Cows, calves and veterinary

getting pregnant

I had a quick look at a couple of lists I made near the start of the mating season, and from this I drew a relatively important conclusion:

A significant determiner of pregnancy during a twelve week mating is whether or not the cow is cycling at the start of mating.

That seems obvious, right?

Well, you would have thought so, but I was still surprised at the numbers considering that I had 100% of the cows mated within six weeks - some of the later calvers assisted with fertility treatments (the Ovsynch program, no CIDRs).
Of about eighty cows cycling before the start of mating, four had cycled within the last three weeks (after week ten of mating).
Of the remaining seventy-five, about sixteen cows had cycled recently.
(Those numbers are off the top of my head - I'd have to check the lists again to quote them accurately)

That is more than ever convincing that priority must be given to having healthy cows cycling before mating starts.
And that means getting all the factors that contribute to healthy cycling cows right: An early, fast calving pattern. Feed well. Minimise dystocia.

Last I checked, my bull had a NRR rate of between 40 and 50% - much better than 22% but still not flash. I've finished another 3 week cycle of AB and decided to just hope that my records were as good as last years since the planned PD fell through (I didn't know I had to collect the platform to bridge the milking pit before the vet arrived) and a further delay would have meant dating pregnancies to ascertain whether they were in calf to AB rather than the bull, rather than being able to give a simple in-calf, not detectably in-calf diagnosis for each cow.
Following last year's experience with vet-dated pregnancies, I'm very disinclined to rely on a vet's assessment of how far pregnant a cow is (in previous years I've double-checked them against mating dates, since I was working in herds that did whole-herd scanning and checked dates for all late calvers, and found the vet to be reasonably accurate. Last year's information was worse than useless).
The bull's got another three weeks, and I'll fall back on the 'they all cycle in the end' philosophy to determine which cows are in-calf, possibly PD-ing any uncertain ones in late March. As long as there aren't gross errors in the records, it should still be possible to effectively select late and empty cows for culling and avoid keeping more than one or two very late or empty cows - not enough to greatly impact stocking rate.

posted by nellta holdings @ 5:17 AM