Background: Vitamin D may improve innate antimicrobial response and the integrity of the intestinal mucosal barrier representing an alternative to antibiotics for improving pig health. Therefore, benefits of dietary supplementation with a product based on vitamin D₃ metabolite-rich plant extracts were assessed in 252 purebred Iberian piglets for a period of 60 days. The study group received 1,25 dihydroxyvitamin D (1,25(OH)₂D) (100 ppm) in the conventional feed, which already included vitamin D (2000 IU in the starter and 1000 IU in the adaptation diets, respectively). Average daily gain (ADG), feed conversion ratio (FCR) and coefficient of variation of body weight (CV-BW) were assessed along the study. Blood samples, from 18 animals of the study group and 14 animals of the control group, were collected at selected time points to determine white blood cell count, concentration of vitamin D₃ and its metabolites, and IgA and IgG in serum. Histopathology, morphometry, and immunohistochemistry (IgA and FoxP3) from small intestine samples were performed on days 30 and 60 of the study from 3 animals per group and time point. Results: The ADG (493 vs 444 g/day) and FCR (2.3 vs 3.02) showed an improved performance in the supplemented animals. Moreover, the lower CV-BW indicated a greater homogeneity in the treated batches (13.17 vs 26.23%). Furthermore, a mild increase of IgA and in the number of regulatory T cells in the small intestine were observed in treated pigs. Conclusions: These results highlight the benefits of this supplementation and encourage to develop further studies along other production stages.

Given the increasing global concern about antimicrobial resistance, it is necessary to identify nutritional alternatives to antibiotics and trace elements in the porcine industry. The present study was carried out to evaluate the safety and effect of the paraprobiotic heat-killed Mycolicibacterium manresensis (hkMm) in weaned piglets. For this purpose, twenty-four-week-old piglets, were assigned to four experimental groups, and the diet of three of them was supplemented with 10, 50 and 100 ppm of hkMm, respectively, during a period of 70 d. Animals were monitored throughout the experiment, and weight data, blood, serum and saliva samples were collected every 2 weeks. At the end of the study, tissue samples were collected for histopathology, histomorphometry, immunohistochemical, and gene expression analyses. Supplemented animals did not show any adverse effects neither significant changes in their production parameters. Piglets supplemented with higher doses of hkMm exhibited a significant increase in salivary adenosine deaminase levels (p = 0.0042), along with a significant decrease in serum haptoglobin concentration (p = 0.0263). HkMm also appeared to induce a mild increase in circulating leukocyte populations at the end of the study, primarily due to elevated neutrophil counts, with smaller increases in lymphocytes and monocytes. Additionally, treated animals showed an increase in the number of regulatory T cells (FOXP3⁺) by immunohistochemistry, along with an increased IFNG response by RT-qPCR. Flow cytometry analysis in PBMC showed a decrease in the frequency of CD8β⁺ T cells (p = 0.0021), together with a higher number of γδ⁺ T cells in the treated animals throughout the study (p = 0.0327). On the other hand, histomorphometry analysis revealed a significant increase in mucosal height (p = 0.0195) and crypt depth (p = 0.0277) in the intestine of piglets receiving higher doses of hkMm. These results indicate that hkMm is a safe paraprobiotic with immunomodulatory potential, capable of enhancing intestinal integrity and absorptive capacity in weaned piglets, supporting its potential as a nutritional strategy to enhance gut health and reduce reliance on antimicrobial agents. Nevertheless, further studies in animals subjected to a challenge would be valuable to assess hkMm’s efficacy under immunological stress.

Assisted reproductive techniques are often extrapolated from horses to donkeys, despite poorer fertility outcomes in jennies. This issue has been attributed to unknown uterine species-specific differences. This study compared, through histomorphometry, the endometrium of jennies and mares. Endometrial biopsies (N = 12) were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorphometric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm²), the number of glands (#G), and glandular tissue percentage (GT, %), measured in the stratum compactum (SC) and spongiosum (SS). A total of 30 measurements of glandular size parameters and 10 fields of glandular density parameters per sample were recorded. Results were statistically compared between species (jennies vs. mares), parity status (maiden vs. foaling), and stratum (SC vs. SS). Jennies exhibited higher (p < 0.05) values than mares for LE, LD-SC, GA-SC, and GT-SC. These findings suggest that the histomorphometric features observed in reproductively sound jennies reflect anatomical differences that might partly explain previously observed species differences in post-breeding uterine response. In conclusion, histomorphometry revealed significant endometrial differences between species, with jennies displaying taller luminal epithelium, greater glandular size, and higher glandular tissue percentage in the SC than mares.

