Why Bacteria Counts Do Make a Difference
I had a discussion this week with a calf manager about the significance of high standard plate counts of bacteria in milk being fed to calves.
My best estimate on his TNTC (too numerous to count) as-fed milk samples for standard plate count is between 100,000 and 200,000cfu/ml.
The calf manager's point of view is that as long as he is not having serious problems with scouring calves the high bacteria counts are not worth his attention. And, to be fair, he is using electrolytes on less than twenty percent of the calves - most of those cases being concentrated in the seven to fourteen days of age calves. And, we know that cyrptosporidiosis is endemic in this herd setting.
My point of view was different. I made the point that they are feeding somewhere between one and two billion bacteria a day to all the calves. Even if the immune systems in his calves are successful enough in coping with this exposure level there has to be an expense. Both protein and energy are being diverted from growth due to the unnecessary bacteria load in the milk.
And, if the calves are exposed to other pathogens, for example bacteria that cause pneumonia, the calves are unlikely to be able to mount as robust defense against the respiratory bacteria as they would in the absence of the huge bacteria load in the milk.
Thus, the risk of lower feed efficiency and other infections would, to me, seem to go up as calves are loaded down with bacteria in their gastrointestinal tract.