency, and enhanced (p < 0.05) antioxidative capacity in serum and liver in HS-challenged rabbits; attenuated HS-induced increases in urea nitrogen (p = 0.03), alanine aminotransferase (p = 0.03), aspartate aminotransferase (p = 0.01), caspase-8 (p = 0.02), and caspase-3 (p = 0.04) as well as decrease albumin (p = 0.04). Moreover, supplementation with CGA upregulated Nrf2/HO-1 pathway-related genes expressions, including Nrf2 (p = 0.009), HO-1 (p = 0.03) and SOD1 (p = 0.04) in HS-challenged rabbits. Our findings demonstrated that dietary CGA supplementation could alleviate HS-induced decline in growth performance, and protect against HS-induced liver damage partially through enhancing antioxidant capacity via acting Nrf2/HO-1 pathway and inhibiting hepatic apoptosis in rabbits.

Metagenomics and metabolomics reveal that gut microbiome adapts to the diet transition in Hyla rabbits.

There is still a lack of longitudinal dynamic studies on the taxonomic features, functional reserves, and metabolites of the rabbit gut microbiome. An experiment was conducted to characterize the bacterial community of rabbits. By combining metagenomics and metabolomics, we have comprehensively analyzed the longitudinal dynamics of the rabbit gut microbiota and its effect on host adaptability. Our data reveal an overall increasing trend in microbial community and functional gene diversity and richness during the pre-harvest lifespan of rabbits. The introduction of solid feed is an important driving factor affecting rabbit gut microbiological compositions. Clostridium and Ruminococcus had significantly higher relative abundances in the solid feed stage. Further, the starch and fiber in solid feed promote the secretion of carbohydrate-degrading enzymes, which helps the host adapt to dietary changes. The rabbit gut microbiota can synthesize lysine, and the synthase is gradually enriched during the diet transformation. The gut microbiota of newborn rabbits has a higher abundance of lipid metabolism, which helps the host obtain more energy from breast milk lipids. The rabbit gut microbiota can also synthesize a variety of secondary bile acids after the introduction of solid feed. These findings provide a novel understanding of how the gut microbiota mediates adaptability to environment and diet in rabbits and provide multiple potential strategies for regulating intestinal health and promoting higher feed efficiency.

Cross-border dual-channel supply chain decision-making under random demand and tariff conditions.

Given the cross-border e-commerce import tariff and random demands, this study establishes a pricing decision model for cross-border e-commerce dual-channel supply chain, which is composed of domestic manufacturers and overseas retailers, so as to analyze the effects of import tariff and random demand on the pricing, demand and profit of cross-border e-commerce. According to the research, import tariffs have a positive correlation with retailers' retail prices and a negative correlation with manufacturers' direct prices, wholesale prices, demand and profit from direct channels, and profit from retail channels. The export tax rebate policy will lessen the negative effects of import tariffs and maximize the best choices made by manufacturers and retailers.

Vitamin A regulates dermal papilla cell proliferation and apoptosis under heat stress via IGF1 and Wnt10b signaling.

Heat stress (HS) negatively affects the development of hair follicles. The present study investigated the effect of vitamin A (VA) on the development of rabbit dermal papilla cells (DPCs) under HS and the underlying regulatory mechanisms. Addition of 0.4 mg/L VA to the culture medium significantly enhanced cell proliferation (P < 0.001) and inhibited the apoptosis of DPCs (P < 0.01). VA decreased the proportion of DPCs in G0/G1 stage of the cell cycle under HS along with the expression of caspase 3, heat shock protein 70 (HSP70), and microRNA 195 (miR-195) (P < 0.05). VA also activated the insulin-like growth factor 1 (IGF1) and Wnt10b/ß-catenin signaling pathways. The results of the dual luciferase reporter assay showed that IGF1 expression was modulated by miR-195-5p. Over-expression of miR-195-5p in DPCs with HS+VA treatment significantly reduced cell viability and IGF1 signaling (P < 0.01) and increased apoptosis (P < 0.01) compared with the HS+VA group. The positive effects of VA on proliferation and apoptosis of DPCs under HS were significantly attenu-ated by blocking Wnt10b and ß-catenin signaling with IWP-2 and XAV-939, respectively. These results demonstrate that VA can promote hair follicle development following HS via modulation of miR-195/IGF1 and Wnt10b/ß-catenin signaling pathways.