The actual role of certain viruses, such as coronavirus (RbCoV) and parvovirus (LBoV), in the digestive diseases of rabbitries remains poorly understood. For this reason, we conducted three different studies. In the detection frequency study, carried out using samples from both sick and healthy animals from farms with recurrent enteric problems, the presence and Cq values obtained by qPCR for these two viruses supported their implication in digestive disorders. In the lesional study, performed on samples from farms experiencing enteric disease outbreaks, the presence of lesions characteristic of both viruses was confirmed, along with other viral, bacterial, and parasitic agents that may have exacerbated the condition. Finally, in the epidemiological study, using samples from rabbits of different ages from farms with enteric problems, a higher prevalence of these viruses was observed during the growing phase, with a significant association with other bacterial agents such as Escherichia coli and Clostridium spiroforme. Overall, these results highlight the importance of both viruses in the aetiology of enteric disease and support their inclusion in the diagnostic enteric profile for rabbits.

Assisted reproductive technologies (ARTs) are often extrapolated from horses to don-keys, despite poorer fertility outcomes in jennies, highlighting the need to identify spe-cies-specific traits to optimize ARTs in donkeys. This study compared, through histo-morphometry, the endometrium of jennies and mares. Endometrial biopsies were taken from reproductively sound jennies (n = 6) and mares (n = 6) in estrus. Histomorpho-metric analysis evaluated luminal (LE, µm) and glandular epithelium height (GE, µm), glandular lumen diameter (LD, µm), glandular area (GA, µm²), number of glands (#G), and glandular tissue percentage (GT, %), measured in the stratum compactum (SC) and spongiosum (SS). Results were statistically compared between species (jennies vs. mares), parity status (maiden vs. foaling), and stratum (SC vs. SS). Jennies exhibited higher (P < 0.05) values than mares for LE, LD-SC, GA-SC, and GT-SC. Greater glan-dular size and density in mares have been linked to susceptibility to endometritis, in-trauterine fluid accumulation, aging, and poorer reproductive outcomes in mares. These findings suggest that the histomorphometric features observed in reproductively sound jennies reflect anatomical differences that might contribute to a distinctive en-dometrial inflammatory response compared to mares. In conclusion, histomorphome-try revealed significant endometrial differences between mares and jennies, the latter displaying larger luminal epithelium, greater glandular size, and density than mares.

Antibiotic restrictions in swine have increased interest in alternative feed additives to support intestinal health and immunity during the post-weaning period. Based on previous findings, this study evaluated the effects of heat-killed Mycolicibacterium manresensis (hkMm) on cellular, humoral, and innate immunity in weaned piglets. Four-week-old piglets were randomly allocated into three groups (n=5) receiving a control diet or diets supplemented with 10 or 50 ppm hkMm. At day 70, duodenal and jejunal samples were collected and analyzed by immunohistochemistry using markers for T cells (CD3, TCRδ, and FoxP3), IFN-γ⁺ cells, B cells (CD20), IgA-producing cells, and macrophages (CD163). Supplemented animals showed increased numbers of CD3⁺, particularly TCRδ⁺ and FoxP3⁺ subsets, resulting in higher TCRδ/CD3 and FoxP3/CD3 ratios. hkMm also enhanced humoral and mucosal immune responses, as indicated by increased numbers of CD20⁺ B cells and IgA+ cells, especially at 10 ppm (p = 0.04). CD163⁺ macrophages showed slight increases, suggesting enhanced regulatory and homeostatic mechanisms, while a moderate increase in jejunal IFN-γ⁺ cells was observed at 10 ppm. Correlation analysis revealed positive associations between CD3 and TCRδ (r = 0.53; p = 0.05), and betweeen TCRδ and CD163 in the jejunum (r = 0.70; p = 0.01), whereas CD163 was negatively associated with IFN-γ in the duodenum (r = −0.53; p = 0.04). Overall, the 10 ppm dose elicited the most consistent responses, promoting coordinated changes in cellular, humoral, and innate immunity. These findings suggest that hkMm may enhance mucosal immune competence while supporting intestinal homeostasis during the post-weaning period.