Impact of bull age, sperm processing, and microclimatic conditions on the viability and DNA integrity of cryopreserved bovine sperm

Burcu Cinar; Heinrich Bollwein; Mathias Siuda; Matthias Lautner; Claus Leiding; Eleni Malama

Just Accepted

This article has been peer reviewed and accepted for publication. It is in production and has not been edited, so may differ from the final published form.

Impact of bull age, sperm processing, and microclimatic conditions on the viability and DNA integrity of cryopreserved bovine sperm

Burcu Cinar, Heinrich Bollwein, Mathias Siuda, Matthias Lautner, Claus Leiding, Eleni Malama

Abstract

Context. Seasonal microclimatic fluctuations can cause changes in sperm quality even in dairy bulls bred under temperate climate. These changes can vary between sires of different age and affect sperm freezability. Aims. We aimed to evaluate the modulating effect of bull age and equilibration time before freezing on the seasonal pattern of sperm viability and DNA integrity post-thaw. Methods. We assessed the integrity of sperm plasma membrane (PMAI) in 15,496 cryopreserved bovine batches, and the percentage of sperm with high DNA fragmentation index (%DFI) after 0 (0 h) and 3 hours incubation at 38 °C post-thaw (3 h) in 3,422 batches. Semen was equilibrated for 24 hours before freezing if collected on Monday or Wednesday and 72 hours if produced on Friday. We investigated the effect of season, bull age, equilibration and temperature-humidity index (THI) on the day of semen collection on sperm traits using mixed-effects linear models. Key results. PMAI and %DFI (0 h, 3 h) deteriorated with increasing THI. The effect of THI on %DFI was detected with a 30-day time lag. Seasonal fluctuations of sperm quality were similar between young, mature and older sires. Prolonged equilibration did not affect PMAI but was linked to elevated %DFI (3 h) in summer. Conclusions. Extending equilibration from 24 to 72 hours is compatible with commercial standards of bovine sperm quality post-thaw; however, it could interfere with the seasonal pattern of latter. Implications. Systematic monitoring of bovine sperm quality enables the prompt detection of stress factors related to microclimate and semen processing.

RD23219 Accepted 11 April 2024