Tetrathiomolybdate Decreases the Expression of Alkaline Phosphatase in Dermal Papilla Cells by Increasing Mitochondrial ROS Production.

Dermal papilla cells (DPCs) play important roles in hair growth regulation. However, strategies to regrow hair are lacking. Here, global proteomic profiling identified the tetrathiomolybdate (TM)-mediated inactivation of copper (Cu) depletion-dependent mitochondrial cytochrome c oxidase (COX) as the primary metabolic defect in DPCs, leading to decreased Adenosine Triphosphate (ATP) production, mitochondrial membrane potential depolarization, increased total cellular reactive oxygen species (ROS) levels, and reduced expression of the key marker of hair growth in DPCs. By using several known mitochondrial inhibitors, we found that excessive ROS production was responsible for the impairment of DPC function. We therefore subsequently showed that two ROS scavengers, N-acetyl cysteine (NAC) and ascorbic acid (AA), partially prevented the TM- and ROS-mediated inhibition of alkaline phosphatase (ALP). Overall, these findings established a direct link between Cu and the key marker of DPCs, whereby copper depletion strongly impaired the key marker of hair growth in the DPCs by increasing excessive ROS production.

Combined Omics Analysis Further Unveils the Specific Role of Butyrate in Promoting Growth in Early-Weaning Animals.

Abnormal mutations in the microbial structure of early-weaning mammals are an important cause of enteritis. Based on the multiple known beneficial functions of butyrate, we hypothesized that butyrate would alleviate the imbalance of intestinal homeostasis induced by early weaning in animals. However, the mechanisms of action between butyrate and intestinal microbes are still poorly explored. In this study, we aimed to investigate whether butyrate exerts beneficial effects on the structure of the intestinal flora of weanling rabbits and their intestinal homeostasis, growth and development, and we attempted to elucidate the potential mechanisms of action through a combined omics analysis. We found that dietary butyrate upregulated the transcription of tight junction-related proteins in the epithelial barrier and improved the intestinal microbial structure by suppressing harmful bacteria and promoting beneficial ones. Intestinal and plasma metabolomes were also altered. The bile acid secretion, α-linolenic acid, apoptotic, and prostate cancer pathways responded to the positive dietary butyrate-induced metabolic changes in the weanling rabbits, resulting in the inhibition of inflammation, improved antioxidant capacity, increased rates of cell proliferation and survival, and decreased levels of apoptosis. Additionally, dietary butyrate suppressed the release of pro-inflammatory factors and enhanced positive appetite regulation, which increased the average daily gain of the rabbits. These results demonstrated that dietary butyrate can help maintain the integrity of the intestinal epithelial barrier, improve the structural composition of the intestinal microflora, enhance organismal metabolism, inhibit inflammation, reduce post-weaning anorexia, and promote growth and development in early-weaning rabbits. These positive effects of dietary butyrate were exerted via the modulation of the microbe-gut-brain axis.

Dietary methionine supplementation to a low-protein diet improved hair follicle development of Angora rabbits.

OBJECTIVE: Angora rabbits fed a low-protein diet exhibit decreased hair production performance. This study was set out to evaluate the effects of methionine on hair properties and nitrogen metabolism in Angora rabbits fed a low-protein diet and to investigate the gene expression related to hair follicle development to determine the possible molecular mechanism of methionine effects on hair follicle development. METHODS: An experiment was conducted to investigate the effects of DL-methionine addition on a low-protein diet on hair development in Angora rabbits. Angora rabbits were divided into 5 groups: fed a normal diet (control), fed a low-protein diet (LP), or fed an LP supplemented with 0.2%, 0.4%, or 0.6% DL-methionine (Met). RESULTS: The results showed that rabbits in the LP group had lower wool yield than the control rabbits, but the addition of 0.4% to 0.6% Met to LP attenuated these effects (p<0.05). Dietary addition of 0.4% to 0.6% Met to LP increased the apparent nitrogen digestibility, nitrogen utilization rate, and feed efficiency (p<0.05). Feeding LP decreased the insulin-like growth factor 1 (IGF1), keratin-associated protein (KAP) 3.1, and KAP 6.1 mRNA levels compared with the control, but the addition of 0.4% Met in LP attenuated these effects (p<0.05). Relative to the LP or control group, dietary addition of 0.4% Met increased versican mRNA levels. CONCLUSION: In conclusion, the addition of Met to LP could improves wool production performance and feed efficiency and reduce nitrogen emissions in Angora rabbits. Met can promote hair follicle development, which may be associated with IGF1, KAP, and the versican signaling.

