Beam S W, Butler W R
Department of Animal Science, Cornell University, Ithaca, NY 14853, USA.
J Dairy Sci. 1998 Jan;81(1):121-31. doi: 10.3168/jds.S0022-0302(98)75559-6.
The objectives of this study were to relate energy balance and metabolic hormones during the early postpartum period in dairy cows with dominant follicle development before first ovulation and to evaluate the effects of prilled lipid on follicular development during the first follicular wave after parturition and the postpartum anovulatory interval. At parturition, 42 cows received a control diet (4.8% fat) or a diet supplemented with prilled fatty acids (7.0% fat). Energy balance was determined daily. Ovarian follicular development was monitored by ultrasonography, and blood plasma or serum was analyzed for estradiol, progesterone, and metabolic hormones. Dry matter intake was lower in cows supplemented with dietary lipids during the first 4 wk of lactation, but energy intake, energy balance, and the postpartum anovulatory interval were similar between diets. A wave of follicular development occurred in all cows during the 2nd wk postpartum, and 50% of all cows ovulated their first dominant follicle. Numbers of follicles that were 3 to 5 mm, 6 to 9 mm, and 10 to 15 mm on d 8 postpartum were similar between diets and unrelated to energy balance or metabolic hormones. Diameter of the dominant follicle during d 8 to 14 postpartum and maximum diameter of the first-wave ovulatory follicle did not differ between diets. Cows with nonovulatory first-wave dominant follicles had lower mean plasma concentrations of estradiol during d 8 to 14 postpartum, a longer interval to the day of the energy balance nadir, lower serum concentrations of IGF-I, and higher 4% FCM yield than did cows with ovulatory first-wave dominant follicles. Serum IGF-I during d 1 to 13 was positively correlated with plasma estradiol during d 8 to 14 postpartum. Possibly because of reductions in dry matter intake, the consumption of prilled lipid by dairy cows during early lactation may be ineffective in altering energy balance, follicular development, and the postpartum anovulatory interval. Ovulation failure of dominant follicles early in the postpartum period is associated with greater production of 4% fat-corrected milk, a delayed energy balance nadir, and reduced concentrations of peripheral IGF-I.
本研究的目的是探讨奶牛产后早期能量平衡和代谢激素与首次排卵前优势卵泡发育之间的关系，并评估颗粒脂肪对产后第一个卵泡波期间卵泡发育及产后无排卵间隔的影响。分娩时，42头奶牛分别采食对照日粮（脂肪含量4.8%）或添加颗粒脂肪酸的日粮（脂肪含量7.0%）。每天测定能量平衡。通过超声监测卵巢卵泡发育，并分析血浆或血清中的雌二醇、孕酮和代谢激素。在泌乳的前4周，采食添加日粮脂肪奶牛的干物质采食量较低，但两种日粮间的能量摄入量、能量平衡和产后无排卵间隔相似。所有奶牛在产后第2周都出现了一波卵泡发育，50%的奶牛排出了第一个优势卵泡。产后第8天，直径3至5毫米、6至9毫米和10至15毫米的卵泡数量在两种日粮间相似，且与能量平衡或代谢激素无关。产后第8至14天优势卵泡的直径以及第一个卵泡波排卵卵泡的最大直径在两种日粮间无差异。与具有排卵性第一波优势卵泡的奶牛相比，具有无排卵性第一波优势卵泡的奶牛在产后第8至14天的平均血浆雌二醇浓度较低，至能量平衡最低点的间隔时间较长，血清IGF-I浓度较低，4%乳脂校正乳产量较高。产后第1至13天的血清IGF-I与产后第8至14天的血浆雌二醇呈正相关。可能由于干物质摄入量减少，奶牛在泌乳早期采食颗粒脂肪可能无法有效改变能量平衡、卵泡发育和产后无排卵间隔。产后早期优势卵泡排卵失败与4%乳脂校正乳产量增加、能量平衡最低点延迟以及外周IGF-I浓度降低有关。
