Artificial Insemination (AI) and Embryo Transfer (ET) are well-established, viable and practical tools to improve rates of genetic gain within the NZ deer farming industry. This has been clearly demonstrated with considerable production gains to date in antler size and high growth rate. While the success rates in red deer are comparable to, or better than other farm animal species, careful planning and execution are required to optimise success.
The use of a sire for natural mating is limited by the inability of the stag to mate with many hinds (see Mating Management), and the physical restriction to one farm for the mating season. AI overcomes these limitations by distributing a stag’s semen over a wider number of hinds and across multiple farms.
This principle is central to the Deer Progeny Test (DPT) programme, where genetic merit of sires are ranked across farms and years by use of AI alongside natural mating. This involves developing sire linkages, in which common sires are used across farms in the same year, and subsequent years, allowing the calculation of across-farm Breeding Values (BVs).
This use of AI is not limited to stud farms; commercial breeders can also acquire top genetics. Used as an alternative option to buying high BV stags – especially within closed herds where there is concern about the introduction of disease through outside animal purchases. Semen has a very low risk of disease introduction.
AI is not something to be embarked upon lightly and involves considerable planning, the use of skilled people, and a time investment. If done well AI is a very successful genetic tool. Success rates of 70-80% pregnancy are commonly achieved with a single-time insemination. This is considerably better than what is achieved in other livestock industries.
See below in the more resources section for links to pages that will take you through the various considerations and actions for a successful AI programme. Attention to detail is important to a rewarding programme.
Semen selection will invariably be based on the perceived or actual genetic merit of the stag(s). In many cases BVs will be available through DEERSelect, making the choices easier. However, for many stags for which semen is commercially available, there are no across-farm BVs for traits of interest (particularly antler traits) and judgement of genetic merit will largely be based on the reputation of the stud breeder and the fit of the available animals with your own breeding objectives.
- The principal reason for using AI is to acquire the best stag genetics for your particular production system. The choices you make for semen purchase will ultimately influence the genetic performance of the whole herd.
- In many respects it may seem that hind selection for AI programmes is secondary to stag selection. However, the hinds carry half of the genetics in any AI programme. Where possible select those hinds with proven track records for production (particularly reproductive success). Also, hinds that display poor temperament often perform poorly in AI programmes particularly if they become highly stressed during handling. Ideally, hinds chosen for AI are the best in the herd for the production traits of interest, and are temperamentally suited to the frequent handling required for AI.
- Another consideration of hind selection is to ensure that they are in good body condition at the time of synchronisation and AI. This may require some preferential treatment and feeding prior to these events; particularly if it has been a hard summer. Early pre-rut weaning of their calves is preferable to allow for an early dry-off. This will help in gaining condition for AI.
Key factors to consider when discussing the option of beginning an AI programme
- Because of the frequent animal handling required for AI programmes, it almost goes without saying that the handling facilities need to be in top order and capable of easily accommodating the mob sizes required for each AI session.
- Hygiene is of utmost importance, so the facilities need to be capable of frequent and thorough cleaning e.g. of floors, table and crush. It is preferable to have a separate clean room particularly for the semen thawing process.
- A pneumatic, hydraulic or manual crush is generally required for CIDR device insertion (oestrous synchronisation) and insemination. Crushes need to be maintained in good working order…crush failure presents a risk to operators and to the hinds themselves. They must secure the hind tightly but without risk of injury to hinds held in them for up to several minutes at a time. Also, inseminators are at risk of receiving severe kicks from the hinds back feet. A padded kicker board up to 300 mm high should be installed at the rear of the crush.
As AI programmes require a minimum of three separate hind yardings over a period of two weeks, it is important that risk of animal injury in minimised (i.e. ensure sharp projections that may injure hinds are identified and removed). The procedures used for AI are reasonably invasive (e.g. CIDR device insertion and removal, trans-cervical insemination) and farmers sometimes note a deterioration in hind behaviour in the yards with each successive yarding. This can be avoided by minimising hind stress during yarding. Attention to detail is important.