Effects of heat stress on growth performance, carcass traits, serum metabolism, and intestinal microflora of meat rabbits.

To investigate the effects of heat stress on meat rabbits, we assigned 80 rabbits to the moderate temperature group (24 ± 1°C; Control group) and the continuous high-temperature group (HT group), then monitored the effects using growth performance, carcass characteristics, biochemical assays, UPLC-MS/MS-based metabolomics, and microbiome. The results showed that after continuous high-temperature exposure, the average daily gain, average daily feed intake, and thymus index were significantly decreased (p < 0.05). Contents of HSP70, ALP, and Cortisol in serum were significantly increased, while TP, GLU, T3, and T4 were significantly decreased (p < 0.05). Nine kinds of differential metabolites were screened by serum metabolomics, which can be used as biomarkers of heat stress in meat rabbits. The selected differential metabolites were analyzed by KEGG annotation and enrichment analysis. The results showed that 14 pathways affected by heat stress were identified by KEGG pathway enrichment analysis, including Sphingolipid metabolism, Pyrimidine metabolism, Citrate cycle (TCA cycle)), aminoacyl-tRNA biosynthesis, and so on. The analysis of the effect of heat stress on the cecal microflora of meat rabbits showed that the abundance of cecal Proteus in the HT group was significantly higher than that in the moderate Control group. The number of Candidatus-saccharimonas in the cecum microflora was significantly higher than that in the moderate temperature group (p < 0.05) which may be related to inflammatory diseases in the heat stress group. These findings indicated that the heat-stressed rabbits were in negative energy balance, which affected protein metabolism, and subsequently affected growth performance and carcass characteristics.

Effects of the SLC38A2-mTOR Pathway Involved in Regulating the Different Compositions of Dietary Essential Amino Acids-Lysine and Methionine on Growth and Muscle Quality in Rabbits.

In recent years, ensuring food security has been an important challenge for the world. It is important to make good use of China's domestic local feed resources to provide safe, stable, efficient, and high-quality rabbit meat products for China and the world. Lysine and methionine are the two most limiting essential amino acids in the rabbit diet. However, little is known about the rational composition of lysine and methionine in rabbit diets and the mechanisms that affect growth and development. Accordingly, in this study, we sought to address this knowledge gap by examining the effects of different compositions of lysine and methionine in rabbit diets. Subsequently, the growth status, nitrogen metabolism, blood biochemical indexes, muscle development, muscle quality, and the growth of satellite cells were evaluated in the animals. The results showed that diets containing 0.80% Lys and 0.40% Met improved average daily weight gain, feed conversion, nitrogen use efficiency, and muscle quality in the rabbits (p < 0.05). Additionally, it altered the amino acid transport potential in muscle by upregulating the expression of the SLC7A10 gene (p < 0.05). Meanwhile, the cell viability and the rate of division and migration of SCs in the 0.80% Lys/0.40 % Met composition group were increased (p < 0.05). SLC38A2 and P−mTOR protein expression was upregulated in the 0.80% lysine/0.40% methionine composition group (p < 0.05). In conclusion, 0.80% Lys/0.40% Met was the most suitable lysine and methionine composition in all tested diets. SLC38A2 acted as an amino acid sensor upstream of mTOR and was involved in the 0.80% Lys/0.40% Met regulation of muscle growth and development, thus implicating the mTOR signaling pathway in these processes.

