Attainment and maintenance of pubertal cyclicity may predict reproductive longevity in beef heifers†.
Attainment and maintenance of pubertal cyclicity may predict reproductive longevity in beef heifers†.
复制标题
青春期周期的实现和维持可以预测肉牛的繁殖寿命。
DOI：
10.1093/biolre/ioab044
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发表时间：
2021
影响因子：
3.6
通讯作者：
Cupp,AndreaS
中科院分区：
文献类型：
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作者：
Nafziger,SarahR;Tenley,SarahC;Summers,AdamF;Abedal-Majed,MohamedA;Hart,Mariah;Bergman,JeffreyW;Kurz,ScottG;Davis,JohnS;Wood,JenniferR;Cupp,AndreaS
我们假设小母牛达到青春期的方式可能表明它们未来的生殖寿命。在青春期达到中断或延迟周期的小母牛可能会有不规则的生殖周期，不排卵和不孕症，在他们的第一个繁殖季节促成较短的生殖寿命。因此，对2012-2017年出生的611头小母牛从断奶到配种期间的血浆孕酮（P4）进行了测量，并确定了4种青春期分类：（1）早期; P4 ≥ 1 ng/ml <3月12日，持续周期性，（2）典型; P4 ≥ 1 ng/ml ≥ 3月12日，持续周期性，（3）开始-停止; P4 ≥ 1 ng/ml但周期性中断;（4）非周期性;无P4 ≥ 1 ng/ml。历史牛群记录表明，在研究前10年，25%的小母牛在3月12日之前达到青春期。开始停止和非循环一岁的小母牛较轻，表明降低生长和生殖成熟特性相比，早期/典型的小母牛。此外，非循环/起止小母牛对前列腺素F2 α（PGF 2 α）启动发情行为和排卵以进行人工授精的反应较低。非循环小母牛的生殖道评分-5较少，并且在其第一个繁殖季节的前21天产犊中出生的小牛数量减少。在开始-停止分类中，50%的小母牛重新启动了周期性，其生长性状和生殖参数与早期/典型分类中的小母牛相似，而那些保持非周期性的小母牛与非周期性组中的小母牛更相似。因此，在青春期达到周期性中断或无周期性的小母牛延迟了生殖成熟，导致生育力低下和潜在的生殖寿命缩短。
We hypothesized the manner that heifers achieve puberty may indicate their future reproductive longevity. Heifers with discontinued or delayed cyclicity during puberty attainment may have irregular reproductive cycles, anovulation, and infertility in their first breeding season contributing to a shorter reproductive lifespan. Therefore, plasma progesterone (P4) was measured from weaning to breeding on 611 heifers born 2012–2017 and four pubertal classifications were identified: (1) Early; P4 ≥ 1 ng/ml < March 12 with continued cyclicity, (2) Typical; P4 ≥ 1 ng/ml ≥ March 12 with continued cyclicity, (3) Start-Stop; P4 ≥ 1 ng/ml but discontinued cyclicity, and (4) Non-Cycling; no P4 ≥ 1 ng/ml. Historical herd records indicated that 25% of heifers achieved puberty prior to March 12th in the 10 years prior to the study. Start-Stop and Non-Cycling yearling heifers were lighter indicating reduced growth and reproductive maturity traits compared with Early/Typical heifers. In addition, Non-Cycling/Start-Stop heifers were less responsive to prostaglandin F2 alpha (PGF2α) to initiate estrous behavior and ovulation to be artificially inseminated. Non-Cycling heifers had fewer reproductive tract score-5 and reduced numbers of calves born in the first 21-days-of-calving during their first breeding season. Within the Start-Stop classification, 50% of heifers reinitiated cyclicity with growth traits and reproductive parameters that were similar to heifers in the Early/Typical classification while those that remained non-cyclic were more similar to heifers in the Non-Cycling group. Thus, heifers with discontinued cyclicity or no cyclicity during puberty attainment had delayed reproductive maturity resulting in subfertility and potentially a shorter reproductive lifespan.