Effect of enzyme addition on the performance and gastrointestinal tract size of chicks fed lupin seed and their fractions

Three experiments were conducted to study the effects of adding a crude enzyme preparation to diets containing whole, dehulled lupins and lupin hulls on performance, dry matter retention (DMR), AME, apparent protein digestibility (APD), and size of gastrointestinal tract of Leghorn and broiler chicks. In the first experiment, Leghorn chicks fed diets containing up to 70% whole lupins showed a depression in the performance. Progressive decreases in DMR (up to 30.2%), AME (up to 6.5%), and APD (up to 6.5%) and an increase in the relative gizzard weight (18.8%) were observed with increasing concentration of lupins (23.1, 46.9, and 70%) in the diet. Enzyme supplementation of diets containing lupins significantly improved the performance of the chicks. DMR and AME were improved by 4.2 and 3.1, respectively, and gizzard size was reduced (7.1%) by addition of the enzymes. In the second experiment, addition of 11.2 and 22.4% of lupin hulls to a dehulled lupin diet resulted in a dramatic depression in chick performance, with values ranging from 6.3% for feed consumption to 60.5% for fed to gain ratio, and an increase in the relative organ weight (up to 29.9%) and length (35.6%). These effects were partially counteracted by the action of enzymes. In the third experiment, increasing concentration of whole lupins (15, 35, and 45%) in broiler chicken diets caused a depression in the performance of birds fed 35 and 45% whole lupins as compared to those fed the wheat-soy diet. In contrast, 15% lupins improved weight gains compared to that obtained with the nonlupin diets. The lower content of lupins in the diet also had no or little effect on other performance values compared to the control group, whereas 35 and 45% dietary lupins tended to have negative effects. Likewise, increasing lupin content in the diet produced an enlargement in the relative size of several sections of the gastrointestinal tract. Enzyme supplementation of lupin diets improved weight gain (5.5%) and feed consumption (3.8%) with the values being similar to those obtained with the wheat-soy diet. Moreover, the enzymes also reduced the relative size of digestive organs from 5.3% for pancreas to 22.2% for crop. In summary, lupins appear to contain fibrous components that reduce the performance of the birds and increase the size of the gastrointestinal tract. The addition of enzymes counteracted these negative effects in birds fed whole, dehulled lupins and lupin hull diets.