One Swallow doesn’t make a Spring!
The origin of this saying comes from the philosopher Aristotle (384BC – 322BC), and can basically be interpreted as ‘a single fortunate event doesn’t mean that what follows will also be good.’
So how does this relate to bulls, bull teams, and breeding decisions made during the early part of Spring?
Let’s go back a step. When a bull enters the Sire Proving Scheme, he gets semen collected off him as a yearling to use for insemination into SPS herds that very same Spring. It then takes three years for his progeny to be born, reared, gotten in calf, and milked. During late September and early October, that bull’s first crop of daughters are being herd tested in those same SPS herds. The herd testing information then flows from the breeding companies into the national herd database called DIGAD and the organisation responsible for administering it – NZAEL. This process is known as a ‘proof’.
There is often a large amount of hype around these ‘Spring Bulls’, especially if they are looking good on BW and some of the Traits Other than Production (TOP) traits. At that stage though, most bulls will have only had around 30-40 daughters herd tested in a small number of herds in earlier calving regions. Additionally, TOP scoring doesn’t usually take place until late October or early November, which means that before a bull has his daughters inspected by a TOP Inspector on behalf of the various breed societies, his TOP values are estimates only.
So on the basis of those small number of herd tested and TOP-scored daughters, bulls tend to be fast tracked into various bull teams for inclusion as a part of fresh daily semen allocations. However, ‘one Swallow doesn’t make a Spring’, and having ‘Spring Bulls’ in your OWN herd on the basis of an extremely limited data set has its risks. Generally, one of these things can occur:
Early data sets reward high octane bulls whose daughters potentially put it all in the vat before Xmas, and fail to get back in calf as a result.
Early data sets reward bulls whose daughters milk their hearts out till Xmas then shut the tap off when the going gets tough in Summer.
Early data sets can give a false indication of TOP scores. One bull who appeared in the Top 10 XB bulls (ranked by BW) on the RAS list in October started the season with an Udder Overall BV of 0.92. He finished the season still in the Top 10 based on BW, but with an Udder Overall BV of 0.50. Ouch!
Over the course of the last year, I’ve taken note of the RAS List at 4 key stages – early October, late December, late February and late May. Using XB bulls as our example, here’s what happened on the RAS List between 7/10/24 and 27/12/24. The #1 ranked bull in October went to #6 in December, the #2 ranked bull dropped to #11 in December, #3 and #5 swapped places between October and December, and the #4 ranked bull in October dropped to #7 in December. The two bolters in the December Top 5 were ranked #10 and #15 in their October AE run.
You can see there’s a heap of movement in the space of 3 months, and that’s only looking at the BW of the top 5 XB bulls. The standard of the Udder Overall (UO) trait also shifted massively between those top 5 bulls during that same October – December period. The Top 5 October bulls had a lowest UO score of -0.12 and a highest of 1.05. Great if you snagged the 1.05 bull as a part of your bull team, less so if you were unlucky and got the other guy. December’s top 5 bulls actually fared worse with a lowest Udder Overall of -0.12 and a high of 0.88. Our 1.05 Udder Overall bull who was sitting at #4 in October then moved outside the top 5 and was replaced in December by a bull with a UO value of 0.32!
Given we’re aiming for a 300-day lactation from our dairy cows, lactation persistency is also important. We’re looking to find those steady-without-being-spectacular performers – the Toyota Hiluxes if you will. We’re certainly not interested in the Tesla Cybertrucks! Those Hilux girls also need to get back in calf again, and have an udder capable of doing at least 450kg/MS. There’s a few challenges there I’ll readily admit!
Looking at lactation persistency, then, and broadening our horizon to include the top 10 XB bulls from each of the 4 months we looked at the RAS List (October, December, February and May), only 50% of the bulls who appeared on the Top 10 list in October made it all the way to the Top 10 list in May. That’s a 50% attrition rate! There were bulls who started strongly then faded away as the season progressed, there were bulls who took a couple of months to get going but hit their straps and held their spot in the Top 10 from December through till May, and there were 3 bolters who weren’t on the Top 10 list for ANY of those months, yet finished the season exceptionally strongly and took spots 8-10 on the May RAS List.
The point I’m trying to make with this article is not to get hung up on early daughter proofs. Stay the course, and wait till bulls have had a season’s worth of herd-tested and TOP-scored daughters before committing. There are a hell of a lot worse things than using daughter proven bulls in your herd! Genetics is a long term game; why would you risk substandard production and poor udders if you didn’t have to?
“Good things come to those who wait.” (Lady Mary Montgomerie Currie, 1843 – 1905).
