A. Brenes et al., EFFECT OF ENZYME SUPPLEMENTATION ON THE PERFORMANCE AND DIGESTIVE-TRACT SIZE OF BROILER-CHICKENS FED WHEAT-BASED AND BARLEY-BASED DIETS, Poultry science, 72(9), 1993, pp. 1731-1739
Three experiments were conducted to study the effects of crude enzyme
preparations on the performance and gastrointestinal tract size of chi
cks fed wheat and barley diets. In the first experiment, enzyme additi
on (100 and 200 mg/kg of Roxazyme(R) G and 1,000 mg/kg of Avizyme SX)
to diets containing Bedford barley improved weight gain (6%) and the f
eed to gain ratio (5%) over a 6-wk period for both male and female bro
ilers. In Experiment 2, enzyme addition to diets containing Scout (hul
less) and Bedford (hulled) barley improved (P less-than-or-equal-to .0
5) weight gains of Leghorn chicks by 25 and 11% and the feed to gain r
atios by 10 and 6%, respectively. Feed consumption increased significa
ntly (16%) only in the case of birds fed enzyme with Scout barley. Cor
responding reductions in the relative weights of the crop and gizzards
were 15 and 17% for birds fed Scout barley and 7 and 8% for those fed
Bedford barley. Enzyme treatment of the diet containing Scout barley
also reduced the relative length of the duodenum, jejunum, and ileum a
nd the relative weight of the proventriculus, whereas a similar treatm
ent of Bedford barley resulted in changes in the relative length of th
e duodenum and jejunum (P < .05). In the final broiler experiment (42
days), crude enzyme addition (100 mg/kg) to wheat and barley diets imp
roved weight gains by 13 and 9% and feed to gain ratios by 7 and 10%,
respectively. The addition of enzyme to the barley-based diet reduced
the relative weights of the proventriculus (39%), pancreas (24%), live
r (8%), duodenum (16%), jejunum (20%), ileum (18%), and colon (29%). E
nzyme treatment of the wheat diets did not affect organ size (P > .05)
. Enzymes improved performance and reduced the size of the gastrointes
tinal tract, pancreas, and liver in birds fed barley-based diets, wher
eas a similar treatment of wheat-based diets resulted in less dramatic
changes in performance and had no effect on organ size.