放牧家畜养分消化率的测定

Determination of the nutrient digestibility of herbage consumed by grazing animals

放牧家畜养分消化率反映牧草供给量和营养品质、家畜的健康状况以及生产性能等,是草原管理的关键指标之一。放牧家畜养分消化率的测定方法主要有直接测定和间接估测两种,直接法包括全收粪法、指示剂法、近红外光谱法(NIRS)等,间接法主要有体内或体外发酵法、牧草品质和气候等预测法。全收粪法是较精确的测定方法,然而耗时、费力,对家畜放牧行为有较大影响,难以体现牧场饲草供给的空间异质性;指示剂法根据不溶物的回收比例估测养分消化率,对家畜放牧行为干扰较小,指示剂不易收集,也不适于野性较高的放牧动物;NIRS法效率高、劳动强度低、成本小、不影响家畜,能够大尺度地估测放牧家畜的养分消化率,需要大量的实测数据完善预测模型;气候估测法快捷、省时,精确性较差,适于大时空尺度。放牧家畜的养分消化率与家畜、草地、放牧方法、温度、降水等生物因子,环境因子和社会因子密切相关,与遥感、无人机(UAV)和人工智能等结合,可以准确、快速地测定放牧家畜养分消化率,为草地生态修复与健康管理提供支撑。

Nutrient digestibility of herbage consumed by grazing livestock is one of the key indicators for grassland management,and is a function of both the biomass and nutritional quality of forage,and the health and production status of livestock. Nutrient digestibility of forage consumed by grazing livestock can be determined by direct or indirect methods. The direct methods include,among others,the total feces collection method,the indigestible marker method and near infrared spectroscopy(NIRS). The indirect methods include in vivo or in vitro fermentation digestibility determinations,the forage quality prediction method and the climate prediction method. The total fecal collection method is a comparatively accurate method,provided that the feed dry matter intake and feces dry weight are accurately determined. However,it is time-consuming and laborious,and has a great impact on the grazing behavior. Moreover,it is difficult to reflect the spatial heterogeneity of forage supply in the pasture. The indigestible marker method estimates the nutrient digestibility according to the proportion of indigestible matter recovered and causes little disturbance to the grazing behavior of livestock. However,it is not easy to analyze for the indigestible marker,and the method is not suitable for wild grazing animals. The NIRS method has high efficiency,low labor intensity,low cost,and does not have any effects on livestock,so it can estimate the nutrient digestibility of forage consumed by grazing livestock on a large scale. However,NIRS requires a lot of directly measured calibration data to improve the prediction accuracy. The climate estimation method is fast,and therefore time-saving but is also less accurate. Climate estimation is therefore suitable for large spatial and temporal scales. The nutrient digestibility of forage consumed by grazing livestock is closely related to biological factors,environmental factors and social factors such as livestock class,grassland type,grazing methods employed,temperature and precipitation. Combined with remote sensing,unmanned aerial vehicle methods and artificial intelligence,the nutrient digestibility of forage consumed by grazing livestock can be accurately and quickly measured,providing support for grassland ecological restoration and livestock health and management.