Wheat does contain higher CP and phosphorus levels than other common grains, so supplemental CP and phosphorus can be reduced in the diet. Wheat is rapidly and extensively digested in the rumen, so when large amounts are fed, cows can become acidotic quickly and go off-feed. Barley is an important component of dairy rations in many parts of the world despite its rapid rate of digestion in the rumen. This rapid starch digestion may dramatically lower rumen pH, cause digestive problems and low milk fat test. Therefore, diets must contain adequate fiber to use significant amounts of barley effectively in the concentrate mix.
Performance is sometimes better when heavy- weight barleys are fed than lightweight barleys.
Some research suggests that replacing a portion of the rapidly digested barley starch with more slowly digesting corn starch reduces the negative effect of starch on fiber digestion. However, convincing evidence of this idea is lacking. When processing barley grain, a coarse grind is preferable to a fine grind because barley becomes very pasty when finely ground. Summary A wide variety of feed grains may be fed to dairy cattle as sources of starch, energy, and protein. However, these grains must be processed properly and fed with the correct levels of dietary forage to avoid off-feed problems, reduced milk yield, and low milk fat test.