Are your AI practices letting you down?
The InCalf Project estimated that every missed heat can cost a farmer around $200. Although you may be successfully catching cows on heat, if your AI practices are not refined, it could have detrimental impacts on your breeding outcomes.
The high surface area to volume ratio of a semen straw leaves them vulnerable to thermal fluctuation. This means that any thermal injury that may occur, will cause permanent and irreversible damage. It’s important to remember that when collecting semen from your AI tank, the canister should be held below the frost line, to limit and minimise the risk of partial-thaw damage.
Semen is stored in liquid nitrogen at -196°C. This temperature increases rapidly the further up the neck of the AI tank you go. If canisters are withdrawn above the frost line, it will compromise all of the semen stored in that canister. This exposure results in the formation of ice crystals, damaging the sperm and rendering them unviable.
It takes no more than 3 seconds of exposure to increased temperatures to cause partial thaw damage. When selecting your straws while holding the canister below the frost line, be mindful to keep the canister at this level for no more than 10 seconds, before it must be lowered back into the liquid nitrogen. Similarly tweezes should be utilised to handle frozen straws instead of fingers to avoid exposure to excess heat.
Straws should be thawed for a minimum of 30 seconds in water between 32-38°C. The added volume of maxi straws should be taken into account, allowing for 45 seconds of thawing before use.
Similarly extra care needs to be taken with sexed semen, being thawed for 45 seconds in water between 35-37°C. Keep in mind the delicate nature of sexed semen and ensure it is inseminated within 5 minutes post thaw for optimal results.
Likewise for conventional semen, only thaw enough straws that can be successfully used within 10 minutes post thaw. The temperature of your thawing water should be regularly monitored to ensure the thawing process is not compromised. The InCalf Project recognised this as a high risk with greater than 50% of those using auto thawers not checking functionality at the start of the season or monthly.
When utilising sexed semen, consider its applicability within your herd and use at least three sexed semen AI bulls to spread the risk.
Heifers should be well grown, healthy, vaccinated and free from reproductive diseases such as Pestivirus. Fertility tends to be lower in cows than in heifers, with conception rates often 10% lower due to the combined effects of age, previous calving, lactation and disease.
The use of sexed semen should be limited to the most fertile cows in order to achieve better, more reliable results. Selected cows should be free of reproductive, metabolic or other disease, calved for a minimum of 40 days, aged between 2–6 years old, and transitioned well into lactation with minimal bodyweight loss.
Post Thaw Handling
Semen is highly sensitive to water and other contaminants. A single drop of water can have detrimental effects on the viability of the sperm, resulting in minimal chances of conception. Therefore, cleanliness and utilisation of paper towel to thoroughly dry straws post thaw is important for AI success.
Once thawed you should protect them from excessive light, wind or temperature variation. This can be done by prewarming AI guns to prevent thermal shock. The InCalf project identified this as a high risk, with 34% of technicians failing to prewarm their guns prior to loading the straws.
Another area of high concern was the level of water in the thawing flask, with 25% having the thaw water levels too high or too low causing improper thawing with low levels and potential leakage of water into the crimp if water is too high. The optimal height of water in the thawing flask should allow for all bar the top centimetre of the straw to be covered.
Take some time this joining season to evaluate your practices by going through this AI checklist, visit https://bit.ly/3lwDjTK If you are interested in finding further ways to improve your farm’s fertility, view the Dairy Australia InCalf Book for Dairy Farmers or contact GippsDairy about attending an In Charge Fertility course at 03 5624 3900 or firstname.lastname@example.org