A:   I would suggest that you test all the forages that you are considering feeding so that combinations can be mixed to do the best job of meeting the cow's requirements and to reduce any off-the-farm purchases to meet requirements. The answer to you question is, it depends. It depends on stage of production and the quality of the corn silage. Corn silage is a high quality feed and you may be able to limit feed it and still meet their requirements. If you were to full feed the cows corn silage, they will easily consume 2.5% of their body weight on a dry matter basis. So if the cows average 1100 lb and their entire diet is corn silage, they will eat 27.5 lb (1100 lb x .025) of silage daily on a dry matter basis. Because corn silage is usually 35% dry matter, 65% water, cows will eat 78.6 lb per head per day (27.5/.35) to account for the water. This amount of silage will supply more than enough energy to meet even a lactating cow's energy requirements.

That 's the reason to test all feeds so that the best combination can be put together to meet their needs. Once you get the analysis, contact your extension person as they can help you put together some combiations to consider.