My favourite topic in reproduction is sexed semen. There’s something about the technology which really gets me going – the concept that you can choose the gender of your calves is so futuristic and exciting. Like science in action! And, of course, the benefits are highly appealing.
Here’s a brief list:
- Female calves are worth far more than male calves, not only as potential milk producers, but also for sale on the domestic or export market
- New generations of calves have better genetics and more production potential than their parents
- More replacement heifers give you a younger herd age structure, resulting in a herd that has less health problems and gets in calf quick
- More replacement heifers mean that you can cull easily at the other end – fewer old and low-producing cows you keep on just to ‘make up numbers’
- Female calves are smaller than male calves, giving you fewer calving problems in general
- More female calves earlier in the season, resulting in next year’s heifers being more mature at joining with a more uniform size and weight
- Fewer male calves mean less wasted animals in dairy systems, meaning better efficiency and animal welfare outcomes.
Phew, that’s quite a lot of benefits! But like with everything, there are also disadvantages:
- You’ll still get 10 per cent male calves, which means that calving ease has to stay a top priority (although good quality sexed Jersey semen is available)
- Sexed semen straws are more expensive than conventional semen straws
- Not all bulls ‘sex’ well and it’s not possible to predict which straws are affected, giving inconsistent results (‘the bull effect’)
- Due to processing, sexed semen straws have less sperm and lower fertility than conventional – resulting in lost days in milk for animals that miss that first round of insemination.
These negatives are reasons why we’re hesitant to recommend sexed semen to all farmers (even though I love the concept). I’ve always strongly supported those who wanted to use it, but suggested that they think long and hard about their decision and what they expect to get out of it. I’ve sat through and costed it for some farmers who subsequently decided that it wasn’t financially worth it. For others, it confirmed their decision and they happily went full steam ahead with everyone’s blessing.
What most complicates the sexed semen story is that some farmers have used it in the past and been burnt by the results. Although sexed semen has been available for over a decade now, recommendations on how to use it have only really emerged in the past few years – and following them can mean the difference between a good result and a horror story that gets passed around at the pub. Sexed semen is an expensive and fragile product. Think about it this way: you wouldn’t give the keys to a new Ferrari to your speed-demon son. Hopefully,*you* would drive it with care and take out comprehensive insurance – and similarly so with sexed semen! It’s most worth using on highly fertile animals (such as your heifers), and entrusted to your favourite AI technicians (who you would support on the day).
So, to sum it all up, the decision-making process I try to run through is:
- Are you going to use it in heifers or cows? If heifers, then are they well-grown? (You can check this by weighing them and comparing them to the Heifers on Target tool – eyeballing is nowhere near as effective). If they’re not mature they won’t be cycling, and you might as well empty your wallet directly into the nearest effluent pond – it would probably save you a considerable amount of effort.
- Are you going to use a synchronisation program? (A decent guide to synchrony programs can be found here). Some farmers have had good results with fixed-time AI, which can help especially for skittish heifers if they’re kept off the main farm on out-blocks. (Ovsynch is generally not recommended – talk to your vet or AI tech.)
- Who’s going to be inseminating on the day? Do they have everything they need? Is everything ready and prepared? Have a look at your facilities and talk to your AI technician. If you’re doing it yourself, then make sure that your AI practices are up to scratch. It might be worth doing a DIY audit before the day – you could find a few percentage points of conception hidden in your technique. Best practice procedures are always improving as more research gets done.
- If you’re using it on cows, then which cows will you choose? The cow that was induced last season, has endometritis, is lame in three feet and takes six straws to get pregnant? (Hopefully this cow doesn’t actually exist). Or that young and easy three-year-old who gets pregnant just from a casual glance?
Just to emphasize: good heifer management is crucial for those who want to use sexed semen. Feeding a high quality supplement should be seen as an investment that will pay off in dividends for consecutive years in the future, not a chore or an unnecessary expense. Heifers are the future of your herd, and there’s no sense in spending extra dollars to get more if you can’t take care of the ones you already have.
Hopefully this article has given you some food for thought. This represents only the basics of what we know about sexed semen – there have been so many improvements in the past 8 months that it will take several more to keep us up to date! But fear not, dear readers, by the end of this series we should have caught up to the latest news on the technology (although those pesky scientists keep churning out more).
In the meantime, what have your experiences been with sexed semen, and what is your strategy for using it? Leave a comment and let me know!