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Resumption of reproductive activity in the early postpartum period of cows
Published online by Cambridge University Press: 27 February 2018
Abstract
Following parturition, there is an early resumption of sequential but transient FSH increases of 2-3 days duration in dairy and beef cows. The first increase results in the emergence of the first postpartum follicle wave and the decline in FSH results in selection of a dominant follicle (DF). The ovulatory fate of this DF is dependent on LH pulse frequency and IGF-I concentrations. The energy status of the cows affects the degree of anoestrus. High yielding cows in prolonged negative energy balance (NEB) have a greater incidence of anoestrous, where the DF is smaller and fails to produce sufficient oestradiol to induce ovulation. Thus, there are sequential follicle waves in anoestrus prior to first ovulation. A small percent of DFs in dairy cows fail to ovulate and they continue to grow due to high LH pulse frequency and form follicular cysts. These cysts produce oestradiol for a variable period and then become physiologically defunct, despite their morphological presence for variable periods before final regression. During their physiological active state, new follicle wave emergence and ovulation are suppressed. A further problem in high yielding cows is the increased incidence of abnormal ovarian cycles after ovulation, and specifically, the high incidence of maintained corpora lutea (CL), probably related to uterine problems in the peri-parturient period. The ovulation of smaller DFs and the high liver metabolic rate may adversely affect oestradiol and progesterone concentrations. The long-term effects of prolonged NEB on oocyte competence, DF physiology and follicular and luteal steroidogenesis all may have detrimental effects on conception rates to AI. Hormonal methods to induce ovulation should be carried out in conjunction with corrective management problems, once diagnosed The pre-treatment of anoestrous cows with progesterone for 5-9 days is a prerequisite for the concomitant expression of oestrus at first ovulation, but whether or not further hormonal therapy is necessary to ensure the ovulation of the DF, is dependent on energy status, body condition score and postpartum interval, which regulate LH pulse frequency.
- Type
- Invited Papers
- Information
- BSAP Occasional Publication , Volume 26 , Issue 1: Fertility in the High Producing Dairy Cow , January 2001 , pp. 31 - 42
- Copyright
- Copyright © British Society of Animal Science 2001
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