Words and Images by Sarah Horrocks — AngusPRO Magazine 2024.
When you’re looking at efficiency in cattle there are two main aspects. There is profitability — maximum output from minimum input — and there’s environmental — every kilo of input produces methane so reducing input ultimately reduces the total methane emissions.
Neither of these concepts is anything new, however, the addition of the Net Feed Intake EBV on animals registered with Angus Australia has brought efficiency into the spotlight here in New Zealand.
Dr Jason Archer from B+LNZ Genetics has been working on efficiency for nearly 30 years and is well qualified to make more than educated statements about it.
He says that from a base level within a cow herd, you want a cow that not only eats efficiently but produces well, gets in calf every year, suits her environment and produces a quality calf that goes on to grow well at a reasonable rate and kills as quality beef.
The traits of a cow need to be balanced to ensure they not only suit the physical environment but also the management environment — some farmers like an animal they can put on the hill and only see twice a year, while others like to manage their stock more intensively — these two situations would suit two different animals.
“There’s no such thing as the perfect cow, it’s about what suits its environment,” says Dr Archer.
Biggest Cost
Feed is the biggest cost in every farming system, whether it be a feedlot or an extensive hill country station, where the land is there to grow feed so almost the entire value of that station could be attributed to feed costs.
Dr Archer completed a research project in the mid-nineties at NSW Agriculture where they wanted to investigate whether there was variation in the conversion of feed to live weight in young, growing animals. This was proven, so the next step was to find out whether that same correlation progressed to the animals at four years of age. It did — the cows still showed the same variation and ranking within their contemporary group as adults, as they did as heifers.
Enter the feed efficiency EBV, which is calculated using data collected on mostly young animals in confined feeding situations. Pedigree gives us the EBVs on most animals here in NZ so accuracies need to be taken into account since it’s highly variable depending on how much data has been collected from close relations. For example, Australian and American AI sires have a lot more data collected through progeny in feedlots so they will have higher EBV accuracies.
Rissington and Te Mania are collecting data on their own young cattle to improve the accuracy on their animals and genomics is also beneficial.
Dr Archer says that while the feed efficiency EBVs are a great inclusion in animal data, they’re just one aspect of efficiency within a cow herd.
Who’s most efficient?
Taking this knowledge to a commercial environment, how do we find the most efficient females in a cow herd?
“There’s no point in having a feed-efficient cow that can’t get back in calf.”
This brings in the concepts of individual animal efficiency and overall system efficiency. Reproduction comes into play in both concepts and the simple answer here is to utilise EBVs in bull selection.
“A bigger cow is not necessarily an inefficient cow, she can still be productive if she produces a good calf with the potential to grow.”
Again, Dr Archer goes back to a cow being well suited to its environment. He says that if you’re able to feed your cows to a level that their body condition scores are 7+ at mating and they’re rebreeding with good fertility rates then you’re in a good zone. If you’re having trouble with that then you’ve either got too many cows on or they’re too big.
From a system point of view, you’ve got to have good rebreeding rates and you should be mating your heifers for maximum efficiency.
The only argument not to mate heifers would be someone farming in tough country who wants a stock class that doesn’t have to be fed very much.
“Even in this instance, they’d be better to have fewer cows and be mating their heifers.”
Yearling heifer mating in a stud environment puts crucial pressure on young females from a fertility perspective.
“It’s easy to get a yearling heifer in calf but it’s getting heifers back in calf as R2s where most of the variation happens.”
In research completed by Dr Archer, he didn’t find any genetic variation in getting the R1 heifers in calf and says that getting a heifer back in calf and culling the dries is crucial for fertility within a stud herd.
Putting yearling heifers to the bull a month earlier than the MA cow mob gives them a better chance of getting back in calf during the first cycle as R2s, providing you can meet their feed requirements at calving. The grass curve can cause issues if you can’t feed them well with their first calves at foot, since if they get stressed and feed deficient they’re less likely to get back in calf.
For this reason, Dr Archer says that arguably the best feed investment you could make throughout the year with your females would be to feed those early calvers some baleage to get them through till the grass growth comes in.
When looking at EBVs for fertility, Days to Calving is the obvious one.
“It indicates how many of a bull’s daughters are going to get in calf on the first cycle vs the second cycle.”
Dr Archer says the scrotal circumference EBV is for the breeder to worry about rather than the commercial farmer since steers are not going to benefit from better genetics for scrotal circumference! The scrotal circumference EBV is only a low correlation to female fertility, and this information is accounted for in the Days to Calving EBV. The commercial farmer buying bulls should still look at the actual scrotal circumference to ensure the bull has sufficient capacity to physically serve cows (although the breeder should have culled out any inadequate bulls anyway).
Age of Females
There is often wonder about how long females should be kept in a herd. Dr Archer suggests that for genetic gain, studs would be cycling genetic gain as fast as possible and therefore turning over females more quickly than a commercial herd, provided their fertility had been tested by producing a calf as a yearling heifer and getting back in calf as a two-year-old heifer.
In the commercial environment Dr Archer says that for efficiency, it’s as much about keeping them in the herd for as long as possible, so long as they’re still productive.
“After 8 they start to drop off a little in productivity but after 10 they can really slip.”
He says you’ll see weaning weights and milk start to slow and you shouldn’t be needing to check teeth.
If you want to upgrade your herd quickly, perhaps to change direction if, for example, you’ve not been looking at IMF until now, then there are genomic tools available to help you select the best replacements for your herd and cull unfavourable females.
“Without EBVs, you’re running blind when selecting replacements”
Dr Archer says that the visually more appealing heifers are often the early-born ones, out of mixed age cows rather than heifers, and a lot of what you are seeing is environment rather than genetics. He says the new genomic tools are one way to make much better-informed selections when choosing heifers to mate and retain.
He says that while EBVs are often not well understood by farmers, they are not “black magic” and are in fact, incredibly logical. In their essence, they do two things: 1) they remove environmental influences (such as sex and age of calf, age of dam and management mobs) and 2) they use family relationships to identify the animals more likely to be carrying the genes most suited to your requirements.