Comparison of ruminal lipid metabolism in dairy cows and goats fed diets supplemented with starch, plant oil, or fish oil
Comparison of ruminal lipid metabolism in dairy cows and goats fed diets supplemented with starch, plant oil, or fish oil
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DOI：
10.3168/jds.2015-10292
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发表时间：
2016-01-01
影响因子：
3.5
通讯作者：
Frutos, P.
中科院分区：
文献类型：
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作者：
Toral, P. G.;Bernard, L.;Frutos, P.
直接比较奶牛和山羊的生产性能和牛奶脂肪酸对已知的引起奶牛乳脂抑制(MFD)的饲料的反应，揭示了瘤胃脂肪代谢中相关物种与饲料的相互作用。因此，本研究旨在推测瘤胃微生物生物氢化(BH)因日粮和反刍动物种类不同而产生差异的潜在机制。为了达到这一目标，12头奶牛和15只山羊按3x3拉丁方设计，按25天试验期，饲喂基础日粮(对照组)、添加2.2%鱼油(FO)的类似日粮或添加5.3%葵花油和额外淀粉的日粮(+38%；SOS)。在每个周期的最后一天，测定瘤胃液样品中的脂肪酸组成(用气相色谱)和细菌群落(用末端RFLP)，以及发酵特性。结果表明，奶牛和山羊对饲料处理的反应存在显著差异，尽管某些发酵参数的变化(例如，由于FO或SOS导致醋酸盐/丙酸比率的降低)在这两个物种中相似。瘤胃BH通路的主要变化可能导致SOS饲料中的MFD(即从反式-11向反式-10 18：1的转变以及反式-10、顺式-12 18：2的相关增加)往往在奶牛中更为明显，这仅与该物种的MFD相一致。然而，与FO诱导的MFD相关的变化(例如，18：0的减少和总反式-18：1的增加)在山羊瘤胃液中更强，这可能解释了它们对FO对乳脂含量的负面影响的意外敏感性(尽管不如牛)。总之，这些结果表明，不同的瘤胃机制导致了每种类型的饮食诱导的MFD，并证实了与物种的显著相互作用。关于微生物区系，奶牛和山羊在瘤胃细菌群落组成上的差异可能是受实验日粮影响的微生物群差异的原因(例如，牛中的瘤胃球菌科、乳螺科和琥珀弧菌科，以及山羊中的假丁状弧菌、梭状芽胞杆菌簇IV、普雷沃特拉菌和韦隆氏菌)，这阻碍了细菌种群分配到特定的BH步骤或路径。此外，微生物群中最相关的变异对应于尚未培养的细菌，表明这些微生物可能在奶牛和山羊的瘤胃脂肪代谢中发挥主导作用。
Direct comparison of cow and goat performance and milk fatty acid responses to diets known to induce milk fat depression (MFD) in the bovine reveals relevant species-by-diet interactions in ruminal lipid metabolism. Thus, this study was conducted to infer potential mechanisms responsible for differences in the rumen microbial biohydrogenation (BH) due to diet and ruminant species. To meet this objective, 12 cows and 15 goats were fed a basal diet (control), a similar diet supplemented with 2.2% fish oil (FO), or a diet containing 5.3% sunflower oil and additional starch (+38%; SOS) according to a 3 x 3 Latin square design with 25-d experimental periods. On the last day of each period, fatty acid composition (by gas chromatography) and bacterial community (by terminal-RFLP), as well as fermentation characteristics, were measured in rumen fluid samples. Results showed significant differences in the response of cows and goats to dietary treatments, although variations in some fermentation parameters (e.g., decreases in the acetate-to-propionate ratio due to FO or SOS) were similar in both species. Main alterations in ruminal BH pathways potentially responsible for MFD on the SOS diet (i.e., the shift from trans-11 to trans-10 18:1 and related increases in trans-10, cis-12 18:2) tended to be more pronounced in cows, which is consistent with an associated MFD only in this species. However, changes linked to FO-induced MFD (e.g., decreases in 18:0 and increases in total trans-18:1) were stronger in caprine rumen fluid, which may explain their unexpected susceptibility (although less marked than in bovine) to the negative effect of FO on milk fat content. Altogether, these results suggest that distinct ruminal mechanisms lead to each type of diet-induced MFD and confirm a pronounced interaction with species. With regard to microbiota, differences between cows and goats in the composition of the rumen bacterial community might be behind the disparity in the microorganisms affected by the experimental diets (e.g., Ruminococcaceae, Lachnospiraceae, and Succinivibrionaceae in the bovine, and Pseudobutryrivibrio, Clostridium cluster IV, Prevotella, and Veillonellaceae in the caprine), which hindered the assignation of bacterial populations to particular BH steps or pathways. Furthermore, most relevant variations in microbial groups corresponded to as yet uncultured bacteria and suggest that these microorganisms may play a predominant role in the ruminal lipid metabolism in both cows and goats.