Yingjie Wu

Light is a critical environmental factor in rabbit production, yet systematic evaluation of low-light conditions for both reproduction and growth remains limited. This study assessed the effects of three combined lighting regimes: bright–dark (80 lx, 16L:8D for 6 days pre-AI plus 0–2 lx, 0L:24D during other periods), bright–dim light (80 lx, 16L:8D for 6 days pre-AI plus 4–6 lx, 24L:0D during other periods), and bright–bright light (80 lx, 16L:8D for 6 days pre-AI plus 75–85 lx, 12L:12D during other periods) on the reproductive performance of nulliparous Hyla does (n = 553 in total, with 185, 184, and 184 does in the bright–dark, bright–dim light, and bright–bright light groups, respectively) across three consecutive 42-day parities, and three single light regimes (dark, dim, bright) on the growth of weaned rabbits (n = 184 per group), over 20 days with digestion and metabolism trials. In the first parity, the bright–dark and bright–dim groups had significantly larger litter sizes and more live-born kits than the bright–bright group, whereas the average individual birth weight of live-born kits was significantly higher in the bright–bright light group than in the bright–dark group, with no significant difference between the bright–bright light and bright–dim groups. By the third parity, dim light improved total litter weight and live-born kit weight compared with bright light. Overall, the bright–dark regime showed more advantages in total and live-born litter size. For weaned rabbits, the dark regime significantly increased average daily gain and feed intake compared with the bright light regime, with higher crude protein and fiber digestibility. The dim regime showed intermediate values for several reproductive and growth outcomes. These findings provide a basis for the further evaluation of stage-specific lighting management, with welfare and behavioral outcomes requiring assessment before practical implementation.

Besides providing nutrients, Sertoli cells support spermatogenic cells development by maintaining seminiferous epithelial polarity, forming the blood-testis barrier (BTB), and phagocytosing residual bodies. Beclin1, a core component of the autophagy initiation complex, is critical for autophagic flux in many cell types. However, its role in Sertoli cells remains unclear. Here, we generated a Sertoli cell-specific Becn1 knockout (cKO) mouse model and found that 9-week-old male cKO mice exhibited reduced fertility with decreased sperm quality and vacuolated seminiferous tubules, and became completely infertile by 12 weeks of age. These defects were associated with disrupted BTB integrity and reduced expression of Claudin-11 in the testes. Further analysis revealed that loss of Beclin1led to impaired autophagosome formation, evidenced by reduced LC3-II/LC3-I ratio. In summary, these findings demonstrate that Beclin1 in Sertoli cells is vital for spermatogenesis and male fertility.

Background: Climate change-driven heat stress (HS) poses a growing threat to pregnancy outcomes; however, the mechanisms linking maternal HS to fetal growth restriction (FGR) remain incompletely understood, and effective nutritional interventions are lacking. The gut–placenta axis critically governs maternal–fetal health, but its role in mediating HS-related FGR has yet to be elucidated. Methods: A murine model of gestational HS (38.5 °C, 2.5 h daily from E0.5 to E12.5) was established to investigate the protective effects of chlorogenic acid (CGA) on HS-induced FGR. Placental efficiency, oxidative status, barrier integrity, and intestinal permeability were assessed. Gut microbiota composition was profiled by 16S rRNA sequencing, while tight junction protein expression in the placenta and intestine was evaluated by Western blot. Additionally, antibiotic-induced microbiota reduction and fecal microbiota transplantation (FMT) were performed to explore the role of gut microbiota in alleviating HS. Results: HS exposure significantly reduced fetal weight without altering litter size, accompanied by reduced placental efficiency and proportion of the labyrinth zone relative to the total placental area. HS triggered oxidative stress and downregulated tight junction proteins (Claudin-1, Occludin) in both the placenta and intestine, indicating compromised barrier integrity. CGA treatment robustly reversed these abnormalities and restored placental structure. In the gut, CGA prevented HS-induced intestinal barrier dysfunction and selectively reshaped the microbiota, enhancing the Firmicutes/Bacteroidetes ratio and promoting beneficial Lactobacillus lineages. Notably, under antibiotic-induced microbial reduction, FMT from CGA-treated donors effectively alleviated HS-induced fetal growth restriction. Conclusions: In summary, our study suggests that gestational HS exposure may trigger FGR through the gut–placenta axis. CGA effectively reverses FGR by restoring placental efficiency and placental barrier integrity, while alleviating maternal gut dysbiosis and intestinal barrier impairment. FMT experiments further confirm that the gut microbiota may play a key role in this protection. Collectively, these findings suggest that targeting the gut–placenta axis with CGA may offer a practical nutritional strategy to mitigate HS-triggered adverse pregnancy outcomes.

