COMPOSITION, AMINO ACID DIGESTIBILITIES AND PROTEIN QUALIT OF HIGH-LYSINE BARLEY LINES FOR GROWING RATS

Abstract

Hiproly barley and five experimental barley lines bred and grown in Alberta under similar soil and environmental conditions were evaluated as sole protein sources in two rat trials. In exp. 1, compared to Gait barley (control), Hiproly and the test lines (Lines 1, 2 and 3) contained 9–22% more nitrogen (N). Hiproly and Line 1 also contained 21 and 29% more lysine, respectively. Consequently, Line 1 could be classified as a "Hiproly" barley, Line 2 as "high protein" barley and Line 3 a "normal" barley. Determined by the fecal analysis method, lysine was least digestible of the amino acids (AA). Apparent lysine digestibilities were similar for all the barleys. In exp. 2, compared to Gait barley (control), Lines 4 and 5 were similar in N content, but contained 13 and 7.5% more lysine, respectively. Measured by the relative protein value method, there were no differences in performance, reflecting the small differences in lysine content among the barleys. The apparent N digestibilities in barley were 10–11 percentage units lower (P < 0.01) than in casein. Calculated chemical scores showed that among the barleys only Line 1 might adequately provide all the AA, including lysine, for 60- to 100-kg pigs. Key words: High lysine barleys, hiproly, barley lines, apparent digestibilities, relative protein values, rats