The study focused on behavioral and cortisol responses to feeding frequency in pregnant sows under isocaloric intake. Twenty-four sows [(Landrace × Yorkshire); BW 216.70 ± 3.98 kg; parity 3.04 ± 0.53] were balanced for parity and randomly assigned to 1 of 3 feeding frequency regimes. Sows were fed corn–soybean meal-based diet 1× [0730 (Control), T1], 2× [half ration at 0730 and 1530 hours, T2], or 3× [one-third portion at 0730, 1130, and 1530 hours, T3] from days 30 to 60 of gestation. Sows received 7055 kcal ME/d during gestation from 2.21 kg of diet formulated to contain SID Lys/ME of 1.71 g/Mcal. Saliva samples were collected every 2 hr from 0630 to 1830 hours on day 52 and assayed for cortisol using ELISA procedure. Behavior data were collected for 7 d from day 53 of gestation by affixing a remote insights ear tag to each sow. Each sow had 120,960 data points categorized into: “Active”, “Feed,” or “Dormant”. Because of housing constraint, all sows were housed in individual stalls in the same room presenting a potential limitation of the study. The data were analyzed using PROC MIXED and GLIMMIX procedures of SAS 9.4 for cortisol and behavior count data, respectively. Sow was the experimental unit. The area under the curve (AUC) is quantitative evaluation of response as threshold varies over all possible values. The T2 sows had reduced 12-hr cortisol AUC compared with control sows (P = 0.024) and T3 sows (P = 0.004), respectively. The T2 sows had lower 3 hr (P = 0.039) and 5 hr (P = 0.015) postfeeding cortisol AUC compared with control sows. Feed anticipatory activity (FAA), 24-hr total activity, and feeding activities (eating and/or sham chewing) were reduced for T2 sows relative to the control and T3 sows (P < 0.01). Consequently, T2 sows had lower 24-hr total activity (P < 0.001) and feeding activities (P < 0.001) AUC compared with both the control and T3 sows, respectively. The T3 sows had greater FAA (P < 0.001) and 24-hr total activity AUC (P = 0.010) compared with control sows. Our data although inconclusive due to small sample size, twice daily feeding appears to be the threshold that reduces sows’ total activity AUC, feeding activity AUC, and activation of hypothalamic–pituitary–adrenal axis, reduced hunger, and exhibit potential to improve sow welfare in relation to once and thrice daily feeding regimes under isocaloric intake per kilogram live metabolic weight.

中文翻译：

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等热量摄入下妊娠母猪的行为和皮质醇对进食频率的响应。

该研究集中于等热量摄入下妊娠母猪的行为和皮质醇对饲喂频率的响应。二十四头母猪[（Landrace×Yorkshire）; 体重216.70±3.98公斤; 均等3.04±0.53]进行了均等平衡，并随机分配给3种进食频率方案中的1种。给母猪饲喂以玉米-豆粕为基础的日粮1×[0730（对照），T1]，2×[0730和1530小时的半定量，T2]或3×[0730、1130和1530的三分之一）小时，T3]从妊娠的30天到60天。母猪在妊娠期间从2.21 kg日粮中配制的含有SID Lys / ME为1.71 g / Mcal的日粮接受了7055 kcal ME / d。在第52天的0630至1830小时之间每2小时收集一次唾液样品，并使用ELISA方法测定皮质醇。通过在每头母猪上贴上一个远程洞察耳标，从妊娠第53天开始收集7天的行为数据。每头母猪有120只，960个数据点分为：“活动”，“进给”或“休眠”。由于居住条件的限制，所有母猪都被安置在同一房间的各个摊位中，这可能会限制这项研究。使用SAS 9.4的PROC MIXED和GLIMMIX程序分别分析皮质醇和行为计数数据。母猪是实验单位。当阈值在所有可能的值上变化时，曲线下的面积（AUC）是对响应的定量评估。与对照母猪相比，T2母猪的12小时皮质醇AUC降低了（4分别用于皮质醇和行为计数数据。母猪是实验单位。当阈值在所有可能的值上变化时，曲线下的面积（AUC）是对响应的定量评估。与对照母猪相比，T2母猪的12小时皮质醇AUC降低了（4分别用于皮质醇和行为计数数据。母猪是实验单位。当阈值在所有可能的值上变化时，曲线下的面积（AUC）是对响应的定量评估。与对照母猪相比，T2母猪的12小时皮质醇AUC降低了（P = 0.024）和T3母猪（P = 0.004）。与对照母猪相比，T2母猪在饲喂皮质醇AUC后的3小时（P = 0.039）和5小时（P = 0.015）较低。相对于对照和T3母猪，T2母猪的预期饲料活性（FAA），24小时总活性和摄食活性（进食和/或假咀嚼）降低（P＜0.01）。因此，T2母猪具有较低的24小时的总活性（P <0.001）和进给运动（P <0.001）AUC分别与控制和T3母猪两者进行比较。T3母猪的FAA（P <0.001）和24小时总活性AUC（P= 0.010）与对照母猪相比。我们的数据虽然由于样本量小而尚无定论，但每天进食两次似乎是降低母猪总活性AUC，进食活性AUC和激活下丘脑-垂体-肾上腺轴，减少饥饿感并具有改善母猪福利的潜力的阈值与每公斤活代谢重量等热量摄入下一次和三次的每日喂养方式有关。