Tuesday, July 6, 2010

Pinkeye in cattle – doesn’t affect the beef quality

But it will get you docked at the auctions. They like their beef black and beautiful…

I’ve had another version of this same bacteria this year and have become a regular customer at my vet to get it treated. This strain seems to only affect new calves, yearlings, and 2-year olds. I did take one of my “grannies” in, and one 4-year old, but otherwise it left the older adults alone.

And it wasn’t the pinkeye I treated last year – most all of these caught it again.

And the reason I wanted them treated was to reduce weight loss, ensure they didn’t lose that eye to blindness, and generally to help them as I could. Antibiotics, given time to clear the system (21 days) does nothing to affect the meat quality.

While I could have treated it myself with a local anti-biotic ointment twice a day for two weeks, this just didn’t work out. No head chute and after they were about a month old, these calves weighed nearly as much as me – and had a lot more spunk.

So the vet dosed them up with long-lasting anti-biotic and I gradually got all of them through the line-up. Now it’s just the newborns which are catching it. And I was hoping their mothers would give them antibodies through the milk…

But I found this write-up from Dr. Bill Shulaw of OSU (in their June Newsletter):

The presence of seed heads on tall stems does not, by itself, cause pinkeye. The presence of seed heads can be a factor causing some eye irritation as the cows and calves graze. Of course, so are dusts, pollen, strong sunlight, and face flies - all considered predisposing factors. But the causative bacteria have to be present, and at least a few non-immune animals have to be present, before the disease appears. And not all the predisposing factors have to be present to have the disease appear. Pinkeye in a non-grazing dairy herd can be a nightmare to deal with to which I can attest from personal experience; several times.

The disease often disappears from a herd after a couple of grazing seasons without any special preventive efforts like vaccination or pasture clipping. I suspect that this is caused by the eventual exposure and development of a good immune response by almost all the cows with the carrier cows eventually clearing the infection from their eyes. Unfortunately, there are several strains of Moraxella bovis out there, and it is a pretty safe bet that the available vaccines do not provide good protection for all of them. Therefore, it is not uncommon to see the disease reappear in a herd previously infected if new animals carrying a different strain are introduced or if the herd grazes close to another herd that has the disease. Face flies can carry the bacteria on their body for up to three days, and can transmit it between animals and between herds. The disease can also be spread cow-to-cow by close facial contact such as around feeders. The bacteria are in the tears. I have never seen any evidence to support that seed heads or other inanimate objects are involved in the spread of the disease from animal-to-animal, but the bacteria certainly are mechanically transmitted by flies, so I suppose it could occur in just the right circumstances.

Pinkeye demonstrates a well-known principle in infectious diseases. Disease usually occurs only when there is a susceptible host (in this case a non-immune cow), an infectious agent (Moraxella bovis for pinkeye), and environmental conditions that favor infection of the host (irritation of the eye to create tears that attract the flies and that favor the attachment of the bacteria to eye tissues). Infectious agents involved in many diseases are relatively common in most cattle herds, but disease isn't usually observed until the other two criteria are present. I have written about this concept in several past articles in the Ohio BEEF Cattle Letter especially in regard to calf scours. This is why management of animals and their environment to reduce the concentrations of infectious agents and the stresses on the animals is so important in the reduction of disease.

So it’s not a real mess like we’ve been told.

My gut feeling is that this is still a nutrition problem in addition to a genetic one. So I’m looking for some better minerals to combat it and increase the forage quality of my pastures.

Again, leave the tractors out of the pastures and let the cows do the clipping. Seed heads don’t have diddly to do with pink-eye or other eye infections. And you want that grass tall for mob grazing…

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