Selection for prolificacy in sows has resulted in higher metabolic demands during lactation. In addition, modern sows have an increased genetic merit for leanness. Consequently, sow metabolism during lactation has changed, possibly affecting milk production and litter weight gain. The aim of this study was to investigate the effect of lactational feed intake on milk production and relations between mobilization of body tissues (adipose tissue or skeletal muscle) and milk production in modern sows with a different lactational feed intake. A total of 36 primiparous sows were used, which were either full-fed (6.5 kg/day) or restricted-fed (3.25 kg/day) during the last 2 weeks of a 24-day lactation. Restricted-fed sows had a lower milk fat percentage at weaning and a lower litter weight gain and estimated milk fat and protein production in the last week of lactation. Next, several relations between sow body condition (loss) and milk production variables were identified. Sow BW, loin muscle depth and backfat depth at parturition were positively related to milk fat production in the last week of lactation. In addition, milk fat production was related to the backfat depth loss while milk protein production was related to the loin muscle depth loss during lactation. Backfat depth and loin muscle depth at parturition were positively related to lactational backfat depth loss or muscle depth loss, respectively. Together, results suggest that sows which have more available resources during lactation, either from a higher amount of body tissues at parturition or from an increased feed intake during lactation, direct more energy toward milk production to support a higher litter weight gain. In addition, results show that the type of milk nutrients that sows produce (i.e. milk fat or milk protein) is highly related to the type of body tissues that are mobilized during lactation. Interestingly, relations between sow body condition and milk production were all independent of feed level during lactation. Sow management strategies to increase milk production and litter growth in modern sows may focus on improving sow body condition at the start of lactation or increasing feed intake during lactation.

母猪繁殖率的选择导致泌乳期间更高的代谢需求。此外，现代母猪在瘦肉方面具有更高的遗传价值。因此，母猪泌乳期间的新陈代谢发生了变化，可能会影响产奶量和垫料增重。本研究的目的是调查哺乳期采食量对产奶量的影响，以及不同泌乳期采食量的现代母猪身体组织（脂肪组织或骨骼肌）的动员与产奶量之间的关系。总共使用了 36 头初产母猪，在 24 天哺乳期的最后 2 周内，它们要么全饲（6.5 公斤/天），要么限制饲喂（3.25 公斤/天）。限制饲喂的母猪在断奶时的乳脂百分比较低，窝增重和估计泌乳最后一周的乳脂和蛋白质产量较低。接下来，确定了母猪身体状况（损失）和产奶量变量之间的几种关系。分娩时母猪体重、腰部肌肉深度和背膘厚度与泌乳最后一周的乳脂产量呈正相关。此外，乳脂产量与背膘厚度损失有关，而乳蛋白产量与哺乳期腰部肌肉深度损失有关。分娩时背膘深度和腰部肌肉深度分别与哺乳期背膘深度损失或肌肉深度损失呈正相关。总之，结果表明母猪在泌乳期间拥有更多可用资源，无论是来自分娩时更多的身体组织，还是来自哺乳期间增加的采食量，都可以将更多的能量用于产奶，以支持更高的窝增重。此外，研究结果表明，母猪生产的乳营养物质（即乳脂肪或乳蛋白）的类型与泌乳期间活动的身体组织类型高度相关。有趣的是，母猪身体状况和产奶量之间的关系都与泌乳期间的饲料水平无关。提高现代母猪产奶量和窝产仔数的母猪管理策略可能侧重于改善泌乳开始时的母猪身体状况或增加泌乳期间的采食量。此外，研究结果表明，母猪生产的乳营养物质（即乳脂肪或乳蛋白）的类型与泌乳期间活动的身体组织类型高度相关。有趣的是，母猪身体状况和产奶量之间的关系都与泌乳期间的饲料水平无关。提高现代母猪产奶量和窝产仔数的母猪管理策略可能侧重于改善泌乳开始时的母猪身体状况或增加泌乳期间的采食量。此外，研究结果表明，母猪生产的乳营养物质（即乳脂肪或乳蛋白）的类型与泌乳期间活动的身体组织类型高度相关。有趣的是，母猪身体状况和产奶量之间的关系都与泌乳期间的饲料水平无关。提高现代母猪产奶量和窝产仔数的母猪管理策略可能侧重于改善泌乳开始时的母猪身体状况或增加泌乳期间的采食量。