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 too 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
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
Remember, timing is everything! Planning and strict attention to detail is the key to a successful AI programme. AI in red deer and wapiti crossbreds involves transcervical inter-uterine insemination, and requires rectal manipulation of the reproductive tract. This procedure is conducted by highly trained AI technicians. Follow the instructions of the AI contractor to the letter.
Due to the rather short AI season, it is very important to arrange for insemination services well in advance of requirements. Generally, inseminators will supply the synchronisation scheduling and organise dispatch and transport of frozen or fresh semen in time for the AI. However, in some cases the farmers themselves may need to co-ordinate semen dispatch from AI centres.
It is normal practice to run the inseminated hinds with ‘back-up’ stags from about 10 days after AI. This ensures that hinds that fail to conceive to AI have a chance of getting pregnant for the year. However, this can mask the success of the AI programme unless hinds are ultrasound scanned early in pregnancy to assess foetal age or DNA is used to assess paternity of calves born.
Pregnancy scanning of AI success is a straight forward procedure, but requires appropriate timing in order to distinguish AI conceptions from those of the ‘back-up’ stags.
The ideal time of scanning is 45-50 days after AI. Foetuses of this age are very easily visualised and distinguished (see attached ultrasonogram of a Day 45 red deer foetus). By contrast, hinds conceiving to ‘back-up’ stags will have a pregnancy at least 10 days younger but most likely to be 18-21 days younger (length of an oestrous cycle).
Semen is collected from stags by electro-ejaculation, a procedure that is conducted by professional Artificial Breeding (AB) companies and veterinarians. In some cases it requires the use of sedatives and anaesthetics.
Generally, the farmer’s only involvement is to yard the stags at a scheduled time, and leave the rest to the professionals. Needless-to-say, good facilities are a must for the safety of everybody concerned.
Semen processing is again at the hands of the professionals and is a reasonably complex process. Collection of an ejaculate from a stag does not necessarily mean that good, usable semen will be obtained. AB companies will assess the semen quality once it is processed and judge whether it is suitable for AI based on a set of quality standards.
It is not uncommon for stags to provide poor quality ejaculates early in the breeding season (remember stags are infertile over spring and early summer) generally semen quality will improve approaching the rut and even well after the rut.
Most stag semen is frozen (‘cryopreserved’) and then thawed immediately before insemination. However, some AB companies can offer fresh semen collected within days of the insemination programme. Whilst frozen semen can be successfully preserved for many years, In terms of conception rates to AI, usually ‘fresh is best’. However, many batches of frozen semen have very high AI success.
Other reasons to collect semen
- to check the stag's fertility
- as a back-up option if the stag dies prematurely as an insurance policy
- post-mortem semen collection
Occasionally valuable stags die during or after the rut. With quick action, it is often possible to remove the testes, store them in a cool box and send them to an AB company for epididymal sperm extraction. The testes need to be processed within 6-8 hours of death. Talk to your nearest AB company to discuss this option should the need arise.
Asher, G. W., Berg, D.K., Evans, G. (2000) Storage of semen and artificial insemination in deer >>
Fennessy, P.F. (1993) Artificial breeding in the New Zealand deer industry: genetic aspects >>
Asher, G. W., Dixon, T.E. (1994) Development of AI and ET of farmed deer >>
Wenkoff, M (2012) Maximise your Artificial Insemination Results (Elk/Wapiti) >>
An article outlining the Application and benefits of different pregnancy scanning techniques. G Asher. Deer Industry News (2003)
Lawrence, D.W., Linney, L. (1998) Utilising data from ultrasound scanning for pregnancy NZVA Deer Branch Conf. Proceedings Vol15/61-64
Shackell, G.H. (1989) Semen evaluation, handling and thawing. Proceedings of a Deer Course for Veterinarians. Deer Branch NZVA. 6: 14-20.
Asher, G.W., Berg, D.K., Evans, G. (2000) Semen collection and AI in deer
Asher, G. W., Berg, D.K., Evans, G. (2000) Storage of semen and artificial insemination in deer. Animal Reproduction Science 62: 195-211.
