Mycotoxins have for long been associated with disease and death in animals,but because of the great variety of fungi present in animal feedstuffs andthe detailed investigations needed to establish a causal relationshipbetween mycotoxin and a clinical disease, few disease syndromes have beenidentified.

In this paper, it is proposed to consider three confirmed clinical diseasescaused by mycotoxins, to review briefly their history and identification andto consider their biological effects in ruminants.

Urolithiasis is not at present an important problem for the livestockindustry in the United Kingdom, but the probable introduction of moreintensive systems of management may change this position. The rapidfattening of male animals with high-energy diets predisposes to formation ofphosphatic calculi and obstructive urolithiasis in the feed lot system ofthe USA and it is a form of this type of management which is most likely tobe introduced to this country. For this reason, this review will be limitedto the problem of phosphatic calculus formation, although other calculi,especially siliceous forms cause economic loss in extensive areas of theworld.

This paper was prepared at very short notice and no written version will bepublished.

The Nutrition Society will publish in its Proceedingspapers presented by invitation at symposia of the Society and abstracts oforiginal communications presented at other meetings.

Invitations to read papers at symposia are issued on the understanding thatthe persons invited send their papers for publication in the Proceedings of The Nutrition Society in the way outlinedin the letter of invitation, at least a fortnight before the meeting, andthat the papers will not be offered in that form for prior publication inany other journal.

Analysis of the effects of amino acid starvation in reticulocytes iscomparatively simple compared with similar analysis in other tissues ofwhole organisms. This is mainly because of the absence of RNA synthesis inreticulocytes, but also because the bulk of the protein being synthesized ishaemoglobin, a protein whose structure is completely known. The absence ofRNA synthesis eliminates complications that would otherwise arise throughRNA-mediated control mechanisms which in turn might mask the effects ofamino acid starvation on the protein synthetic machinery in the cells(Munro, 1969). Consequently reticulocytes have been used to study the effectof amino acid starvation on the actual process of protein synthesis andassembly.

The earliest estimates of protein requirements, such as those of Smith(1863) and Pavy (1874) who recommended about 125 g per day for the averageworking man, were based on studies of the diets of individuals or of groupsof subjects who were considered to be healthy and leading normal activelives. Such estimates were simply a reflection of the dietary habits ofthose under study, but helped to establish minimum standards of feeding ininstitutions. About the turn of the century, similar recommendations rangingfrom 118 to 150 g were made by Voit (1881), Atwater (1895) and Rubner (1903)(Fig. 1), and these came to be vigorously defended as representing notmerely feeding standards but as irreducible minima below which a properstate of health and vigour could not be maintained.