Determining the Optimal Macroenvironment Temperature to Improve Lactating Sow and Piglet Productivity

Abstract Pre-weaned piglets prefer higher temperatures than lactating sows. To address this, swine producers use heating lamps or pads in combination with maintaining farrowing room macroenvironment temperatures at the upper end of the thermoneutral zone (24-25℃) of the lactating sow. This may inadvertently cause thermal stress for lactating sows resulting in decreased feed consumption, and ultimately, reduced milk production and litter growth. Therefore, the objective was to determine the sow level macroenvironment temperature that would improve both sow and litter productivity. In two repetitions, 37 lactating sows (parity = 3.1 ± 1.7) and their litters (d 1 litter size = 12.0 ± 1.0) were housed within 1 of 3 farrowing rooms set to different macroenvironment temperatures: LOW (n = 12 sows and litters; 15.0 ± 0.4℃), MID (n = 13 sows and litters; 19.3 ± 0.2℃), and HIGH (n = 12 sows and litters; 24.6 ± 0.8℃). Lactating sows and their litters were on trial from the onset of farrowing until weaning (19.8 ± 0.9 d of age). Individual farrowing crate temperatures were recorded throughout the trial in 0.14 s intervals using thermocouples mounted at sow head height. Piglets were provided a 0.34 x 1.52 m heating pad with a verified steady state of 35.0℃. Sow body weight (BW) was recorded at 24 h post-farrowing and at weaning, and piglet weights were measured on d 1, 7, 14 and at weaning to determine average daily BW gain (ADG). Liveborn piglet mortality was recorded throughout the trial. Sow feed intake (FI) was recorded daily from d 1 post-farrowing until weaning. The sow was considered the experimental unit for sow level measures and the litter was considered the experimental unit for piglet measures. Data were analyzed using PROC GLIMMIX in SAS 9.4 and using GLM in JMP 15. Regression models were used to determine the optimal macroenvironment temperature to improve sow FI and piglet ADG. Sow FI was greater (P < 0.01) for LOW (7.91 ± 0.38 kg) and MID (7.32 ± 0.37 kg) versus HIGH (6.37 ± 0.39 kg) sows, but similar for LOW and MID sows. Piglet ADG was greater from d 1 to weaning (P < 0.01) for LOW (0.25 ± 0.01 kg) and MID (0.26 ± 0.01 kg) versus HIGH (0.21 ± 0.01 kg) piglets, but similar for LOW and MID piglets. Pre-weaning mortality was similar (P = 0.32; 15.6%) among all treatments. A quadratic effect was observed (P < 0.01) where sow FI was maximized at a macroenvironment temperature of 17.2℃. A cubic effect was observed (P < 0.01) where piglet ADG was greatest at 17.0℃. In summary, these data have implications towards housing lactating sows and their litters at lower macroenvironment temperatures to improve growth performance.