Kiwipost: Mark Bryan writes from New Zealand.

My new passion is swimming, and I’m quite proud of it. I realise that to Australians this is about as interesting as the remarkably witty comment to Scots about “what’s under your kilt” whenever we wear one. But that’s the point?

Us poor Scottish people don’t do swimming. Although, like you, we live on an island; and although, like you, we’re a bit rough around the edges; unlike you, none of our watery bits ever gets above two degrees; and we’re simply not that rough and tough.

We do have some warmer water- notably the stuff around the nuclear power plants that the Poms decided could supply England with power from as far away from England as possible. And we don’t have many things that would eat you that live in our watery bits. But that’s because there wouldn’t be much to eat- normal peoples’ genitalia simply disappear upon immersion in the North Sea.

So, swimming is all new and I must say it’s great. However, I can’t help noticing at and around the pool that there are some excellent opportunities for the Japanese, who are currently struggling in the Southern Ocean trying to target their prey. My wife, who is a much nicer person than me, berates me for remarking on this, saying that at least these rather oversize people are at the pool and not at home eating. And that’s a scary thought.

Recently, I risked career and reputation by running my epidemiological eye over the young boys in the change rooms. (If questioned I was going to say I was auditioning for Pope. I think I would have been let off, or possibly even recommended). Fifty percent were lardy. These are boys that are under 12. This is not their fault but their parents. Think of how hard it is for us to stay lean in middle age when we have grown up lean- these kids haven’t a hope.

Currently, we are spending a lot of time measuring the body condition score (BCS) of cows. It’s very challenging to do this on a thousand cows and then go down to the local pool, without casting judgement. A past-president of Federated Farmers once memorably lamented that “we want our cows at BCS 5 and our women at BCS 3”. He had a point of course, but to expand on that, we wouldn’t really want our cows at BCS 15, which is not an uncommon sight in the pool in Southland.

Measuring BCS in dairy herds is a good and objective way of detecting feeding issues. It’s a tool that has been promoted by both the vet profession and DairyNZ for a number of years now, and is finally gaining traction among the more progressive farmers. Typically, we would do whole herd BCS about four times a year. And, because the Kiwi dairy system is built around feeding as little as possible to as many as possible with as little thought to nutrition as possible, you can imagine there’s a fair bit of work to do.

The key to monitoring BCS is not the mean, which is largely meaningless, if you’ll pardon the pun. We’re interested in the spread- we want a mean of 4.5 or 5, but we don’t want to achieve that by having heaps of cows at three and heaps at seven. We want as small a spread as possible. This also means we have a very consistent herd, and this means they are easier to manage.

The simple equation- which should be tattooed somewhere (added to all the other tattoos, presumably) on the parents of these fat kids- is that energy out needs to equal energy in. Dairy farmers get this. They spend their whole lives trying to maximise energy in so that whatever’s left over can go on the cows’ backs. BCS allows us to identify cows that are lighter than others and manage those differently.

BCS directly impacts on reproductive indices. If we can better manage BCS at drying off, at calving and at mating we will better manage herd reproductive performance. So, whilst BCS is a proxy for nutrition, it’s a very simple and effective proxy. In a season such as the one we’re having, with large parts of the key dairy areas in NZ officially in drought, BCS monitoring becomes a critical tool.

We track the data from all the farms we monitor and benchmark it- I think the benchmarking is also a critical part of the process, because it adds another layer of objectivity to farmers when we feedback. We can say “Here are your herd results.” but also “Here’s how you compare within the region at the same time.” Farmers appear more comfortable with this approach than if we just told them the cows were too fat or thin, and we have seen some good and positive responses from feeding this information back.

Measuring BCS in large herds is like swimming 60 lengths. It’s undoubtedly boring, but it’s effective, measurable and important. And it’s worth comparing with that other bizarre sight at the pool- the Aquajogging class. If BCS is like doing lengths; Aquajogging is like metrichecking. Nobody has any idea whether it’s doing any good; and a large part of you feels that you’d be just as effective lying in bed thinking about doing it.

MARK BRYAN