Chlorogenic acid improves growth performance of weaned rabbits via modulating the intestinal epithelium functions and intestinal microbiota.

This study was conducted to investigate the impacts of chlorogenic acid (CGA) on growth performance, intestinal permeability, intestinal digestion and absorption-related enzyme activities, immune responses, antioxidant capacity and cecum microbial composition in weaned rabbits. One hundred and sixty weaned rabbits were allotted to four treatment groups and fed with a basal diet or a basal diet supplemented with 400, 800, or 1,600 mg/kg CGA, respectively. After a 35-d trial, rabbits on the 800 mg/kg CGA-supplemented group had higher (p < 0.05) ADG and lower (p < 0.05) F/G than those in control (CON) group. According to the result of growth performance, eight rabbits per group were randomly selected from the CON group and 800 mg/kg CGA group to collect serum, intestinal tissue samples and cecum chyme samples. Results showed that compared with the CON group, supplementation with 800 mg/kg CGA decreased (p < 0.05) levels of D-lactate, diamine oxidase, IL-1ß, IL-6, and malondialdehyde (MDA), and increased IL-10 concentration in the serum; increased (p < 0.05) jejunal ratio of villus height to crypt depth, enhanced (p < 0.05) activities of maltase and sucrase, increased (p < 0.05) concentrations of IL-10, T-AOC, MHCII and transforming growth factor-α, and decreased (p < 0.05) levels of TNF-α and MDA in the jejunum of weaned rabbits. In addition, results of high-throughput sequencing showed that CGA supplementation elevated (p < 0.05) microbial diversity and richness, and increased (p < 0.05) the abundances of butyrate-producing bacteria (including genera V9D2013_group, Monoglobus, Papillibacter, UCG-005, and Ruminococcus). These results indicated that dietary supplementation with 800 mg/kg CGA could improve the growth performance of weaned rabbits by enhancing intestinal structural integrity, improving the intestinal epithelium functions, and modulating the composition and diversity of gut microbiota.

Copper Depletion Strongly Enhances Ferroptosis via Mitochondrial Perturbation and Reduction in Antioxidative Mechanisms.

Copper serves as a co-factor for a host of metalloenzymes, particularly cytochrome c oxidase (COX). Although it is known that impaired COX function can lead to the excessive accumulation of reactive oxygen species (ROS), the mechanisms underlying how copper depletion leads to cell damage are poorly understood. Here, we have investigated the role of copper depletion during ferroptosis. The bathocuproinedisulfonic (BCS) treatment depolarized the mitochondrial membrane potential, increased the total cellular ROS levels, stimulated oxidative stress, and reduced the glutathione levels. Moreover, the depletion of copper limited the protein expression of glutathione peroxidase 4 (GPX4), which is the only enzyme that is known to prevent lipid peroxidation. Furthermore, we found that copper depletion decreased the sensitivity of the dermal papilla cells (DPCs) to erastin (an inducer of ferroptosis), and the ferroptosis inhibitor ferrostatin-1 (Fer-1) partially prevented BCS-mediated cell death. Overall, these findings establish a direct link between copper and ferroptosis; BCS-mediated copper depletion strongly enhances ferroptosis via mitochondrial perturbation and a reduction in antioxidative mechanisms.

mTORC1 Mediates the Processes of Lysine Regulating Satellite Cells Proliferation, Apoptosis, and Autophagy.

Lysine (Lys) is essential for skeletal muscle growth and protein synthesis in mammals. However, the regulatory network underlying Lys-regulated skeletal muscle development is unknown. To determine whether any cross-talk occurs among mammalian targets of rapamycin complex 1 (mTORC1) and Lys in the regulation of muscle satellite cells (SCs) proliferation, we applied the treatment rapamycin (a mTORC1 inhibitor) and MHY1485 (a mTORC1 activator) on Lys-added or -deficient SCs. The results show Lys deprivation significantly decreases SCs viability, protein synthesis, and cell cycling, increases autophagy and apoptosis, and inhibits the mTORC1 signaling pathway. Restoration of Lys content significantly attenuates this effect. mTORC1 signaling pathway activation during Lys deprivation or mTORC1 signaling pathway inhibition during Lys addition attenuates the effect of Lys deprivation or addition on SCs viability, protein synthesis, cell cycling, autophagy, and apoptosis. In conclusion, Lys could improve SCs proliferation, and inhibit SCs apoptosis and autophagy, via the mTORC1 signaling pathway.

