R A. Drake

Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science

First Advisor

L. D. Kamstra


New feeds are continually being developed, especially from by-products of an industrial process which produces a product already in demand. For example, soybean oil meal was initially a by-product of an extraction process for soybean oil, a product in great demand at the time as the base material of paints. As the demand for the oil subsided, the by-product, soybean oil meal, assumed the major role as a protein supplement for livestock. Alfalfa, on the other hand, has always been an important feedstuff, as well as many of its related products such as alfalfa leaf meal and dehydrated alfalfa. The continuous demand for high quality protein sources in human and animal diets has caused an intensive search for protein from many plant sources, including alfalfa. It has been found that, if the soluble alfalfa leaf proteins are removed (Pro-Xan process) for use in poultry diets or for preparation of milk replacers, a rather high protein by-product still remains. This by-product, press cake, could be a valuable feed supplement for lower grade feedstuffs. An explanation of this protein extraction process may be helpful in estimating the feeding value of the alfalfa plant components. Pro-Xan is a leaf protein concentrate extracted from freshly cut alfalfa. In this process, the material is macerated and compressed to remove the soluble (green) juices. The fibrous by-product is termed "press cake." The soluble (green) juices undergo further processing to remove the high protein fraction, Pro-Xan. The remaining (brown) juices may or may not be added back into the press cake fraction. The more fibrous by-product, press cake, might be a suitable feedstuff for ruminants, either as a roughage source or as a low level protein source. Numerous studies have already been conducted on the benefits of the Pro-Xan fraction. Press cake, the by-product of the Pro-Xan process, has been studied very little and has no established market as the feed value has yet to be established. The experiments reported here were designed to determine the feeding value of press cake in relation to alfalfa hay and dehydrated alfalfa as protein and roughage sources for ruminants. With the advent of the large packaging systems, corn stover can be transported easily from the field to the feedlot, thus providing the opportunity to also establish the feeding value of corn stover in winter growing rations as well as to compare the two methods of handling corn stover, stacked or ensiled. Growing steers were utilized in this experiment, as their requirements for protein were much higher than with animals in later stages of growth. When feeding high-concentrate rations, as in the second experiment, the roughage portion need not be of high quality, since the digestibility of fiber decreases rapidly as the concentrate portion of the diet exceeds 30%. This provides an opportunity to use a variety of fibrous materials to replace more expensive choices of roughages such as dehydrated alfalfa or high-quality alfalfa hay as long as the protein values are similar. Because corn is normally considered adequate in protein for finishing steers, the protein content of the alfalfa products was not as critical to this experiment as the roughage additions. In this study, press cake was compared to dehydrated alfalfa and alfalfa hay.

Library of Congress Subject Headings

Beef cattle -- Feeding and feeds
Alfalfa as feed
Corn stover



Number of Pages



South Dakota State University