Even before the current run of favourable market conditions, many Australian beef producers have been artificially inseminating their commercial heifers. The current boom in beef breeding has seen an even greater uptake of the practice. I’m often asked why we don’t AI the commercial heifers in our enterprise. This post lays out the reasons why we don’t do it, but please note, the reasons are quite specific to our environment and production system – they may not apply to yours.
For reference, our commercial enterprise is a Spring calving, self-replacing Angus herd in the high rainfall zone (HRZ) with Winter/Spring dominant rainfall. We join all our heifers and grow all our steers to feeder specification (475kgs) at 13-14m.
The case for FTAI
Firstly, you may like to familiarise yourself with the case for fixed time artificial insemenination (FTAI). If you haven’t already heard about the Producer Demonstration Site (PDS) Dr Enoch Bergman ran at Esperance WA, I highly recommend it. Here’s a written summary and here’s the 45min video of his Beef Australia presentation.
Dr Bergman provides a compelling case for FTAI commercial heifers in Southern Australia, however, when I apply some of the selling points used by Bergman (and others), they don’t resonate with our commercial enterprise.
Reduced Average Calving Date – Increased weaning weight
By synchronising a mob of heifers, the average calving date is brought forward. The portion of heifers that conceive to AI effectively do so on day 1 of the joining period. Most of those that don’t conceive to AI conceive to the mop-up bulls on their next cycle (~21 days). Sometimes the hormones administered during FTAI can also cause non-cycling to heifers to start cycling. Consequently, the average birth date of the total crop of calves (both AI and mop-up sires) moves forward. In Bergman’s project, the synchronised heifers calved (on average) ~8 days earlier than the control group. The benefit of an earlier average calving date is the extra age and therefore extra weight in the calves when weaned. In Bergman’s PDS, the increased weaning weight was 15kg/head.
That’s all pretty cut and dry . The bit I contend is the value assigned to the extra weaning weight. Firstly, increased production isn’t without cost as increased outputs require increased inputs – i.e. feed resources are not infinite. If your average calving date is 8 days earlier, your calves are consuming 8 days more feed and your cows are lactating 8 days longer. The dairy industry is leading the discussion about this concept and the folly of chasing ever increasing production with finite resources. Secondly, if you don’t sell your calves as weaners then the value in increased weaning weight is only theoretical i.e. it is not cash in the bank. While the increased weaning weight puts those weaners in good stead for achieving later targets like puberty or market specification, it’s a bit of a stretch to list the value as a benefit of FTAI in dollar terms. Arguably, pasture composition, soil fertility and parasite management have a far more significant influence on yearling cattle performance.
First Calver Re-breeding Outcomes
The next argument used widely by advocates of FTAI is that heifers that calve early in their first joining will calve early for the rest of their lives. It sounds logical and was (sort of) supported by a robust study done in Missouri which showed slightly greater lifetime longevity in heifers that got in calf early. I realised I could use our own foetal ageing data from many years of pregnancy testing to check if this was happing on our farm.
To interrogate the ‘early for life’ assumption, I reviewed the data for 4 cohorts of heifers. For each animal, I used foetal ageing data to determine the difference in conception week in year 1 (maiden heifer) and year 2 (first calver) as a proxy for calving interval. The observations were consistent across 4 cohorts representing a wide variety of seasonal conditions. The graphs below relate to the Q drop heifers. The missing label on the dark green slice is 2%. That is, 2% of heifers shaved 4 weeks off their conception interval while 16% of heifers shaved 3 weeks off their conception interval etc.
The graph above shows an equal propensity for heifers to shorten or extend their conception interval. However, when we look at the heifers grouped by the timing of their first pregnancy, a pretty interesting picture becomes evident.
Our farm data shows that late heifers on average rejoin 21 days earlier than the mob average. Early heifers rejoin 9 days later than the mob average. Wait, what? It’s obvious if you think about it for a minute. A heifer that conceives in the first week of the joining can only go backwards because we don’t give her the opportunity to go forward (the bulls are deployed on the same date each year). She also has one of the biggest (first born) calves at foot and therefore experiences higher lactational demand at joining. Meanwhile, the opposite applies to the late heifers who get earlier access to the bull (relative to calving) and have a younger calf at foot. A late calver also spends more of her lactation period on better pasture compared to an early calver.
The late calvers were also not overly represented in the heifers who failed to conceive in Y2 (PTEs). Across the 4 cohorts, there appears to be no correlation between PTE’s and their conception pattern.
This chart shows the PTEs were made up of heifers who previously conceived in week 1 (8%), week 2 (13%), week 5 (13%).
The ‘early for life’ claim doesn’t stack up on our farm. The data shows only 41% of early heifers stayed early for their 2nd conception. Only 25% of mid heifers stayed mid. 0% of late heifers stayed late. I’m not saying the research is incorrect. They had big samples over 11 years and academic statistical rigour. But that production system in Missouri is no doubt a very different system and environment to mine.
