Katagiri S, Moriyoshi M
J. Reprod. Dev. 2013 Oct;59(5):415-20
PMID: 24162805
Abstract
Poor reproductive efficiency is a worldwide problem that has affected the dairy industry during the last several decades. In an attempt to explain the changes in reproductive physiology caused by high milk production, a model of elevated steroid metabolism in lactating dairy cows has been proposed. A slow increase in levels and low peak levels of estradiol (E₂) and progesterone (P₄) characterize endocrine changes in high producing cows. Similar changes have been reported in the repeat breeder cows. The abnormal changes in E₂ and P₄ concentrations of these cows may cause an improper uterine environment due to disturbed expression of growth factors and cytokines in the endometrium. This review focuses on the alteration in epidermal growth factor (EGF) profile in the endometrium during the estrous cycle. The normal cow has two peaks of EGF concentrations on days 2-4 and 13-14. Low concentrations of EGF on these days distinguished both high-producing and repeat breeder cows from normal cows. Alteration of the EGF profile could be found in 70 and 40% of the repeat breeder and high-producing cows, respectively. Treatment with a high dose of estradiol benzoate and an intravaginal progesterone-releasing device restored the normal EGF profile in about 70% of the affected cows. The cows having a normal EGF profile after treatment showed a higher pregnancy rate than the cows with the altered profile. Further studies to understand the etiology of the alteration in the EGF profile are needed to develop another treatment option and preventive management for this problem.
histotroph: the sum total of nutritive material derived from maternal tissue other than the blood, utilized by the early embryo.
postovulatory: Of or occurring in the period shortly after ovulation.
asynchrony: lack of synchronism; disturbance of coordination. 非同期性, 非同調性
indistinguishable: understand or make out; vague: 識別不能な, 区別不能な
superovulated: (To cause (an animal) to superovulate.) 過排卵する
patency: The state or quality of being open, expanded, or unblocked. 開存性
“The reasons for the decline in fertility of modern dairy cows are multifactorial; thus, it is most important to exclude animals with any known causes of infertility when seeking hidden causes of infertility in repeat breeder cows.”
“Decreased EGF (Epidermal growth factor) concentrations on day 3 and 14 clearly distinguished the repeat breeder cows showed this alternation.”
contribute: To help bring about a result; act as a factor:〈助言・援助などを〉〔…に〕与える，ささげる，貢献する
Suggested treatment of RB
day0 (insertion of CIDR): estradiol benzoate 5mg, PGF2α
at withdrawal of CIDR: estradiol benzoate 5mg, PGF2α
preclude: To make impossible, as by action taken in advance; prevent.〈人が〉〔…するのを〕妨げる，〈人に〉〔…できなく〕する.
predispose: To provide an inclination or susceptibility:〔病気に〕かかりやすくする