Abstract
This study aimed to investigate the effects of feed intake of humic substances (HS) on the cellulolytic and amylolytic activities, and the digestibility of dry matter (DM) in the chymus of the intestine and ileum of broiler chickens (Cobb 500). Four groups of birds (A, B, C, negative control; n = 120) were fed with mash diets (starter HYD1 230.20, grower HYD2 222.20, finisher HYD3 209.40 g crude protein (CP) per kg of DM) with the added HS from day 1 to 37 days as follows: A ‒ 0.7 % Humac nature; B ‒ 0.7 % Humac nature monogastric (HNM); C ‒ 0.5 % HNM (Humac Ltd., Slovakia). The cellulolytic activities were increased in the intestine in B/C by 2.50 (P < 0.01)/1.65 (P < 0.05) on day 3 and 1.02 (P < 0.001)/0.3 (P < 0.05) µmol.l−1.min−1.g−1 on day 24. There were observed higher values of digestibility coefficient of DM in the intestine (P < 0.05) in C by 15.14 % and 14.85 %, and in B by 20.73 % on days 17, 24 and 31, respectively. The enhancement of ileal digestibility of DM was observed in B by 7.38 % (P < 0.05) and CP in A and B by 3.7% and 6.1% (P < 0.05). The feed intake of HS favourably influenced the cellulolytic activities and increased the DM digestibility in the intestine and the ileum, as well as the CP digestibility in the ileum.