Reproductive inefficiency associated with impaired oocyte competence and embryonic loss remains a major limitation in livestock production. Although glycine is classified as a non-essential amino acid, its endogenous synthesis is often insufficient to meet increased metabolic demands during gestation and early embryonic development. This suggests that glycine has a conditionally essential role in reproductive physiology. However, the mechanisms through which glycine integrates metabolic and signaling processes to regulate reproductive outcomes are not fully understood. This review summarizes the recent advances in understanding glycine’s role in animal reproduction, emphasizing its function as a metabolic regulator rather than merely a structural component. Glycine contributes to reproductive processes by maintaining redox homeostasis, supporting mitochondrial function and stabilizing cellular environments as part of its osmolyte function during critical developmental stages. Additionally, glycine participates in one-carbon metabolism, influencing nucleotide synthesis and epigenetic regulation. Furthermore, emerging evidence suggests that glycine may modulate key signaling pathways, including the AMP-activated protein kinase (AMPK)-mechanistic target of rapamycin complex 1 (mTORC1) pathway. Consistent with these mechanistic roles, glycine supplementation has been associated with improvements in oocyte maturation and embryonic development, particularly in vitro. These findings highlight the potential of glycine as a dietary or culture medium supplement to enhance reproductive performance in livestock. However, most current evidence is derived from in vitro systems, and the translation of these findings into livestock production strategies requires validation through well-designed in vivo studies.

In vitro maturation (IVM) of oocytes remains suboptimal due to oxidative stress and disrupted cumulus–oocyte communication. Oocyte-derived factors (ODFs) are key mediators of this crosstalk and crucial for oocyte competence. Here, we provide systematic evidence that ephrin-A5 (EFNA5) is an oocyte-derived membrane ligand capable of regulating oocyte quality during IVM. Cross-species transcriptomic analysis revealed that EFNA5 is stably enriched in mammalian oocytes but markedly reduced in in vitro-matured oocytes compared with in vivo counterparts. Using the ovine IVM model, supplementation with recombinant EFNA5 significantly improved blastocyst formation, increased total cell numbers, and reduced apoptosis. Mechanistically, EFNA5 promoted cumulus–oocyte complex expansion, reduced reactive oxygen species accumulation, activated NRF2-dependent antioxidant signaling, and suppressed NF-κB-driven inflammation. RNA-seq and functional validation further confirmed that EFNA5 enhanced redox homeostasis and decreased DNA damage, collectively improving oocyte developmental potential. These findings establish EFNA5 as a novel and conserved ODF that alleviates oxidative and inflammatory stress to enhance oocyte quality and embryo development, providing mechanistic insight and a potential strategy for improving assisted reproductive technologies.

The efficiency of the laparoscopic ovum pick-up and in vitro embryo production (LOPU-IVEP) system in sheep is governed by a complex interplay of genetic and environmental factors. This study comprehensively evaluated the effects of breed, season, and their interaction on oocyte retrieval, embryonic development, and pregnancy outcomes in a commercial setting. A 20-month longitudinal analysis of a large commercial cohort revealed that breed was the dominant factor determining oocyte quantity, whereas season exerted a stronger influence on developmental competence. Specifically, autumn and winter provided optimal conditions, resulting in significantly higher cleavage rate and blastocyst rate (p < 0.05). A significant breed-by-season interaction further identified synergistic combinations, such as Black-headed Suffolk in autumn or winter, which achieved superior embryo production outcomes. Importantly, correlation analysis revealed that oocyte quantity was not predictive of developmental potential or pregnancy success. These findings underscore the necessity of a precision management strategy that aligns LOPU schedules with breed-specific seasonal advantages to maximize annual embryo production efficiency.

