Tips to get the best from sexed semen

1. Select your best
2. Take extra care of yearling heifers
3. Hone your heat detection skills
4. Get it right on the day

For a printable summary click here.

By using frozen sexed semen, there is an added benefit of targeting the best cows in your herd – which will deliver accelerated genetic gain.

It all starts with a plan to ensure that you have a target cow list for mating.

• Start with a list of cows that are in the top 25% of your herd – depending on your breeding goal, cows should be ranked on NZMI, PW or BW.
• Identify cows that calve in the first 3 weeks – these animals have the longest recovery time ahead of mating and if well managed, will have reached their second heat (or greater) at the point of insemination – resulting in higher non-return-rates (more cows in calf).
• Choose fertile cows – younger cows are more fertile, and once they reach 8 years old, their fertility declines. You can also refer to their fertility breeding value.
• Well-conditioned cows – heifers who reach a body condition target of 5.5 at calving, and cows who reach a body condition target of 5. Additionally, they should lose a maximum of 1 body condition score by mating (aim for 0.5 of a condition score).
• Healthy cows – remove any cows from your list who had a difficult calving (including twins), or who have had a health condition since calving, such as milk fever, endometritis, mastitis, or lameness.
• Cycling cows – cows must have had their first (silent) heat during the pre-mating period to ensure that by planned start of mating, they have reached their second or subsequent heat. This increases their conception rate. Best practice is to apply heat detection aids 5 weeks before planned start of mating and record animals that have had a heat. Those that haven’t cycled should be excluded from the target list.

Your target cow list should ideally contain more animals than you need to inseminate with sexed semen. For example, if you are using 100 sexed semen straws, aim to identify 125 cows. This will give you options on the day of insemination – for example, where a cow meets all success criteria but gets sick, is below body condition, or doesn’t have a strong heat.

Your plan should ensure that all sexed semen is used in the first 3 weeks of mating, and conventional semen should be used for any animals that return.

Want help selecting?

Talk to us about building a personalised mating plan that uses herd information to select which animals should go to sexed, conventional or beef.

Speak to your sales consultant for more details or contact us here.

Farmers have started to use sexed semen as part of an insemination programme for yearling heifers. This is common practice overseas and is a great way to breed 'the best from the best'.

To ensure success with this group of animals, it’s even more important to have a solid plan. Yearling heifers start cycling once they have hit a target weight, which is calculated at 60% of your average cow mature liveweight on farm. Some breeds are therefore, later maturing.

The following factors are important to consider.

• Yearling weights – ideally you have individual yearling weights by running them over a weigh scale 4 – 6 weeks before mating. Body condition scoring is not a reliable tool in yearlings, as the main driver for fertility/cycling behaviour is their physical weight.
• Nutrition – all animals should be on a rising plane of nutrition heading into mating, but this is especially important for yearlings.
• Genetic merit – not only do you want the best-grown animals, but you want to target replacements from the top 25% of animals in terms of genetic merit. Animals can be ranked based on NZMI or BW. Consider only targeting your top heifers with sexed semen to get the best return on investment, and the remainder with conventional semen.
• Fertile yearlings – as with cows, the best results will be seen with yearlings who are inseminated at their second (or later) heat, rather than on their first heat – which has a reduced conception rate. Pre-mating heats (or pre-mating synchronisation) will help to identify target yearlings.
• Healthy yearlings – ensure preventative health treatments such as vaccination, drenching and trace element supplementation are up to date.
• Synchrony programmes – there are a range of synchrony programmes available for yearlings. Speak to your vet about options.

Sexed semen is a more fragile product than conventional semen and therefore has a shorter life inside the reproductive tract – so timing of insemination is everything. Ideally, this timeframe is 18 – 24 hours after the start of heat behaviour, which can be challenging to measure.

It all starts with pre-mating heat detection, to determine which animals have had one or more heats in the pre-mating period – as conception rate increases markedly from the second heat onwards.

Pre-mating heat detection should begin 5 weeks (35 days) before the planned start of mating. A variety of heat detection aids can be used for this purpose – but key factors remain the same:

• Ensure heat detection aids are correctly applied and are working correctly
• For aids that require topping up (such as tail paint), try to ensure that the same person is responsible for this.
• Monitor cows regularly and record pre-mating heats into your herd recording software. This information helps when using non-cycler intervention and gives a sense of how the herd is performing – a high performing herd in NZ will still have up to 15% of cows who are not cycling at the planned start of mating.
• Ensure everybody on farm is educated on how to spot a cow on heat, and have a plan to feed this information back to a central point (ideally into herd recording software).
• Put someone in charge of the heat detection plan – this is known to deliver a better result.
• Ensure on-farm maintenance is up to scratch – for example, that the drafting gate is working correctly.

• Ensure target cows are clearly marked – your AB technician needs to be clear that different cows are being inseminated with different types of straw. You may be using sexed semen, conventional semen and beef semen.
• To make identification simple, one option is to use a different coloured heat detection aid to identify the different mobs of cows. For example, some of our customers use Fuchsia (pink) ESTROTECTs on sexed semen cows, yellow on conventional semen cows, and green on beef cows. This avoids any confusion.
• A final decision should be made cow-side as to which straw goes into each cow. For example, if a cow’s heat detection aid suggests a weak heat, or she is skinnier than you’d like, you may choose to not inseminate sexed semen and go with an alternative instead.
• If using ESTROTECT, only cows with a patch score of 3 or 4 should be inseminated with sexed semen. Most wearable products also give an indicator of heat intensity. Frozen sexed semen gives absolute choice – if in doubt, don’t inseminate and keep the straw for the other target cows on your list.
• Ensure straw handling practices are top notch. CRV AB technicians are trained to handle frozen sexed semen straws.
• If you are a DIY technician, familiarise yourself with sexed semen straw handling practices and adhere to them closely.