Heat Stress Impairs Male Reproductive System with Potential Disruption of Retinol Metabolism and Microbial Balance in the Testis of Mice.

BACKGROUND: Heat stress (HS) has a harmful impact on the male reproductive system, primarily by reducing the sperm quality. The testicular microenvironment plays an important role in sperm quality. OBJECTIVES: This study aimed to explore the underlying mechanism by which HS impairs the male reproductive system through the testicular microenvironment. METHODS: Ten-week-old male mice (n = 8 mice/group) were maintained at a normal temperature (25°C, control) or subjected to HS (38°C for 2 h each day, HS) for 2 wk. The epididymides and testes were collected at week 2 to determine sperm quality, histopathology, retinol concentration, the expression of retinol metabolism-related genes, and the testicular microbiome. The testicular microbiome profiles were analyzed using biostatistics and bioinformatics; other data were analyzed using a 2-sided Student's t test. RESULTS: Compared with the control, HS reduced (P < 0.05) sperm count (42.4%) and motility (97.7%) and disrupted the integrity of the blood-testis barrier. Testicular microbial profiling analysis revealed that HS increased the abundance of the genera Asticcacaulis, Enhydrobacter, and Stenotrophomonas (P < 0.05) and decreased the abundance of the genera Enterococcus and Pleomorphomonas (P < 0.05). Notably, the abundance of Asticcacaulis spp. showed a significant negative correlation with sperm count (P < 0.001) and sperm motility (P < 0.001). Moreover, Asticcacaulis spp. correlated significantly with most blood differential metabolites, particularly retinol (P < 0.05). Compared with the control, HS increased serum retinol concentrations (25.3%) but decreased the testis retinol concentration by 23.7%. Meanwhile, HS downregulated (P < 0.05) the expression of 2 genes (STRA6 and RDH10) and a protein (RDH10) involved in retinol metabolism by 27.3%-36.6% in the testis compared with the control. CONCLUSIONS: HS reduced sperm quality, mainly because of an imbalance in the testicular microenvironment potentially caused by an increase in Asticcacaulis spp. and disturbed retinol metabolism. These findings may offer new strategies for improving male reproductive capacity under HS.

Evaluating the Impact of an Organic Trace Mineral mix on the Redox Homeostasis, Immunity, and Performance of Sows and their Offspring.

The objective of the study was to evaluate the effects of trace mineral supplementation in sows during gestation and lactation on the performance and health status of sows and their offspring. Sows (n = 30; Landrace × Yorkshire; avg parity = 3.9) were randomly allocated into two dietary treatments. Sows received a basal diet supplemented with 12 mg/kg Cu, 30 mg/kg Fe, 90 mg/kg Zn, 70 mg/kg Mn, 0.30 mg/kg Se, and 1.5 mg/kg I from an inorganic trace mineral source (ITM) or a blend of hydroxychloride and organic trace mineral source (HOTM) from day 1 of gestation until the end of the lactation period at day 21. Compared to the ITM, the HOTM supplementation increased (P < 0.05) both litter birth weight and individual piglet birth weight. Although not statistically significant, HOTM tended to increase (P = 0.069) the level of lactose in colostrum. HOTM increased (P < 0.05) the concentration of Mn and Se in the colostrum, milk, and serum of sows and/or piglets. Notably, the Zn concentration in the serum of sows was higher in sows supplemented with ITM compared to HOTM. Moreover, HOTM increased (P < 0.05) the activities of GPX and SOD in gestating sows and piglets, as well as increased (P < 0.05) cytokines (IL-1ß, TNF-α, and IL-10) in the serum of sows. The immunoglobulins (IgA, IgG, and IgM) also increased in sows and/or piglets at certain experimental time points. In conclusion, HOTM supplementation positively affected piglet development and improved the health status of sows and piglets potentially by regulating redox homeostasis and immunity.

Estimation of Protein and Amino Acid Requirements in Layer Chicks Depending on Dynamic Model.

