Plasma fatty acid profile in dairy cows associated with the inclusion of annatto in their diet

ABASTRACT. The objective of this study was to evaluate the plasma lipid profile and plasma fatty acids of dairy cows receiving diets supplemented with annatto. A total of 32 Holstein cows (550 kg), distributed in a completely randomized design, were allocated to individual stalls and submitted to following treatments: C0 = no annatto; C4 = inclusion of annatto at 4 g kg-1 dry matter (DM) of diet (0.07 g bixin kg-1 diet); C5 = inclusion of annatto at 5 g kg-1 DM of diet (0.09 g bixin kg-1 diet); and C7 = inclusion of annatto at 7 g kg-1 DM of diet (0.12 g bixin kg-1 diet). Blood samples were collected via epigastric vein puncture, centrifuged, and frozen for subsequent analysis. The results indicate that the inclusion (p > 0.05) of annatto does not decrease the total cholesterol or low and high density lipoproteins. However, it impacts the profile of fatty acids, evidenced by the reduction (p < 0.05) in levels of hypercholesterolemic fatty acids viz, myristic acid and palmitic acid. It also causes an increase in the levels of arachidonic acid, rumenic acid, linoleic acid, and total polyunsaturated fatty acids. Therefore, bixin included in the diets of dairy cows induces changes in the plasma fatty acid profile.

摘要
本研究旨在评估饲喂添加胭脂树橙（annatto）日粮的荷斯坦奶牛（Holstein cows）的血浆脂质谱（plasma lipid profile）与血浆脂肪酸（plasma fatty acids）水平。试验共选取32头体重550 kg的荷斯坦奶牛，采用完全随机试验设计，将其安置于个体限位栏中，并设置如下处理组：C0组不添加胭脂树橙；C4组按日粮干物质（dry matter, DM）4 g·kg⁻¹的比例添加胭脂树橙（对应日粮中胭脂树素（bixin）含量为0.07 g·kg⁻¹）；C5组按日粮干物质5 g·kg⁻¹的比例添加胭脂树橙（对应日粮中胭脂树素含量为0.09 g·kg⁻¹）；C7组按日粮干物质7 g·kg⁻¹的比例添加胭脂树橙（对应日粮中胭脂树素含量为0.12 g·kg⁻¹）。通过腹壁静脉穿刺（epigastric vein puncture）采集血液样本，经离心处理后冷冻保存，以待后续分析检测。
结果显示，添加胭脂树橙对总胆固醇（total cholesterol）、低密度脂蛋白（low density lipoprotein, LDL）与高密度脂蛋白（high density lipoprotein, HDL）水平无显著影响（p > 0.05）。但胭脂树橙可显著改变血浆脂肪酸谱，表现为致高胆固醇血症脂肪酸（hypercholesterolemic fatty acids）——即肉豆蔻酸（myristic acid）与棕榈酸（palmitic acid）——的水平显著降低（p < 0.05）；同时，花生四烯酸（arachidonic acid）、共轭亚油酸（rumenic acid）、亚油酸（linoleic acid）及总多不饱和脂肪酸（polyunsaturated fatty acids）的水平显著升高。综上，在奶牛日粮中添加胭脂树素（bixin）可改变其血浆脂肪酸谱。