PERFORMANCE OF BROILER-CHICKENS AS INFLUENCED BY A DIETARY ENZYME COMPLEX WITH AND WITHOUT ANTIBIOTIC SUPPLEMENTATION

An enzyme complex (Roxazyme G) produced by the fermentation of Trichoderma viride was tested in broiler diets (20 % CP, 11.6 MJ/kg) where the cereal part consisted of barley (50 %), wheat (40 %) and oats (10 %). The design was a 2x3-factorial experiment with 2 levels of feed antibiotic (virginiamycin, 0 and 20 ppm) and 3 enzyme levels (0, 100 and 200 ppm). The experiment involved 3744 Ross broiler chickens and was carried out between 0 and 44 days of age. The average performance of the birds was considered to be satisfactory despite the diet being based on barley. Average live weight, FCR and mortality were 1522 g, 1.80 and 3.3 %, respectively, at 35 days of age. Corresponding results at slaughter (44 days) were 1929 g, 2.05 and 6.0 %, respectively. There was a highly significant difference in mortality between antibiotic-supplemented and non-supplemented groups (2.4 and 9.6 %), due to outbreaks of necrotic enteritis. There was an indication that, when no antibiotic was included, birds fed enzyme supplemented diets resisted illness longer than the others. In diets without feed antibiotic, the enzyme preparation was very active and resulted in a 4 % increase in growth rate and improved FCR. It also decreased water intake, the frequency of sticky droppings, mortality, condemnating due to liver lesions and improved litter condition. The lower tested level (100 ppm) appeared to be sufficient for optimal performance. In the antibiotic supplemented diet, the effect of the enzyme preparation was not significant for growth rate, negligible for FCR but significantly decreased water intake and improved litter condition.