Uterine Involution and Ovarian Activity in Postpartum Holstein Dairy Cows. A Review - Uterine Involution and Ovarian Activity in Postpartum Holstein Dairy Cows. A Review - Open Access Pub

Following parturition in the cow, there is a significant period of sexual quiescence of variable length. This period of reproductive quiescence was found to be longer in suckling or intensively milked animals.This acyclic period is generally considered as the postpartum anoestrous period. The postpartum period constitutes an important period in the reproductive life of dairy cows because of its enormous influence upon subsequent fertility. The entire postpartum period, puerperium, is defined as the period from parturition until the genital organs return to its normal physiological and histological condition, as in normal non-gravid state. They added that any extension of the puerperium in cows might have a detrimental effect on the reproductive performance of the individual animal. Thus, the main determinant of this period is essentially dependent on the resumption of normal ovarian cycles, the manifestation of estrus behaviour and conception following insemination. DOI10.14302/issn.2575-1212.jvhc-18-2447 Puerperium in cattle is classified into three stages, early puerperium, clinical puerperium, and whole puerperium. The author added that early puerperium lasts nine days during which the placenta must be dropped either naturally or manually. Clinical puerperium stays 21 days during which the uterus returns to its normal size, but not normal histological structure. The whole puerperium lasts about 42 days during which the uterus regains its normal histological structure as before pregnancy. Depending on the endocrine status the puerperium is classified into the puerperal period, intermediate period or pre-ovulatory period and post-ovulatory period. Puerperal period extends from calving to the onset of pituitary sensitivity to GnRH at 10-12 days postpartum. The intermediate or pre-ovulatory period is the period which extends from the onset of pituitary sensitivity to GnRH until first ovulation at 20-30 days postpartum. The post-ovulatory period is the period which begins with first ovulation and lasts until complete uterine involution at 40-45 days postpartum. The postpartum female undergoes a series of physiological and anatomical re-adjustments in both the uterus and ovaries for the restoration of her reproductive capacity. These physiological changes that occur during the puerperium, include uterine involution, resumption of ovarian function and return to cyclical activity as well as the elimination of bacterial contamination of uterine lumen that occurs during parturition. Uterine Involution The restoration of the uterus to its normal non-pregnant