Embryo transfer, synchronisation and sexed semen use in the suckler herd

Teagasc ran a number of beef webinars over the last few weeks as part of its Future Beef programme. Last Tuesday night saw the Future Beef team take a look at the latest technologies in beef breeding and how to use them – including synchronisation and embryo transfer.

Billy Fraher, who is involved in the suckler herd at Kildalton college, also gave an overview of how AI is used in the college herd and how he is producing weanlings for export on his home farm.

Synchronisation

Synchronisation was one of the first topics discussed on the night. The process involves using hormones to bring a group of cows or heifers into heat at the same time.

Conception rates generally range between 65% and 70% for heifers – once heifers have gone through puberty and are having regular heat cycles –and greater than 55% and up to 65% for cows.

If a cow has been cycling before the synchronisation programme is started, there will be a higher conception rate achieved from the programme. It’s also important to have cows gaining body condition score at the time.

There are a number of reasons why farmers use synchronisation as part of their breeding programme. Labour is probably the biggest reason. Part-time farmers who work away from the farm aren’t able to heat check enough to have a successful outcome with artificial insemination (AI), so bringing the cows into heat at the same time is one solution which negates the need for heat checking a few times a day.

Other farmers use it to induce heat in non-cycling cows. It’s a way of increasing the use of AI in your herd and it can also help shorten the breeding season and lead to a more compact calving pattern. Professor David Kenny, Teagasc, said: “It’s important to point out that we are using the synthetic forms of naturally occurring hormones, so there are no negative impacts to subsequent conception rates or heat activity after the synchronisation has taken place.”

Table 1 outlines a typical heifer synchronisation programme. It’s important that heifers are well grown for age before they start this programme. If your mature cow liveweight is around 700kg, your heifers need to be 420-430kg at 14-15 months of age.

Heifers must also be cycling before they start this programme and the use of an easy-calving bull on maiden heifers is also important. Kenny said: “You need to use proven easy-calving bulls with high reliability calving figures along with no myostatin mutations to avoid the risk of running into calving difficulty with maiden heifers.”

Heat detection is important for the programme outlined in Table 1 and a vasectomised bull will help to detect heifers in heat. All of the injections are prescription-only medicines so farmers have to engage with their vet to talk about the preferred protocol for your farm.

Table 2 outlines a beef cow synchronisation programme developed by Teagasc following a research project involving over 2,500 cows. The programme was developed to try to minimise the number of handlings to fit into a suckler system. For this programme to be successful, cows need to be 35 days calved. They need to be in good body condition and preferably on a rising plane of nutrition like spring grass or top-quality silage along with supplementary concentrates. The programme has three handlings involved.

Cows can be inseminated on heat or fixed-time AI on this programme. Typical AI costs range from €30-€40/cow. If a vet call-out charge is applied, you also need to factor in a cost of €50-€70 which will increase the costs per cow depending on the number of cows that are being synchronised. Farmers will achieve higher conception rates off a standing heat compared to fixed-time AI.

Farmers often ask if all cows will calve on the same day. Kenny said: “If there were 10 cows synchronised on a farm, you wouldn’t expect any more than one cow to calve per day when they are due to calve.”

Sexed semen

Fraher talked about the use of sexed semen on the Kildalton suckler herd. Sexed semen was used on the heifers in the herd in 2024, but didn’t achieve good results. One theory behind the poor conception rates was the fact that the crush where the heifers were being inseminated was about five minutes from where the straws were stored in the AI flask and they believe that maybe the straws were too long in the thawing flask before the heifers were inseminated. Timing of AI is very important to achieve high conception rates with sexed semen. Table 4 outlines the different times for AI using sexed semen in relation to heat onset. Cows should be served 14-20 hours after heat onset (first standing mount) which is quite a narrow window.

The sexing process causes some damage to the sperm with the result that the sexed semen aren’t as robust as semen in a conventional straw. This then means that the semen won’t last as long in the cow’s reproductive tract, hence the timing is very important. For sexed semen to be a success cows need to be greater than 35 days calved, have cycled at least once prior to AI and be in good condition.

Fraher recommended using a panel of bulls to eliminate any particular issues with one bull. In Teagasc, Kildalton cows are picked to breed replacements based on performance and replacement value. Cows with a replacement index of over €140 are used to breed replacements.

Embryo transfer

Dáire Markham runs Roscommon-based vetembryos.ie where he flushes over 300 cows annually and implants over 700 embryos on an annual basis.

Embryo transfer has increased in popularity in recent years in both pedigree herds and commercial herds with many of the “big money” commercial females being purchased with a view to flushing and breeding high numbers of progeny to recoup the purchase price.

Embryo transfer can take place by superovulating the donor cow, inseminating her and then flushing her, or via an IVF donor where oocytes (unfertilised eggs) are collected and then fertilised in a lab. Recipient heifers can then be synchronised and embryos transferred, or they can also be transferred seven days after a natural heat.

Some farmers also choose to purchase embryos and implant into heifers.

Typical conception rates for Grade 1 frozen embryos would be around 50%. Markham said: “Using maiden heifers and Grade 1 fresh embryos could see conception rates as high as 70-80% where everything is done right.”

The cost of flushing a cow is around €600/cow with an embryo implant fee ranging from €50-€80/embryo. Embryos can be frozen after flushing and stored in liquid nitrogen indefinitely.

Some of the downsides include costs and you need to be prepared for low conception rates along with cows not flushing well.

Calving difficulty can also be an issue depending on breed with many farmers opting for elective Caesarean sections on recipient heifers to avoid any chances of losing calves at calving time. “Embryo transfer is a tool where you breed your best cow to the best bull you can find to accelerate the genetic gain in your herd,” Markham said. “Farmers embarking on embryo transfer for the first time need to walk before they can run with attention to detail being very important.”

In short