The nutritive value of new high-lysine barley mutants

Four new high-lysine barley mutants, the mother variety ‘Sultan’, and the cultivar ‘Lysimax’ with the high-lysine gene lys3a were grown in a field trial in 1992 at Riso, Denmark. Yield and 1000 kernel weights were measured. The material was analyzed for protein, fat, starch, soluble non-starch polysaccharides, insoluble non-starch polysaccharides, lignin, β-glucans, sugars, energy and amino acids.

The nutritive value was evaluated in balance experiments with rats. The mutants yielded less than the mother cultivar ‘Sultan’ in the range 80–96%. Thousand kernel weights were also lower than for the mother cultivar. The protein concentration was higher in the mutants, with the highest value of 14·2% vs 12·9 in ‘Sultan’.

The fat content was usually higher in the mutants, with the highest value of 5·3% vs 3·9% for ‘Sultan’. The starch content varied considerably, from 51·2%–60·3% for the mutants, while ‘Sultan’ contained 58·2%. The level of dietary fibre was usually higher in the mutants compared to the level in ‘Sultan’ (19·7%). β-glucan and sugar contents varied among the mutants, with values higher and lower than in ‘Sultan’. ‘Sultan’ contained 3·31 g lysine/ 16 g N vs 4·73 g N in one of the mutants.

The higher lysine content resulted in an 11·6% unit increase (P<0·05) in biological value (77·6% for ‘Sultan’ vs 88·2% for this mutant). The protein digestibility was usually higher (P<0·05) in ‘Sultan’ (87·1%). Energy digestibility was slightly lower (P<0·05) in the mutants compared to the value for ‘Sultan’ (84.1%).