238 Effect of electronically controlled floor cooling pad on semen performance of Duroc boars during the summer heat stress

Abstract

Abstract The objective of the study was to evaluate the effects of using electronically controlled floor cooling pad (ECP) on boar semen production during the summer season in a boar stud in Scottsville, Kentucky. Sixty boars (526.26 ± 188.69 d old) were placed in two rows of pens (2.06 x 0.66 m) in a 350 head tunnel ventilated boar barn and were randomly assigned to either CONTROL (n = 30; no ECP) or PAD (n = 30) treatments. The ECP had 4.25 L cold water flushed through a group of 5 pads connected to each other, when temperature sensors reached 27°C or every 4 mins for sensors placed on 5th pad and 24°C or every 4 mins for sensors placed on 1st pad. Boars experienced natural summer heat stress (daily temperature, humidity and dewpoint: Mean = 24.03°C, 87.9%, 21.7°C, hourly mean high = 28.9°C, 83.4%, 25.8°C) for a period of 30 d from July 15, 2023 to August 14, 2023 wherein the cooling pad remained on and were flushing based on the set points mentioned above. Semen was collected from each boar at least once each week and semen samples were diluted in a commercial semen extender and analyzed for motility using a CASA system, volume using a gram scale, and concentration using a spermiodensimeter. A semen sample was also stained using Hancock stain and evaluated at 100x oil immersion to assess sperm morphology (100 sperm cells analyzed as normal or having retained cytoplasmic droplets, distal midpiece reflex or other head/tail abnormalities). Total sperm production, percentage of morphologically normal sperm, percentage of motile sperm were calculated and used to determine whether the ejaculate met threshold for use in an artificial insemination program or whether the ejaculate was trashed. Data were evaluated using PROC MIXED for repeated measures in SAS (v.9.4) with the main effects of treatment and week, using the age of the boar, and the number of days between collections as covariates, and boar nested within treatment as a random effect. There were no differences between CONTROL and PAD boars for semen production measures (P > 0.05). PAD boars had greater morphologically normal sperm compared with CONTROL boars using Hancock stain (P = 0.0362); however, this effect was lost when the percentage of total normal sperm for the entire ejaculate was calculated (P = 0.56). Overall, maintaining boars on floor cooling pads during the summer months had minimal impacts on semen production and reduced the presence of morphologically abnormal sperm.