In ruminants, dietary C18:3n-3 can be lost through biohydrogenation in the rumen; and C18:3n-3 that by-passes the rumen still can be lost through oxidation in muscle, theoretically reducing the deposition of C18:3n-3, the substrate for synthesis of poly-unsaturated fatty acids (n-3 LCPUFA) in muscle. In vitro studies have shown that rumen hydrogenation of C18:3n-3 is reduced by supplementation with palm oil (rich in cis-9 C18:1). In addition, in hepatocytes, studies with neonatal rats have shown that cis-9 C18:1 inhibits the oxidation of C18:3n-3. It therefore seems likely that palm oil could reduce both rumen biohydrogenation of C18:3n-3 and muscle oxidation of C18:3n-3. The present experiment tested whether the addition of palm oil to a linseed oil supplement for goat kids would prevent the losses of C18:3n-3 and thus improve the FA composition in two muscles, Longissimus dorsi and Biceps femoris. To investigate the processes involved, we studied the rumen bacterial communities and measured the mRNA expression of genes related to lipid metabolism in Longissimus dorsi. Sixty 4-month-old castrated male Albas white cashmere kids were randomly allocated among three dietary treatments. All three diets contained the same ingredients in the same proportions, but differed in their fat additives: palm oil (PMO), linseed oil (LSO) or mixed oil (MIX; 2 parts linseed oil plus 1 part palm oil on a weight basis). Compared with the LSO diet, the MIX diet decreased the relative abuandance of Pseudobutyrivibrio, a bacterial species that is positively related to the proportional loss rate of dietary C18:3n-3 and that has been reported to generate the ATP required for biohydrogenation (reflecting a decrease in the abundance of rumen bacteria that hydrogenate C18:3n-3 in MIX kids). In muscle, the MIX diet increased concentrations of C18:3n-3, C20:5n-3, C22:6n-3, and n-3 LCPUFA, and thus decreased the n-6/n-3 ratio; decreased the mRNA expression of CPT1β (a gene associated with fatty acid oxidation) and increased the mRNA expression of FADS1 and FADS2 (genes associated with n-3 LCPUFA synthesis), compared with the LSO diet. Interestingly, compared to Longissimus dorsi, Biceps femoris had greater concentrations of PUFA, greater ratios of unsaturated fatty acids/saturated fatty acids (U/S), and poly-unsaturated fatty acids/saturated fatty acids (P/S), but a lesser concentration of saturated fatty acids (SFA). In cashmere goat kids, a combination of linseed and palm oils in the diet increases the muscle concentration of n-3 LCPUFA, apparently by decreasing the relative abundance of rumen bacteria that are positively related to the proportional loss rate of dietary C18:3n-3, by inhibiting mRNA expression of genes related to C18:3n-3 oxidation in muscle, and by up-regulating mRNA expression of genes related to n-3 LCPUFA synthesis in muscle, especially in Longissimus dorsi.

中文翻译：

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棕榈油保护 α-亚麻酸免受羊绒山羊的瘤胃生物氢化和肌肉氧化

在反刍动物中，日粮 C18:3n-3 可通过瘤胃中的生物氢化作用而丢失；而绕过瘤胃的 C18:3n-3 仍然可以通过肌肉中的氧化作用流失，理论上减少了肌肉中合成多不饱和脂肪酸 (n-3 LCPUFA) 的底物 C18:3n-3 的沉积. 体外研究表明，通过补充棕榈油（富含 cis-9 C18:1）可减少 C18:3n-3 的瘤胃氢化。此外，在肝细胞中，对新生大鼠的研究表明，cis-9 C18:1 可抑制 C18:3n-3 的氧化。因此，棕榈油似乎可以减少 C18:3n-3 的瘤胃生物氢化和 C18:3n-3 的肌肉氧化。本实验测试了在山羊孩子的亚麻籽油补充剂中添加棕榈油是否会防止 C18 的损失：3n-3 从而改善背最长肌和股二头肌两块肌肉的 FA 组成。为了研究所涉及的过程，我们研究了瘤胃细菌群落并测量了背最长肌中与脂质代谢相关的基因的 mRNA 表达。60 名 4 个月大的阉割雄性 Albas 白色羊绒儿童被随机分配到三种饮食治疗中。所有三种饮食都含有相同比例的相同成分，但脂肪添加剂不同：棕榈油 (PMO)、亚麻籽油 (LSO) 或混合油（MIX；2 份亚麻籽油加 1 份棕榈油重量） . 与 LSO 饮食相比，MIX 饮食降低了 Pseudobutyrivibrio 的相对丰度，Pseudobutyrivibrio 是一种与饮食 C18 的比例损失率呈正相关的细菌：3n-3 并且据报道可产生生物氢化所需的 ATP（反映在 MIX 儿童中氢化 C18:3n-3 的瘤胃细菌数量减少）。在肌肉中，MIX 饮食增加了 C18:3n-3、C20:5n-3、C22:6n-3 和 n-3 LCPUFA 的浓度，从而降低了 n-6/n-3 比率；与 LSO 饮食相比，降低了 CPT1β（与脂肪酸氧化相关的基因）的 mRNA 表达，并增加了 FADS1 和 FADS2（与 n-3 LCPUFA 合成相关的基因）的 mRNA 表达。有趣的是，与背最长肌相比，股二头肌的 PUFA 浓度更高，不饱和脂肪酸/饱和脂肪酸 (U/S) 和多不饱和脂肪酸/饱和脂肪酸 (P/S) 的比例更高，但更少饱和脂肪酸 (SFA) 的浓度。在羊绒山羊孩子中，