Phillips C J, Tenlep S Y, Pennell K, Omed H, Chiy P C
Department of Clinical Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge, UK.
Vet J. 2001 Jan;161(1):63-70. doi: 10.1053/tvjl.2000.0519.
A high herbage K:Na ratio increases the risk of ruminal tympany in cattle, which may relate to digestion rate. Experiment 1 examined whether in vitro digestibility of ryegrass was affected by NaCl fertilizer or by Na concentration in artificial saliva. Fertilizer Na increased grass digestibility, but Na in artificial saliva decreased it, probably due to the energy cost of sodium exclusion from bacteria. Increased herbage digestibility with fertilizer Na is therefore not due to additional Na, but may relate to increased water-soluble carbohydrates. Experiment 2 examined whether NaCl fertilizer applied at 35 or 70 kg Na ha(-1)to ryegrass and white clover affected in vitro gas production. Sodium fertilizer increased maximum gas output from grass and rate of production, confirming the increase in grass digestibility recorded previously, but in clover it had the opposite effect, thereby potentially reducing ruminal tympany in cows fed a high legume diet.
牧草中较高的钾钠比会增加牛患瘤胃酸中毒的风险，这可能与消化率有关。实验1研究了黑麦草的体外消化率是否受氯化钠肥料或人工唾液中钠浓度的影响。肥料中的钠提高了草的消化率，但人工唾液中的钠却降低了消化率，这可能是由于细菌排除钠的能量成本所致。因此，肥料钠增加牧草消化率并非由于额外的钠，而是可能与水溶性碳水化合物增加有关。实验2研究了以35或70千克钠/公顷的用量施用于黑麦草和白三叶的氯化钠肥料是否会影响体外产气。钠肥增加了草的最大气体产量和产气速率，证实了之前记录的草消化率的提高，但对三叶草却有相反的效果，从而可能降低采食高豆科植物日粮奶牛的瘤胃酸中毒风险。
