Uses for genomic testing

Uses for genomic testing on dairy farms

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Genomic testing is a great advance for agriculture - but how can it be used on dairy farms in Australia?

FUTURE VIEW: Genomic testing can be used to peer into the future - to show what a calf might become when it is still young.

FUTURE VIEW: Genomic testing can be used to peer into the future - to show what a calf might become when it is still young.

In my last column, I outlined some of the basic science underlying genomic testing. In short: genomic testing looks at the genetic code of an individual animal. It gives us information about that animal by comparing parts of their genetic code to a reference population of animals with known codes and performance characteristics.

Okay, so it's nice that there's this new tool - it's shiny, Australian-made, and pioneered in dairy cattle. Other industries are desperately trying to catch up to us, and it's been a great advance for agriculture in general. But what about individual dairy farmers? Does it have a place in your farm business? Let's look at how genomic testing might be used.

First and most simply, genomic testing can be used to verify parentage. Any farmer who has had to pull 10 calves out of the calving pad in the morning knows how tricky it can be to match them to their mothers. For a farmer who cares about accurate record-keeping and the pedigree of their animals, this can be a frustrating issue. Genomic testing can also be used to screen for a variety of diseases and desirable traits, such as bovine leukocyte adhesion deficiency (bad!) or polled/A2A2 status (good).

Secondly, at a deeper level, genomic testing can be used to peer into the future. The process can tell you - before a calf has done anything more interesting than suck on its herd mate's ear and bawl endlessly at your rearer - how that animal is going to perform in the dairy, how fertile it's going to be and if it'll be worth the $1300 to $2000 it's going to cost you to rear it to maturity.

Growing out heifers is an expensive process when done correctly. Farmers in denial about the true cost of heifer rearing should sit down and figure out the cost of supplements fed, of milk lost or calf milk replacer bought, health costs, the cost of labour, agistment/lease costs or the opportunity cost of using land to raise young stock. This isn't even mentioning the heartache and stress that can come along with raising a large number of sometimes terminally curious young animals who insist on getting into things they shouldn't and licking things that aren't supposed to be licked...

However, good rearing should result in an animal that will calve without assistance, survive a first lactation producing at least 80 per cent of a mature cow's milk yield, compete well upon entering the herd, and get in calf again without issue. One way to assess for yourself is to compare first-calving heifer reproductive performance with the rest of the herd - if they're not your most fertile animals, something has gone wrong.

Growing out heifers is also an expensive process when done incorrectly. Heifers that are not fed appropriately post-weaning, and that end up in a back paddock and are ignored for long periods, are unlikely to cope well or milk well when entering the herd. Also, heifers that leave the herd due to infertility after a single lactation are not profitable cows - in fact, they are costing you money.

Genomic testing can be a way of reducing these rearing costs by only keeping the best animals and selling the remainder with absolute confidence. This works best for a farmer who has excess replacement heifers due to sexed semen use or great fertility (or both) and is interested in pursuing genetic improvement. Some farmers also see it as part of the story of reducing non-replacement calves, addressing the concerns of consumers (and in many cases, themselves).

Other genomic-testing strategies include the selective use of sexed semen on genetically elite animals, or if not sexed semen, then things like embryo transfer or sire selection. In an ideal future, animals that have been genomically tested should also be worth more than untested animals - although this is largely going to be up to who buys your heifers, or at some point, your whole herd.

These are a few ways I think genomic testing can be useful. However, one of the fascinating things about working in the dairy industry but not actually being a dairy farmer, is watching to see how tools and new developments are implemented on-farm. One has only to see the multitude of ways that baling twine or perfectly shaped rocks can be used in order to recognise the day-to-day creativity of farmers. (This becomes a negative is when it is used to prop up failing safety equipment - to the farmers using bits of string, chains or leg straps to hold your crush together, yes friend, I'm looking at you.)

Farmers are highly capable of figuring out new ways of using new tools. So, at the industry level, all we can do is make recommendations on how we think the things we build should be used, and then watch with interest as farmers work out ways to take it further. In what ways are you using genomic testing in your herd?

*Ee Cheng Ooi is a cattle veterinarian undertaking a PhD at Agribio in dairy fertility and genetics. All comments and information discussed in this article are intended to be of a general nature only. Please consult the farm's vet for herd health advice, protocols and/or treatments that are tailored to a herd's particular needs.

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