本试验旨在研究不同磷酸脲添加量对羔羊血清和肌肉钙(Ca)、磷(P)含量及血清相关激素含量的影响。选用80只F₁代杜寒杂交羔羊,随机分为5组,每组8个重复,每个重复2只。分别在各组精料中添加0、1.0%、2.0%、4.0%和8.0%的磷酸脲以替代部分豆粕等蛋白质饲料。预试期为12 d,正试期为60 d。预试期内饲喂精料和粗料比为1:1,自由采食。正试期内肉羊精料和粗料采食量比为1:1,各组实际采食饲粮中的磷酸脲含量分别为0(对照组)、0.5%(0.5%组)、1.0%(1.0%组)、2.0%(2.0%组)和4.0%(4.0%组)。每组选取8只羊在1(预试期开始当天)、13和73 d晨饲前采集血液,测定1、13和73 d血清钙、磷含量及1和13 d血清甲状旁腺素(PTH)、降钙素(CT)、25-羟基维生素D(25-OH-VD)含量;73 d每组选取6只羊屠宰,取背腰最长肌进行肌肉中钙、磷含量的测定。结果表明:1)随饲粮中磷酸脲添加量的增加,血清钙含量降低,磷含量增加。其中,血清钙含量在1和73 d时各组间差异不显著(P>0.05),但在13 d时4.0%组显著低于其他各组(P<0.05)。血清磷含量在1 d时各组间差异不显著(P>0.05);13 d时4.0%组显著高于对照组、0.5%组和2.0%组(P<0.05);73 d时4.0%组显著高于对照组和0.5%组(P<0.05),对照组显著低于1.0%组、2.0%组、4.0%组(P<0.05)。2)各组背腰最长肌中的钙、磷含量差异不显著(P>0.05)。3)血清中各组间的PTH、25-OH-VD含量差异不显著(P>0.05);13 d时,1.0%组和2.0%组的血清CT含量显著低于对照组和4.0%组(P<0.05)。由此可见,磷酸脲的添加可使得血清和肌肉中钙含量降低、磷含量增加,对血清PTH和25-OH-VD含量无显著影响,但会引起血清CT含量的显著变化;饲粮添加4.0%的磷酸脲会引起羔羊增重受到抑制。

This experiment was conducted to study the effects of different levels of urea phosphate supplementation on calcium (Ca) and phosphorus (P) contents in serum and muscle and related hormone contents in serum of lambs. Eighty Dorper×thin-tailed Han F₁ crossbred lambs were randomly divided into 5 groups with 8 replicates per group and 2 lambs per replicate. Soybean meal and some other protein feeds were replaced by 0, 1.0%, 4.0% and 8.0% of urea phosphate in concentrate, respectively. During the 12-day adaptation period, the ratio of concentrate to roughage was 1:1, and lambs were fed ad libitum; during the 60-day experimental period, the intake of ratio of concentrate to roughage was 1:1, and the actually intake of urea phosphate levels were 0 (control group), 0.5% (0.5% group), 1.0% (1.0% group), 2.0% (2.0% group) and 4.0% (4.0% group), respectively. On 1 (the starting day of adaptation period), 13 and 73 days, blood samples were collected from 8 lambs of each group before morning feeding to determine the contents of Ca, P (1, 13 and 73 d) parathyroid hormone (PTH), calcitonin (CT) and 25-hydroxy vitamin D (25-OH-VD) (1 and 13 d). On 73 days, six lambs of each group were slaughtered and the longissimus dorsi was sampled to analyze the contents of Ca and P. The results showed as follows: 1) in serum, Ca content decreased and P content increased with the increasing level of urea phosphate. Serum Ca content showed no significant difference on 1 and 73 days among groups (P>0.05), while that of 4.0% group was significantly lower than that of the other groups on 13 days (P<0.05). No significant difference was found in serum P content on 1 day (P>0.05). Serum P content of 4.0% group was significantly higher than that of control, 1.0%, and 2.0% groups on 13 days (P<0.05). On 73 days, serum P content of 4.0% group was significantly higher than that of control and 0.5% groups (P<0.05), and control group was significantly lower than that of 1.0%, 2.0%, and 4.0% groups (P<0.05). 2) There were no significant differences of Ca and P contents in longissimus dorsi among groups (P>0.05). 3) The differences among the contents of PTH and 25-OH-VD in serum were not significant (P>0.05). The content of CT in 1.0% and 2.0% groups was significantly lower than that of control and 4.0% groups on 13 days (P<0.05). In conclusion, Ca content decreases while P content increases in serum and muscle with the supplementation of urea phosphate. Serum of PTH and 25-OH-VD contents are not affected by urea phosphate. The supplementation of urea phosphate can significantly change serum CT content. The supplementation of 4.0% of urea phosphate inhibits the increase in weight of lambs.