本试验旨在探讨饲粮钙水平对妊娠中期和后期云南半细毛羊氮平衡和氮磷排放的影响，为从环保角度阐明妊娠期云南半细毛羊饲粮钙添加量提供理论依据。试验选用50只体况良好、体重相近、配种日期一致的经产2胎妊娠期云南半细毛羊，随机分成5个组，每组10只。5组试验羊在妊娠中期分别饲喂钙水平为0.42%、0.45%、0.56%、0.65%和0.82%的饲粮，在妊娠后期分别饲喂钙水平为0.40%、0.50%、0.60%、0.69%和0.87%的饲粮。试验期共104 d，其中预试期14 d，正试期90 d。在妊娠中期和后期分别从各组中选择5只试验羊进行为期5 d的消化代谢试验。结果表明：妊娠中期，0.82%组沉积氮及氮沉积率显著高于0.56%组（P<0.05），其他组间差异不显著（P>0.05）。妊娠后期，0.69%组和0.87%组沉积氮极显著高于其他组（P<0.01），其他组间差异不显著（P>0.05）；0.69%组和0.87%组氮沉积率极显著高于0.50%组（P<0.01），显著高于0.40%组和0.60%组（P<0.05），其他组间差异不显著（P>0.05）。无论是在妊娠中期还是在妊娠后期，5组的氮平衡均为正平衡。妊娠中期饲粮钙水平为0.65%时粪干物质排放量最低，妊娠后期粪干物质排放量不受饲粮钙水平的显著影响（P>0.05）；妊娠中期0.56%组、妊娠后期0.40%组尿排放量极显著高于其他组（P<0.01），其他组间差异不显著（P>0.05）。随饲粮钙水平的提高，妊娠中期云南半细毛羊氮、磷总排放量无显著变化（P>0.05）。在妊娠后期，饲粮钙水平对云南半细毛羊氮总排放量的影响不显著（P>0.05），但0.87%组磷总排放量显著低于其他组（P<0.05）。由此得出，在本试验条件下，饲粮钙水平显著影响妊娠中期和后期云南半细毛羊的沉积氮和氮沉积率，沉积氮和氮沉积率在妊娠中期以0.82%组最高，在妊娠后期以0.69%组和0.87%组较高；饲粮钙水平对妊娠中期和后期云南半细毛羊氮总排放量无显著影响，对妊娠中期磷总排放量也无显著影响。

This study aimed to elucidate the effects of dietary calcium (Ca) level on nitrogen balance and emission of nitrogen and phosphorus of Yunnan semi-fine wool sheep in mid and late gestations, for providing theoretical guidance of Ca supplementation in the diet of Yunnan semi-fine wool sheep from the perspective of environmental protection. Fifty multiparous sheep in good body condition and with similar body weight and breeding date were randomly blocked to 5 groups with 10 sheep in each group. Sheep in the 5 groups were fed diets with varying Ca levels which were 0.42%, 0.45%, 0.56%, 0.65% and 0.82% in mid gestation, and 0.40%, 0.50%, 0.60%, 0.69% and 0.87% in late gestation, respectively. The experiment lasted for 104 days, with the first 14 d as the preliminary period and the following 90 d as the formal period. Five sheep from each group were selected in mid and late gestations for digestion and metabolism trial, and the digestion and metabolism trial lasted for 5 days. The results showed that nitrogen retention and nitrogen retention rate in mid gestation in 0.82% group were significantly higher than those in 0.56% group (P<0.05), but did not differ significantly among other groups (P>0.05). Nitrogen retention in late gestation in 0.69% and 0.87% groups were significantly higher than that in other groups (P<0.01), and no significant difference among other groups (P>0.05). The nitrogen retention rate in late gestation in 0.69% and 0.87% groups was significantly higher than that in 0.50% group (P<0.01), and was significantly higher than that in 0.40% and 0.60% groups (P<0.05), but there were no significant differences among other groups (P>0.05). Nitrogen balance in all the groups was in positive in mid and late gestations. Fecal dry matter emission was the lowest in 0.65% group in mid gestation, and it was not significantly affected by dietary Ca level in late gestation (P>0.05). The urine emission in 0.56% group in mid gestation and in 0.40% group in late gestation was significantly higher than that in other groups (P<0.01), but no significant differences were found in urine emission among other groups (P>0.05). However, total nitrogen emission and total phosphorus emission in mid gestation had no significant changes with the increase of dietary Ca level (P>0.05). In late gestation, the total nitrogen emission did not affect by dietary Ca level (P>0.05), but the total phosphorus emission in late gestation in 0.87% group was significantly lower than that in other groups (P<0.05). In conclusion, under the conditions of this experiment, dietary calcium level significantly affects the nitrogen deposition and nitrogen deposition rate in mid and late gestations of Yunnan semi-fine wool sheep, which in 0.82% group are the highest in mid gestation, and in 0.69% group and 0.87% group are higher in late gestation. Dietary calcium level has no significant effects on total nitrogen emission in mid and late gestations and total phosphorus emission in mid gestation of Yunnan semi-fine wool sheep.