The objectives of this study were to determine the effects of shading wallows during the summer months on lactating sow behavior, performance, and physiology. A total of 128 sows were used during warm weather (May to August 2001) to determine the effects of unshaded (control; n = 8) vs. shaded (SH; n = 8) wallows. Sows ranged over 6 parities and were fed a completely balanced sorghum-based diet. Behavioral data were collected by 15-min scan samples over a 24-h period/wk for a total of 16 wk. All sows were observed twice when litter age was 5 and 15 d, respectively. Respiration rates (breaths/min) were collected on 50 sows (control, n = 25; SH, n = 25) over an 8-wk period when the maximum temperature exceeded 32°C. Ten milliliters of clotted blood and 20 mL of whole blood were obtained by jugular puncture from each sow on the day of weaning to determine total white blood cells, acute phase proteins, packed-cell volume, and Chemotaxis and chemokinesis. Descriptive water temperature profiles were measured by using data loggers positioned at 3 levels per wallow: surface water, shallow mud, and deep mud. Behavioral, postural, location, performance, and physiological measurements did not differ (P > 0.05) among wallow treatments. Regardless of treatment, sows spent approximately 82% of their total time budget inside the farrowing hut and only approximately 7% of their total time budget in the wallow. A total of 428 piglets died, 219 in the control treatment and 209 in the SH treatment. The majority of piglets in both treatments died of crushing within the first 72 h after parturition, and most of the piglets had suckled. Shade kept the shallow water profile cooler during the hotter afternoon temperatures compared with the control wallows. In SH for both the shallow and deep mud profiles, temperatures were consistent throughout the day. In conclusion, sows spent a large percentage of their daily time budget inside the farrowing hut and spent only brief episodes in the wallow. Shading the wallow did not result in increased wallow use time or improvements in sow physiology and overall performance.
- Heat stress