Addition of Different Levels of Humic Substances Extracted from Worm Compost in Broiler Feeds

Abstract

Different sources and inclusion levels of humic substances (HS) have been tested in broiler rations as an alternative to the addition of growth promoter antibiotics (GPA) with promising results. The current study was carried out to assess the influence of HS extracted from worm compost on broiler production parameters, carcass yield, tibia characteristics, lactic acid bacteria (LAB) counts, excretion of Eimeria oocysts, and antioxidant status of breast meat. A total of 1200 broilers were used, housed in groups of 30 per pen, and assigned to five treatments: 1 = basal diet with GPA (positive control), 2 = basal diet without GPA (negative control), 3–5 = basal diet with 0.15, 0.30, and 0.45% HS, respectively. The data was subjected to a variance analysis and orthogonal contrasts. The FI decreased linearly (p < 0.05) from 1–14, 29–42, and 1–42 days as the inclusion of HS in the feed increased. The FCR had quadratic responses (p < 0.01) from 29–42 and 1–42 days concerning the HS inclusion levels. Lactic acid bacteria was higher (p ˂ 0.05) in ten-day-old chicks with 0.45% HS in the diet. The 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity antioxidant potential decreased linearly (p < 0.05) concerning increasing HS in the feed. The results indicate that HS can be used as growth promoters in broiler feeds.

Mechanisms of Action of Humic Substances as Growth Promoters in Animals

“…In several experiments, enhanced final body weight and weight gain and reduced feed conversion ratio have been reported in HS-added broilers using different commercial sources of HS [24,68,113,114]. In agreement with these results, using a liquid or dry extract of HS from worm compost, higher final body weight and weight gain and lower feed conversion ratio have been reported in broiler chickens [19,31,77,146].…”

“…The enhanced immune response in HS-added animals may be the cause of the reduced severity of diarrhea reported in pigs [40][41][42] and calves [43][44][45] and to the strong tendency of lower mortality reported in broilers [25,67,76,77], Japanese quails [27], and pigs [41,78].…”

“…It is probably that in the simulated digestive system the rapid transit time through the digestive compartments, the addition of the buffering solutions and the presence of several dietary components in the intestine overcome the possible accumulation of toxic metabolites [96]. In two recent in vivo studies, increased lactic acid bacteria counts were reported in the gut of HS-added broilers [77,91].…”

Effects of Manganese Hydroxychloride on Growth Performance, Antioxidant Capacity, Tibia Parameters and Manganese Deposition of Broilers

“…The recommended Mn content for broilers is 120 mg/kg during 1–3 weeks and 100 mg/kg during 4–6 weeks by the Feeding Standard of Chicken in China. Additionally, we searched recent related articles on broiler experiments in Animals and also found that the amount of added Mn in the diet was around 100 mg/kg [ 18 , 19 , 20 , 21 , 22 ]. So we added 100 mg/kg Mn in the form of MnSO 4 as the positive control.…”

Use of Humic Substances from Vermicompost in Poultry

“…In a recent report, broilers kept in floor pens from 1 to 42 days of age and fed increasing levels of HS from vermicompost, showed lower feed intake (FI) and overall mortality, besides, a better feed conversion rate (FCR) compared to negative control birds not supplemented with HS and positive control birds added with antibiotics (Table 4) [59]. The greatest benefits of adding HS were observed in the last period of the trial, from 29 to 42; these findings closely resemble the observations in previous research.…”