Cai Jie, Miao Chao, Chen Yi, Xie Yunyi, Liu Jianxin, Wang Diming
Key Laboratory of Molecular Animal Nutrition of Ministry of Agriculture, College of Animal Sciences, Institute of Dairy Science, Zhejiang University, Hangzhou 310058, China.
Anim Nutr. 2021 Dec;7(4):1024-1030. doi: 10.1016/j.aninu.2021.06.003. Epub 2021 Sep 4.
This study aimed to evaluate role of nano-sized zinc (Zn) on lactation performance, health status, and mammary permeability of lactating dairy cows. Thirty multiparous dairy cows with similar days in milk (158 ± 43.2) and body weight (694 ± 60.5 kg) were chosen based on parity and milk production and were randomly assigned to 3 treatment groups: basal diet (control, 69.6 mg/kg of Zn adequate in Zn requirement), basal diet additional Zn-methionine (Zn-Met, providing 40 mg/kg of Zn), and basal diet additional nano-sized Zn oxide (nZnO, providing 40 mg/kg of Zn). The study lasted for 10 wk, with the first 2 wk as adaptation. Feed intake, milk yield and the related variables, and plasma variables were determined every other week. Blood hematological profiles were determined in the 8th week of the study. We found that feed intake, milk yield, and milk composition were similar across the 3 groups. The nZnO- and Zn-Met-fed cows had greater milk Zn concentrations in the milk (3.89 mg/L (Zn-Met) and 3.93 mg/L (nZnO)) and plasma (1.25 mg/L (Zn-Met) and 1.29 mg/L (nZnO)) than the control cows (3.79 mg/L in milk and 1.21 mg/L in plasma). The nZnO-fed cows had higher Zn concentrations in plasma but not in milk compared to Zn-Met-fed cows. The Zn appearance in milk was greater in nZnO-fed (area under curve during the first 4 h post-feeding for milk Zn: 16.1 mg/L) and Zn-Met-fed cows (15.7 mg/L) than in control cows (15.0 mg/L). During the first 4 h post-feeding, milk to blood Zn ratio was greater in nZnO-fed animals but lower in Zn-Met-fed cows compared with control cows. Oxidative stress-related variables in plasma, blood hematological profiles, and mammary permeability related variables were not different across treatments. In summary, lactation performance, Zn concentrations in milk and plasma, hematological profiles, mammary permeability were similar in cows fed nZnO and Zn-Met. We therefore suggested that nZnO feeding can improve Zn bioavailability without impairing lactation performance, health status, and mammary gland permeability in dairy cows.
本研究旨在评估纳米锌（Zn）对泌乳奶牛泌乳性能、健康状况和乳腺通透性的作用。根据胎次和产奶量选择30头产奶天数相近（158±43.2天）且体重相近（694±60.5千克）的经产奶牛，并随机分为3个处理组：基础日粮组（对照组，锌含量满足需求，为69.6毫克/千克）、基础日粮添加蛋氨酸锌组（Zn-Met，额外提供40毫克/千克锌）和基础日粮添加纳米氧化锌组（nZnO，额外提供40毫克/千克锌）。研究持续10周，前2周为适应期。每隔一周测定采食量、产奶量及相关变量和血浆变量。在研究的第8周测定血液血液学指标。我们发现，3组之间的采食量、产奶量和乳成分相似。与对照组奶牛（牛奶中3.79毫克/升，血浆中1.21毫克/升）相比，饲喂Zn-Met和nZnO的奶牛牛奶中锌浓度更高（Zn-Met组为3.89毫克/升，nZnO组为3.93毫克/升），血浆中锌浓度也更高（Zn-Met组为1.25毫克/升，nZnO组为1.29毫克/升）。与饲喂Zn-Met的奶牛相比，饲喂nZnO的奶牛血浆中锌浓度更高，但牛奶中锌浓度无差异。饲喂nZnO的奶牛（采食后前4小时牛奶锌曲线下面积：16.1毫克/升）和饲喂Zn-Met的奶牛（15.7毫克/升）牛奶中锌的表观含量高于对照组奶牛（15.0毫克/升）。在采食后前4小时，与对照组奶牛相比，饲喂nZnO的动物牛奶与血液锌比值更高，但饲喂Zn-Met的奶牛更低。各处理组之间血浆中氧化应激相关变量、血液血液学指标和乳腺通透性相关变量无差异。总之，饲喂nZnO和Zn-Met的奶牛泌乳性能、牛奶和血浆中锌浓度、血液学指标、乳腺通透性相似。因此我们建议，在不损害奶牛泌乳性能、健康状况和乳腺通透性的情况下，饲喂nZnO可提高锌的生物利用度。