Deer farmers use multiple ovulation and embryo transfer (MOET) to maximise the numbers of offspring from genetically elite hinds and stags. It is based on the production of multiple high-merit embryos from each ‘donor’ hind but uses low merit ‘recipient’ hinds as surrogate mothers.
Naturally, hinds produce a single calf annually from a single ovulation event. However, treatment of hinds with various reproductive hormones (principally FSH and eCG) can induce multiple ovulations at time of mating or insemination. Although the hind cannot gestate all the resulting embryos, they can be physically removed from the donor hind and transferred individually into synchronised recipient hinds to be gestated and reared. Thus, it is possible within one season for an elite hind to generate multiple progeny.
Multiple ovulation and embryo transfer or MOET involves considerable complex programming and planning. It requires the involvement of highly skilled professionals, including vets and AB technicians. As such, its adoption has been largely confined to deer stud operations with high-value recorded female stock. However, commercially available frozen (‘cryopreserved’) embryos can occasionally be obtained by commercial breeders, usually by private treaty but sometimes by auction. The procedures for embryo transfer into recipient hinds are less complex than for an entire MOET programme, and can improve the genetic merit of herds.
It is important to remember with a MOET programme, that for each donor hind there are no guarantees of success. The induction of multiple ovulations produces highly variable results between donor hinds within each programme. Be prepared for some hinds to fail. Results can vary from no recoverable embryos to a highly successful tally of 10-15 recoverable embryos. On average, a successful MOET programme will yield 4-6 transferable embryos per donor hind.
See below in the more resources section for references and links to articles that will take you through considerations and actions for a successful MOET programme. As with AI, attention to detail is important to achieving rewarding ET results.
Donor selection (both donor hind and donor stag) is the single biggest consideration of the MOET programme. Let’s face it, MOET is expensive and must target the very best genetics to be financially viable.
As stag selection can include semen, there are many options for selecting individuals with recorded traits and ‘across-farm’ BV’s. This is not necessarily the case for donor hinds, and choices are generally limited to within farm. Good pedigree records and inter-generational records on hind production are the prime decision-making requisites.
Irrespective of genetic attributes, donor hinds must be in very good physical body condition and be temperamentally suited to repeated handling required for MOET.
While recipient (surrogate) hinds are of lower genetic merit than donor hinds, they still need to be healthy individuals with a good track record for rearing calves. They carry a major responsibility as surrogates to highly valuable donor offspring.
Recipient hinds are synchronised in exactly the same manner as hinds programmed for AI (see Artificial Insemination), the main consideration being that they are not inseminated or joined with stags at all. They must be non-pregnant in order to receive the transferred embryo.
The other important consideration is that they must be at the same stage of the cycle as the donor hind, therefore they are synchronised slightly (12-24 hours) ahead of the donor hinds (the earlier timing is because the follicle stimulating hormone (FSH) given to donors slightly advances the timing of their ovulation and insemination. The differential timing of the donors and recipients aligns their respective ovulation timing).
The real ‘trick of the trade’ is synchronising the right number of recipient hinds for the numbers of embryos likely to be collected for transfer (4-6 per donor hind) pretty hard to get this one 100% correct.
The synchronisation and induction of multiple ovulation (sometimes called ‘superovulation’) in donor hinds uses intravaginal progesterone CIDR devices (see Artificial Insemination) to synchronise the onset of oestrus and ovulation (as for AI) and various gonadotrophic/pituitary hormones to cause multiple eggs ('ova') to be shed by the ovaries at the end of the synchronisation procedure.
What materials are involved?
The main hormones used are Follicle Stimulating Hormone (FSH) and equine Chorionic Gonadotrophin (eCG). The actual combinations of hormones, the dosages and the delivery schedule are determined by the AB professionals based on a number of factors, including hind genotype and body mass. eCG is not always used in MOET programmes, and if it is , seldom without FSH. Because FSH has a short half-life following injection, it is normally administered a 12-hour injections for 3-4 days around the timing of CIDR device removal.
What is the procedure?
The general procedure for synchronising and multiple ovulating donor hinds is as follows:
- Two CIDR devices are tied together and inserted into the anterior chamber of the vagina (as for AI).