Methionine can subside hair follicle development prejudice of heat-stressed rex rabbits.

In the present experiment, we study the function of methionine on hair follicle development in heat-stressed Rex Rabbits and its potential molecular mechanism. Rex rabbits were randomly divided into 5 groups (30 replicates per group): control group (20-25°C, fed basic diet), heat stress group (30-34°C, fed basic diet), heat stress + methionine group (30-34°C, fed 0.15% methionine in addition to the basic diet). fed basic diet (control), heat stress + methionine group (30-34°C, fed 0.3% methionine in addition to the basic diet), heat stress + methionine group (30-34°C, fed 0.45% methionine in addition to the basic diet). The results show that heat stress decreases the hair follicle density of Rex rabbits, and the diet methionine addition significantly increases the hair follicle density of heat-stressed Rabbits (p < .05). Heat stress increased serum HSP70 concentration and skin HSP70 gene expression, 0.15%-0.3% methionine but not 0.45% addition alleviated the effect of heat stress. Dietary 0.15% methionine addition significantly increases the gene expression of Wnt10b, ß-catenin, LEF, FZD4, LRP6, Shh, HGF, EGF, and Noggin in heat-stressed Rex rabbits and observably decreases the gene expression of BMP2/4 and TGFb. There was no significant effect of methionine on the expression of IGF1 and FGF5/7 gene expression. In conclusion, methionine maybe promotes hair follicle development via TGFß-BMP/Shh-Noggin, Wnt10b/ß-catenin, EGF, and HGF signaling pathways in heat-stressed rabbits.

FumDSB can alleviate the inflammatory response induced by fumonisin B1 in growing pigs.

Fumonisin B1 (FB1) has the highest natural contamination rate among all fumonisin analogs and can inhibit food intake and weight gain of pigs. Under laboratory conditions, carboxylesterase FumDSB has a high FB1 degradation rate and excellent pH and thermal stability. The present study sought to estimate the effects of FumDSB on growing pigs from the perspective of a brain-intestinal axis. Twenty-four growing pigs of similar weight were divided into Control, FB1 (5 mg FB1/kg feed), and FumDSB (5 mg FB1/kg and 0.1% FumDSB in the feed) groups. After 42 days of feeding, hypothalamus and jejunum samples were collected for quantitative real-time fluorescence, western blotting, and immunohistochemistry. The results showed that FB1 consumption can destruct the tissue structure of hypothalamus and jejunum, affect the expression and distribution of several appetite-related neuropeptides and inflammatory cytokines, thereby inducing neuroinflammatory responses and affecting food intake and weight gain. However, these anorexia effects and inflammatory responses are alleviated when FumDSB is added to the feed. In short, FumDSB can alleviate the inflammatory response induced by FB1 in growing pigs.

Copper Modulates Mitochondrial Oxidative Phosphorylation to Enhance Dermal Papilla Cells Proliferation in Rex Rabbits.

Copper (Cu) is an important coenzyme factor in cell signaling, such as cytochrome c oxidase (Complex IV). Metabolism plays an important role in regulating the fate of mammalian cells. The aim of this study is to experimentally investigate the effect of copper on cell metabolism in the dermal papilla cells of the Rex rabbit. In this study, Cu promoted proliferation of dermal papilla cells (p = 0.0008) while also increasing levels of cellular CIII, CIV, Complex IV and ATP. Moreover, fifty metabolites that were significantly different between Cu and controls were identified as potential biomarkers of Cu stimulation. Copper-stimulated cells had altered levels of arachidonic acid derivatives, S-glutamic acid, and citric acid, which were primarily linked to two different pathways: arachidonic acid metabolism (p < 0.0001) and alanine, aspartate and glutamate metabolism (p = 0.0003). The addition of Cu can increase the proliferation of Rex rabbit dermal papilla cells. Increased levels of ubiquinol-cytochrome c reductase complex core protein 2 (CIII) and cytochrome c oxidase subunit 1 (CIV) were associated with the increased levels of cellular cytochrome c oxidase (Complex IV) and adenosine triphosphate (ATP). In a word, copper promotes cell proliferation by maintaining the function of the cellular mitochondrial electron transport chain (ETC) pathway.

