Feature in Dairy Farmer Magazine - July 2020

Cogent Breeding’s reproductive training manager Jeremy Dain offers instruction to inseminators about AI techniques and particularly best practice when it comes to using sexed semen in your herd.

Stress free calving, nutrition and health can all influence breeding success, and without them all working together it will have a negative effect on the successful use of any semen product, let alone a sexed product.

However, we all know the environment is not always perfect but there are areas that we can control to make sure we maximise the use of sexed semen.

For a start, targeting the right animals for sexed semen will most certainly have an impact on our success rate. In the past sexed semen has been mainly used in youngstock breeding strategies based on the reasoning that younger females would in general be more fertile and likely to be the most genetically advanced.

Now, with the advances in sexed/sorted semen products and genomic testing, we are seeing sexed semen being used a lot more in the adult herd population. Nevertheless, whatever the policy, there are a few simple guidelines that we use for targeting the right animals within the Precision Repro service to bring us the most success when using sexed semen.

Guidelines for targeting the right animals within the Precision REPRO service to bring the most success:

• Maiden heifers up to 2 inseminations
• Maiden heifers to be well grown and in good condition (hitting farm specific targets)
• Use on 1^st & 2^nd Lactation animals
• Under 100 DIM
• No history of poor uterine health – RFM, metritis etc
• No recent history of ovarian cysts or fertility issues
• At least one good clean heat to be recorded before exiting VWP
• Not lame
• BCS to be taken into consideration and greater than 2.00
• Energy status of herd/individuals to be considered where possible
• 2 x inseminations using sexed, if unsuccessful move to conventional/beef for 3^rd upwards

The decision to breed an animal should be driven by good heat detection, physical signs and good historical data to reference eligibility. We recommend that a decision to breed an animal with sexed semen should include the following elements.

Firstly, good heat detection practices – use chalk or other detection aids or regular structured visual checks. Animals showing good strong signs, high activity levels or chalk rubs etc to be put forward for possible AI.

Secondly, physical checks to confirm eligibility such as clean, good strong heat with secondary signs such as bulling mucus.

And thirdly, use data from the animal’s fertility history ie no history of poor uterine health or fertility issues, past VWP with previous heat recorded, less than 100 DIM, service number, genomic test data etc.

Right we’ve selected the right animals but what about handling the semen itself. Maximising the live cells per straw is vital, and poor practices can have a huge negative effect on your results.

Handling sexed semen and gun loading are both areas that need continuous efforts to maintain high standards. Poor practice will work against maximising live cells and will undoubtably have a huge negative effect on your results. Here are a few pointers that we emphasize as best practice within the Precision Repro service when it comes to handling sexed semen.

Best practice within the Precision REPRO service for handling sexed semen:

1. Use a clear semen flask location chart
2. Never take out an individual straw to check it then put it back (location chart helps with this)
3. Use tweezers, never fingers to handle straws
4. Minimise the time the canister is in the neck of the flask and above the LN level (5 sec MAX) If you need longer then lower canister back into the LN for a min of 10 seconds before trying again.
5. Follow product advised thaw times e.g. SexedULTRA 4M – minimum of 40 seconds in water at 37°C (preferably an electric thaw unit, ensure to check the temperature of the thaw unit daily with a thermometer).
6. When loading AI guns pre warm the AI gun, sheath and even the tissue you use to dry the straw. Limit temperature fluctuation during the process.
7. Use AI sanitaire/chemises on all inseminations using sexed semen.
8. Never load more than 2 straws of sexed semen at one given time.
9. Keep the loaded AI gun insulated between completion of loading and AI’ing the animal.
10. Complete insemination within 10 mins of the straw initially entering the thaw bath.

Having strong data to highlight what is working and what is not is the key to making progress. Recording information such as the sire, inseminator and strength of heat can all be used positively to identify areas for improvement. These can also be used ultimately for changing protocols in the light of such things as marginal heats and animals served off the back of various fertility interventions like Pgf2a injections at vet routines. Using protocols to standardise what everyone involved in the breeding of animals does minimises risks and variation, especially when the use of sexed semen is involved.

Another element is the actual timing of insemination to get the best results. As many of you will know capacitation is the process the sperm cell undergoes before it has the opportunity to fertilise an egg. This process starts from the moment that sperm cell leaves the testicles of the bull, which means that the time an ejaculate is processing in the lab before it is frozen is highly relevant.

Conventional semen is frozen within a very short time after collection, but due to the 10-12 hour processing that is required for sexed semen, it means those sperm cells are much further down the path of development and therefore have a shorter window for successful insemination.

The insemination procedure for sexed semen differs little from conventional, but females should be served slightly later during the heat period, ideally 18-24 hours after the onset of heat. If this advice is not observed, it can be another factor that could have a negative effect on conception rates.

SexedULTRA 4M has now been proven by UK farmers as a highly fertile product, comparable to conventional semen across the UK on many different systems and herd sizes.

The following data has been derived from 73,370 inseminations on 30, 830 milking cows and 11,303 maiden heifers in 164 herds shows that SexedULTRA 4M is almost as high performing as conventional semen on the cow group, when following the correct guidelines.

SexedULTRA 4M is almost as high performing as conventional semen on the cow group, when following the correct guidelines.