The iron status of sows has a great influence on reproductive performance. Iron deficiency reduces reproductive performance and newborn piglet survival rate of sow. The hemoglobin is a potential predictor for the iron status of sows and is convenient for rapid detection in pig farms. However, the relationship between iron status, hemoglobin, placental trace elements, and reproductive performance remains unclear. In this study, the hemoglobin and reproductive performance of more than 500 sows with first to sixth parities at different gestation stages (25, 55, 75, 95, and 110 d of gestation) in two large-scale sow farms were collected, and the content of placental Fe, Zn, Mn, and Cu was analyzed. The results show that hemoglobin levels of sows during pregnancy (days 75, 95, and 110) decreased significantly (P < 0.001). As the parity increases, the hemoglobin levels of sows at days 25 and 55 of gestation and placental mineral element contents including Fe, Zn, Mn, and Cu at delivery decreased (P < 0.05), while the litter size, birth alive, and litter weights increased gradually (P < 0.001). Furthermore, hemoglobin during pregnancy had a negative linear correlation with litter weight and average weight (P < 0.05), and higher hemoglobin at day 25 of gestation may reduce the number of stillbirths (P = 0.05), but higher hemoglobin at day 110 of gestation may tend to be a benefit for the birth (P = 0.01). And there was a significant positive linear correlation between hemoglobin at day 110 of gestation and placental Fe and Mn levels (P = 0.002, P = 0.013). There was also a significant positive linear correlation among Fe, Zn, Mn, and Cu in the placenta (P < 0.001). The levels of Fe, Zn, and Mn in the placental at delivery were positively related to the average weight of the fetus (P = 0.048, P = 0.027, P = 0.047), and placental Cu was linearly correlated with litter size (P = 0.029). Our research revealed that the requirements for iron during gestation were varied in different gestation periods and parities. The feeds should be adjusted according to the gestation periods, parities, or iron status to meet the iron requirements of sows and fetal pigs.

中文翻译：

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妊娠母猪妊娠血红蛋白水平、胎盘微量元素含量与繁殖​​性能的相关性

母猪的铁状况对繁殖性能有很大的影响。缺铁会降低母猪的繁殖性能和新生仔猪存活率。血红蛋白是母猪铁状况的潜在预测指标，便于猪场快速检测。然而，铁状态、血红蛋白、胎盘微量元素和生殖性能之间的关系仍不清楚。本研究收集了两个大型母猪场500多头第一胎至第六胎母猪在不同妊娠期（妊娠25、55、75、95、110天）的血红蛋白和繁殖性能，分析胎盘铁、锌、锰和铜的含量。结果显示，母猪在怀孕期间（第 75、95 和 110 天）的血红蛋白水平显着下降（P < 0.001）。随着平价的增加，母猪妊娠25天和55天血红蛋白水平和分娩时胎盘矿质元素Fe、Zn、Mn、Cu含量均下降（P < 0.05），产仔数、产活率和窝重逐渐增加（ P＜0.001）。此外，孕期血红蛋白与窝重和平均体重呈负线性相关（P < 0.05），妊娠 25 天较高的血红蛋白可减少死胎数（P = 0.05），但妊娠 110 天较高的血红蛋白妊娠可能对分娩有益 (P = 0.01)。妊娠第110天血红蛋白与胎盘铁、锰水平呈显着正线性相关（P=0.002，P=0.013）。胎盘中的Fe、Zn、Mn和Cu之间也存在显着的正线性相关(P < 0.001)。分娩时胎盘Fe、Zn、Mn水平与胎儿平均体重呈正相关（P=0.048，P=0.027，P=0.047），胎盘Cu与产仔数呈线性相关（P= 0.029）。我们的研究表明，妊娠期间对铁的需求在不同的妊娠期和胎次中是不同的。应根据妊娠期、胎次或铁状况调整饲料，以满足母猪和胎猪对铁的需要。