International Journal of Veterinary Science and Agriculture Research Volume 3 Issue 4, November-December 2021 ISSN: 2582-4112, Available at www.ijvsar.com Enzymatic Activities in the Intestinal Apparatus of Chickens after Peroral Intake of Humates 1 University of Veterinary Medicine and Pharmacy in Košice, Department of Animal Nutrition and Husbandry, Komenského 73, 04181 Košice, Slovak Republic *For Correspondence Correspondence Author Department of Animal Nutrition and Husbandry, University of Veterinary Medicine and Pharmacy in Košice, Slovakia frantisek.zigo@uvlf.sk Keywords:Intestine, humic substances, casein, cellulose, starch Abstract:The effects of dietary intake of humates on the proteolytic, amylolytic and cellulolytic activities in the intestine of broiler chickens Ross 308 (starting weight 37.79 ± 0.58 g) were analyzed. Three experimental (A, B, C) and one control groups of birds (n=120) were fed with mixtures Hyd1 236.0 (day 1 - 10), Hyd2 222.40 (day 11 - 30), Hyd3 193.30 (day 31 - 42) g.kg -1 crude protein. Humates (HM or HN) were added into feed mixtures: A group – 0.7% HM containing an absorbent of mycotoxins, B group – 0.7% HN without the absorbent, C group – 0.3% HM and the control without humates. There were measured body weights and feed consumption, as well as the average daily weight gains and the feed conversion ratio, were calculated once a week. On one hand, the positive effects of 0.7% humates were observed on the increase (P <0.05) of proteolytic on day 21 (B) by 7.92 (azocaseing.ml - 1 .min -1 .g -1 ), cellulolytic on day 28 (A) by 0.89 (glucose mol.l -1 .min -1 g -1 ) in the intestine of broiler chickens measured in the excrement. On the other hand, the decrease (P <0.001) of amylolytic activities was observed on day 33 (A) by 1.58 and (B) by 1.43 (glucose mol.l -1 .min -1 g -1 ). In the case of intake of 0.3% humates, the proteolytic or cellulolytic were decreased in C on day 21 or 28 by 16.39 and 2.41, respectively. The recommended level of added humates into a feed of chickens is 0.7%. I. INTRODUCTION Humates are complex mixtures of heterogeneous organic compounds of biotic origin that have undergone extensive transformations since they were first produced by plants. Lignin is probably an important precursor and based on solubility, humates can be classified into humic acids (insoluble below pH 2), fulvic acids (soluble at any pH), and humin (insoluble in water). Because of the complexity and irregularity of humates, and the pathways of their formation, they should not be considered as strictly defined molecules, but can rather be characterized by average properties [1].The positive effect of humates on the growth and feed conversion of broiler chickens was demonstrated in the study performed by [2]. Humate supplementation increased the feed conversion efficiency and egg production in hens but did not effect on feed intake [3]. Sopoliga et al. [4] reported the positive influence of humates on egg production and the quality of quails and pheasants as well. According to Yeo [5], the improvement in weight gain and better feed conversion may be related to promotional effects on metabolic processes of digestion and utilization of nutrients. The scientific hypothesis was based on the positive effects of humates on the detoxication of exogenous and endogenous poisons, stabilization of intestinal microflora, prevention of digestive problems, activation of Andrej Marcin 1 , Pavel Naď 1 , Lukáš Bujňák 1 and František Zigo 1