Assessment for animal feed of maize kernels naturally-infected predominantly with Fusarium moniliforme and Diplodia maydis. II. Nutritive value as assessed by feeding to rats and pigs

Abstract

Four batches of ear-rot damaged maize grain and a batch of reportedly sound maize were assessed by rat and pig growth assay and digestibility determination in pigs. All batches were the yellow hybrid, Dekalb XL81, except one which was a white variety, Dekalb DS456W. The fungus most frequently isolated from damaged kernels was Fusarium monilifome, with the exception of one batch where Diplodia maydis was equally prevalent. Traces of aflatoxin were detected in two samples but ochratoxin A, sterigmatocystin, zearalenone, T-2 toxin, deoxynivalenol, nivalenol, diacetoxyscirpenol and moniliformin were not detected. In the growth assays, no illness was apparent in any of the rats but scouring, vomiting and a persistent and generalized muscle tremor were observed in a number of pigs. Diets based on sound maize resulted in better (P < 0.05) growth performance of both rats and pigs than those based on mouldy maize. The apparent digestibility of the sound maize was better than each batch of mouldy yellow maize, but no better than the batch of mouldy white maize. Differences in nutritive value between the batches of maize were more closely related to the degree of fungal damage and the nature of the endosperm than to either the proximate chemical or amino acid composition of the grain. The muscle tremor observed in some pigs might have been due to undetected mycotoxins.