Pharmacological treatments to support luteal function and prevent precocious luteolysis
Administration of GnRH and hCG post insemination
Administration of hCG (4-6d after AI) and GnRH (11-12d after AI) are well established as methods to improve fertility in cattle herds, through prevention of early embryonic mortality.
Both treatments aim at elimination of the pro-luteolytic effect of oestradiol and benefit from the formation of additional corpora lutea and increased production of progesterone.
There are some differences in the timing of these two approaches:
| Treatment | Follicular turnover | Luteal function and P4 levels | Results - timing |
|---|---|---|---|
| hCG at 4-6d post AI | Prevention of precocious luteolysis - elimination of early luteal phase follicles still growing after AI. | Increase in P4 levels thanks to the creation of accessory corpora lutea Direct stimulation of CL function (LH effect) | The result measured as decrease of oestradiol levels and increase in progesterone levels approx. 6-7d post AI |
| GnRH at 11-12d post AI | Prevention of precocious luteolysis - elimination of early luteal phase follicles still growing after AI. | Increase in P4 levels thanks to the creation of accessory corpora lutea | The result measured as decrease of oestradiol levels and increase in progesterone levels approx. 12-13d post AI |
For more details see:
- Administration of hCG after AI
- Administration of GnRH after AI
- Results of hCG treatment after AI in dairy cows
- Results of hCG treatment after embryo transfer in dairy cows
- Results of GnRH treatment after AI
Supplementation of exogenous progesterone/progestagens
Administration of exogenous progesterone or progestagens to improve theluteal environment for the developing embryo have so far met with limited success.
Factors limiting success of the method are:
- uncertainty about the best time to initiate the treatment
- wide discrepancy of the recommended dose
- administration route: majority of products available on the market are intravaginal devices
Reported results of the use of progesterone for early pregnancy maintenance
