日粮磷水平对空怀期云南半细毛羊养分消化率的影响

为研究日粮磷（P）水平对空怀云南半细毛羊养分消化率的影响，选择25只空怀期云南半细毛羊随机分为5组，分别饲喂5种不同磷水平（0.19%、0.32%、0.45%、0.56%和0.64%）日粮，14 d预饲期后进行消化试验（5 d）。采样期每天采集各组精料200 g，粗料200 g。每只羊的鲜粪样混匀称重后取20%分成两份，一份按5%的比例加入10%的稀盐酸进行固氮。每天采集的饲料样和粪样经55℃风干后回潮24 h，粉碎过40目筛，进行相应指标的测定。结果表明：日粮磷水平对钙（Ca）的表观消化率无影响（P>0.05）。随着日粮磷水平的增加，干物质（DM）和粗蛋白质（CP）表观消化率逐渐降低，且0.19%、0.32%磷水平组极显著高于0.64%磷水平组（P<0.01）；能量（EG）、粗脂肪（EE）、粗灰分（Ash）、中性洗涤纤（NDF）和酸性洗涤纤维（ADF）表观消化率逐渐升高后降低再逐渐升高，拐点出现在0.45%磷水平组。随着日粮磷水平的增加，磷的表观消化率逐渐降低，0.19%磷水平组极显著高于0.45%、0.56%、0.64%磷水平组（P<0.01），其他组间差异不显著（P>0.05）。通过回归分析发现，日粮磷水平与干物质、粗蛋白质、磷的表观消化率之间呈显著的线性关系（R²分别为0.7823、0.8386、0.9976）。综上所述，在本试验条件下，日粮磷水平对空怀期云南半细毛羊钙的表观消化率无影响，随日粮磷水平的增加，干物质、粗蛋白质和磷的表观消化率逐渐降低。当日粮磷水平为0.32%时空怀期云南半细毛羊对主要营养成分的表观消化率最高。

Effects of Dietary Phosphorus Level on Nutrient Digestibility in Non-Pregnant Yunnan Semi-fine Wool Ewes

25 non-pregnant Yunnan semi-fine wool sheep were allocated to 5 groups corresponding to 5 dietary treatments with P levels at 0.19%,0.32%,0.45%,0.56% and 0.64%,for investigating the effect of dietary P level on nutrient digestibility.19 d digestion trial were conducted,with 14 d preliminary period and 5 d formal period.During the official period,200 g of concentrate and 200 g of crude material were collected in each group every day.Each feces sample was weighed,20% was taken and divided into two parts,one part was added 10% HCL to fix nitrogen.The percentage of 10% HCL in the mixture was 5% (W/W).Each day,the feed and feces were dried at 55℃,followed by rehydration for 24 hours.Then the dry samples were smashed and filtrated through 40 meshes,and the corresponding indicators were determined.The results showed that dietary P levels significantly affected nutrient digestibility,with the exclusion of Ca digestibility.Digestibility of DM and CP decreased with the elevated dietary P levels,and that in 0.19% and 0.32% P level groups was higher than that in 0.64% P group (P<0.01).Digestibility of gross energy,crude fat,ash,NDF and ADF increased with the increasing of P levels,then decreased till dietary P reached 0.45%,after that it increased again with the inflexion of 0.45% P level.Digestibility of P decreased with the elevated dietary P levels,and that in 0.19% P group was higher than that in 0.45%,0.56% and 0.64% P level (P<0.01).There was no differences on P digestibility among other groups (P>0.05).Regression analysis revealed that the linear relationship between dietary P levels and digestibility of DM,CP and P were significant (R² were 0.7823,0.8386 and 0.9976,respectively).In conclusion,dietary P levels did not affect Ca digestibility.Digestibility of DM,CP and P decreased with the elevated dietary P levels.The highest digestibility of nutrients always happened in 0.32% group.