FEEDS, FEEDING & COW HEALTH
Clell V. Bagley, D.V.M.
USU Extension Veterinarian
It is well recognized that the nutrients fed (or not fed) affect the health of dairy cows. It is also important to recognize that feed quality, form and how the feed is fed may also affect cow health. Each feeding system brings its own advantages and problems. Weather and harvest conditions result in continuing changes in forage quality and characteristics.
This year, rained-on hay presents a major challenge, but wise dairy producers will be able to make the needed adjustments through the use of forage analysis and ration balancing. A major loss from rained-on hay is protein. However, many producers feed higher levels of protein than needed - and in fact may be feeding so much they are actually causing a detrimental effect on reproduction. So, they could afford to lose some protein from the hay and still do just fine. But the key is to know what you are doing (through ration balancing) and why (through forage analysis) - not to just take a "shot in the dark" and hope it comes out alright. If extra protein is needed, it can be obtained from other feeds and the hay that is available may still be useful.
Be aware of the potential problems that are likely to develop with your specific type of feeding system. With a total mixed ration (TMR) be aware of the hazards of over-mixing as this will decrease the fiber length and increase the fines and result in serious problems with acidosis and displaced abomasum. The same problems can result after extended mixer use when the mixing apparatus becomes worn and does not adequately break up the long hay. This allows the cows to make choices of what they eat. Those recently fresh will seek out much more concentrate than is their share, and certainly more than is good for their health. The result is, again, acidosis and DA's in the herd.
With a computer feeder system the origin of problems is usually a malfunction that allows some cows to obtain excess grain. The problem can also come because of their choosing to eat grain before they eat forage. Either way, it still results in acidosis and DA's. A malfunction may prevent access to sufficient concentrate, but this causes a drop in milk production instead of the other problems.
For those producers who top-dress concentrate onto forage, the real challenge is often the "holes" that have developed from the cows eating at the bunker. These holes in the forage layer fill with the concentrate and allow cows (often those recently fresh) to choose to eat more than their share of concentrate by seeking out these "pockets." The result once more is acidosis and DA's, even though there is plenty of fiber and fiber length provided in the ration.
As we continue to push our cows for higher production, perhaps we have to expect an occasional health problem such as acidosis or a DA. But, when these begin to increase in number it is a signal that something has changed or gone wrong in our feed or feeding system. You may be able to monitor for decreased butterfat levels or an inversion of milk protein and butterfat values and detect the problem before sick cows become apparent. But, this effect may not become apparent because of the large number of cows milked and the relatively small number actually affected - so the change
is just not shown adequately in the values from the bulk tank milk.