Diet-induced milk fat depression is associated with alterations in ruminal biohydrogenation pathways and formation of novel fatty acid intermediates in lactating cows
Diet-induced milk fat depression is associated with alterations in ruminal biohydrogenation pathways and formation of novel fatty acid intermediates in lactating cows
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DOI：
10.1017/s0007114517000010
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发表时间：
2017-02
影响因子：
3.6
通讯作者：
L. Ventto;H. Leskinen;P. Kairenius;T. Stefański;A. Bayat;J. Vilkki;K. Shingfield
中科院分区：
文献类型：
--
作者：
L. Ventto;H. Leskinen;P. Kairenius;T. Stefański;A. Bayat;J. Vilkki;K. Shingfield
摘要乳脂减少的生物氢化理论认为，奶牛乳脂减少的原因是瘤胃内脂肪酸的形成。反式-10，顺式-12-共轭亚油酸是唯一已知的抑制乳脂合成的生物氢化中间体，但不确定瘤胃合成增加是否是MFD的唯一解释。采用4头泌乳奶牛按2×2析因设计的4×4拉丁方试验，研究了不同日粮对瘤胃脂肪代谢和乳脂合成的影响。处理包括基于牧草青贮饲料的总混合日粮，其中草料：精料比为35：65或65：35，含有0或50 g/kg向日葵籽油（SO）。与其他处理相比，用SO补充高浓缩饲料将乳脂合成从-20.2%降低到-31.9%。乳脂的减少伴随着有利于反式-10途径的瘤胃生物氢化的改变，以及特定中间体（包括反式-4至反式-10-18：1、反式-8，10-CLA、反式-9，11-CLA和反式-10，15-18：2）形成的增加。反式-10，顺式-12-共轭亚油酸在重瓣的流量是更大的高浓缩比低浓缩饮食，但不受SO。总之，瘤胃反式-10，顺式-12-共轭亚油酸的形成并没有增加饮食引起MFD表明，其他生物氢化中间体或其他机制有助于调节牛乳腺中的脂肪合成。
Abstract The biohydrogenation theory of milk fat depression (MFD) attributes decreases in milk fat in cows to the formation of specific fatty acids (FA) in the rumen. Trans-10, cis-12-CLA is the only biohydrogenation intermediate known to inhibit milk fat synthesis, but it is uncertain if increased ruminal synthesis is the sole explanation of MFD. Four lactating cows were used in a 4×4 Latin square with a 2×2 factorial arrangement of treatments and 35-d experimental periods to evaluate the effect of diets formulated to cause differences in ruminal lipid metabolism and milk fat synthesis on the flow of FA and dimethyl acetal at the omasum. Treatments comprised total mixed rations based on grass silage with a forage:concentrate ratio of 35:65 or 65:35 containing 0 or 50 g/kg sunflower oil (SO). Supplementing the high-concentrate diet with SO lowered milk fat synthesis from −20·2 to −31·9 % relative to other treatments. Decreases in milk fat were accompanied by alterations in ruminal biohydrogenation favouring the trans-10 pathway and an increase in the formation of specific intermediates including trans-4 to trans-10-18 : 1, trans-8, trans-10-CLA, trans-9, cis-11-CLA and trans-10, cis-15-18 : 2. Flow of trans-10, cis-12-CLA at the omasum was greater on high- than low-concentrate diets but unaffected by SO. In conclusion, ruminal trans-10, cis-12-CLA formation was not increased on a diet causing MFD suggesting that other biohydrogenation intermediates or additional mechanisms contribute to the regulation of fat synthesis in the bovine mammary gland.