Jones K L, King S S
Department of Animal Science, Food and Nutrition, Southern Illinois University Carbondale, Carbondale, IL 62901, USA.
J Anim Sci. 2009 Jul;87(7):2227-38. doi: 10.2527/jas.2008-1641. Epub 2009 Mar 27.
This study continues a series of investigations evaluating fescue endotoxin exposure in beef heifer production. The objectives were to evaluate fatty acid compositions in plasma and follicular fluid, and to assess oocyte quality from cattle fed fescue diets. The ability of domperidone, a dopamine antagonist, to mitigate these variables was also assessed. Thirty heifers were divided into 3 treatment groups (n = 10/group) and administered treatment regimens for 24 d, at which time blood samples were collected. The treatment regimens were a diet with endophyte-free fescue (EF), a diet with endophyte-infected fescue (EI), or EI supplemented with daily subcutaneous injections of domperidone (0.44 mg/kg of BW; EID). Three heifers/group were administered treatments for an additional 10 d, at which time their luteal phase ovarian follicular fluid and oocytes were collected. Plasma and follicular fluid samples were analyzed to determine fatty acid concentrations. Oocytes were matured in vitro to assess quality. In addition, abattoir oocytes were cultured in plasma from treated heifers. In plasma, arachidonic acid was less (P < 0.001) in EF-fed compared with EI-fed heifers. Decreased (P < 0.05) total n-6 fatty acid concentration was observed in EF-fed compared with EI-fed heifers. Similarly, the EF-containing diets decreased (P < 0.05) concentrations of eicosapentaenoic acid and C22:5n-3 (P < 0.05) compared with EI-containing diets. Domperidone supplementation increased (P < 0.05) C18:2 cis-9, trans-11, C17:1n-7, and several C18:1 isomers compared with the diet with EI and no supplementation. No differences between fescue endophyte groups were detected in any of the fatty acid concentrations analyzed in follicular fluid from small follicles. In follicular fluid from large follicles, C18:4n-3 and C22:6n-3 concentrations were greater (P < 0.05) in EI-fed compared with EF-fed heifers. Oocytes cultured in serum (control) or plasma from EF-, EI-, or EID-fed cattle did not differ in their ability to progress to metaphase II. These observations indicate that fescue endotoxins can alter fatty acid composition and may contribute to altered physiology in heifers.
本研究延续了一系列评估肉牛生产中牛尾草内毒素暴露情况的调查。目标是评估血浆和卵泡液中的脂肪酸组成，并评估饲喂牛尾草日粮的牛的卵母细胞质量。还评估了多巴胺拮抗剂多潘立酮减轻这些变量的能力。30头小母牛被分为3个处理组（每组n = 10头），并接受24天的处理方案，在此期间采集血样。处理方案为不含内生菌的牛尾草日粮（EF）、含内生菌的牛尾草日粮（EI）或补充每日皮下注射多潘立酮（0.44 mg/kg体重；EID）的EI日粮。每组另外3头小母牛再接受10天的处理，此时采集它们黄体期的卵巢卵泡液和卵母细胞。分析血浆和卵泡液样本以确定脂肪酸浓度。卵母细胞在体外成熟以评估质量。此外，在屠宰场将卵母细胞在经处理的小母牛的血浆中培养。在血浆中，与饲喂EI日粮的小母牛相比，饲喂EF日粮的小母牛的花生四烯酸含量更低（P < 0.001）。与饲喂EI日粮的小母牛相比，饲喂EF日粮的小母牛的总n-6脂肪酸浓度降低（P < 0.05）。同样，与含EI日粮相比，含EF日粮的二十碳五烯酸和C22:5n-3浓度降低（P < 0.05）。与含EI且未补充的日粮相比，补充多潘立酮使C18:2顺-9，反-11、C17:1n-7和几种C18:1异构体增加（P < 0.05）。在小卵泡的卵泡液中分析的任何脂肪酸浓度方面，未检测到牛尾草内生菌组之间的差异。在大卵泡的卵泡液中，与饲喂EF日粮的小母牛相比，饲喂EI日粮的小母牛的C18:4n-3和C22:6n-3浓度更高（P < 0.05）。在来自EF、EI或EID饲喂的牛的血清（对照）或血浆中培养的卵母细胞在进入中期II的能力方面没有差异。这些观察结果表明，牛尾草内毒素可改变脂肪酸组成，并可能导致小母牛生理变化。
