Humic acid and its effect in broiler chickens

European legislation has banned the use of antibiotics as growth promoters and for prophylactic purposes to avoid the development of cross-resistance to antibiotics used in animal therapy. The move to improve food safety has thus imposed the development of new feeding strategies in order to reduce the risk and economic impact of digestive diseases. One of the main challenges at poultry farms is presented by digestive disorders, especially in the first phase of rearing, often leading to a serious degradation of sanitary conditions and the consequent increased and often uncontrolled use of antibiotics to avoid huge losses of animals. Studies on the use of feed additives (probiotics, prebiotics, organic acids, plant extracts) in poultry have been given special attention because of the high susceptibility of the animals to digestive troubles.

Humic acid can decrease levels of mycotoxins in feed

In the search for natural solutions, humic substances (humic and fulvic acids) administered in the feed or drinking water are proving to be of interest. Humic substances are a class of compounds resulting from the decomposition of organic matter, particularly plants. Many studies and trials have showed their capacity to inhibit bacterial and fungal growth (decreasing levels of mycotoxins in feed), reduce stress by hormones, and improve the immune system, anti-inflammatory and antiviral properties, as well as to prevent and cure intestinal disorders. Humic substances also improve the nutritive value of feed and trace element utilisation, with positive effects on growth performances and a reduction in mortality.

Trial in broilers

A feed material* characterised by a high content of humic and fulvic acids has been shown to improve the nutritive value of feed, productive performance and the health status of animals. This component was further studied in a trial carried out at a private experimental farm located in Taragona, Spain. The trial aimed to further test its effect on the growth performance and health status of broiler chickens. The trial was performed on 384 one-day-old Ross 308 male broiler chickens up to 42 days of age (age at slaughter). The chicks were divided into three groups of 128 animals each and submitted to three treatments, differing only in the dietary inclusion level of the feed material. The diets (Table 1) were formulated in order to cover the high requirements of the animals. The experimental diets of the first and second period (starter and growing) were formulated to meet the nutritional standards for broiler chickens in the growing and fattening periods. The diets were free from other additives and anti-biotics, only having different inclusions of the feed material. The collective live weight and collective feed intake were recorded once a week for all animals.

Fewer digestive disorders

During the trial, the animals’ health status was very good. In fact, only two broiler chickens died, due to respiratory and digestive diseases, but these health problems were not associated with the dietary treatments. More specifically, the animals died in the groups fed with the C and M2, respectively. Growth performance during the first period (from 1 to 21 days), the second period (22 to 42 days of age) and the whole period (Table 2) were partially influenced by supplementation of the feed material or by the inclusion level. The absence of severe digestive disorders (resulting in a low mortality rate) and antibiotics treatment during the whole period of the trial, meant that chicken performance was on average satisfying and consistent with the growth curves of the corresponding genetic type.
At the end of the trial, at 42 days of age, animals weighed 2,898 g, owing to a daily growth rate and feed intake during the trail of 68.0 and 117 g/d, respectively, with feed conversion averaging 1.72 (Table 2). The analysis of the growth rate, feed intake and feed conversion (Table 2) showed, in the third trial week (21 days of age), a trend towards a linear increase of live weight (P=0.08) at the highest level of inclusion of the supplement (799.06 vs. 782.81 vs. 815.78 g for diets C, M2 and M5, respectively). This data is supported by better weight gain in the first period of rearing and, in particular, from 14 to 21 days of age in the group M5 (P>0.05; data not showed).

Better FCR

In the second period of the trial, daily growth and feed intake was similar among the groups, but the feed conversion ratio improved significantly (P=0.02) in the group M2 because of the recovered weight gain; lower in the first period of rearing. From the trial data, the researchers concluded that this humic acid feed ingredient showed positive effects in the first and delicate phase of rearing (starter phase) in broiler chickens.

*Minerva (produced by Pacta)