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

Theriogenology. 2016 Sep 1;86(4):924-933. doi: 10.1016/j.theriogenology.2016.03.015. Epub 2016 Mar 19.


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.

Keywords: Bovine; Chromatin integrity; In vitro fertilization; Sperm-head morphometry.

MeSH terms

  • Animals
  • Cattle / physiology*
  • Cryopreservation / veterinary
  • Embryonic Development / physiology*
  • Fertilization in Vitro / veterinary*
  • Hot Temperature
  • Male
  • Scrotum / physiology*
  • Semen Preservation / veterinary
  • Spermatozoa / physiology*