An easy test you can run on your own data is to make a list your PTE 1st calvers and check their previous (maiden) pregnancy diagnosis. Are they mostly late calvers or a real mix of everything like mine?
I believe the thought of accessing elite sires from a semen catalogue is actually what motivates most breeders to use FTAI. However, the genetic advantage of using a semen sire over a herd bull is a calculation most advocates of FTAI avoid making. That’s because it is hard to do, and the quantified differences are typically small. The latest Angus Breeding Index model is the best index we’ve ever had access to and something I’m happy to recommend. Let’s use it to compare a popular elite semen sire with a bull you might buy in an upcoming auction.
This handsome devil is QHF WWA Black Onyx and is currently the most popular choice in the Genetics Australia catalogue for FTAI commercial heifers.
He’s a great option with combined calving ease and growth EBVs. His Angus Breeding Index value is +$279 which is in the top 2% breed.
Meanwhile, over at Angus Online I can see there’s around 2500 bulls listed in upcoming auctions. 67% of them are above the breed average of +$194 for Angus Breeding Index. 44% of them are in the top 25%. Let’s look at the difference between Black Onyx and a herd sire at the 25th percentile for Angus Breeding Index.
Black Onyx +$279 Herd Bull +$221 Difference +$ 58
Now we have to apply some discounts.
50% +$29 (the sire is only half the mating) 55% +$16 (a generous AI success rate) 50% +$ 8 (genetic benefit in daughters only) 50% +$ 4 (the proportion of the index relating to on-farm)
I’ve applied a 50% discount to reflect the on-farm portion of the index value. That’s because the index value (as published) represents profit for all players in the supply chain. In my experience building custom indexes in Breed Object, 50% is about right – you’ll just have to take my word for it. I’ve also applied a discount to the genetic gain above to just the daughters as they will stay in the herd as future breeders. Let’s add some value back in for the steer progeny using yearling weight rather than index.
Difference +24 (400D: 122-98) 50% +12 (the sire is only half the mating) 50% + 6 (the steer portion of the calf crop) 55% + 3 (a generous AI success rate) $5.90 $18 (last years feeder steer rate)
So, for every 100 heifers joined, assuming a total pregnancy rate of 84% and 50:50 split of male and female calves:
42 x $ 4 = $168 (heifer calf genetic gain) 42 x $18 = $756 (steer calf genetic gain) $924 (combined genetic gain)
So that’s a $924 total benefit for every 100 heifers joined to Black Onyx over a herd bull ranked at the 25th percentile. Compare that to the costs of FTAI:
$30 Semen (Black Onyx) $15 Treatments $12 Labour $10 Technician $67/head $6,700 for the mob
If that’s not disparaging enough, consider this last point regarding the influence of an FTAI heifer program in your herd. In a self replacing herd joining 80% of all heifers born, the daughters from the elite semen sires will make up only 16.8% of next years total heifer crop. At a joining rate of 70%, only 14.6% of the heifer crop will be sired by AI.
Other benefits to FTAI in the commercial setting
There are other claimed benefits to FTAI programs.
Higher pregnancy rate.
In theory, a higher pregnancy rate may be achieved by FTAI because when backed-up by a 44 day natural joining, all heifers have 3 cycles in which to conceive whereas typically, a high proportion of the herd would only have 2 if they had not been synchronised. As already mentioned, the hormones may even cause some heifers to cycle that hadn’t already cycled naturally.
Interestingly, a recent article by Phil Holmes on Beef Central says the opposite is true – the synchronisation hormones actually reduce the overall pregnancy rate. We have seen lower overall pregnancy rates when comparing our AI’d seedstock heifers to our naturally mated commercial heifers. Last year we had a much lower preg rate in AI’d heifers (75%) to naturally mated heifers (84%).
Ease of Management.
Many advocates of FTAI point to ease of management of heifers when 50% of the mob calves in the first week. I think having heifers calving in a condensed period is a negative with increased confusion resulting in mis-mothering and abandoned calves. A more stretched out calving causes less stress on the new mums and the humans watching them. Let’s also not discount that major work load that FTAI places on the enterprise at the busiest time in the farm calendar – it clashes with Silage, natural joining, calf marking, feeder steer marketing etc.
There’s no doubt that calf and heifer mortalities are major loss makers and we need to do everything we can to mitigate the risk of dystocia. However, any benefit that safer genetics can contribute to less dystocia is just as achievable with natural mating as with AI. Producers using FTAI already have to ensure the bulls mopping-up are safe for heifers anyway.
Decreased Bull Team.
FTAI does not reduce the number of bulls you need. The heifers that return to oestrus do so in a synchronised manner. Those mop-up bulls will be overwhelmed if there isn’t a sufficient number of them.
As is always the case in agriculture, it is essential to look at the the big picture – whole of enterprise profitability – when considering making any change to a production system. It’s too easy to be distracted by single point metrics like weaning weight or sale price. FTAI might be a great fit for your enterprise, but then again, it may not be.