Document Type

Dissertation - Open Access

Award Date


Degree Name

Doctor of Philosophy (PhD)

Department / School

Animal Science

First Advisor

C.W. Carlson


Despite the extensive data that have accumulated on the detrimental effect of molds on the growth of farm animals, very little is known as to the beneficial role of fungi in animal feed. Recent studies at South Dakota State University research laboratories revealed, however, that only 164 of 392 strains of Aspergilli were found to be toxic. When the cultures were grown on sterile soybeans or wheat, some of the tested cultures exerted positive effects on growth of chicks and mice. Hence, the investigations reported herein were initiated to obtain further information on those cultures beneficial to chick performance and to attempt to identify factor(s) responsible for these growth-promoting effects. In addition, studies were designed to investigate the beneficial effects of some Rhizopus and Actinomucor cultures on broiler growth. The effect of certain species of Apergilli beneficial to broilers on the life cycle performance of Japanese quail (Coturnix coturnix japonica) were also investigated and reported. The data obtained from the first seven factorial experiments demonstrated that feeding full-fat soybeans fermented with 15 of the 19 species of Aspergilli gave significant (P<0.05 or P<0.01) improvements in weight gain and feed efficiency of broiler chicks. The rates of growth enhancement ranged from 4.4 percent to 16.0 percent and the greatest percentage growth responses were consistently shown with the lowest protein diets. No marked toxic effect was indicated from any of the cultures tested. The subsequent analytical data demonstrated that chicks fed the fermented soybean diets made, in general, superior use of dietary energy, nitrogen and dry matter. Carcass composition data showed that the diets made with fermented soybeans produced chicks that were significantly (P<0.05) higher in protein and ash and lower in total lipids. Amino acid analyses indicated that the beneficial fermented soybeans contained substantially greater quantities of several essential amino acids. Further investigations were made by supplementing the control diet with certain deficient essential amino acids so as to simulate the amino acid content of the fermented soybeans. Similar positive growth responses were noted. All the growth promotion effects could therefore be explained largely on the basis of a superior amino acid balance of the fermented soybean diets. The cultures of Rhizopus and Actinomucor tested did not illustrate any positive growth response or improved feed utilization of broiler chicks. Thus, the data suggested little promise for these cultures as a means of improving the nutritional quality of soybeans. Feeding the fermented soybeans to 10-day old quail chicks largely confirmed the findings observed with the broiler experiments. Hen-day egg production and egg size were not significantly altered by diets made with fermented soybeans. On the other hand, a consistent advantage in hatchability was observed with fermented soybeans. Some carry-over effects of fermented diets fed to the dams were noted with chicks in terms of increased growth responses although the effects were not conclusive.

Library of Congress Subject Headings

Poultry -- Feeding and feeds
Broilers (Poultry)




South Dakota State University