Summary. The relative virulence of Cryptococcus neoformans serotypes A, B, C and D in four mouse strains was assessed by measuring their migration from the foot-pad of the animals to the spleen, lungs and brain in 6-week-old DBA/2, BALB/c, A/J and a hybrid mouse strain by re-isolating yeasts from the internal organs. Comparable doses of each C. neoforrnans serotype were inoculated into the foot-pads of the mice. C. neoformans var neoformans strains A68, D52, A-(IN) and D-(IN) were more virulent than C. neoformans var gatti strains B 112 and C18. However, the differences in the relative virulence of the var neoformans and the var gatti serotypes for the mouse strains were not significant (p > 0-05). Re-isolation of yeasts from mice showed that the BALB/c mice, in particular, and the DBA/2 mice were more susceptible to disseminated C. neoformans infection. The virulence of C. neoformans serotypes through foot-pad inoculation of mice was established.

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The possibility of upgrading spent sorghum grains to chicken feed through microbial processing was investigated. Spent sorghum grains (SSG) were fermented for a period of 21 days at 25 ± 2 o C using a consortium of A. niger, C. globosum and S. cerevisiae. The effects of microbial processing on the nutrient composition of the SSG were assessed and the nutrient composition of the microbe-processed product was compared with the nutrient requirements of chicken. Fermentation led to increases in the contents of crude protein (56%), crude fat (59.65%) and ash (38%). Crude fibre and NFE contents were decreased by 24.84% and 35.43% respectively. Energy content increased by 7.8%. The percent dry matter values of fifteen amino acids (lysine, histidine, arginine, aspartic acid, glutamic acid, proline, glycine, alanine, cystine, valine, methionine, isoleucine, leucine tyrosine and phenylalanine) were found to increase. Elemental analysis revealed increases in the values of calcium, phosphorus, potassium and iron, and decreases in the values of magnesium, manganese, copper and zinc. Microbial processing with the test organisms generally enhanced the nutritional quality of SSG, but for it to be used as chicken feed, there is need for further fibre reduction, energy enhancement and mineral supplementation.

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