Somatic Cell Counts and Feeding Waste Milk
I was asked today if I knew of an upper limit for somatic cell counts (SCC) in pasteurized waste milk (nonsaleable milk) being fed to calves. If the SCC is over 500,000 or 1,000,000 should it still be fed to calves?
First, how do we expect the nonsaleable milk to be any different that the milk we are selling? That means we have to think about where this milk comes from. The reason we are not selling the milk is frequently the presence of antibiotic residues. While some cows are being treated for a uterine or respiratory infection others have received treatment for mastitis.
So, it is logical that this nonsaleable milk partly from mastitis cows could be higher in SCC than the milk being sold. In addition some farms supplement their volume of sick cow milk for calves with that from one or more of the highest SCC cows in the herd - this keeps the SCC in the saleable milk tank lower and effectively increases the calf milk supply.
Second, do we have published research showing that the SCC in pasteurized nonsaleable milk has negative consequences for calves? That is, do calves avoid drinking it? Or, does high SCC milk cause digestive upsets or lower rates of growth? I have no knowledge of any such research.
Third, is high SCC milk different from low SCC milk in some other ways? We do know there is a tendency for high SCC milk to be lower in total solids and protein than low SCC milk.
So, are there guidelines for SCC in milk fed to calves?
1. I do not think so at least based on published research. If any reader knows about such research do me a favor and send me an e-mail with the reference [firstname.lastname@example.org].
2. If SCC is at 1,000,000 or higher it probably is a best management practice to check the milk solids level with a refractometer before feeding this milk to calves. We might need to supplement our milk with milk powder of our choice to bring it up to our desired level (e.g., 12%, 15% solids).