云贵高原石漠化地区人工草场营养价值评价研究

The nutritional value evaluation of artificial grassland in karst region in Yunnan-Guizhou Plateau

人工草地是云贵高原石漠化地区的主要放牧地。本研究通过放牧试验、饲喂试验和消化代谢试验相结合的方法,评价了云贵高原石漠化地区2个人工草场的营养价值和转化效率。放牧试验结果表明,相同放牧压力下,永善试验地的土壤养分、微量元素和牧草产量显著低于寻甸试验地,但两地人工草地中牧草的营养成分没有显著差异。饲喂试验结果表明,绵羊对永善试验地牧草的利用效率要高于寻甸试验地,绵羊对永善试验地牧草中Mg、Fe、Cu、Mn等元素的消化率和沉积率均显著高于寻甸试验地。消化代谢试验结果表明,寻甸试验地粗蛋白、粗脂肪、粗灰分、粗纤维、无氮浸出物等牧草养分的含量高于永善试验地,绵羊的消化率也高;采食量和体增重2个指标的各自变化趋势也和以上研究结果基本相同。上述结果表明,虽然永善试验地牧草土壤相对贫瘠,牧草产量低,但家畜转化效率高,因此高原石漠化地区应在牧草成熟期后放牧绵羊,并补饲一定的微量元素。

Artificial grassland is main rangeland in Karst region in Yunnan-Guizhou Plateau. In this paper, nutritional value and conversion efficiency of grasses of two artificial grasslands were tested through grazing test, feeding experiment, and digestion and metabolism trial. Testing under the same grazing pressure, grazing experiment showed that soil nutrients, trace elements and forage yield of Yongshan Artificial Grassland was significantly lower than Xundian Artificial Grassland, but no significant difference in nutritional content between the two artificial grasslands were detected. Feeding trial showed that grass usage efficiency by sheep on Yongs-han Artificial Grassland was higher than Xundian Artificial Grassland, digestibility and deposition rate of min- eral trace elements in sheep grazing on Yongshan Artificial Grassland were significant higher than Xundian Artificial Grassland. Digestion metabolic test showed that nutrient content including crude protein, crude fat, crude ash, crude fiber, nitrogen free extract in grasses of Xundian Artificial Grassland were higher than Yongs-han Artificial Grassland. Comparison of digestive rate, feed intake and body weight gain of sheep gazing on the two artificial grasslands showed the same trend with nutrient content. The above results indicated that, a high conversion efficiency was produced by livestock grazing on Yongshan Artificial Grassland, where was a relative- ly barren field with a lower forage production than Xundian Artificial Grassland. According to the results, we proposed to feed on livestock after maturity of grasses, and supplementation of certain trace elements. At the same time, we proposed, grass and artificial grassland nutritive value evaluation needs not only the determination of its nutritional content, but also its final value, namely, animal weight gain, because conversion efficiency of livestock directly affects the efficiency of grassland animal husbandry. The output of artificial grassland can only be evaluated accurately by combination of nutrition value evaluation and livestock conversion efficiency estimation.