Effect of 2-row or 6-row barley and a commercial enzyme preparation on growing-finishing broiler chickens from 3 to 6 weeks of age

Abstract

A study was conducted to determine the efficacy of barley-based diets with or without a crude enzyme preparation for male broiler chickens from 3 to 6 wk of age. Treatments consisted of feeding grower and finisher diets based on two locally grown cultivars of barley, 2-row (unspecified cultivar) and 6-row (Leger) added at 0, 20, 40 and 60%, with 0 or 1000 mg commercial enzyme preparation/kg diet. The starter diet contained no barley. Enzyme addition to the 2-row barley-based diets resulted in significantly heavier 6 wk body weights compared to the non-supplemented diets and significantly improved feed efficiencies during the 5- to 6-wk period indicating an enzyme response in older birds. Level of 2-row barley did not have significant main effects on 6 wk body weight, weight gain, feed consumption, feed efficiency, mortality, or live grade, except for leg abnormalities. A significant linear contrast revealed increased percentage of leg abnormalities as the level of barley in the diet increased. Significant interactions were found between level of 2-row barley and enzyme addition for feed consumption and feed efficiency from 3 to 5 wk of age. Significant quadratic contrasts for level of barley within non-supplemented treatments indicated lower feed consumption of the 20 and 40% barley-fed birds than the 0 and 60% barley-fed birds during the 3-to 5-wk period. During the 5- to 6-wk period, feed consumption of the enzyme-supplemented diets increased linearly with percentage of barley in the ration. Neither level of 6-row barley nor enzyme addition to the 6-row barley diets had significant main effects on 6 wk body weight, weight gain, feed consumption, feed efficiency, or live grade. Significant interactions were found between level of 6-row barley and enzyme addition for 6 wk body weight, 3–6 wk weight gain and feed consumption for the 5–6 wk period. A significant quadratic contrast for level of barley within non-supplemented treatments revealed lower feed consumption of the 20 and 40% barley-fed birds compared to the 0 and 60% barley-fed birds during the 5–6 wk period. Thus, for the diets without glucanase, there was an effect of barley percentage which became apparent at different ages depending on the barley cultivar. As with the 2-row barley diets, there was a significant linear increase in feed consumption of the enzyme-supplemented diets as the level of 6-row barley in the diet increased during the 5–6 wk period. It appears from the results that the grower and finisher diets could contain up to 60% barley without being detrimental to growth but incidence of mortality or leg abnormality may increase somewhat. Enzyme addition improved feed efficiency for the 2-row barley diets, and erased the quadratic effects of barley level apparent when diets did not include β-glucanase. Key words: Barley, broiler chicken, enzyme, growth