Grain yield and nutritive value of high oil, opaque and waxy maize hybrids

Abstract

Grain yields, chemical compositions and protein qualities were measured for 11 maize varieties (four high oil, four opaque, two waxy, one normal) cultivated in Yugoslavia. Protein quality assessment was based on amino acid composition, and true protein digestibility, biological value, net protein utilisation and utilisable protein were determined in nitrogen balance experiments with rats. The protein concentration in dry matter varied from 8·63 to 11·88% while the fat concentration varied from 4·84 to 8·19%. There were only minor differences in starch+sugar, ash and crude fibre. Lysine levels were approximately 30% higher for the opaque varieties compared with normal maize, while leucine levels were about 30% lower. Yields were extremely high for all varieties with the highest value being 15·5 tonnes/ha. Even though the protein concentrations were relatively low, all varieties produced more than 1000 kg protein/ha, the highest value being 1847 kg/ha. This resulted in high yields of amino acids/ha. Protein utilisation was very high in the opaque varieties, which had the highest lysine contents. The biological values were close to 80 in these varieties whereas they were only 60 in the normal maize variety.