The objective of the study was to evaluate the productive, carcass, and tibia mineralization responses in broiler chickens supplemented with a liquid extract of humic substances (HS) in the drinking water. Chicks were housed in holding cages from 8-42 days of age and were randomly assigned to one of five increasing HS levels in the drinking water (0, 161, 322, 483, and 644 µg/L). At 21 and 42 days, to obtain carcass and tibia measurements half of the broilers were slaughtered. ANOVA and linear regression were used to analyze the data. The HS chemical composition and flat structures were estimated. At 21 days, increasing levels of HS in the drinking water resulted in a cubic response on breast weight (p<0.05), tibia ashes percentage (p<0.05) and tibia Ca percentage, as well as a linear increasing response (p<0.05) on P percentage. HS elicited a quadratic response on the tibia DM percentage (p<0.05), Ca content (p<0.01), and P content (p<0.05) at 42 days.The optimal HS supplementation level to achieve the highest tibia DM percentage, Ca and P content were 345.00, 322.46, and 347.75 µg/L, respectively. Increasing HS levels also resulted in a cubic response in tibia Ca (p<0.05) and P percentage (p<0.01). In conclusions, HS supplementation in drinking water improved bone mineralization in broiler chickens at 21 and 42 days of age.

The mechanisms of action of humic substances (HS) as growth promoters in poultry are unknown. In this study, the productive performance, histology, and number of goblet cells (GC) in the intestinal villi of broilers under steady-state digestive conditions and under abrupt changes in diet with the addition of HS was evaluated. Broilers housed individually were offered three treatments from 14–28 days: 1 = diet with white corn/soybean meal, without growth promoter antibiotics (nonGPA); 2 = with GPA (GPA); and 3 = with 0.3% HS. At day 28, two diets were suddenly introduced: (A) white corn/soybean meal plus dried distillers’ grains with solubles (DDGS); and (B) white/blue corn/soybean meal/DDGS, keeping the three original treatments. Diets A and B were also exchanged on day 37. FCR was lower with GPA and HS compared to nonGPA from 14–38 days (p < 0.05); at day 28, under steady-state digestive conditions, HS had a similar effect to GPA on the histology and GC number in the jejunum villi. The number of GC in the jejunum of HS-fed broilers on days 29 and 38, after diet changes, behaves similarly to that of AGP-fed broilers (p > 0.05). HS appears to strengthen the mucosal protection of the epithelium of the intestine.

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The objective was to evaluate the productivity, microbiology and histopathology of the jejunum, ceca and liver in broilers fed a control or a high non-starch polysaccharide (HNSPs) diet added with an extract of humic substances (EHS). 240 broilers individually allocated, from 21-42 d of age were assigned to a factorial arrangement of 2 types of diets: 1) A corn/soybean meal diet (Control) and 2) As Control plus 7% distillers dried grain with solubles and 12% of wheat bran (HNSPs), and 3 growth promoters: 1) Antibiotic growth promoters (AGP); 2) without AGP (NAGP) and C) with 0.5% of EHS. At the end of the trial, the breast and carcass were weighed and samples of the intestine, ceca and liver were taken for microbial and histopathology analysis. Results were subjected to ANOVA. EHS-fed broilers had lower feed conversion ratio (FCR) and total aerobic bacterial (TAB) counts in the liver and higher ashes digestibility with the Control diet, but negative responses were seen with the HNSPs diet (Type of diet and growth promoter interaction, p≤0.05). The lesion scores in the jejunum were lower in EHS-fed broilers with the Control and HNSPs diet (p≤0.05). The TAB and E. coli were lower in the jejunum and ceca of AGP-fed broilers (p<0.01) compared to NAGP and EHS groups. EHS-fed broilers showed improved FCR and ileal ashes digestibility and lower TAB in the liver with the Control diet and had lower lesion score in the jejunum and similar weight gain compared to the AGP-fed broilers.