|CABEZÓN, FRANCISCO - Purdue University|
|SCHINCKEL, ALLAN - Purdue University|
|STWALLEY, ROBERT - Purdue University|
Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2017
Publication Date: 10/20/2017
Citation: Cabezón, F.A., Schinckel, A.P., Marchant Forde, J.N., Johnson, J.S., Stwalley, R.M. 2017. Effect of floor cooling on late lactation sows under acute heat stress. Livestock Science. 206: 113-120.
Interpretive Summary: Elevated core body temperatures in lactating sows can have lasting effects on performance, reproductive efficiency, and animal welfare. Unfortunately, selection for increased sow productivity including litter size and litter weaning weight has reduced the modern sow’s upper critical temperature to approximately 18ºC and increased their heat production in comparison to past sows. For sows to achieve a high percentage of their genetic potential for milk production and subsequent piglet weaning weights, while minimizing body weight loss during lactation, some of the excess heat produced must be removed. Therefore, the study objectives were to evaluate the impact of an acute heat stress protocol with higher environmental temperatures (35ºC) on sow heat stress responses, and to evaluate the impact of different water flow rates through a cooling pad on the estimated amount of heat removal and reduction in the sow’s responses to heat stress. It was determined that cooling pads with LOW, MEDIUM, and HIGH water flow rates reduced respiration rates, rectal temperatures, and vaginal temperatures in lactating sows by removing excess heat from sows. The design and materials used in the cooling pad device were able to remove efficiently the excess heat from sows with a low usage of water. Further studies are required to evaluate the optimum water flow rate at each environmental condition.
Technical Abstract: The objective was to evaluate the effects of floor cooling on late lactation sows under severe summer heat stress. Ten multiparous sows were provided with a cooling pad built with an aluminum plate surface, high-density polyethylene base and copper pipes. Treatments were randomly allotted to sows to receive a constant cool water flow of 0.00 (CONTROL, n = 4), 0.25 (LOW, n = 2), 0.55 (MEDIUM, n = 2) or 0.85 (HIGH, n = 2) l/min for 100 min. The cooling was initiated 1 h after the room reached 35ºC. Respiration rates (RR), vaginal temperature (VT), and skin temperature (ST, 15 cm posterior to the ear) were recorded before the trial, prior to cooling, and 5 times (20 min intervals) after the cooling phase began. Rectal temperature (RT) was recorded before the trial, prior to cooling, and in the last 20 min of cooling. Water flow rates, inlet, and outlet temperatures were recorded 5 times (20 min intervals) to calculate heat removal after the cooling started. The procedure was repeated 8 times (2 times/d for 4 d), and treatments were randomly switched in each repetition. The mean room temperature and relative humidity during the trial were 35.1 ± 0.4ºC and 68.4 ± 3.2%, respectively. Cooling treatments impacted RR, VT, ST, and RT after 80 min of cooling, where the mean RR was 122, 76, 67, and 45 breaths/min for the CONTROL, LOW, MEDIUM, and HIGH flow rate treatments, respectively (P < 0.001). After 80 min of cooling the mean VT, RT, and ST were 40.1, 40.0, and 39.4ºC, respectively for the CONTROL; 39.5, 39.5, and 39.0ºC, respectively for the LOW; 39.4, 39.2, and 38.9ºC, respectively for the MEDIUM; and 39.2, 39.0, and 38.6ºC, respectively for the HIGH flow rate treatment (P < 0.001). Overall heat removal during the trial was 193, 321, and 365 watts for the LOW, MEDIUM, and HIGH flow rate treatments, respectively (P < 0.001). Cooling pads with LOW, MEDIUM, and HIGH water flow rates reduced RR, RT, and VT in lactating sows.