학술논문
Attainment and maintenance of pubertal cyclicity may predict reproductive longevity in beef heifers
Research Article
Research Article
Document Type
Academic Journal
Author
Source
Biology of Reproduction. June 2021, Vol. 104 Issue 6, p1360, 13 p.
Subject
Language
English
ISSN
0006-3363
Abstract
Introduction Puberty is a dynamic and critical time point in the life of a female. At puberty, a female achieves regular cyclicity and is able to conceive and reproduce. Women [...]
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 [greater than or equal to] 1 ng/ml < March 12 with continued cyclicity, (2) Typical; P4 [greater than or equal to] 1 ng/ml [greater than or equal to] March 12 with continued cyclicity, (3) Start-Stop; P4 [greater than or equal to] 1 ng/ml but discontinued cyclicity, and (4) Non-Cycling; no P4 [greater than or equal to] 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 (PGF2[alpha]) 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. Summary sentence Puberty attainment of beef heifers as classified by circulating plasma progesterone profiles from weaning to breeding can be used to predict future reproductive fertility and longevity. Key words: puberty, progesterone, ovary, domestic animal reproduction, female infertility, ruminants.
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 [greater than or equal to] 1 ng/ml < March 12 with continued cyclicity, (2) Typical; P4 [greater than or equal to] 1 ng/ml [greater than or equal to] March 12 with continued cyclicity, (3) Start-Stop; P4 [greater than or equal to] 1 ng/ml but discontinued cyclicity, and (4) Non-Cycling; no P4 [greater than or equal to] 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 (PGF2[alpha]) 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. Summary sentence Puberty attainment of beef heifers as classified by circulating plasma progesterone profiles from weaning to breeding can be used to predict future reproductive fertility and longevity. Key words: puberty, progesterone, ovary, domestic animal reproduction, female infertility, ruminants.