Acetate Dose-Dependently Stimulates Milk Fat Synthesis in Lactating Dairy Cows
Acetate Dose-Dependently Stimulates Milk Fat Synthesis in Lactating Dairy Cows
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DOI：
10.3945/jn.116.245001
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发表时间：
2017-05-01
影响因子：
4.2
通讯作者：
Harvatine, Kevin J.
中科院分区：
文献类型：
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作者：
Urrutia, Natalie L.;Harvatine, Kevin J.
背景：醋酸酯是一种短链脂肪酸，对奶牛特别重要，因为它是从头合成脂肪酸的主要底物。目的：研究增加醋酸盐供应对哺乳期奶牛乳脂合成的影响。方法：6头经产荷斯坦奶牛随机分成两组，采用重复设计，研究醋酸盐供应对乳脂合成的影响。试验设0(对照组)、5、10、15摩尔醋酸酯/d 4个处理，连续4d，测定瘤胃内短链脂肪酸、血浆激素及代谢产物、乳脂浓度、乳脂肪含量和乳脂肪酸组成。结果：与对照组相比，添加5、10和15摩尔/d的醋酸组乳脂量分别增加7%、16%和14%，乳脂浓度线性增加6%、9%和11%(P<；0.001)。乳脂产量的增加主要是由于16碳脂肪酸的线性增加(P<；0.001)和从头合成的FA的二次增加(<；16-碳FAs；P<；0.01)，表明有从头合成途径的刺激。醋酸盐到乳脂的表观转移率分别为33.4%、36.2%和20.6%(5、10、15摩尔/d)。饲喂醋酸盐能线性提高瘤胃醋酸酯的相对浓度(P<；0.001)，但不能提高饲喂后的瘤胃醋酸酯相对浓度。与对照组相比，饲喂后醋酸盐线性增加血浆β-羟丁酸29%、50%和78%(P<；0.01)。结论：增加哺乳奶牛的醋酸盐供应可以增加乳脂的合成，这表明增加瘤胃醋酸盐吸收的营养策略有望通过增加乳脂的新合成来增加乳脂。
Background: Acetate is a short-chain fatty acid (FA) that is especially important to cows because it is the major substrate for de novo FA synthesis. However, the effect of acetate supply on mammary lipid synthesis is not clear.Objective: The objective of this experiment was to determine the effect of increasing acetate supply on milk fat synthesis in lactating dairy cows.Methods: Six multiparous lactating Holstein cows were randomly assigned to treatments in a replicated design to investigate the effect of acetate supply on milk fat synthesis. Treatments were 0 (control), 5, 10, and 15 mol acetate/d continuously infused into the rumen for 4 d. Rumen short-chain FAs, plasma hormones and metabolites, milk fat concentration, and milk FA profile were analyzed on day 4 of each treatment. Polynomial contrasts were used to test the linear and quadratic effects of increasing acetate supply.Results: Acetate increased milk fat yield quadratically (P < 0.01) by 7%, 16%, and 14% and increased milk fat concentration linearly (P < 0.001) by 6%, 9%, and 11% for 5, 10, and 15 mol acetate/d, respectively, compared with the control treatment. Increased milk fat yield predominantly was due to a linear increase in 16-carbon FAs (P < 0.001) and a quadratic increase in de novo synthesized FAs (< 16-carbon FAs; P < 0.01), indicating that there was stimulation of de novo synthesis pathways. Apparent transfer of acetate to milk fat was 33.4%, 36.2%, and 20.6% for 5, 10, and 15 mol/d, respectively. Acetate infusion linearly increased the relative concentration of rumen acetate (P < 0.001) before feeding, but not after feeding. Acetate linearly increased plasma beta-hydroxybutyric acid by 29%, 50%, and 78%, respectively, after feeding compared with the control treatment (P < 0.01).Conclusions: Increasing acetate supply to lactating cows increases milk fat synthesis, suggesting that nutritional strategies that increase ruminal acetate absorption would be expected to increase milk fat by increasing de novo FA synthesis.