Effect of cultivar and environment on the feeding value of Western Canadian wheat and barley samples with and without enzyme supplementation

The feeding value of nine wheat cultivars grown in replicate in three locat ions in each of two crop years, and 14 barley cultivars grown in seven loca tions over three crop years was tested with or without an appropriate comme rcial enzyme using a broiler chick bioassay. Four pens of six male broilers were fed mash diets containing 80% of the test cereal with or without enzy me from 4 to 17 d. Digestibilities were determined using an acid insoluble ash marker at 1.1% of diet. Significant intraclass correlation coefficients between duplicate wheat samples suggested a common effect of the location, but their low to moderate values suggested the presence of random variatio n or variation due to unique growing conditions within location. For both w heat and barley samples, the growing location affected the feeding value of the cereal grain and subsequent broiler chick performance. Durum wheat cul tivars had higher feeding values than that of other wheat classes, both wit h and without enzyme supplementation, and the response to enzyme supplement ation was low, likely reflecting a low level of soluble non-starch polysacc harides. The values of hulless barley cultivars were similar to those of hu lled cultivars without enzyme, but the lower crude fibre in hulless barley resulted in higher feeding values when diets were supplemented with enzyme. The response to enzyme supplementation for both wheat and barley cultivars was dependent on the feeding value of the cereal grain without supplementa tion. Knowledge of variation in enzyme response could be used by feed manuf acturers to determine the economic merit of supplementing with enzymes.