Four trials were conducted to establish a protein and amino acid requirement model for layer chicks over 0-6 weeks by using the analytical factorization method. In trial 1, a total of 90 one-day-old Jing Tint 6 chicks with similar body weight were selected to determine the growth curve, carcass and feather protein deposition, and amino acid patterns of carcass and feather proteins. In trials 2 and 3, 24 seven-day-old and 24 thirty-five-day-old Jing Tint 6 chicks were selected to determine the protein maintenance requirements, amino acid pattern, and net protein utilization rate. In trial 4, 24 ten-day-old and 24 thirty-eight-day-old Jing Tint 6 chicks were selected to determine the standard terminal ileal digestibility of amino acids. The chicks were fed either a corn-soybean basal diet, a low nitrogen diet, or a nitrogen-free diet throughout the different trials. The Gompertz equation showed that there is a functional relationship between body weight and age, described as BWt(g) = 2669.317 × exp(-4.337 × exp(-0.019t)). Integration of the test results gave a comprehensive dynamic model equation that could accurately calculate the weekly protein and amino acid requirements of the layer chicks. By applying the model, it was found that the protein requirements for Jing Tint 6 chicks during the 6-week period were 21.15, 20.54, 18.26, 18.77, 17.79, and 16.51, respectively. The model-predicted amino acid requirements for Jing Tint 6 chicks during the 6-week period were as follows: Aspartic acid (0.992-1.284), Threonine (0.601-0.750), Serine (0.984-1.542), Glutamic acid (1.661-1.925), Glycine (0.992-1.227), Alanine (0.909-0.961), Valine (0.773-1.121), Cystine (0.843-1.347), Methionine (0.210-0.267), Isoleucine (0.590-0.715), Leucine (0.977-1.208), Tyrosine (0.362-0.504), Phenylalanine (0.584-0.786), Histidine (0.169-0.250), Lysine (0.3999-0.500), Arginine (0.824-1.147), Proline (1.114-1.684), and Tryptophan (0.063-0.098). In conclusion, this study constructed a dynamic model for the protein and amino acid requirements of Jing Tint 6 chicks during the brooding period, providing an important insight to improve precise feeding for layer chicks through this dynamic model calculation.

Translocation of gut microbes to epididymal white adipose tissue drives lipid metabolism disorder under heat stress.

Heat stress induces multi-organ damage and serious physiological dysfunction in mammals, and gut bacteria may translocate to extra-intestinal tissues under heat stress pathology. However, whether gut bacteria translocate to the key metabolic organs and impair function as a result of heat stress remains unknown. Using a heat stress-induced mouse model, heat stress inhibited epididymal white adipose tissue (eWAT) expansion and induced lipid metabolic disorder but did not damage other organs, such as the heart, liver, spleen, or muscle. Microbial profiling analysis revealed that heat stress shifted the bacterial community in the cecum and eWAT but not in the inguinal white adipose tissue, blood, heart, liver, spleen, or muscle. Notably, gut-vascular barrier function was impaired, and the levels of some bacteria, particularly Lactobacillus, were higher in the eWAT, as confirmed by catalyzed reporter deposition fluorescence in situ hybridization (CARD-FISH) staining when mice were under heat stress. Moreover, integrated multi-omics analysis showed that the eWAT microbiota was associated with host lipid metabolism, and the expression of genes involved in the lipid metabolism in eWAT was upregulated under heat stress. A follow-up microbial supplementation study after introducing Lactobacillus plantarum to heat-stressed mice revealed that the probiotic ameliorated heat stress-induced loss of eWAT and dyslipidemia and reduced gut bacterial translocation to the eWAT by improving gut barrier function. Overall, our findings suggest that gut bacteria, particularly Lactobacillus spp., play a crucial role in heat stress-induced lipid metabolism disorder and that there is therapeutic potential for using probiotics, such as Lactobacillus plantarum.

Organic Acids Improve Growth Performance with Potential Regulation of Redox Homeostasis, Immunity, and Microflora in Intestines of Weaned Piglets.

The objective of this study is to evaluate the effects of organic acids on piglet growth performance and health status. A total of 360 weanling pigs (5.3 ± 0.6 kg) were randomly allotted to 3 treatment groups with 12 replicates of 10 pigs/pen. Piglets were fed the same basal diet and given either water (control) or water plus 2.0 L/Ton organic acid (OA) blends, such as OA1 or OA2, respectively, for 7 weeks. Compared to the control, OA1 and OA2 improved growth performance and/or reduced the piglets' diarrhea rate during the various periods and improved small intestinal morphology at days 14 and/or 49. OA1 and OA2 also increased serum CAT and SOD activities and/or T-AOC and, as expected, decreased MDA concentration. Moreover, at day 14 and/or day 49, OA1 and OA2 increased the jejunal mRNA levels of host defense peptides (PBD1, PBD2, NPG1, and NPG3) and tight junction genes (claudin-1) and decreased that of cytokines (IL-1ß and IL-2). Additionally, the two acidifiers regulated the abundance of several cecum bacterial genera, including Blautia, Bulleidia, Coprococcus, Dorea, Eubacterium, Subdoligranulum, and YRC2. In conclusion, both of the organic acid blends improved piglet growth performance and health status, potentially by regulating intestinal redox homeostasis, immunity, and microflora.