饲粮蛋白质水平对空怀期云南半细毛羊氮沉积和养分排放的影响

Effects of Dietary Protein Level on Nitrogen Deposition and Nutrient Emissions of Non-Pregnant Yunnan Semi-Fine Wool Ewes

本试验旨在研究饲粮蛋白质水平对空怀期云南半细毛羊氮沉积和养分排放的影响,以期为空怀期云南半细毛羊饲粮配比和减少环境负荷研究提供理论参考。试验选用50只体况良好、体重相近、38月龄的空怀期云南半细毛羊,随机分成5个组(每组10只),分别饲喂蛋白质水平为7.60%(组1)、9.49%(组2)、11.29%(组3)、11.56%(组4)和14.96%(组5)的饲粮,饲粮其他营养水平保持一致。试验羊进行19d的饲养试验,其中预试期14d,正试期5d。正试期从每组选择5只试验羊进行消化代谢试验,试验羊在代谢笼中单笼饲养,采用全收粪尿法连续收集5d粪便,并采集饲粮样品。结果表明:1)饲粮蛋白质水平对空怀期云南半细毛羊的干物质采食量和粪干物质排放量无显著影响(P>0.05)。2)随着饲粮蛋白质水平的升高,氮摄入量呈显著或极显著增加(P<0.05或P<0.01);组3的氮沉积率极显著高于组1(P<0.01),其他组间差异不显著(P>0.05)。3)粪氮排放量随饲粮蛋白质水平的升高逐渐增加,组2与组1、组3差异不显著(P>0.05),其他组间差异极显著(P<0.01);粪钙排放量以组3最低(5.04g/d),且极显著低于组5(P<0.01);粪磷排放量随饲粮蛋白质水平的升高逐渐增加,组1、组2、组3极显著低于组5(P<0.01),组4显著低于组5(P<0.05)。4)尿氮排放量随着饲粮蛋白质水平的升高逐渐增加,组2与组1、组3差异不显著(P>0.05),其他组间差异极显著(P<0.01);尿钙排放量以组3最低,为1.18g/d,比组1、组5分别降低0.53和0.78g/d;尿磷排放量组1显著低于组5(P<0.05),其他各组间差异不显著(P>0.05)。5)粪尿氮排放总量组5极显著高于其他组(P<0.01),粪尿钙排放总量组3极显著低于其他组(P<0.01),粪尿磷排放总量组1、组2极显著低于组5(P<0.01)。6)粪氮占比为72.44%~42.06%,随着饲粮蛋白质水平的升高逐渐降低,尿氮占比为27.56%~57.94%,随着饲粮蛋白质水平的升高逐渐升高;粪、尿钙和磷占比各组间差异不显著(P>0.05)。综合各项指标,在本试验条件下,当饲粮蛋白质水平为11.29%时,空怀期云南半细毛羊的氮沉积最佳,粪尿钙排放总量最低;饲粮蛋白质水平在一定范围(7.06%~11.56%)时对空怀期云南半细毛羊粪尿磷排放总量无显著影响;空怀期云南半细毛羊对钙、磷的排放以从粪中排放为主,多余的氮则主要从尿中以尿氮的形式排出。

This experiment was conducted to study the effects of dietary protein level on nitrogen deposition and nutrient emissions of non-pregnant Yunnan semi-fine wool ewes,in order to provide a theoretical reference for non-pregnant Yunnan semi-fine wool ewes diet proportion and environmental load reduction.Fifty health non-pregnant Yunnan semi-fine wool ewes with similar body weight and at the age of 38 months were randomly divided into 5 groups with 10 ewes per group.Ewes in the 5 groups were fed diets with different proteins levels [7.60%(group 1),9.49%(group 2),11.29%(group 3),11.56%(group 4) and 14.96%(group 5),respectively] and the same other nutrient levels.All the tested sheep were reared for 19 days,including 14 days of pre-test and 5 days of formal trial.During the formal trial period,five sheep were selected from each group for digestion and metabolism test.The test sheep were raised in a single cage in a metabolic cage.The feces and urine were collected continuously for 5 days,and diet samples were collected.The results showed as follows: 1) dietary protein level had no significant effects on dry matter intake and fecal dry matter emission of non-pregnant Yunnan semi-fine wool ewes ( P >0.05).2) With the increase of dietary protein level,nitrogen intake was increased significantly ( P <0.05 or P <0.01);nitrogen deposition rate in group 3 was significantly higher than that in group 1 ( P <0.05),but there was no significant difference among other groups ( P >0.05).3) With the increase of dietary protein level,fecal nitrogen emission was gradually increased,there was no significant difference between group 2 and groups 1 and 3 ( P >0.05),but there was significant difference among other groups ( P <0.01);fecal calcium emission in group 3 was the lowest (5.04 g/d),which was significantly lower than that in group 5 ( P <0.01);fecal phosphorus emission was gradually increased with the increase of dietary protein level,and it in group 5 was significantly higher than that in other groups ( P <0.05 or P <0.01 ).4) With the increase of dietary protein level,urinary nitrogen emission was gradually increased,there was no significant difference between group 2 and groups 1 and 3 ( P >0.05),but there was significant difference among other groups ( P <0.01);fecal calcium emission in group 3 was the lowest (1.18 g/d),and it was decreased by 0.53 and 0.78 g/d compared with groups 1 and 5,respectively;urinary phosphorus emission in group 1 was significantly lower than that in group 5 ( P <0.05),but there was no significant difference among other groups ( P >0.05).5) Fecal and urinary nitrogen total emission in group 5 was significantly higher than that in other groups ( P <0.01),fecal and urinary calcium total emission that in group 3 was significantly lower than that in other groups ( P <0.01),and fecal and urinary phosphorus total emission in groups 1 and 2 was significantly lower than that in group 5 ( P <0.01).6) Fecal nitrogen rate was 42.06% to 72.44% and urinary nitrogen rate was 27.56% to 57.94%,the fecal nitrogen rate was gradually decreased and the urinary nitrogen rate was gradually increased with the increase of dietary protein level.No significant differences were found in fecal and urinary calcium and phosphorus rates among groups ( P >0.05).By comprehensive consideration,under the condition of this experiment,when dietary protein level is 11.29%,the nitrogen deposition of non-pregnant Yunnan semi-fine wool ewes is the best,and the calcium total emission from feces and urine is the lowest.Dietary protein level within a certain range (7.06% to 11.56%) has no significant effects on phosphorus total emission from feces and urine.For non-pregnant Yunnan semi-fine wool ewes,the calcium and phosphorus emissions are mainly from feces,and the excess nitrogen was mainly discharged as urine nitrogen from urine.