Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)


Animal Science


Many workers have suggested the possibility of an unidentified growth factor (s) in certain feed ingredients. Feeding trials conducted to determine the effect of unidentified growth factor sources on growth rates have produced inconsistent results. One of the biggest problems has been the isolation and identification of the compound responsible for the growth stimulus often obtained when unidentified growth factor sources are fed. Empirical fractionations have been done with some unidentified growth factor sources. Growth stimulation has been reported with various fractions extracted with different organic solvents, with a water extract as well as the ash of growth factor sources. The most common sources of unidentified growth factors are the b-product feeds, although claims have been made that these factors are also present in grass juices and dehydrated alfalfa meal. The byproduct feeds are mainly from three industries - the beverage distillers, the cheese manufacturers and the fish processors. Their by-products are distillers dried solubles, distillers dried grains with solubles, dried whey and condensed fish solubles. These byproducts are rich sources of many of the B-complex vitamins; often they contain more of these vitamins than the primary product. At one time these by-products were used as vitamin supplements in livestock feeds. If these by-product do contain an unknown, required nutrient, the use of various sources of the unidentified growth factors might result in more efficient conversion of feed to pork. However, the method by which the unidentified growth factor supplements produce a growth stimulus is not yet known. It is possible that they contain an unknown vitamin or a mineral not yet recognized as essential. Some workers have suggested that these feeds supplement a ration to provide a more optimum balance of known nutrients. Perhaps they affect ration digestibility so that animals can more efficiently use the nutrients in the ration. The reasons for undertaking this study were: (1) To determine the effect of distillers dried grains with solubles, dried whey and condensed fish solubles on the average daily gains and feed efficiency of growing-finishing swine. (2) To determine the effect of distillers dried grains with solubles on ration digestibility when fed at levels of 5, 10 and 20 percent of the ration.

Library of Congress Subject Headings

Swine--Feeding and feeds




South Dakota State University