饲粮磷水平对空怀期云南半细毛羊养分排泄和氮平衡的影响

Effects of Dietary Phosphorus Level on Nutrient Excretions and Nitrogen Balance of Yunnan Semi-Fine Wool Sheep during Non-Pregnancy Period

本试验旨在研究饲粮磷水平对空怀期云南半细毛羊氮、钙、磷排泄和氮平衡的影响。选择体况良好、体重(46.36±2.77)kg、38月龄的经产2胎空怀期云南半细毛羊50只,按体重随机分为5组,每组10只,每只羊为1个重复。5组试验羊分别饲喂磷水平为0.19%、0.32%、0.45%、0.56%和0.64%的饲粮,饲粮其他营养水平基本保持一致。所有试验羊进行为期44 d的饲养试验,其中预试期14 d,正试期30 d。在正试期第9天从各组中选取5只母羊,放入代谢笼中预饲3 d,在第12~16天(5 d)进行消化代谢试验。结果表明:1)饲粮磷水平对氮总排泄量和尿氮排泄量的影响不显著(P>0.05);0.45%磷水平组粪氮排泄量显著高于0.32%磷水平组(P<0.05),与0.19%、0.56%和0.64%磷水平组差异不显著(P>0.05)。2)随着饲粮磷水平的升高,磷总排泄量和粪磷排泄量极显著升高(P<0.01);尿磷排泄量以0.64%磷水平组最高,0.19%磷水平组最低,而0.32%、0.45%和0.56%磷水平组间差异不显著(P>0.05)。3)钙总排泄量和粪钙排泄量均以0.19%磷水平组最高,显著高于0.45%、0.56%和0.64%磷水平组(P<0.05),以0.64%磷水平组最低,极显著低于其他各组(P<0.01);尿钙排泄量以0.32%磷水平组最高,显著高于0.19%、0.56%和0.64%磷水平组(P<0.05),以0.56%磷水平组最低,显著低于其他各组(P<0.05)。4)0.19%、0.32%和0.45%磷水平组干物质采食量显著高于0.56%和0.64%磷水平组(P<0.05);0.19%磷水平组食入氮和沉积氮极显著高于其他各组(P<0.01),0.32%和0.45%磷水平组食入氮显著高于0.56%和0.64%磷水平组(P<0.05),沉积氮在0.32%、0.45%、0.56%和0.64%磷水平组间无显著差异(P>0.05);氮沉积率以0.19%磷水平组最高,显著高于0.45%、0.56%和0.64%磷水平组(P<0.05),与0.32%磷水平组差异不显著(P>0.05);5个组试验羊的氮平衡均为正氮平衡。综上所述,饲粮磷水平在0.19%~0.32%时既可以提高空怀期云南半细毛羊的沉积氮和氮沉积率,又有利于减少氮、磷排泄量,降低环境污染。

The current study was conducted to evaluate the effects of dietary phosphorus(P)level on excretions of nitrogen(N),calcium(Ca)and phosphorus(P)and N balance of non-pregnant Yunnan semi-fine wool sheep during non-pregnant period.Fifty healthy non-pregnant multiparous Yunnan semi-fine wool sheep at the age of 30 months and with the body weight of(46.36±2.77)kg were randomly divided into 5 groups with 10 replicates per group and 1 ewe per replicate.The P levels of diets for 5 groups were 0.19%,0.32%,0.45%,0.56%and 0.64%,respectively,and other nutrient levels in the diets were essentially consistent.The experiment lasted for 44 d.There was a pretrial period of 14 d followed by an experimental period of 30 d.On the 9th day of the experimental period,five ewes were randomly selected from each group for digestion and metabolism experiment with a 3-d pretrial period by a 5-d trial period(the 12th to 16th day).The results showed as follows:1)dietary P level had no significant effects on the excretions of total N and urine N(P>0.05).Fecal N excretion in 0.45%P level group was significantly higher than that in 0.32%P level group(P<0.05);however,there was no significant difference compared with 0.19%,0.56%and 0.64%P level groups(P>0.05).2)Excretions of total P and fecal P were significantly increased with the dietary P level increasing(P<0.01).Urine P excretion was the highest in 0.64%P level group and the lowest in 0.19%P level group(P<0.01),while there was no significantly difference among 0.32%,0.45%and 0.56%P level groups(P>0.05).3)Excretions of total Ca and fecal Ca were the highest in 0.19%P level group,which was significantly higher than those in 0.45%,0.56%and 0.64%P level groups(P<0.05).The lowest excretions of total Ca and fecal Ca were observed in 0.64%P level group,which was significantly lower than those in other groups(P<0.01).Similarly,urine Ca excretion was the highest in 0.32%P level group,which was significantly higher than that in 0.19%,0.56%and 0.64%P level groups(P<0.05);however,the lowest urine Ca excretion was found in 0.56%P level group,which was significantly lower than that in other groups(P<0.05).4)Dry matter intake(DMI)in 0.19%,0.32%and 0.45%P level groups was significantly higher than that in 0.56%and 0.64%P level groups(P<0.05).N intake and N retention in 0.19%P level group were significantly higher than those in other groups(P<0.01),and the N intake in 0.32%and 0.45%P level groups was significantly higher than that in 0.56%and 0.64%P level groups(P<0.05).There was no significant difference in the N retention among 0.32%,0.45%,0.56%and 0.64%P level groups(P>0.05).The highest N retention rate was observed in 0.19%P group,which was significantly than that in 0.45%,0.56%and 0.64%P level groups(P<0.05);however,there was no significant difference between 0.19%and 0.32%P level groups(P>0.05).Nitrogen balance in the 5 groups was positive.According to above findings,when the dietary P level is 0.19%to 0.32%,it is beneficial to enhance the N retention and N retention rate of Yunnan semi-fine wool ewes during non-pregnancy period,decrease the excretions of N and P,and reduce environmental pollution.