Shifts in the intestinal microflora of meat rabbits in response to glucocorticoids.

BACKGROUND: As major stress hormones, glucocorticoids can directly or indirectly affect the intestinal microflora, although few studies have focused on changes in the composition of the intestinal microflora. In this study, rabbits were randomly divided into two groups: gavage administration with saline, and the same doses of dexamethasone (1 mg kg-1 ). After 7 days, the microbial diversity of the jejunum contents was analysed. RESULTS: The gut microflora richness and diversity had no significant difference between the two groups. The proportions of Firmicutes and Bacteroidetes were the most abundant in the jejunum of meat rabbits. Dexamethasone injection led to a change in the structure of the gut microflora composition, and we found that there were six biomarkers with linear discriminant analysis score >4 (Firmicutes, Caproiciproducens, Clostridiales, Clostridia, Psychrobacter, and Psychrobacter faecalis), moreover, the results of this study provide new insight into alleviating the effects of stress on meat rabbits. CONCLUSION: It was concluded that glucocorticoids caused changes in the composition of intestinal microflora. © 2022 Society of Chemical Industry.

Effect of sodium butyrate on slaughter performance, serum indexes and intestinal barrier of rabbits.

The purpose of this study was to investigate the effect of sodium butyrate on slaughter performance, serum indexes and the intestinal barrier in rabbits. Six hundred healthy weaned rabbits were randomly divided into three groups (5 replicates per group, 40 rabbits per replicate): control (fed a basal diet), sodium butyrate (fed a basal diet containing 0.5% sodium butyrate) and antibiotic (fed a basal diet containing 0.004% antibiotic). The trial lasted 35 days, including 7 days of pretesting and 28 days of formal testing. The results showed that dietary sodium butyrate supplementation increased the full-bore weight, the half-bore weight and the half-bore rate of rabbits. Meanwhile, the content of aspartate aminotransferase (AST) in serum was increased in rabbits fed the sodium butyrate diet. According to the intestinal barrier, after adding sodium butyrate to feed, the tight junction function of the rabbit intestine is enhanced, and the intestinal microbial composition is also improved. To sum up, after sodium butyrate was added to feed instead of antibiotics, slaughter performance was significantly enhanced, serum indexes were improved, and intestinal barrier function was also enhanced. Therefore, sodium butyrate can be added to feed as an additive and can replace antibiotics.

Mechanistic target of rapamycin and an extracellular signaling-regulated kinases 1 and 2 signaling participate in the process of acetate regulating lipid metabolism and hormone-sensitive lipase expression.

OBJECTIVE: Acetate plays an important role in host lipid metabolism. However, the network of acetate-regulated lipid metabolism remains unclear. Previous studies show that mitogen-activated protein kinases (MAPKs) and mechanistic target of rapamycin (mTOR) play a crucial role in lipid metabolism. We hypothesize that acetate could affect MAPKs and/or mTOR signaling and then regulate lipid metabolism. The present study investigated whether any cross talk occurs among MAPKs, mTOR and acetate in regulating lipid metabolism. METHODS: The ceramide C6 (an extracellular signaling-regulated kinases 1 and 2 [ERK1/2] activator) and MHY1485 (a mTOR activator) were used to treat rabbit adipose-derived stem cells (ADSCs) with or without acetate, respectively. RESULTS: It indicated that acetate (9 mM) treatment for 48 h decreased the lipid deposition in rabbit ADSCs. Acetate treatment decreased significantly phosphorylated protein levels of ERK1/2 and mTOR but significantly increased mRNA level of hormone-sensitive lipase (HSL). Acetate treatment did not significantly alter the phosphorylated protein level of p38 MAPK and c-Jun aminoterminal kinase (JNK). Activation of ERK1/2 and mTOR by respective addition in media with ceramide C6 and MHY1485 significantly attenuated decreased lipid deposition and increased HSL expression caused by acetate. CONCLUSION: Our results suggest that ERK1/2 and mTOR signaling pathways are associated with acetate regulated HSL gene expression and lipid deposition.

