Fungal Degradation and Nutritional Value of Cellulosic Wastes

Abstract

The purposes of these experiments were (1) to determine the extent of fiber degradation of several cellulosic waste residues by the fungus Diplodia gossypina and (2) to determine the nutritional value and possible physiological effects of cultures of D. gossypina grown in cottonseed waste when fed to weanling rats. Sterile cottonseed waste, peanut hulls, corn cobs, corn stalks and wheat straw hydrated with water or a mineral salt solution containing inorganic nitrogen were incubated for 14 or 28 days with D. gossypina. Similarly prepared uninoculated materials were controls. The growth of D. gossypina on cellulosic waste residues resulted in consistent increases in substrate N along with losses in substrate dry matter. This indicates N was being concentrated within substrates. Substrate dry matter lost NDF, hemicellulose and cellulose. The ADF and lignin fractions were increased. The most consistent change across all substrates was the reduction of available cell wall fractions. Weanling female rats were fed a ration mixed with 0, 10, 20 and a 40% culture of the fungus D. gossypina grown on cottonseed waste. A 40% uninoculated treatment was included. All rats were on a continuous 15-day N balance trial. Reductions in body weight (P<.01), feed intake (P<.05), N balance (P<.01), N retained (P<.01) and N digested (P<.01) were shown. Fecal N was increased (P<.01). Several treatment effects on organ weights were shown but a specific fungal effect with a reduction (P<.05) in spleen size was shown. Whole blood creatinine (P<.05) and amino N (P<.01) were reduced. The daily excretion of urinary creatinine (P<.01) and amino N (P<.05) was also reduced. The results of this study indicate both nutritional stress and possible adverse physiological effects of feeding D. gossypina cultures of cottonseed waste to weanling rats. Copyright © 1977. American Society of Animal Science . Copyright 1977 by American Society of Animal Science.