本试验研究了阴外动脉灌注乳脂前体物对奶牛产奶量及乳腺内短链脂肪酸摄取规律的影响。选择8头健康荷斯坦奶牛分为2组，每组4头牛。采用2×2交叉试验设计，2组分别饲喂2种不同粗饲料[苜蓿（MF组）、玉米秸秆（CS组）]的饲粮，饲粮的精粗比为45∶55。试验分为2阶段，每阶段20 d，其中预试期14 d，载体灌注期3 d，乳脂前体物灌注期3 d。在载体灌注期，MF组与CS组均接受载体灌注，分别命名为MFC₁组和CSC组；在乳脂前体物灌注期，MF组继续接受载体灌注（MFC₂组），CS组灌注乳脂前体物（CSF组）。测定产奶量、干物质采食量及乳成分。采集尾动脉和乳静脉血浆测定短链脂肪酸浓度和脂肪酸比例。结果表明：1）在灌注乳脂前体物前，CSC组产奶量、4%乳脂校正乳产量、乳脂产量、乳蛋白产量和产乳脂效率显著低于MFC₁组（P<0.05），CSC组尾动脉血浆中短链脂肪酸浓度及短链脂肪酸/长链脂肪酸有低于MFC₁组的趋势（0.05≤P < 0.10）。2）灌注乳脂前体物后，CSF组产乳脂效率和乳蛋白率显著高于CSC组（P<0.05），CSF组产奶量、4%乳脂校正乳产量、乳脂率和乳蛋白率尽管在数值上仍然低于MFC₂组，但组间差异不显著（P>0.05），而CSF组产乳脂效率显著高于MFC₂组（P<0.05）。3）灌注乳脂前体物后，CSF组尾动脉血浆中乙酸、丙酸以及短链脂肪酸浓度显著高于CSC组（P<0.05），且乙酸、丁酸及短链脂肪酸浓度显著高于MFC₂组（P<0.05），短链脂肪酸/长链脂肪酸有低于MFC₂组的趋势（0.05≤P < 0.10）。4）除CSF组丁酸动静脉差有高于CSC组的趋势（0.05≤P < 0.10）外，CSC组与MFC₁组、CSC组与CSF组、CSF组与MFC₂组乳腺对乙酸、丙酸、丁酸、短链脂肪酸的摄取量、摄取率和动静脉差均无显著差异（P>0.05）。结果提示，以玉米秸秆为粗饲料奶牛灌注乳脂前体物可显著增加奶牛的产奶量、乳脂率和乳脂产量，并达到与以苜蓿等为粗饲料相似的水平，且具有较高的产乳脂效率，但对乳腺内短链脂肪酸的摄取量和摄取率无显著的影响。

This experiment was conducted to investigate the effects of infusing milk fat precursors to external pudic artery on milk yield and uptake rule of short-chain fatty acids in mammary gland of dairy cows. Eight healthy Holstein cows were divided into two groups with four cows per group. A 2×2 cross-over experimental design was adopted. Cows in the two groups were fed diets with two kinds of roughages: corn stover (CS group) and alfalfa (MF group), and the diet concentrate to roughage ratio was 45∶55. The experiment was divided into two stages, and each stage lasted for 20 days, including 14 days of preliminary feeding period, 3 days of carrier infusion phase and 3 days of milk fat precursors infusion phase. During carrier infusion period, MF group and CS group received carrier infusion, and were named MFC₁ group and CSC group, respectively; during milk fat precursors infusion period, MF group continued to accept carrier infusion (MFC₂ group), while CS group accepted milk fat precursors infusion (CSF group). Milk yield, dry matter intake and milk composition were determined. Plasma in caudal artery and internal mammary vein was collected to determine short-chain fatty acid concentrations and fatty acid proportions. The results showed as follows: 1) before milk fat precursors infusion, CSC group had significantly lower milk yield, 4% fat corrected milk (FCM) yield, milk fat yield, milk protein yield and milk fat producing efficiency than MFC1 group (P<0.05), and short-chain fatty acid concentration and short-chain fatty acid to long-chain fatty acid rate in plasma of caudal artery in CSC group tended to be higher than those in MFC₁ group (0.05≤P < 0.10). 2) After milk fat precursors infusion, milk fat producing efficiency and milk protein percentage in CSF group were significantly higher than those in CSC group (P<0.05), and CSF group still below in MFC₂ group in milk yield, 4% FCM yield, milk fat percentage and milk protein percentage, but no significant differences was found between groups (P>0.05); CSF group was significantly higher than MFC₂ group in milk fat producing efficiency (P<0.05). 3) After milk fat precursors infusion, the concentrations of acetic acid, propionic acid and short-chain fatty acids in plasma of caudal artery in CSF group were significantly higher than those in CSC group (P<0.05), and the concentrations of acetic acid, butyric acid and short-chain fatty acids in CSF group was significantly higher than those in MFC₂ group (P<0.05), but short-chain fatty acids to long-chain fatty acids rate in CSC group tended to be lower than that in MFC₂ group (0.05≤P < 0.10). 4) Except that artery-vein difference of butyric acid in CSF group tended to be higher than that in CSC group (0.05≤P < 0.10), and there were no significant differences in uptake quantity, uptake rate and artery-vein difference of acetic acid, propionic acid, butyric acid and short-chain fatty acids between CSC group and MFC₁ group, CSC group and CSF group, CSF group and MFC₂ group (P>0.05). The results indicate that dairy cows fed corn stover as roughage infused milk fat precursors can significantly increase the milk yield, milk fat percentage and milk fat yield, and closely achieves the levels in dairy cows fed alfalfa as roughage, especially has producing efficiency of milk fat, but has no significant effects on uptake quantity, uptake rate of short-chain fatty acids in mammary gland.