Methods to Supply Chilled Drinking Water for Lactating Sows During High Ambient Temperatures

The aim of this study was to determine an effective method to supply chilled water (CW) for lactating sows during high ambient temperatures. One hundred twenty multiparous sows (Yorkshire × Landrace; parity range: 2 to 5) and their litters [Duroc × (Yorkshire × Landrace)] were divided into four groups of 30 sows each. Each group was used to investigate the effects of the four water supplying methods (Control: free access to unchilled water at 22°C; FACW: free access to chilled drinking water at 15°C; RACW: restricted access to chilled water at 15°C; and RACW+SS: restricted access to chilled water at 15°C + sound stimulus) under farm conditions with ambient temperatures above 25°C. Sows in the FACW, RACW, and RACW+SS groups ate and drank more than the sows in the control group that received water at 22°C (P<0.01). Respiration rate and rectal temperature were lower in sows in the CW groups than in the control group (P<0.01). Litter size on 0 day post-partum and at weaning did not differ among treatments, whereas average weaning weight and average daily gain (ADG) of piglets from the FACW, RACW, and RACW+SS groups were higher than those in the control group (P<0.01). There were no differences in the measured variables among treatment groups that received water chilled to 15°C (P>0.05). These results suggest that the optimal CW supplying method, from an energy viewpoint, may be RACW.