Veterinary Sciences

Maternal rumen–gut microbes transform nutrients, but their specific contribution to placental signaling and offspring development remains unresolved. This focused narrative review assesses primary ruminant studies and selected non-ruminant mechanisms through four causal gates: microbial production or transformation (G1), quantified maternal circulatory exposure (G2), route-appropriate placental or fetal target engagement (G3), and developmental effects attributable to the specified upstream step (G4). Candidate signals include fermentation acids, succinate, amino-acid and one-carbon metabolites, tryptophan derivatives, and bile acid- and lipid-related molecules. Ruminant studies document gestational microbial remodeling, maternal–fetal metabolic responses, and placental or fetal effects of nutritional interventions. However, paired microbiome–metabolome profiles do not establish microbial source-to-blood transfer; placental tissue accumulation is not systemic exposure; and altered transporter expression is not target dependence. Ewe-derived gastrointestinal material transferred to antibiotic-treated pregnant mice conveys biological activity without isolating a metabolite-specific mechanism in pregnant ruminants. Among ruminant experiments critically assessed, none established all four gates for the same defined microbial signal. Future work requires source-resolved tracing, quantitative compartment sampling, functional target perturbation, and longitudinal offspring follow-up with postnatal exposure controls. The framework separates testable microbiome-mediated mechanisms from direct dietary effects and developmental-programming claims that remain unsupported.

Hexavalent chromium [Cr(VI)] is a highly toxic heavy metal pollutant widely distributed in the environment. It accumulates in target organs such as the liver and kidneys of animals, inducing serious tissue necrosis and inflammatory damage. Traditional toxicological studies have mainly focused on Cr(VI)-induced cell apoptosis; however, recent studies indicate that pyroptosis is a more critical driver of target organ damage. This review systematically clarifies that Cr(VI) generates reactive oxygen species (ROS) during intracellular reduction, resulting in mitochondrial stress. The ectopic leakage of mitochondrial DNA (mtDNA) into the cytoplasm is recognized as a damage-associated molecular pattern (DAMP) by the DNA sensor cGAS, thereby activating the cGAS–STING signaling pathway. Activated STING not only drives the transcription of pro-inflammatory cytokines but also promotes the assembly of the NLRP3 inflammasome, which in turn activates caspase-1 to mature IL-1β and IL-18 to trigger pyroptosis. Clarifying the toxicological mechanism of the mtDNA–cGAS–STING–NLRP3 axis not only fills the theoretical gap regarding Cr(VI)-induced inflammatory damage in animal target organs but also provides a new therapeutic target for clinical intervention.

Porcine circovirus 2 (PCV2) and porcine circovirus 3 (PCV3) are widespread in domestic pigs and common in wild boar, but Serbian wild boar data come predominantly from the east. Tissue pools from 90 wild boar hunted in West Bačka District, Vojvodina, in 2021 and 2022, collected within national swine fever surveillance, were screened by real-time PCR. PCV2 was detected in 17 animals (18.9%; 95% CI 11.4–28.5) and PCV3 in 12 (13.3%; 95% CI 7.1–22.1), with no co-infection. Four partial PCV2 capsid sequences were obtained, three PCV2b and one PCV2d, all within the diversity already reported from Serbian wild boar and European domestic pigs. Five complete PCV3 genomes differed by no more than 1.46% and met the distance criteria for PCV3-a; at the complete-genome level, the closest reference sequences came mainly from domestic pigs in Serbia and Hungary. Neither of the two PCV3 recombination signals met the acceptance criteria, so no event could be attributed to these sequences; breakpoint analysis of the combined reference-and-study alignment detected topological incongruence at the Cap coding-region boundary, an exploratory finding that does not demonstrate recombination in these genomes. Both viruses circulate in this population, carrying diversity that these data do not separate from that of European domestic pigs.