- CIDR devices are removed 12 days later. Starting 12-24 hours before CIDR device removal, donor hinds each receive intramuscular injections of FSH for up to 4 days.
- Donor hinds are joined with stags shortly after CIDR device removal or are artificially inseminated (see Artificial Insemination) 36-44 hours after CIDR device removal (note that this is earlier than for AI).
The next step is to recover embryos 5-6 days following mating/insemination. This is usually done by surgical laparotomy, whereby the uterus is exteriorised and cathetarised to allow flushing of embryos from the tract. Obviously this is a highly technical operation by highly skilled professionals, involving full anaesthesia of the hinds.
Embryos are flushed into a glass dish and visualised under the microscope to assess their developmental stage and viability. The desired embryo stages for cryopreservation or direct transfer are morulae and blastocysts.
Meantime, the donor hinds are stitched up and undergo recovery from surgery. They are normally re-united with stags a week or two later in order to get pregnant.
Embryos recovered from donor hinds, once they have been assessed by the artificial breeding technician as ‘usable’, are generally transferred within a few hours of harvesting (surplus embryos may be cryopreserved).
Embryo transfer, in which single embryos are transferred to each recipient, can be done either surgically or non-surgically.
Ultrasound scanning provides an early indicator of success of the transfer programme. This is best done 35-50 days after transfer, when the foetuses from successful transfers will be about 43-58 days of age. This timing is particularly important if the recipients were joined with stags at some stage after the transfers, in order to differentiate between successful transfers and later conceptions to ‘back-up’ stags.
Recent studies indicate that abortion is occurring at a higher rate amongst hinds in some herds than others, and may even be a significant cause of overall wastage. If farmers suspect they have a problem, it is important to monitor the issue closely.
How can I look for abortions?
It is very difficult to find aborted foetuses in the paddock. Sometimes dead foetuses are simply resorbed by the hind. On other occasions when they are expelled they are eaten by scavengers (e.g. hawks) or even the hinds themselves. If you suspect that hinds in your herd (particularly first-calver hinds) are aborting their pregnancies, the best option is to double scan the herd to identify missing pregnancies. Always consult your vet about possible options to test aborting hinds for diseases that may have caused foetal death.
The double scanning method
This method relies on two ultrasound scans of all the hinds in the herd. The first scan in early pregnancy (late May to mid June) and the second scan in late pregnancy (September to mid-October). Pregnancies detected at the first scan that are missing at the second scan are clearly indicative of foetal wastage.
What should I do next?
If you identify a problem, or even just suspect a problem, consult with your vet. It may be possible to identify the cause of foetal wastage and correct the problem in subsequent years. Blood sampling of aborting hinds may provide antibody evidence of disease. However, the best incriminating evidence will generally come from aborted foetal tissues. If the scanner operator identifies a dead foetus still inside the hind, it may pay big dividends to euthanize the hind and send foetal tissues to the lab for analysis. Consult your vet about doing so.
Fennessy, P.F., Fisher, M.W., Shackell, G.H., Mackintosh, C.G. (1989) Superovulation and embryo recovery in red deer (Cervus elaphus) hinds. Theriogenology 32: 877-883.
Fennessy, P.F., Asher, G.W., Beatson, N.S., Dixon, T.E., Hunter, J.W., Bringans, M.J. (1994) Embryo transfer in deer. Theriogenology 41: 133-138.
Asher, G.W., O’Neill, K.T., Scott, I.C., Mockett, B.G., Pearse, A.J. (2000) Genetic influences on reproduction of female red deer (Cervus elaphus). (2) Seasonal and genetic effects on the superovulatory response to exogenous FSH. Animal Reproduction Science 59: 61-70.
Asher, G.W., Wilson, P.R. (2011) Reproductive productivity of farmed red deer: a review. Proceedings of a Deer Course for Veterinarians. Deer Branch NZVA 28: 23-29.
Information on A successful pregnancy: preventing foetal losses is available in a convenient DINZ Deer Fact sheet (August 2017). Download your own copy here >>