SYNCHRONIZATION OF ESTRUS IN FARM ANIMALS

Team Pashudhan Praharee

April 19, 2020

1387

BY-

L.Kipjen Singh^a* and K. Merina Devi^b

^aAnimal Reproduction Gynaecology and Obstetrics Division, ICAR-National Dairy Research Institute, Karnal-132001,

^bDepartment of Livestock Farm Complex, COVSc & A.H.,CAU, Jalukie, Nagaland-797110,

*Corresponding author:laishramkipjen04@gmail.com

What is synchronization of estrus?

Synchronization of estrus implies the manipulation of the estrous cycle or induction of estrus to bring all females into estrus at a predetermined time with a reasonable accuracy.

Approaches or methods of estrus synchronization

Hormonal method

Extending the luteal phase (using exogenous progesterone)
Shortening the luteal phase (using prostaglandin and its analogs)

Non-hormonal method

Male effect
Artificial lighting
Weaning

Advantages of estrus synchronization

Allows fixing of breeding time within a short predefined period
Can schedule the parturition time at the most favorable season
Produces more uniformity of calves at weaning.
Enables wider use of artificial insemination or through natural selection of superior sires.
Reduced time and workload for heat detection
Provides more economic returns by improving animal production efficiency
Silent estrus and anestrous are handled effectively

Disadvantage of estrus synchronization

Expensive of drug and labor under field conditions
Difficulties in small animal holders
Prostaglandins only act in cyclic animals

Synchronization of estrus in cattle:

Two shot prostaglandin

Prostaglandin acts as a luteolytic agent (regression of corpus luteum in cyclic animals). It is classified as natural and synthetic prostaglandin.

*Estrus rate: 80% in non-descript and 100% in crossbred cows

Progesterone treatment

Progesterone exerts negative feedback on LH (Luteinizing hormone) secretion after the regression of corpus luteum. Administration of progesterone can be done through a vaginal sponge i.e., CIDR (Controlled internal drug release) and PRID (Progesterone releasing intra-vaginal device).

*Synchronization rate~ 30% and pregnancy rate~20% in anestrous and cyclic females

Ovsynch Protocol (GPG Protocol)

Gonadotropin-releasing hormone (GnRH) affects follicular growth by causing either ovulation or luteinization of the largest follicle and prevents estrus until after the prostaglandin injection, which causes the corpus luteum or luteinized follicle to regress.

*Synchronizes the estrous cycles of 70-80% cyclic cows

GnRH– PG System (Select-synch)

Synchronization of estrus in sheep and Goats:

Two shot prostaglandin

*Estrus behavior in goats: 95-100%, Estrus response in sheep: 100%

Progestogen and eCG combination

Sheep

Goat

The male effect

The introduction of male animals to isolated anoestrus female animals during breeding and non-breeding season at least for three weeks leads to luteolysis and ovulation (Ram effect in sheep and Buck effect in goat). The physiological basis for this response is due to its smell and sight. The female animals showed estrus within 72-144 hrs.

Artificial Lighting

Alteration of day length by artificial lighting i.e., 8hrs light followed by 16 hrs of darkness can increase the breeding efficiency of sheep.

Melatonin

Subcutaneous implants of melatonin (18mg) for 30-40 days in seasonally anoestrus sheep during early or transition period will return to normal cyclicity in ewes.

Synchronization of estrus in horse:

Prostaglandin