Faculty Veterinary Medicine, Department of Farm Animal Health, Utrecht University, 3584 CL the Netherlands.
J Dairy Sci. 2010 Dec;93(12):5684-95. doi: 10.3168/jds.2010-3159.
A randomized, controlled field trial with dairy cows demonstrated an adverse effect of vitamin E supplementation during the dry period on mastitis incidence in early lactation. This study was conducted on farms with historically high rates of mastitis to investigate the benefit of vitamin E supplementation on udder health; however, the outcome showed an adverse effect. The aim of the study was to evaluate whether daily supplementation of 3,000 IU of vitamin E to dairy cows during the dry period could improve udder health in commercial herds with a high incidence of mastitis. On 5 dairy farms, dry cows were randomly divided into 2 experimental groups: a high and a low group. Both groups received a dry cow mineral mix providing 3,000 or 135 IU of vitamin E/cow per day, respectively, between dry-off and calving for a mean period of 8 wk. Providing 3,000 IU of vitamin E exceeds NRC standards, but this amount has been used in previous studies. The experiment, as well as the majority of the statistical analysis, were carried out blinded. Blood was sampled 3 times before calving and on calving day. Serum was analyzed for vitamin E and cholesterol. Vitamin E and the vitamin E:cholesterol ratio were analyzed as dependent variables in mixed models and Student's t-tests to study trends in time and differences between groups. Relative risk calculation and survival analysis were used to study the effect of supplementation on mastitis incidence in the first 3 mo of lactation. The results showed that vitamin E supplements increased both absolute vitamin E and the ratio of vitamin E to cholesterol in blood. In the high group, significantly more subclinical and clinical cases occurred, showing the same trend on all farms. In this study, an initial vitamin E level at dry off above 14.5 μmol/L was a risk factor for clinical mastitis, suggesting that the vitamin E status at the start of the dry period is important. It is recommended to work out exactly at what threshold vitamin E is harmful for udder health before new trials with high dosages of vitamin E are started. Additionally, further research is required to investigate the mechanism by which vitamin E affects udder health.
一项针对奶牛的随机对照田间试验表明，在干奶期补充维生素 E 会对泌乳早期乳腺炎的发病率产生不良影响。这项研究是在乳腺炎发病率历来较高的农场进行的，旨在研究维生素 E 补充剂对乳房健康的益处；然而，结果显示出了不良影响。该研究的目的是评估在干奶期每天给奶牛补充 3000IU 的维生素 E 是否可以改善乳腺炎高发的商业牛群的乳房健康。在 5 个奶牛场，干奶牛被随机分为 2 个实验组：高剂量组和低剂量组。两组在干奶期到分娩期间分别接受含有 3000 或 135IU 维生素 E/奶牛/天的干奶牛矿物质预混料，平均持续 8 周。提供 3000IU 的维生素 E 超过了 NRC 标准，但在以前的研究中已经使用了这个量。实验以及大多数统计分析都是盲法进行的。在分娩前和分娩当天采集了 3 次血样。血清用于分析维生素 E 和胆固醇。维生素 E 和维生素 E:胆固醇的比值作为因变量进行混合模型和学生 t 检验分析，以研究时间趋势和组间差异。相对风险计算和生存分析用于研究补充维生素 E 对泌乳早期前 3 个月乳腺炎发病率的影响。结果表明，维生素 E 补充剂增加了血液中的绝对维生素 E 和维生素 E 与胆固醇的比值。在高剂量组中，明显更多的亚临床和临床病例发生，在所有农场都表现出相同的趋势。在这项研究中，干奶期开始时的初始维生素 E 水平超过 14.5μmol/L 是临床乳腺炎的一个危险因素，这表明干奶期开始时的维生素 E 状况很重要。建议在开始高剂量维生素 E 的新试验之前，确定维生素 E 对乳房健康有害的确切阈值。此外，还需要进一步研究维生素 E 影响乳房健康的机制。
