Energy balance and ovarian follicle development prior to the first ovulation postpartum in dairy cows receiving three levels of dietary fat
Energy balance and ovarian follicle development prior to the first ovulation postpartum in dairy cows receiving three levels of dietary fat
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DOI：
10.1095/biolreprod56.1.133
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发表时间：
1997-01-01
影响因子：
3.6
通讯作者：
Butler, WR
中科院分区：
文献类型：
--
作者：
Beam, SW;Butler, WR
本研究的目的是表征奶牛产后早期（PP）卵泡发育的特征，并评估能量平衡（EB）和膳食脂肪水平对优势卵泡发育和功能的影响。 45 头经产荷斯坦奶牛在分娩时开始饲喂低（LF，3.3%）、中（MF，5.2%）或高（HF，7.1%）总膳食脂肪，并测定所有奶牛的每日 EB。通过超声检查监测卵泡发育，并分析血浆中的代谢物、代谢激素、黄体酮、雌二醇和 FSH。在第 1-5 天期间平均血浆 FSH 增加 (p < 0.01) 后，无论饮食或 EB 如何，所有奶牛在第二周 PP 期间都经历了一波卵泡发育。与 LF 饮食相比，饲喂 MF (p < 0.05) 或 HF (p < 0.06) 饮食会在第 14 天产生更多数量的 IV 级 (> 15 mm) 卵泡。与 LF 和 HF 奶牛相比，饲喂 MF 日粮的奶牛在第一个卵泡波期间血浆雌二醇峰值较高（p < 0.05），并且距第一次排卵的间隔较短（p < 0.05）。第一次排卵前卵泡发育的特征是第一个优势卵泡的排卵（OV，n = 19），一波或多波非排卵优势卵泡（NOV，n = 18），或卵泡囊肿的形成（CYST，n = 8）。第一卵泡波 PP 期间排卵失败伴有血浆雌二醇峰值较低（p < 0.001）（0.96 +/- 0.36 与 5.0 +/- 0.35 pg/ml）、较小（p < 0.01）最大卵泡直径（16.0 +/- 0.9 与 20.0 +/- 1.0 mm）、较低（p < 0.09）血浆胰岛素样生长因子-I (ICF-I；73.5 +/- 10.1 与 102.9 +/- 9.9 ng/ml) 水平，以及达到 EB 最低点的时间间隔较长 (p < 0.02)（14.6 +/- 1.9 与 6.4 +/- 1.9 天）。首次排卵的天数与 EB 最低点的天数呈正相关 (r = 0.55)，在 EB 最低点后出现的优势卵泡表现出雌二醇产量增加 (p < 0.01) 和更高的排卵成功率 (p < 0.01)。大（> 10毫米）优势卵泡的发育并不是PP生殖恢复的限制因素，适度的膳食脂肪缩短了首次排卵的间隔。早期 PP 的卵泡能力与较高的血浆 IGF-I 和较短的 EB 最低点间隔相关。
The objectives of this study were to characterize early postpartum (PP) follicular development in dairy cows and to evaluate the influence of energy balance (EB) and the level of dietary fat on dominant follicle development and function. Forty-five multiparous Holstein cows were fed either low (LF, 3.3%), moderate (MF, 5.2%), or high (HF, 7.1%) total dietary fat beginning at parturition, and daily EB was determined for all cows. Follicular development was monitored by ultrasonography, and blood plasma was analyzed for metabolites, metabolic hormones, progesterone, estradiol, and FSH. After an increase (p < 0.01) in mean plasma FSH during Days 1-5, all cows experienced a wave of follicular development during the second week PP regardless of diet or EB. Feeding the MF (p < 0.05) or HF (p < 0.06) diet resulted in a greater number of class IV (> 15 mm) follicles on Day 14 PP as compared to the LF diet. Cows fed the MF diet had higher (p < 0.05) peak plasma estradiol during the first follicular wave and a shorter (p < 0.05) interval to first ovulation than both LF and HF cows. Follicular development prior to first ovulation was characterized by either ovulation of the first dominant follicle (OV, n = 19), one or more waves of nonovulatory dominant follicles (NOV, n = 18), or the formation of a follicular cyst (CYST, n = 8). Ovulation failure during the first follicular wave PP was accompanied by lower (p < 0.001) peak plasma estradiol (0.96 +/- 0.36 vs. 5.0 +/- 0.35 pg/ml), a smaller (p < 0.01) maximum follicle diameter (16.0 +/- 0.9 vs. 20.0 +/- 1.0 mm), lower (p < 0.09) levers of plasma insulin-like growth factor-I (ICF-I; 73.5 +/- 10.1 vs. 102.9 +/- 9.9 ng/ml), and a longer (p < 0.02) interval to the EB nadir (14.6 +/- 1.9 vs. 6.4 +/- 1.9 days). The number of days to first ovulation was positively correlated with days to the EB nadir (r = 0.55), with dominant follicles that emerged after the EB nadir exhibiting enhanced (p < 0.01) production of estradiol and greater (p < 0.01) ovulatory success. The development of large (> 10 mm) dominant follicles was not a limiting factor in PP reproductive recovery, and moderate dietary fat shortened the interval to first ovulation. Follicular competence early PP was associated with higher plasma IGF-I and a shorter interval to the EB nadir.