Selected sperm traits are simultaneously altered after scrotal heat stress and play specific roles in in vitro fertilization and embryonic development.

Improvements in the estimation of male fertility indicators require advances in laboratory tests for sperm assessment. The aims of the present work were (1) to apply a multivariate analysis to examine sperm set of alterations and interactions and (2) to evaluate the importance of sperm parameters on the outcome of standard IVF and embryonic development. Bulls (n = 3) were subjected to scrotal insulation, and ejaculates were collected before (preinsulation = Day 0) and through 56 days (Days 7, 14, 21, 28, 35, 42, 49, and 56) of the experimental period. Sperm head morphometry and chromatin variables were assessed by a computational image analysis, and IVF was performed. Scrotal heat stress induced alterations in all evaluated sperm head features, as well as cleavage and blastocyst rates. A principal component analysis revealed three main components (factors) that represented almost 89% of the cumulative variance. In addition, an association of factor scores with cleavage (factor 1) and blastocyst (factor 3) rates was observed. In conclusion, several sperm traits were simultaneously altered as a result of a thermal insult. These sperm traits likely play specific roles in IVF and embryonic development.

Ovarian activity and oocyte quality associated with the biochemical profile of serum and follicular fluid from Girolando dairy cows postpartum.

This study was designed to evaluate the influence of heat stress (HS) on the metabolic profile of serum and follicular fluid (FF), ovarian follicle development, and oocyte quality of Girolando dairy cows. Oocytes, blood, and FF (follicles ≥9mm) samples were obtained at 30, 45, 60, 75, and 90 days postpartum in the summer and winter seasons. During transvaginal follicular aspiration, rectal temperature (RT), body condition score (BCS), number of ovarian follicles, and quality of oocytes were recorded. The ambient air temperature (AT) and relative humidity (RH) were also recorded to calculate the temperature humidity index (THI). Glucose, total cholesterol (TC), triglycerides (TG), urea, sodium (Na), potassium (K), and calcium (Ca) concentrations were determined using serum and FF samples. The RT, THI, and BCS loss were greater (P<0.01) in the summer; however, glucose, Na, and K serum concentrations decreased in the same season (P<0.05). Degenerated oocytes were positively associated (P<0.05) with THI (r=0.14) and AT (r=0.13), and negatively associated with glucose (r=-0.12) and K (r=-0.11) serum concentrations. HS induces metabolic changes, which compromise the number of ovarian follicles and the follicular environment, thus resulting in morphologically damaged oocytes.