Reproductive Characteristics of Boars during and after Exposure to Increased Ambient Temperature2

Abstract

SummaryReproductive performance of 12 ll-monthold Yorkshire boars was determined during and after exposure to control or increased ambient temperatures. After 3 weeks adjustment at 23 C in temperature controlled chambers, six boars were heat stressed by exposure to 34.5 + 1.0 C for 8 hr and 31.0 • 1.0 C for 16 hr during each 24-hr period and six control boars were maintained at 23.0 + 1.0 C for 11 weeks. All boars were subsequently exposed to 23 C for 6 weeks. Semen was collected twice weekly before, during and after heat stress and boars were naturally mated with gilts during weeks 7 to 11 of treatment. Daily rectal temperatures and respiratory rates were increased during heat stress, but the ability to ejaculate and semen volume were not altered. Percentage motile sperm was decreased during heat stress (P<.O05) and did not return to normal values until 5 weeks after the end of exposure to increased ambient temperatures. Daily sperm output from heat stressed boars was decreased (P<.025) during daily ejaculation on days 33 to 38 of treatment and averaged 54% of the total sperm ejaculated by control boars. At 30 days after natural breeding only 59% (P<.05) of the gilts bred by heat stressed boars were pregnant compared to 82% for gilts mated to control boars.

Climate Change Impacts on Livestock Production Systems: A Review

“…Boars when subjected to 32-34 C for three consecutive days have increased number of morphologically abnormal sperm cells and lowered sperm motility. Thus, elevated temperature conditions are detrimental to spermatogenesis (Wettemann et al, 1979). Similar observations were reported by Tummuruk et al(2002) in Thailand on the seasonal effects of high ambient temperature on reproductive performance of sows.…”

Scrotal heat stress causes sperm chromatin damage and cysteinyl aspartate-spicific proteinases 3 changes in fertile men

“…Previous experimental data from animal models suggested that scrotal heat stress may be a reversible method for contraception [35]. In boars, the number of spermatozoa was not affected in many heat experiments, but motility and the percentage of normal spermatozoa fell between 1 and 6 weeks after the heat exposure; when the heating was for only a limited period, motility and the percentage of normal spermatozoa recovered after about 6 weeks [36][37][38][39][40].…”

Seasonal infertility in large pig production units in an Eastern-European climate

“…2 Elevated ambient temperatures have similar detrimental effects on the boar, resulting in decreases in both the motility and quantity of sperm and increases in the proportion of abnormal sperm. 4 Some studies have demonstrated that elevated temperatures significantly decrease ovulation rate, 2,5 while another study revealed no such effect. 6 Edwards et al 5…”