不同种类精饲料中磷的瘤胃降解特性研究

测定了谷物籽实、豆类籽实及根茎三类共计15种饲料的磷含量,并应用尼龙袋法测定其在山羊瘤胃内的降解率。结果表明：三类饲料的磷含量存在明显差异,以豆类籽实最高,谷物籽实其次,根茎类最低。饲料种类间磷的瘤胃降解率差异极显著（P〈0.001）,谷物类、豆类和根茎类饲料中快速降解磷（A）分别以玉米（88.82%）、豌豆（92.66%）和红薯（94.69%）最高,而以大米、赤豆和木薯为最低。除大麦、大米和小米外,其他饲料的快速降解磷均在60%以上。除小麦外,慢速降解的磷（B）都低于40%。磷在瘤胃中的降解速率（C）都超过10%/h以上,仅大米、小米和土豆的慢速降解部分的降解速率低于10%/h。不同种类精饲料总的可降解磷（A＋B）都在80%以上。不同种类饲料磷的有效降解率都随外流速率的增大而下降,除大米和小米外,其他饲料磷的有效降解率都超过了80%。饲料中磷的含量与磷的有效降解率呈显著正相关关系,磷的降解速率与粗脂肪含量呈极显著正相关关系,淀粉含量则与磷的有效降解率呈显著负相关关系,磷的含量与粗蛋白含量间呈极显著正相关关系。上述结果显示,饲料中磷在瘤胃中绝大部分都可释放出来,故配制反刍动物日粮时必须考虑饲料原料中磷的含量及其有效降解率。

Study on in situ phosphorus rumen degradability of several feeds in growing goats fed a maize stover-based diet

The rumen phosphorus degradabilities were determined for cereals,beans and earthnuts,three types and fifteen varieties feedstuffs,using the nylon bag technique in growing goats.The results showed that phosphorus contents had significant difference in different feedstuffs,the phosphorus content was the highest in beans,followed by cereals,the least one was earthnuts.There were significant differences(P<0.001) in phosphorus rumen degradability among different feedstuffs,the rapidly degradable phosphorus fraction(A) was highest for maize(88.82%),pea(92.66%) and sweat potato(94.69%) in cereal,beans and earthnuts,respectively.The A values of rice,rice bean and tapioca were the least in three types of feedstuffs.The A values were basically above 60% except for barley,rice and millet.Nevertheless,the slowly degradable phosphorus fractions(B) of feedstuffs were below 40% except for wheat.The phosphorus degradation rates(C) of rice,millet and potato were below 10%/h,the others were all above 10%/h.The total degradable phosphorus(A B) of all varieties was above 80%.Effective degradabilities were decreased with increasing the ruminal outflow rates,which were above 80% except for rice and millet.Effective degradability had a remarkable positive relationship(P<0.001) with the phosphorus content,had a negative correlation(P<0.001) with the starch content.The phosphorus degradation rate had a remarkable positive correlation(P<0.001) with the crude fat content.The phosphorus content had a greatly positive correlation with the crude protein content.This experiment indicated that phosphorus in feedstuffs was almost completely degraded in the rumen,it suggests that the phosphorus content in feedstuffs be considered for the ration formulation of ruminants.