Effect of ovulatory follicle size and expression of estrus on progesterone secretion in beef cows
Effect of ovulatory follicle size and expression of estrus on progesterone secretion in beef cows
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DOI：
10.2527/jas.2007-0570
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发表时间：
2008-03-01
影响因子：
3.3
通讯作者：
Smith, M. F.
中科院分区：
文献类型：
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作者：
Busch, D. C.;Atkins, J. A.;Smith, M. F.
在产后肉牛中诱导小优势卵泡（SF，< 12 mm; CO-Synch方案）排卵导致黄体（CL）的形成，与来自大优势卵泡（LF，> 12 mm）的CL相比，CL表现出延迟的孕酮升高（P4）。实验1的特点P4浓度从排卵到随后的发情之间GnRH诱导或自发排卵SF（= 12毫米），以确定是否P4分泌的CL形成GnRH诱导SF仍然较低的排卵后在非泌乳肉牛。非泌乳肉牛在PGF（2 α）（CO-Synch;第9天GnRH，第2天PGF 2a，第0天GnRH）后48小时诱导排卵，或在PGF 2a后出现发情并自发排卵。在诱导排卵的奶牛中，在第二次GnRH时测量卵泡大小，或者对于自发排卵的奶牛，在发情开始后约3小时测量卵泡大小。将奶牛分为4组之一：1）GnRH诱导排卵-SF（= 12 mm; Ind-LF; n = 16）; 3）自发排卵-SF（= 11 mm; Spon-SF; n = 8）; 4）自发排卵-LF（= 12 mm; Spon-LF; n = 22）。与Ind-LF（P = 0.05）、Spon-SF（P = 0.07）和Spon-LF（P = 0.03）相比，Ind-SF从第3天到第15天的血清P4浓度降低。实验2的特点P4浓度（0至60天后AI）之间的GnRH诱导或自发排卵的SF（= 12毫米）或LF（= 13毫米），以确定是否P4分泌的CL从GnRH诱导的SF形成在妊娠早期仍然较低。在PGF（2 α）（CO-Synch）后48小时用GnRH诱导排卵或自发排卵，并在AI时测量排卵卵泡大小。将泌乳奶牛分为3组：1）GnRH诱导排卵-SF（
Induced ovulation of small dominant follicles (SF, < 12 mm; CO-Synch protocol) in postpartum beef cows resulted in formation of corpora lutea (CL) that exhibited a delayed rise in progesterone (P4) compared with CL from large dominant follicles (LF, > 12 mm). Experiment 1 characterized P4 concentrations from ovulation to subsequent estrus among GnRH-induced or spontaneously ovulated SF (= 12 mm) to determine if P4 secretion by CL formed from GnRH-induced SF remains lower postovulation in nonlactating beef cows. Nonlactating beef cows were induced to ovulate 48 h after PGF(2 alpha) (CO-Synch; GnRH on d-9, PGF2a on d-2, and GnRH on d 0) or exhibited estrus and spontaneously ovulated after PGF2a. Follicle size was measured at the second GnRH in cows induced to ovulate or similar to 3 h after the onset of estrus for cows that ovulated spontaneously. Cows were classified into 1 of 4 groups: 1) GnRH-induced ovulation-SF (= 12 mm; Ind-LF; n = 16); 3) spontaneous ovulation-SF (= 11 mm; Spon-SF; n = 8); 4) spontaneous ovulation-LF (= 12 mm; Spon-LF; n = 22). Serum concentrations of P4 from d 3 to 15 were reduced in the Ind-SF compared with the Ind-LF (P = 0.05), Spon-SF (P = 0.07), and Spon-LF (P = 0.03). Experiment 2 characterized P4 concentrations (0 to 60 d postAI) among GnRH-induced or spontaneously ovulated SF (= 12 mm) or LF (= 13 mm) to determine if P4 secretion by CL formed from GnRH-induced SF remained lower during early gestation. Ovulation was induced with GnRH 48 h after PGF(2 alpha) (CO-Synch) or occurred spontaneously, and ovulatory follicle size was measured at AI. Lactating cows were classified into 1 of 3 groups: 1) GnRH-induced ovulation-SF (