Dietary lysine supplementation improves growth performance and skeletal muscle development in rabbits fed a low protein diet.

The purpose of this study was to investigate the effects on growth of Lysine (Lys) supplementation in a low protein diet. We also investigated the gene or protein expression related to skeletal muscle development and intestinal amino acid transporters, and determined the major signalling associated with Lys-regulating skeletal muscle development. 1000 healthy, weights averaging 938.6 ± 6.54 g weaned rabbits were randomly divided into five groups (five replicates in each group and 40 rabbits in each replicate). These groups consisted of the normal protein group (NP group, consuming a diet containing 16.27% protein), the low protein group (LP group, 14.15%-14.19% protein) and the LP group with an addition of 0.15%, 0.3% or 0.45% Lys. The trial included 7 d of pre-feeding and 28 d of exposure to the treatment. Compared with NP diet and LP diet, LP+0.3% Lys group improved growth performance (p < 0.05), full-bore weight and half-bore weight of rabbits (p < 0.05). The LP+0.3% Lys group also resulted in a decrease in the excretion of faecal nitrogen and urinary nitrogen (FN; UN; p < 0.05), and an increase in nitrogen utilisation rate (NUR; p < 0.05). LP diet increased the mRNA expression of MSTN and WWP1, and decreased the mRNA expression of IGF1 (p < 0.05). LP diet decreased the protein expression of P-P70S6K1, P-4EBP1 and P-S6 (p < 0.05). LP+0.3% Lys group attenuated the effects of LP diet on the expression of MSTN, WWP1, IGF1, P-P70S6K1, P-4EBP1 and P-S6 (p < 0.05). LP+0.3% Lys group resulted in an increase in mRNA expression of MyoD and protein expression of P-mTOR relative to the NP and LP groups (p < 0.05). In summary, the addition of Lys to a LP diet provides a theoretical basis for the popularisation and application of Lys in rabbit production.

Vitamin A alleviates heat stress-induced damage to hair follicle development in Rex rabbits.

BACKGROUND: Rex rabbits are important fur rabbits. Heat stress severely reduces the fur quality of Rex rabbits. The aim of this study was to experimentally investigate the effect of dietary vitamin A (VA) addition on hair follicle development and related signal pathways in Rex rabbits under heat stress. RESULTS: In the experiment, 90 Rex rabbits were randomly divided into three groups: control group (20-25 °C, fed basic diet), heat stress group (30-34 °C, fed basic diet), and heat stress + VA group (20-25 °C, fed 12 000 IU/kg VA in addition to the basic diet). VA could significantly increase the hair follicle density (P < 0.01), hair length (P < 0.05), and the ratio of secondary to primary hair follicles (P < 0.05). In addition, VA could significantly inhibit the expression of BMP2, BMP4, FGF5, TGF-ß1, and miR-214 in heat-stressed Rex rabbits and significantly increase the expression of noggin, IGF1, IGF1R, Wnt10b, CTNNB1, SHH, and miR-203 and the levels of Wnt10b and p-ß-catenin; however, there was no significant effect of VA on the expression of EGF and miR-205. CONCLUSION: The dietary addition of VA can increase the hair follicle density and fur quality of heat-stressed Rex rabbits. Wnt10/ß-catenin, insulin-like growth factor 1 (IGF1), fibroblast growth factor 5 (FGF5), noggin-BMP, and sonic hedgehog (SHH) signaling were associated with VA regulation under heat stress. It is possible that miR-205 and miR-194 contribute to the regulation of Wnt10/ß-catenin and bone morphogenetic protein (BMP) signaling. © 2021 Society of Chemical Industry.