The United Kingdom produces enough barley grain to meet its needs for animal feed and brewing. The Scottish grain whisky trade, however, imports large quantities of high-diastase barley from Canada (Hayter & Allison, 1975). The breeding of highdiastase cultivars which could be grown in Scotland and so replace these imports has been pursued at the Scottish Crop Research Institute (SCRI).

Leucaena leucocephala (Lam.) de Wit, a leguminous shrub, has come into use as a fodder plant for animals in the Ryukyu Islands as it provides highly palatable, high quality feed (Kitamura, 1985). It is superior to other feeds available in this regard (Higashiohmine, Aramoto & Yamashiro, 1971; Isa et al. 1982).

Classically the plant-growth regulator chlormequat (2-ohlorethyl trimethylammonium chloride, CCC) is applied to bread wheat crops (Triticum aestivutn L.) to shorten the basal internodes of the culm (Koranteng & Matthews, 1982) and thus prevent lodging (Cyanamid, 1966). Further, yield variations in cereal crops can be induced by chlormequat application in the absence of lodging. These effects may result from a manipulation of growth (e.g. barley: Koranteng & Matthews, 1982; wheat: Wunsche, 1971; triticale: Hankins, 1975) or development (e.g. barley: Wunsche, 1972; wheat: Harris, 1978; triticale: Green & McDonald, 1985).

Andropogon gayanus Kunth var. bisquamulatus Hack, is a polymorphic bunch grass, widely distributed throughout most of the tropical and subtropical savannahs of Africa, south of the Sahara in areas with a long dry season. This grass was introduced into the Colombian Llanos from the Shika Agricultural Research Station, northern Nigeria, in 1974. Subsequent to its introduction, a series of agronomic trials were initiated by Centro Internacional de Agricultura Tropical (CIAT) at the Carimagua Research Centre and various national research institutions in Latin America to evaluate the potential of A. gayanus, primarily in the vast Ultisol and Oxisol savannah regions of the continent. As a result of further evaluation at a number of locations, accession A. gayanus var. bisquamulatus CIAT 621 was released in 1980 in Brazil as cv. Flanaltina and in Colombia as cv. Carimagua 1. During 1982–3 Peru, Venezuela and Panama subsequently released the same accession under the cultivar names of San Martin, Sabanero and Veranero, respectively. It is estimated that 168000 ha have been sown with A. gayanus in Brazil since 1982 (J. E. Ferguson, C. Sere and R. de Andrade, personal communication). Smaller areas have been established in other countries.

A ruminant animal is largely dependent upon microbial protein synthesized within the reticulorumen for amino acids to meet its requirements for maintenance and production. The major precursor for rumen microbial protein synthesis is ammonia arising both from degradation of feed proteins within the rumen and from nitrogen recycled to the rumen. The concentration of rumen ammonia-N required to sustain maximal rates of microbial protein synthesis in vivo has been variably reported to range from 22 to 235 mg ammonia-N/1 rumen fluid (Miller, 1982). Most experiments which have investigated the concentrations of rumen ammonia-N required for maximal rates of microbial protein synthesis have used the addition of urea to the diet as the means of increasing rumen ammonia-N concentrations. However, little attention has been paid to the effects upon rumen ammonia-N concentrations and upon the efficiency of rumen microbial protein synthesis of supplying increasing amounts of a readily degradable protein in the diet, although Beardsley et al.(1977) found that as increasing amounts of soya-bean meal were fed to sheep, net losses of N across the forestomachs of the sheep were increased. In this paper, two experiments are described in which increasing amounts of soya-bean meal were fed to sheep receiving a basal ration of rolled barley and hay; the digestion of organic matter (OM) and of amino acid N (AAN) within the rumen, the net quantities of microbial AAN entering the small intestine and the efficiency of rumen microbial AAN synthesis were measured.