Induction of Estrus in Cows

Induction of estrus in cows is a reproductive management practice used to stimulate and synchronize the oestrous cycle in non-cycling or anestrous cows.

Hormones Used for Induction of Estrus and Ovulation

Induction of Estrus in Cows

The major hormones used for induction of estrus in cows are as follows:

• Follicle Stimulating Hormone (FSH)
• Gonadotrophin Releasing Hormone (GnRH)
• Progesterone

Follicle Stimulating Hormone (FSH)

FSH hormone is to induce follicular growth. Once follicular growth is induced, the estrogen secreted by the developing follicle induces an endogenous Luteinizing hormone (LH) surge for ovulation.

But, in several cases of anestrus, administration of FSH alone would not benefit, as ovulation is not ensured.

Administration of LH or hCG (human chorionic gonadotrophin) may be necessary to favour ovulation.

Generally, LH is administered after 48-72 h of FSH administration. Follicular growth can be induced in anestrus animals by exogenous administration of FSH or equine chorionic gonadotrophin (eCG) also called as pregnant mare serum gonadotrophin (PMSG).

The latter is having both FSH & LH activity and preferred for treatment of anestrus due to its long half-life.

Dosage of FSH

• FSH: 1000 IU intramuscular
• eCG (Folligon, Trophovet): 500-1000 IU intramuscular
• hCG (Chorulon): 1500 IU intramuscular

Gonadotrophin Releasing Hormone (GnRH)

Gonadotrophin Releasing Hormone (GnRH) can be used to treat anestrus animals either as single or double injection; the latter method gives better results.

This hormone acts better when follicle is present in the ovary.

In double injection method, administration of GnRH at 10 days apart induces estrus and improves the ovulation and conception rates.

Dosage of GnRH

• Gonadorelin (Fertagyl): 250-500 µg intramuscular
• Buserelin acetate (Receptal): 10-20 µg intramuscular

Progesterone

• Administration of progesterone mimics the presence of corpus luteum and induces follicular growth and ovulation when withdrawn.
• There are several methods of administration of this hormone viz. oral, intravaginal, injection and ear implants.
• The hormone should be administered for a minimum of 10 days and estrus is induced with in 3 -5 days of removal of progesterone.
• Oral feeding of progestational compounds continuously for 14-18 days induces estrus within 3 -5 days of last day of feeding, however, fertility at this estrus is not optimum. When administered through injection also it has to be administered for 10-14 days.

Oral Progesterone

• MGA: 0.5–1mg/day/cow
• DHPA: 120–150 mg/day/cow
• MPA: 180 mg/day/cow
• CAP: 5–10 mg/day/cow

Injectable Progesterone and Combination of Hormones

• 17 alpha hydroxy progesterone caproate(Duraprogen, Proluton)
• Several combinations of above said hormones (eg. progesterone releasing intravaginal device- PRID; Norgestomet ear implants) are also used to augment fertility in anestrus cattle and buffaloes.
• Recently, administration of GnRH and PGF2 alpha has been reported to induce estrus within 3-5 days of treatment.

GnRH and PGF₂ alpha Schedule

• Day 1: GnRH (8 m g intra muscular)
• Day 7: GnRH (8 m g intra muscular)
• Day 17: PGF₂ a (25 mg-Dinoprost)

Non-Hormonal Approach

• Supplementation of minerals and some herbal drugs fall in this category.
• Simple utero-ovarian massage is also useful in some anestrus cases. Treatment with different mineral mixtures, boluses, herbal compounds (Aloes compounds, Prajana, Janova etc) and were also reported to be effective in treatment of anestrus cases.
• Treatment with Lugol‘s iodine was also proved worthy in treating some anestrus cattle and buffaloes.
• Swabbing of uterin externum with 5% Lugol‘s solution causes local irritation and hyperemia of uterus and ovaries.
• Besides this, iodine stimulates the thyroid glands directly or indirectly and iodine deficiency, if any, is corrected. It was also reported that swabbing of Lugol‘s iodine releases uterine PGF2 alpha acting via the utero-ovarian and utero-pituitary-ovarian pathway.