Liu Han-Ken, Long David W, Bacon Wayne L
Department of Animal Sciences, Ohio Agricultural Research and Development Center, The Ohio State University, Wooster, OH 44691-4096, USA.
Gen Comp Endocrinol. 2005 Sep 1;143(2):168-77. doi: 10.1016/j.ygcen.2005.03.010. Epub 2005 Apr 25.
The frequency of preovulatory luteinizing hormone (LH) surges is an important determinant of ovulation and oviposition rates in turkeys. Egg production rate is relatively poor in heavy weight-sire line type turkey hens and declines with advancing duration of the reproductive period. The purpose of this study was to measure frequency and characteristics of preovulatory LH surges in turkey hens of a heavy weight-sire line type early, at peak of egg production (Early), and late, after egg production rate had declined (Late), in a reproductive period. The Early hens were photostimulated with a continuous photoperiod [24 h light (L):0 h dark (D)] at 40 weeks of age and sampled during peak egg production at about 47 weeks of age. The Late hens were photostimulated at 40 weeks of age with a long day photoperiod (14L:10D). After a 27-week egg production period, the Late hens were switched to the 24L:0D photoperiod and sampled at 74 weeks of age. Continuous lighting was used during blood sampling to allow the rhythm of preovulatory LH surges to free run. All hens were cannulated 3-5 days before starting sampling and hourly blood samples were collected for 200 h. All hens were necropsied and ovarian and oviductal morphologies were measured after serial bleeding. The Late hens had a longer interval between intra-clutch preovulatory LH surges than the Early hens, and a higher incidence of atretic ovarian follicles. The Early hens had higher baseline and surge amplitude LH concentrations but lower progesterone (P4) surge amplitude concentrations than the Late hens. The duration of preovulatory LH surges, incidence of "blind" preovulatory LH surges, baseline P4 concentrations, and overall estradiol-17beta (E2) concentrations were not different between Early and Late hens. In conclusion, a longer interval between preovulatory LH surges, lower LH baseline and surge amplitude concentrations, a higher incidence of atretic follicles, and higher P4 surge amplitude concentration were associated with the decline in egg production late in the reproductive period in a heavy weight-sire line of turkey hens.
排卵前促黄体生成素（LH）激增的频率是火鸡排卵和产卵率的重要决定因素。重型父系品系火鸡母鸡的产蛋率相对较低，并且随着繁殖期的延长而下降。本研究的目的是测量重型父系品系火鸡母鸡在繁殖期早期（产蛋高峰期，Early）和晚期（产蛋率下降后，Late）排卵前LH激增的频率和特征。Early组母鸡在40周龄时采用连续光照周期[24小时光照（L）：0小时黑暗（D）]进行光刺激，并在约47周龄产蛋高峰期进行采样。Late组母鸡在40周龄时采用长日照光周期（14L：10D）进行光刺激。经过27周的产蛋期后，Late组母鸡改为24L：0D光周期，并在74周龄时进行采样。采血期间使用连续光照，以使排卵前LH激增的节律自由运行。所有母鸡在开始采样前3 - 5天进行插管，并每小时采集一次血样，共采集200小时。所有母鸡在连续采血后进行剖检，并测量卵巢和输卵管形态。Late组母鸡窝内排卵前LH激增的间隔时间比Early组母鸡长，且闭锁卵泡的发生率更高。Early组母鸡的LH基线浓度和激增幅度浓度较高，但孕酮（P4）激增幅度浓度低于Late组母鸡。Early组和Late组母鸡排卵前LH激增的持续时间、“无排卵”LH激增的发生率、基线P4浓度以及总体雌二醇-17β（E2）浓度没有差异。总之，排卵前LH激增间隔时间延长、LH基线浓度和激增幅度浓度降低、闭锁卵泡发生率增加以及P4激增幅度浓度升高与重型父系品系火鸡母鸡繁殖后期产蛋率下降有关。
