Date Full Report Received


Date Abstract Report Received



Primary Investigator:

The impact of heat stress on sperm production and quality has been demonstrated previously. This project aimed to quantify some temperatures in commercial studs and then evaluate mitigation strategies for boars subjected to conditions seen in ‘the real world’. Hobo temperature loggers were placed in ten commercial studs in IL, MO, MC, MO and TX with varying cooling systems. We anticipated air conditioned studs would have very little variation so only included one. Interestingly, some studs with cool cells were better able to maintain conditions in the thermoneutral range during the period of data collection. As expected, cool cells were generally more effective under conditions of low ambient relative humidity. We selected a cycle within the range observed under commercial conditions and programmed that for our environmental chambers.

Twelve boars were moved to our chambers and surgically implanted with temperature sensors in the abdominal cavity and in the scrotum. We monitored effectiveness of cooling strategies to reduce efforts to cope with heat stress (e.g. less impact on respiration rate or skin temperature) and to maintain homeostasis in the body and scrotum. Each boar rotated among all cooling strategies. Strategies tested included all combinations of fans and drippers on the neck and scrotum as well as a commercially available water cooled floor panel. Each cooling strategy worked to varying degrees. Ultimately the most effective strategy was used to provide a 9wk treatment of boars under summer conditions. The strategy most effective at internal temperature regulation was the one that had both fans and drippers on both the neck and the scrotum. The twelve boars were housed every other stall with cooling or not. At the end of 9wk boars were sacrificed and samples collected to evaluate effectiveness of this strategy to mitigate the impact of heat on sperm quality measures. Results demonstrated that cooling was effective at reducing the negative impact of elevated ambient temperatures.

Key Findings:
• Elevated ambient temperatures observed in commercial studs lead to elevated respiration rate and skin and rectal temperature when replicated under controlled conditions.
• Interventions (drippers, fans, cooled floors) resulted in modest improvements in measured variables.
• Even with modest impact on measured variables, improvements were observed for sperm quality traits post-mortem.

Dr. Tim Safranski
University of Missouri
(573) 884-7994