试验选用20头经产母猪(3.4±1.2胎),分别处于不同阶段,7头未怀孕母猪、6头妊娠中期母猪(58.5±5.68d),7头妊娠后期母猪(104.7±2.8天)。每头母猪单独测量温度偏好性,环境温度从10.4至30.5梯度提高,母猪可以自由选择合适温度。正式试验前,有24小时适应期,适应期后一次饲喂全天日粮,然后进入试验舍。在24小时试验期中,全程视频录像,记录母猪行为(不活动时间)、姿势(站立、趴卧、侧躺),并且每15分钟瞬时扫描样本记录位置信息。试验数据用SAS9.4的PROC MIXED模型进行分析。基于其待的时间最长的位置或温度,使用三次回归模型计算母猪最喜欢的温度。以最喜欢温度±SE计算每头母猪的适宜温度范围。



Evaluation of sow thermal preference across three stages of reproduction
The metabolic heat production of modern pigs has increased by an average of 16%, compared with sows of 30 years ago. Therefore, it is likely that temperature recommendations require updating to meet the needs of modern pigs. The objective of this study was to evaluate whether different reproductive stages of sows altered thermal preference and if current recommendations required updating. Twenty multiparous sows (3.4 ± 1.2 parity) in different reproductive stages (nonpregnant: n = 7; mid-gestation: 58.5 ± 5.68 d, n = 6; and late-gestation: 104.7 ± 2.8 d, n = 7) were tested. Thermal preference was individually tested, and sows could freely choose a temperature, using a thermal gradient between 10.4 and 30.5 °C. Sows were given 24 h to acclimate to the thermal apparatus. Before testing began, sows were given daily feed allotment and returned to the apparatus. Video from the 24-h test period was used to record sow behavior (time spent inactive), posture (upright and sternal and lateral lying), and location using instantaneous scan samples every 15 min. Data were analyzed using PROC MIXED procedure in SAS 9.4. A cubic regression model was used to calculate the sow’s most preferred temperature based on the location, or temperature, in which they spent the most time. The preference range was calculated using peak temperature preference ±SE for each sow. The reproductive stage altered where sows spent their time within the thermal gradient (P < 0.01). Late-gestation sows preferred cooler temperatures (14.0 °C) than mid-gestation (14.8 °C; P < 0.01) and nonpregnant sows (14.8 °C; P < 0.01). In summary, sow thermal preferences were within the lower half of the current recommended range (10 to 25 °C). This indicates that temperatures at the higher end of the recommended range could be uncomfortable to sows and that the thermal comfort zone of sows may be narrower than recommendations indicate.


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