The effect of different processing methods on rumen degradation of protein and starch in threshed peas

Legumes have increased in interest as a locally produced low input protein feed for ruminants in northern Europe. Peas are of special interest in Sweden since they are possible to cultivate on most farms. Protein feed is also a limited resource in organic farming, especially for high producing dairy milk cattle. Farmers often have to complement feed rations with conventional produced protein concentrate. The limitation with all legume grains, including peas, is that their protein is very soluble in the rumen. As a result, the pea protein is almost immediately degraded to a great deal and much of the protein, which is transformed to ammonia, is lost through the rumen wall, transported with the blood and excecreted with the urine. The consequence is that much nitrogen is lost to the environment instead of being synthesised as microbe protein. Different methods of feed processing, including preservation of feed and milling, rolling and heat treatment could improve protein utilisation. Of great importance affecting rumen degradation rate is particle size in processed peas. The extent to which peas are processed may also affect the passage rate through the rumen. A combination of different processing: preservation methods (i.e. wet or dry), grinding, flaking and cracking might give an additive effect in reducing protein degradation in the rumen