Intestinal morphology and activity of digestive enzymes in broilers fed crude propolis.

摘要

Propolis is a resin produced by bees that has been investigated for its potential to increase the performance of broiler chickens. Therefore, this study aimed to evaluate the inclusion of crude propolis in the diets of broiler chickens from 1 to 21 d of age. A total of 1020 male chicks were distributed in a completely randomized experimental design into six treatments (0, 100, 200, 300, 400 and 500 ppm of crude propolis), with five replications, and 34 birds per experimental unit. The experimental diets were provided from 1 to 21 d of age and subsequently (from 22 to 42 d of age) the birds were fed a nutritionally complete ration based on corn and soybean meal. All supplemented groups showed similar growth performance in all growth phases (P>0.05); however, there was a linear increase in carcass yield at 42 d of age according to increase in crude propolis inclusion from 1 to 21 d of age (P<0.05). At 7 d of age, relative weight of the gizzard increased linearly (P<0.05) with increasing propolis, and at 21 d of age, relative weight of the large intestine showed a quadratic (P<0.05) response, with the lowest value predicted to occur at 278 ppm of crude propolis. The ileum crypt depth at 21 d of age was affected by propolis, with a quadratic response (P<0.05) and highest value estimated at 323 ppm. At 21 d of age, sucrase activity in the jejunum increased linearly with increasing propolis and maltase activity in the ileum showed a quadratic (P<0.05) response, which predicted highest activity at 292 ppm. Amylase activity was lower in animals supplemented with 100 and 400 ppm of propolis at 21 d of age (P<0.05) compared with the control group. Thus, the crude propolis supplementation is not recommended in broiler diets from 1 to 21 d old given that it does not influence the performance, despite small changes in intestinal morphophysiology at 21 d of age.