Luteolysis occurs around day 17 of physiological oestrus in the cow. Luteolysis is triggered by the secretion of prostaglandin F2a to ensure initiation of a new oestrus cycle and ovulation. Corpus luteum that persists on the ovary beyond day 20 is considered persistent.
Cows with persistent corpus luteum are not observed in heat and can be mistakenly considered as pregnant.
The presence of active luteal tissue on the ovary leads to the anovulatory state where growing follicles of consecutive waves proceed to dominance but fail to ovulate. This is due to the negative feedback of progesterone on LH release.
The pathogenesis of persistency of luteal tissue in cattle is not yet completely known. The direct underlying cause is undoubtedly inadequate secretion of luteolytic factor – PGF2α.
The following conditions have been associated with prolonged luteal function:
Treatment of CL persistent is relatively simple. Luteolytic doses of PGF2α are administered. This can be combined with a dose of GnRh analogue approximately 48-56h later to stimulate ovulation. Click on the thumb nail sketch for a full sized image.
Cows can be inseminated in the induced heat.
Ovary with corpus luteum