Hinds are fertile for a very short period (12 hours) every 18-21 days, when they show oestrus (heat) and ovulate. The insemination of hinds needs to be aligned as closely as possible to the precise timing of oestrus and ovulation. Unfortunately, there is insufficient natural synchrony between hinds to be able to inseminate at a natural oestrus (heat). Besides, oestrus detection is very difficult in deer. This means we are obliged to artificially synchronise oestrus and ovulation in hinds for successful AI programmes. Such synchronisation programmes are generally performed by vets.
When should synchronisation be done?
The seasonal timing of the synchronisation/insemination programme is a very important consideration. The primary concern is to ensure that the procedures are conducted within the natural timing of breeding (i.e. CIDR device removal occurs close to the time when most or all hinds would have naturally shown oestrus). There is a temptation to conduct the programme earlier in the season on the belief that the synchronisation procedure will advance the seasonal timing of oestrus and ovulation …this is simply not the case! In some cases we have seen catastrophic failure of AI programmes because synchronisation was conducted to early in the season and hinds failed to ovulate following CIDR device removal.
The window of opportunity for AI programmes (i.e. planned insemination dates) are from late March/early April to late April. Early-mid March inseminations run a high risk of failure.
What materials will the vet supply?
Research during the 80s looked at various ways to synchronise hinds but only one method ultimately proved highly successful….the “intravaginal progesterone type-G CIDR (‘Controlled Internal Drug Releasing’) device”. This device is supported by the injection of eCG (equine chorionic gonadotrophin) in red deer and wapiti-cross hinds. Two type-G CIDR devices are inserted intravaginally for 12 days early in the breeding season and between 150 and 250 units of eCG are injected intramuscularly at device removal. Hinds will come into oestrus about 36-48 hours later and ovulate about 12 hours after the onset of oestrus. AI is timed to occur 54-58 hours after CIDR device removal.
What is the procedure?
The procedure for synchronising hinds is as follows:
- Two CIDR devices are tied together (by their strings) and inserted into the anterior chamber of the vagina via an applicator device liberally coated in lubricant (an alternative method is to insert a single CIDR device initially and replace it with a new device 8 days later, but this requires an additional hind yarding and does not seem to improve success rates).
- The devices are removed 12 days later, at which time each hind is given an i.m. injection of eCG (generally in the neck). The timing of CIDR device removal during the day is dependent on the planned timing of insemination for batches of 40-60 hinds. This will necessitate in some cases the removal of CIDR devices during the hours of darkness for batches of hinds.
- Hinds are inseminated 54-58 hours later
Show me the science
Fennessy, P.F., Fisher, M.W., Webster, J.R., Mackintosh, C.G., Suttie, J.M., Pearse, A.J.T., Corson, I.D. (1986) Manipulation of reproduction in Red Deer NZVA Deer Branch Conf. Proceedings No.3 / 103-120 View paper here