Department of Animal Science, Aarhus University, DK-8830 Tjele, Denmark.
Sherbrooke R & D Centre, Agriculture and Agri-Food Canada, Sherbrooke, QC J1M 0C8, Canada.
J Anim Sci. 2022 Jun 1;100(6). doi: 10.1093/jas/skac176.
The physiology during late gestation and the transition period to lactation changes dramatically in the sow, especially during the latter period. Understanding the physiological processes and how they change dynamically as the sow approaches farrowing, nest building, giving birth to piglets, and producing colostrum is important because these processes greatly affect sow productivity. Glucose originating from assimilated starch accounts for the majority of dietary energy, and around farrowing, various organs and peripheral tissues compete for plasma glucose, which may become depleted. Indeed, physical activity increases shortly prior to farrowing, leading to glucose use by muscles. Approximately ½ to 1 d later, glucose is also needed for uterine contractions to expel the piglets and for the mammary gland to produce lactose and fat for colostrum. At farrowing, the sow appears to prioritize glucose to the mammary gland above the uterus, whereby insufficient dietary energy may compromise the farrowing process. At this time, energy metabolism in the uterus shifts dramatically from relying mainly on the oxidation of glucogenic energy substrates (primarily glucose) to ketogenic energy supplied from triglycerides. The rapid growth of mammary tissue occurs in the last third of gestation, and it accelerates as the sow approaches farrowing. In the last 1 to 2 wk prepartum, some fat may be produced in the mammary glands and stored to be secreted in either colostrum or transient milk. During the first 6 h after the onset of farrowing, the uptake of glucose and lactate by the mammary glands roughly doubles. Lactate is supplying approximately 15% of the glucogenic carbon taken up by the mammary glands and originates from the strong uterine contractions. Thereafter, the mammary uptake of glucose and lactate declines, which suggests that the amount of colostrum secreted starts to decrease at that time. Optimal nutrition of sows during late gestation and the transition period should focus on mammary development, farrowing performance, and colostrum production. The birth weight of piglets seems to be only slightly responsive to maternal nutrition in gilts; on the other hand, sows will counterbalance insufficient feed or nutrient intake by increasing mobilization of their body reserves. Ensuring sufficient energy to sows around farrowing is crucial and may be achieved via adequate feed supply, at least three daily meals, high dietary fiber content, and extra supplementation of energy.
母猪在妊娠后期和泌乳期的生理变化非常显著，尤其是在后期。了解生理过程以及它们如何随着母猪接近分娩、筑巢、产仔和分泌初乳而动态变化非常重要，因为这些过程会极大地影响母猪的生产力。来自淀粉同化的葡萄糖占日粮能量的大部分，在接近分娩时，各种器官和外周组织会争夺血浆葡萄糖，这可能会耗尽。事实上，分娩前的体力活动会增加，导致肌肉利用葡萄糖。大约在分娩后 1/2 到 1 天，子宫收缩排出仔猪和乳腺分泌乳糖和脂肪产生初乳也需要葡萄糖。在分娩时，母猪似乎会优先将葡萄糖输送到乳腺，而不是子宫，因此，膳食能量不足可能会影响分娩过程。此时，子宫的能量代谢会从主要依赖于糖质能量底物（主要是葡萄糖）的氧化转变为来自甘油三酯的酮质能量供应。乳腺组织在妊娠后期的最后三分之一迅速生长，并在接近分娩时加速生长。在产前最后 1 到 2 周，乳腺中可能会产生一些脂肪并储存起来，以便在初乳或过渡乳中分泌。在分娩开始后的前 6 小时内，乳腺对葡萄糖和乳酸的摄取量大致增加了一倍。大约有 15%的乳腺摄取的糖质碳来源于强烈的子宫收缩的乳酸。此后，乳腺对葡萄糖和乳酸的摄取量下降，这表明此时分泌的初乳量开始减少。妊娠后期和泌乳期母猪的最佳营养应侧重于乳腺发育、分娩性能和初乳生产。仔猪的出生体重似乎只对后备母猪的母体营养有轻微的反应；另一方面，母猪会通过增加自身储备的动员来弥补饲料或营养摄入的不足。确保母猪在分娩前后有足够的能量非常重要，可以通过充足的饲料供应、至少每日三餐、高膳食纤维含量和额外的能量补充来实现。
