阴外动脉灌注脂多糖对泌乳奶牛乳的成分和脂肪酸组成的影响

摘要

The study was designed to evaluate milk composition, content of synthesis precursors and milk fat constituents in response to the infusion of lipopolysaccharide (LPS) into external pudendal artery of lactating dairy cows. Six multiparous Holstein cows [ (185 ±30) days of lactation, BW = (576 ±36) kg] were randomly divided into two group. A crossover trial design was used in the study, and cows in experimental group and control group were infused LPS (Escherichia coli 0111:B4, 0. 01 μg/kg BW) and physiological saline into external pudendal artery, respectively. The study consisted of 2 experimental periods with 7 d each and a 14-day-intermission between. The results showed as follows; dry matter intake (DMI) was not significantly affected by LPS challenge (P > 0.01); milk protein percentage was significantly increased (P > 0.05), but milk fat percentage was not significantly affected by LPS challenge (P >0. 05) ; LPS challenge also significantly reduced the plasma non-esterified fatty acid (NEFA) content (P <0.01) , which was the synthesis precursor of milk fat, meanwhile, the hydroxybutyric acid (BHA) content tended to decrease at first and then increase (P >0.05); by the challenge of LPS, the contents of saturated fatty acids ( P >0. 05) and short-chain fatty acids (P >0. 05) were decreased, but the ones of unsaturated fatty acids and middle-chain fatty acids were increased (P>0.05), in addition, the desaturation of fatty acids was also affected. It can be concluded that LPS is one of the major factors in affecting milk fat synthesis. [ Chinese Journal of Animal Nutrition, 2011, 23(8) :1317-1323]%本试验旨在研究阴外动脉灌注脂多糖(LPS)对泌乳奶牛乳成分、乳脂合成前体物和脂肪酸组成的影响.选用6头处于泌乳期第(185±30)天、体重(576±36) kg的经产的荷斯坦奶牛,随机分成2组.采用交叉试验设计,试验组阴外动脉灌注LPS(Escherichia coli O111:B4,0.01 μg/kg BW),对照组灌注生理盐水.试验分2期,每期试验7d,2期间隔14 d.结果表明:泌乳奶牛干物质采食量受LPS影响差异不显著(P＞0.05)；LPS显著提高乳中乳蛋白率(P＜0.05),对乳脂率无显著影响(P＞0.05)；LPS极显著降低血浆中乳脂合成前体物非酯化脂肪酸的含量(P＜0.01),β-羟丁酸含量呈先降低后升高的趋势(P＞0.05)；LPS不同程度地降低了乳脂中饱和脂肪酸(P＞0.05)和短链脂肪酸(P＞0.05)的含量,提高了乳脂中不饱和脂肪酸(P＞0.05)和中长链脂肪酸(P＞0.05)的含量,并影响脂肪酸的去饱和作用.结果提示,LPS是诱发乳脂合成发生变化的主要激发因子之一.