The aims of the study were to determine the long-term effects of dietary supplementation with microalgae (SCIM) on milk and blood fatty acid (FA) composition and reproductive hormones in early lactation dairy cows. Sixty Holstein–Friesian dairy cows (30 per treatment) were unsupplemented (Control) or supplemented with 100 g of SCIM (Schizochytrium limacinum sp.) per cow per day from 25 ± 0.5 d post-partum for 98 d. Intake and milk yield were recorded daily, with milk samples collected at weeks 0, 1, 2, 4, 8 and 14, and blood samples collected from 12 representative pairs per treatment at weeks 0, 2, 4, 8, and 14 for subsequent analysis of FA, β-hydroxybutyrate, non-esterified fatty acids and glucose. At 33 ± 0.9 d postpartum the oestrus cycle of 24 cows (12 per treatment) were synchronized and plasma 13,14-dihydro-15-keto PGF2α (PGFM) concentrations determined following an oxytocin challenge. Data were analysed by repeated measures analysis of variance. There was no effect of treatment on dry matter intake, milk yield or milk fat content, with mean values across treatments of 22.1 and 40.6, and 37.2 g/kg respectively. Milk fat concentration of C22:6 n-3 increased rapidly in cows receiving SCIM, reaching a maximum of 0.38 g/100 g FA by week 14. Similarly, blood concentration of C22:6 n-3 increased to 1.6 g/100 g FA by week 14 in cows fed SCIM. There was no effect of treatment on plasma metabolites, but plasma glucose was lower in cows fed SCIM compared to the Control at week 2, and higher in week 8. There was no effect of treatment on peak plasma PGFM concentration or area under the curve. It is concluded that feeding SCIM rapidly increases blood and milk concentrations of C22:6 n-3 which are maintained over time, but does not improve plasma PGFM in dairy cows.

中文翻译：

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长期膳食补充微藻可增加牛奶和血浆中的血浆二十二碳六烯酸，但不影响奶牛血浆 13,14-dihydro-15-keto PGF2α 浓度

该研究的目的是确定在早期泌乳奶牛中添加微藻 (SCIM) 膳食补充剂对牛奶和血液脂肪酸 (FA) 组成以及生殖激素的长期影响。60 头荷斯坦-弗里西亚奶牛（每次处理 30 头）未添加（对照）或添加 100 克 SCIM（裂殖壶菌sp.) 每头牛每天从产后 25 ± 0.5 天开始，持续 98 天。每天记录摄入量和产奶量，在第 0、1、2、4、8 和 14 周采集奶样，并在第 0、2、4、8 和 14 周从每次治疗的 12 对代表性对采集血样用于后续FA、β-羟基丁酸、非酯化脂肪酸和葡萄糖的分析。在产后 33 ± 0.9 天，24 头奶牛（每次处理 12 头）的发情周期同步，血浆 13,14-二氢-15-酮 PGF2α(PGFM) 浓度在催产素激发后测定。通过重复测量方差分析对数据进行分析。处理对干物质摄入量、产奶量或乳脂肪含量没有影响，处理的平均值分别为 22.1 和 40.6 和 37.2 g/kg。接受 SCIM 的奶牛的 C22:6 n-3 乳脂浓度迅速增加，到第 14 周达到最大值 0.38 g/100 g FA。同样，C22:6 n-3 的血液浓度增加到 1.6 g/100 g FA到第 14 周喂食 SCIM 的奶牛。治疗对血浆代谢物没有影响，但在第 2 周喂食 SCIM 奶牛的血糖低于对照组，在第 8 周升高。治疗对血浆 PGFM 峰值浓度或曲线下面积没有影响。