季节变化及不同加工方式对旋扭山绿豆牧草缩合单宁含量的影响

Effect of different seasons and processing methods on condensed tannin content in Desmodium intortum

缩合单宁普遍存在于热带亚热带豆科牧草中,其含量的高低会影响到动物的饲养效果。文章研究了不同季节及不同加工方式对旋扭山绿豆牧草缩合单宁含量的影响。结果表明,除高温夏季外,旋扭山绿豆的缩合单宁含量均较为适中。加工存储不但导致旋扭山绿豆缩合单宁含量的下降,还会改变3种类型单宁的比例,与鲜草相比,草粉、颗粒料和青贮饲料的缩合单宁含量分别下降了38.3%、43.1%和94.6%,蛋白结合缩合单宁的占比在草粉和颗粒料中下降,而在青贮料中却显著升高。因此,在高温季节,尽管旋扭山绿豆牧草的营养价值会因高水平的缩合单宁而降低,但是通过改善栽培措施及制粒或青贮等存贮方式可以把缩合单宁含量降低到合理的水平。

Condensed tannins(CT) are ubiquitous in most of the tropical and subtropical forage and variation for their concentrations will impact animal performance. Studies were carried out to investigate the effects of season, processing and storage on the variability of CT in Desmodium intortum. The results showed that except for hot summer season, Desmodium intortum had moderate CT concentrations. The storage processes not only led to the decrease of CT level, but also altered the ratio of the three CT fractions. Compared with fresh forage, the CT in powder, pellet and silage decreased by 38.3%,43.1% and 94.6%, respectively, and the proportion of protein-bound CT in powder and pellet declined while in silage were significantly increased. Thus, although Desmodium intortum forage showed low nutritional value during hot season due to high level of CT, the improved cultivation or storage processes such as pelleting or silaging was effective for reducing CT to a reasonable level.