Aiken G E, Strickland J R, Looper M L, Bush L P, Schrick F N
USDA-ARS, Forage-Animal Production Research Unit, Lexington, KY 40546, USA.
J Anim Sci. 2009 Jun;87(6):2142-50. doi: 10.2527/jas.2008-1562. Epub 2009 Feb 27.
Doppler ultrasonography was used to compare blood flow characteristics in the caudal artery of heifers fed diets with endophyte (Neotyphodium coenophialum) noninfected (E-, 0 microg of ergovaline/g of DM), a 1:1 mixture of endophyte-infected and E- (E+E-; 0.39 microg of ergovaline/g of DM), or endophyte-infected (E+, 0.79 microg of ergovaline/g of DM) tall fescue (Lolium arundinaceum) seed. Eighteen crossbred (Angus x Brangus) heifers [345 +/- 19 kg (SD)] were assigned to individual pens and fed chopped alfalfa hay plus a concentrate that contained E- tall fescue seed for 7 d during an adjustment period. A 9-d experimental period followed with feeding treatments of chopped alfalfa hay plus a concentrate with E+, E-, or E+E- seed being assigned randomly to pens. Doppler ultrasound measurements (caudal artery luminal area, peak systolic velocity, end diastolic velocity, mean velocity, heart rate, and flow rate) and serum prolactin were monitored during the adjustment (3 baseline measures) and during the experimental period (7 measures). Statistical analyses compared proportionate differences between baseline and responses at 3, 27, 51, 75, 171, and 195 h from initial feeding of the experimental diets. Serum prolactin concentrations for E+ and E+E- diets were less (P < 0.001) than baseline concentrations beginning at 27 and 51 h, respectively, from initial feeding of the diets. Although baseline measures were taken when ambient temperatures were likely below thermoneutrality, caudal artery luminal cross-sectional area in E+ heifers had declined (P = 0.004) from baseline by 27 h and remained less (P < 0.02) until 195 h, and caudal artery luminal area declined (P = 0.004) in E+E- heifers from baseline by 51 h and remained less (P < 0.07) until 171 h. Blood flow rate was slower than the baseline rate at 51 h for E+ (P = 0.058) and E+E- (P = 0.02 heifers, but blood flow remained slower in E+E- heifers for 48 h, whereas it remained slower in E+ heifers for 96 h. Adjustments in artery luminal area and blood rate with the 3 diets appeared to parallel the increases in ambient temperature. Heifers fed a diet containing a larger amount of ergot alkaloids had less of a response to ambient temperature than heifers consuming the diet with less or no ergot alkaloids.
使用多普勒超声检查来比较饲喂含内生真菌（Neotyphodium coenophialum）的不同日粮的小母牛尾动脉中的血流特征，这些日粮分别为未感染内生真菌的（E-，麦角缬氨酸含量为0微克/克干物质）、内生真菌感染与未感染的1:1混合物（E+E-，麦角缬氨酸含量为0.39微克/克干物质），或感染内生真菌的（E+，麦角缬氨酸含量为0.79微克/克干物质）高羊茅（Lolium arundinaceum）种子。18头杂交（安格斯×婆罗格斯）小母牛[体重345±19千克（标准差）]被分配到单独的畜栏中，并在适应期内饲喂切碎的苜蓿干草加含有E-高羊茅种子的浓缩料，持续7天。随后是为期9天的试验期，将切碎的苜蓿干草加含有E+、E-或E+E-种子的浓缩料的饲喂处理随机分配到畜栏。在适应期（3次基线测量）和试验期（7次测量）期间监测多普勒超声测量值（尾动脉管腔面积、收缩期峰值速度、舒张末期速度、平均速度、心率和流速）以及血清催乳素。统计分析比较了从开始饲喂试验日粮起3、27、51、75、171和195小时时基线与反应之间的比例差异。E+和E+E-日粮的血清催乳素浓度分别从开始饲喂日粮起27小时和51小时开始低于（P<0.001）基线浓度。尽管基线测量是在环境温度可能低于热中性温度时进行的，但E+小母牛的尾动脉管腔横截面积在27小时时已从基线下降（P = 0.004），并在195小时前一直较低（P<0.02），而E+E-小母牛的尾动脉管腔面积在51小时时从基线下降（P = 0.004），并在171小时前一直较低（P<0.07）。E+（P = 0.058）和E+E-（P = 0.02）小母牛在51小时时的血流速度比基线速度慢，但E+E-小母牛的血流在48小时内一直较慢，而E+小母牛的血流在96小时内一直较慢。3种日粮对动脉管腔面积和血流速度的调节似乎与环境温度的升高平行。饲喂含有较多麦角生物碱日粮的小母牛对环境温度的反应比饲喂含有较少或不含麦角生物碱日粮的小母牛小。
