Effects of a subacute ruminal acidosis model on the diet selection of dairy cows
Effects of a subacute ruminal acidosis model on the diet selection of dairy cows
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DOI：
10.3168/jds.s0022-0302(02)74419-6
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发表时间：
2002-12-01
影响因子：
3.5
通讯作者：
McBride, BW
中科院分区：
文献类型：
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作者：
Keunen, JE;Plaizier, JC;McBride, BW
本试验通过两个试验研究了亚急性瘤胃酸中毒（SARA）模型对奶牛日粮选择的影响。在第一个试验中，25%的自由采食的干物质摄入量（WBP）的总混合日粮（TMR）被替换为小麦-大麦颗粒（WBP，50%小麦粉，50%大麦粉）。在4头泌乳中后期奶牛中通过留置式探针连续测定瘤胃pH值。这种饮食变化使瘤胃pH值降低了0.14 +/- 0.02 pH单位（平均SE），并将低于pH 6.0的时间从319 +/- 86 min（-1）增加到641 +/- 36 min（-1）。因此，营养模型成功诱导SARA。第二个实验确定了与苜蓿颗粒相比，诱导SARA是否增加了对长苜蓿干草的饲料偏好。诱导SARA的2 wk与1个对照wk间隔。四头奶牛在SARA和对照饮食中选择2种饲料，每天2次，持续30分钟。与对照周（0.60 +/- 0.03）相比，两个SARA周期间苜蓿干草的偏好比（PR =干草消耗量/干草+颗粒消耗量）更大（0.85 +/-0.03）。在SARA周中，与对照组相比，平均瘤胃pH值低0.23 +/- 0.03单位，低于pH 6.0和5.6的时间更长。这些结果表明，当给予饲料选择时，奶牛改变其饮食选择以试图减弱SARA。
Two experiments were conducted to study the effects of a subacute ruminal acidosis (SARA) model on diet choice in dairy cows. In the first experiment, 25% of the ad libitum dry matter intake (DMI) of the total mixed ration (TMR) was replaced with wheat-barley pellets (WBP, 50% ground wheat, 50% ground barley). Rumen pH was measured continuously via in-dwelling probes in 4 mid to late lactation cows. This diet change reduced rumen pH by 0.14 +/- 0.02 pH units (mean SE) and increased time below pH 6.0, from 319 +/- 86 min(-1) to 641 +/- 36 min(-1). Hence, the nutritional model successfully induced SARA. The second experiment determined if inducing SARA increases the feed preference for long alfalfa hay compared with alfalfa pellets. The 2 wk of inducing SARA were separated by 1 control wk. Four cows on either SARA and control diets were given a choice of 2 feeds, 2 times per d, for 30 min. The preference ratios (PR = Amount of Hay consumed/Amount of Hay + Pellets consumed) for alfalfa hay during two SARA weeks was greater (0.85 +/- 0.03) compared with the control week (0.60 +/- 0.03). In SARA weeks, average rumen pH was 0.23 +/- 0.03 units lower, and time below pH 6.0 and 5.6 was higher compared to control. These results suggest that when given a choice of feeds, dairy cows alter their diet selection to attempt to attenuate SARA.