N-氨甲酰谷氨酸对奶牛超排效果及血液指标的影响

本研究旨在探讨饲喂N-氨甲酰谷氨酸（NCG）对奶牛超数排卵效果及血液生化指标的影响。选取荷斯坦育成牛16头，随机分为2组，每组8头，对照组饲喂基础饲粮，试验组在基础饲粮的基础上饲喂20 g/（d·头）的NCG，采用连续4 d递减注射FSH法测定NCG饲喂时间对供体牛超排效果的影响，分别在3次超排处理的第0、5、9天采集尾根静脉血测定激素指标及血清生化指标。结果表明，①NCG饲喂20 d时（第1次超排），试验组头均回收胚数、可用胚数、退化胚数、未受精卵数与对照组相比差异均不显著（P>0.05）；NCG饲喂50 d时（第2次超排），试验组头均回收胚数显著高于对照组（P<0.05）；NCG饲喂80 d时（第3次超排），试验组头均可用胚数显著高于对照组（P<0.05）；综合考虑3次超排效果，试验组头均回收胚数显著高于对照组（P<0.05）。②NCG饲喂时间对供体牛血清中促卵泡素、促黄体素、孕酮、雌二醇的浓度均无显著影响（P>0.05），说明NCG饲喂时间对奶牛生殖激素的分泌无影响或为次要影响因素，超排效果的变化与生殖激素变化无明显的关联作用。③NCG饲喂时间对供体牛血清中谷草转氨酶的浓度无显著影响（P>0.05）；在NCG饲喂13 d时，试验组供体牛血清中葡萄糖浓度显著高于对照组（P<0.05）；在NCG饲喂34 d时，试验组供体牛血清中尿素氮浓度显著低于对照组（P<0.05）；在NCG饲喂43和69 d时，试验组供体牛血清中一氧化氮浓度显著高于对照组（P<0.05）。综合考虑，在重复3次超排时，每头供体牛每天饲喂20 g NCG，可提高3次连续超排的回收胚数4.98枚及可用胚数1.8枚，进而降低胚胎的生产成本。

Effect of N-carbamylglutamate on Superovulation and Blood Indexes in Dairy Cows

The purpose of this study was to explore the effects of N-carbamylglutamate (NCG) feeding for different periods on superovulation and blood biochemical indicators in dairy cows. A total of 16 Holstein heifers were selected and randomly divided into two groups, each with 8 heifers. The control group was fed with a basal diet, and the test group was fed 20 g/(d·head) of NCG on the basis of the basal diet. The effect of feeding period of NCG on the superovulation effect of donor cattle was measured by the FSH method of decreasing injection for 4 consecutive days. Tail root vein blood were collected on the 0, 5, and 9 d of the 3 superovulation treatments to determine hormone indicators and serum biochemical indicators. The results showed that:①NCG was fed for 20 d (the frist superovulation), there were no significant differences in the number of recovered embryos, available embryos, degenerated embryos and unfertilized oocytes between test and control groups (P>0.05). When NCG was fed for 50 d(the second superovulation), the number of embryos recovered in test group was significantly higher than that in control group (P<0.05). When NCG was fed for 80 d (the third superovulation), the number of available embryos in test group was significantly higher than that in control group (P<0.05). In 3 superovulation tests, the number of embryos recovered in the test group was significantly higher than that in control group (P<0.05). ②The feeding period of NCG had no significant effect on the concentrations of FSH, LH, P₄ and E₂ in the blood of donor cattle (P>0.05). It showed that NCG feeding period had no effect or was a secondary influencing factor on the secretion of reproductive hormones, and there was no significant correlation between the change of superovulation effect and the change of reproductive hormones. ③The feeding period of NCG had no significant effect on the concentration of AST in the blood of the donor cattle (P>0.05). The concentration of GLU in the calf serum of the donors in test group was significantly higher than that in control group when NCG was fed for 13 d (P<0.05). The concentration of BUN in the calf serum of the donors in test group was significantly lower than that in control group when NCG was fed for 34 d (P<0.05). The concentration of NO in the calf serum of the donors in test group was significantly higher than that in control group when NCG was fed for 43 and 69 d (P<0.05). In conclusion, each donor heifer was fed with 20 g NCG per day for 3 consecutive superovulation, the number of recovered embryos and the number of available embryos could be increased by 4.98 and 1.8, respectively, and then reduce the production cost of embryos.