The efficiency of the laparoscopic ovum pick-up and in vitro embryo production (LOPU-IVEP) system in sheep is influenced by a complex interplay of genetic and environmental factors. This study comprehensively evaluated the effects of breed, season, and their interaction on oocyte retrieval, embryonic development, and pregnancy outcomes. A 20-month longitudinal analysis was conducted on a large commercial cohort comprising five breeds: Black-headed Suffolk (n = 3,024), White-headed Suffolk (n = 699), Australian White (n = 760), Black-headed Dorper (n = 1,109), and East Friesian (n = 1,077). We found that breed was the predominant factor affecting oocyte quantity and initial quality, with East Friesian yielding the highest number of total and available COCs. In contrast, season exerted a stronger influence on developmental competence, with autumn and winter providing optimal conditions, resulting in the highest cleavage rates (64.05%), blastocyst rates (59.02%), and pregnancy rates for single embryo transfer (73.04-75.31%). A significant breed-by-season interaction further identified Black-headed Suffolk in autumn/winter as a superior combination for embryo production. Correlation analysis revealed that oocyte quantity parameters were not predictive of developmental potential or pregnancy success. Our findings advocate for a precision management strategy that aligns the LOPU schedule with breed-specific seasonal advantages to maximize annual embryo production efficiency.

In vitro maturation (IVM) of oocytes remains suboptimal due to oxidative stress and disrupted cumulus–oocyte communication. Oocyte-derived factors (ODFs) are key mediators of this crosstalk and crucial for oocyte competence. Here, we provide systematic evidence that EFNA5 is an oocyte-derived membrane ligand capable of regulating oocyte quality during IVM. Cross-species transcriptomic analysis revealed that EFNA5 is stably enriched in mammalian oocytes but markedly reduced in in vitro–matured oocytes compared with in vivo counterparts. Using the ovine IVM model, supplementation with recombinant EFNA5 significantly improved blastocyst formation, increased total cell numbers, and reduced apoptosis. Mechanistically, EFNA5 promoted cumulus–oocyte complex expansion, reduced reactive oxygen species accumulation, activated NRF2-dependent antioxidant signaling, and suppressed NF-κB–driven inflammation. RNA-seq and functional validation further confirmed that EFNA5 enhanced redox homeostasis, and decreased DNA damage, collectively improving oocyte developmental potential. These findings establish EFNA5 as a novel and conserved ODF that alleviates oxidative and inflammatory stress to enhance oocyte quality and embryo development, providing mechanistic insight and a potential strategy for improving assisted reproductive technologies.

Embryo genomic selection (EGS) is a contemporary breeding strategy that combines genomic selection (GS) methodology with embryo biotechnology. By conducting genotyping and genomic prediction at the pre-implantation stage, embryos with superior breeding value can be identified for transfer, markedly increasing breeding efficiency while reducing the uncertainty and temporal expenditure associated with conventional GS. This study establishes a reliable embryo biopsy-based GS pipeline for sheep, incorporating optimized whole-genome amplification and microcell genotyping techniques. We developed a high-efficiency in vitro sheep embryo production platform compatible with embryo biopsy. Systematic comparison of Multiple Displacement Amplification (MDA) and Multiple Annealing and Looping Based Amplification Cycles (MALBAC) whole-genome amplification systems yielded high-quality genotypes from biopsy samples of embryos containing as few as 10 cells. Imputation using 10× whole-genome sequencing data significantly increased both genotype call rates and accuracy. High concordance was observed between embryo and lamb genotypes, and genomic estimated breeding values (GEBVs) for key growth traits exhibited strong correlations (R²: 0.91–0.98). This system enables accurate preimplantation genomic evaluation and provides an efficient strategy to accelerate genetic improvement in sheep breeding programs.