Location: Livestock Behavior ResearchTitle: Initial evaluation of floor cooling on lactating sows under severe acute heat stress Author
|Cabezon, Francisco - Purdue University|
|Schinckel, Allan - Purdue University|
|Smith, A - Purdue University|
|Stwalley, Robert - Purdue University|
Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/25/2017
Publication Date: 4/1/2017
Citation: Cabezon, F., Schinckel, A., Smith, A.J., Marchant Forde, J.N., Johnson, J.S., Stwalley, R. 2017. Initial evaluation of floor cooling on lactating sows under severe acute heat stress. Professional Animal Scientist. 33(2):254-260. http://doi.org/10.15232/pas.2016-01584.
Interpretive Summary: Heat stress not only affects swine welfare, but is also estimated to cost the U.S. pork industry over $360 million annually. Heat stress negatively impacts sow fertility and when heat stressed, lactating sows reduce their internal heat production by reducing their daily feed intake and milk production, which then also impacts piglet growth. To improve both welfare and productivity during hot conditions, some of the excess heat produced must be removed. Recently, we designed a water-cooled floor pad to remove excess heat of lactating sows in high environmental temperatures and carried out an initial study to evaluate different water flow rates on the estimated amount of heat removal and reduction in the sow’s responses to heat stress. We compared a constant cool water flow of 0.00 (CONTROL), 0.25 (LOW), 0.55 (MEDIUM) or 0.85 (HIGH) l/min for 90 minutes. The cooling was initiated 1 hour after the target room temperature of 35ºC was reached. We found that all treatments decreased respiration rate and rectal temperature. At the end of the study period, the mean respiration rates were decreased by 33-77% relative to control sows. The rectal temperatures were decreased by 0.4-0.8ºC relative to control. We concluded that our heat stress protocol did induce a heat stress response in the sows, and that the cooling pad worked to reduce this stress response, especially at the medium and high flow rates. The cooling pads have the potential to improve sow welfare and sow and piglet productivity during a heat stress event. Further testing is in progress.
Technical Abstract: The objectives were to evaluate an acute heat stress protocol for lactating sows and evaluate preliminary estimates of water flow rates required to cool sows. Twelve 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 = 5), 0.25 (LOW, n = 3), 0.55 (MEDIUM, n = 2) or 0.85 (HIGH, n = 2) l/min for 90 mins . The cooling was initiated 1 h after the room reached 35º C. Respiration rates (RR), rectal temperature (RT) and skin temperature (ST, 15 cm posterior to the ear) were recorded before the trial, prior to cooling, and after 90 mins of cooling. Water flow rates, inlet and outlet temperatures were recorded, to calculate the heat removal, 6 times (every 15 mins) after the cooling started. In each of 3 repetitions, treatments were switched randomly. The mean room temperature and relative humidity during the trial were 35.3 ± 0.7º C and 57.8 ± 3.1%, respectively. Treatments impacted RR and RT after 90 mins of cooling. At the end, the mean RR and RT were 132.0 breaths/min and 39.9º C for the CONTROL; 88.6 breaths/min and 39.5º C for the LOW; 71.0 breaths/min and 39.2º C for the MEDIUM; and 30.6 breaths/min and 39.1º C for the HIGH treatment (P < 0.001 and P < 0.001, respectively ). In the present study, the protocol to produce an acute heat stress in lactating sows and the preliminary water flow rates selected were adequate for the cooling pad device and the room environmental conditions at which the trial was performed. The MEDIUM and the HIGH flow rate treatments were able to reduce RR and RT in sows, indicating successful cooling. Further study is required using a larger sample size and repetitions to refine the target heat removal rates in high environmental temperatures.