Research: Effects of Bovine Somatotropin Treatment on Performance, Reproductive, and Physiological Responses of Replacement Beef Heifers

Oh yes, rBST (or BST, rBGH, “hormone injections”, “chemicals”, or any lay term the media can come up with), clearly the reason we are all getting cancer with every steak we eat and glass of milk we drink (second only to cell phone radiation and airport scanners). Animal science faces many of the same problems as food science. If the media can report on it and with scary images, all the while promoting ignorance of the processes of food production, then they will gladly jump on any and all practices in food production. This is super effective because everyone eats, and so we are sensitive to news that what we eat may harm us. I’ll discuss a little more about rBST use in Oregon, but fist I want to examine this proposal we’ll be examining at the EOARC.

The premise of the proposal is that in cow-calf operations, replacement heifers become less and less financially viable if they take longer to reach puberty, or miss their first breeding season. Previous research done at the EOARC has shown that higher IGF-1 (insulin like growth factor 1) concentrations are found in heifers that reach puberty by 12 months compared to non-pubertal heifers of the same age (Cooke et al., 2007). These levels are usually encouraged by using a high plane of nutrition; however, in eastern Oregon we generally run our cow-calf operations on poor forage because it’s economical, it’s what we have, and what we can take advantage of. The idea of the study then, is to see if rBST administration will result in higher IGF-1 levels which will hasten puberty compared to untreated cattle. Additionally, because the normal high plane of nutrition would also raise levels of insulin, blood glucose, and leptin which could also affect onset of puberty, this study will single out IGF-1 levels and determine if the absence of those other factors plays a role in puberty onset.

The procedures are pretty standard, so I won’t rewrite them all here, I’ll post the proposal below so you can read them yourself if you want to examine the methods. One thing I’m impressed by is the rotation of bulls between the treatment and control groups to account for bull effects. I’ve learned about estrus synchronization and other pheromone effects in repro, but the effects a specific bull might have are even more interesting. I wrote about one of these effects when looking at stallions kept on home pasture with pregnant mares a while ago, and was fascinated by the idea of spontaneous (or conscious!) abortion in the presence of specific stallions.

One thing I was a little concerned about is the sample size of the proposal. I’m told anything over 20 is considered viable, but you can’t really lock in any trends you may find with a sample size that small. This particular study will use 40 cattle, which makes the control and treatment groups composed of 20 animals. I think that we’ll still get good data, but that more research with more animals will be necessary to fortify the conclusions that come out of this study.

So that’s pretty much all I have for this one, it’s pretty straightforward. The only problem I have is that, while I support the use of rBST, the current trend is to abandon its use, which may end up making this research obsolete.

This needs to be said in any discussion about the hormone, and it isn’t said enough: the FDA has not found any significant effects resulting from the ingestion of milk from rBST treated cattle. It’s clever advertizing! And we as consumers have to start making the harder choices. We either have to start paying more for our food, or allow our farmers to use safe treatments to increase yields. We can’t have it both ways. I admire people who buy organic items because by purchasing them at a higher price they acknowledge that our agriculture industry needs to make money, and that the margins for small farms are incredibly slim. It’s the ones who want to limit the industry by preventing the use of tools that increase production, but still want to pay 2 dollars for a gallon of milk that make it harder and harder to strengthen the industry.

Coincidentally, this is why student fees and current national budget are so hard to set. No one ever wants to pay more, but we certainly can’t take away any of our provided services either. Something has to give there.


You can read the full research proposal here.

You can read a statement from the FDA on “rBST free” labeling here.

You can read a short statement (followed by a list of stores that sell rBST free milk) from the Oregon Physicians for Social Responsibility here. This group has worked hard to discourage use of rBST in small dairy’s across Oregon.