Effect of retained placenta and clinical mastitis on reproduction parameters, immune response, and steroidogenic receptors gene expression in postpartum crossbred dairy cows.

The purpose of this study was to evaluate the effect of retained placenta (RP) and clinical mastitis (CM) on the reproductive efficiency of crossbred dairy cows during the postpartum period and the effect in some innate immune system indicators. For this, two experiments were carried out. In the first, a total of 232 cows were evaluated and divided as: healthy control (n = 184), RP (n = 22), and CM (n = 26) groups. The RP and CM was evaluated until 30 days postpartum (DPP) and reproductive rates were measured. In experiment 2, cows were divided in control (n = 10), RP (n = 10), and CM (n = 30) groups. Between 40 and 50 DPP, clinical, gynecological examination and endometrial cytobrush were performed to evaluate subclinical endometritis (SE) and gene expression of interleukins 1ß (IL-1ß) and 6 (IL-6), chemokine ligand 5 (CCL5), estrogen α (ESR1), and progesterone (PGR) receptors by qRT-PCR analysis. In experiment 1, the conception rate at 1st artificial insemination (AI) was lower in RP and CM groups and pregnancy rate at 150 days decreased in CM group. Calving-to-1st AI interval and days open were shorter in healthy cows. In experiment 2, the occurrence of SE was 26.7% and higher in RP and CM groups. The expression of IL-1ß increased in RP and CM groups, while IL-6 was less expressed in RP group. The CCL5, ESR1, and PGR were similar between groups. In conclusion, cows with RP and CM had their reproductive efficiency negatively affected and had they initial pro-inflammatory response improved by the increase of IL-ß.

Three-dimensional levitation culture improves in-vitro growth of secondary follicles in bovine model.

RESEARCH QUESTION: Does a three-dimensional culture system based on magnetic levitation with nanoparticles assembly maintain the follicular structure and viability with adequate growth rates leading to oocyte maturation after long-term culture? DESIGN: Randomized-controlled trial of treatments in a bovine model. Secondary follicles (n = 213) isolated from bovine ovaries were cultured in a two-dimensional system (two-dimensional control) or three-dimensional levitation system with different concentrations (three-dimensional 50 µl/ml, 100 µl/ml and 200 µl/ml) of magnetic nanoparticles. Follicular growth (diameter, daily growth and growth patterns), morphology (normal, degenerated and extruded follicles), antrum formation, oocyte viability and chromatin configuration were assessed. RESULTS: Secondary follicles of three-dimensional 200-µl/ml treatment showed higher viability, antrum formation and lower degeneration rates than two-dimensional control. Also, follicles cultured in the three-dimensional 200-µl/ml treatment presented a most homogenous daily growth rate as shown by the lowest variance and standard deviation. Compared with the two-dimensional control, the proportion of non-growing and slow-growing follicles were 3.8-fold lower and 1.6-fold higher, respectively, in the three-dimensional 200-µl/ml treatment. After in-vitro maturation, the three-dimensional 200-µl/ml had a greater proportion of viable oocytes (1.7-fold) and meiotic resumption rates (2.4-fold) than the two-dimensional control treatment. CONCLUSION: The three-dimensional levitation culture system improves the viability of in-vitro development of bovine secondary follicles, antrum formation and lower extrusion and degeneration rates and adequate growth rate leading to relevant oocyte viability and meiotic resumption after in-vitro maturation. This approach does not require a specific medium, and has the potential as an alternative method to in-vitro follicle culture in several species, including humans.