Effect of the substitution of different levels of Biochar with mineral premix in diet on growth performance variables, meat quality and bone ash of broiler

Chicken meat is one of the most important foods and its economic production is essential. In industrial poultry farms, about 70 to 75 percent of production costs are related to feed costs. Therefore, one of the most important goals of poultry nutrition researchers, along with improving the performance and characteristics of poultry carcasses, is to reduce the cost of feed. In addition to edible materials, dietary feed includes feed additives that improve feed conversion, maintain bird health and, consequently, reduce costs and earn the most economic benefits. Any substance that can improve the health and safety of the digestive tract is of particular importance in feeding poultry. The presence of minerals in animal feed is necessary for the animal’s metabolic processes.  In fact, they are catalyst for many enzymatic systems, and part of hundreds of molecules involved in intermediary metabolism, hormone secretion, antibacterial effects, and immune defense systems; as a result, it influences growth performance, meat quality and appetite of broiler chickens. Traditionally, according to various feeding standards, minerals are supplemented in broiler diet in the form of inorganic salts, i.e.: carbonates, oxides, or sulfates to provide the birds’ requirements.Therefore, one of the ways to reduce the cost of feed rations is to replace useful and low-cost compounds with mineral supplements. In recent decades, the use of feed additives in poultry diets has been considered to increase their production. One of these additives is humic compounds. Humic compounds are a compelex of compounds that are produced from the decomposition of organic matter, especially plants, soil and coal. Biochar is produced by pyrolysis from various types of biomass in a low-to-no oxygenthermal process at temperatures ranging from 350 to 1,000ºC. In addition to its use as a dietary supplement, the use of biochar in nutrition has been considered as a dietary supplement in recent years. It improves nutrition and thus better digestion and absorption of nutrients and limits the activity of toxins such as dioxin, glyphosate, mycotoxins and pesticides and reduces side effects on the gastrointestinal tract. This experiment was carried out to study the effects of replacement different levels of Biochar with the mineral supplement of diet on performance, meat quality, and bone ash in broiler chickens.

 This experiment was conducted with 250 male broiler chicks (Ross 308) in a completely randomized design with five treatments, and five replicates (10 birds per replicate) for 42 days. The treatments included: 1) control diet (without Biochar, contain mineral supplement), 2) control diet whit 25% Biochar plus 75% mineral supplement, 3) control diet whit 50% Biochar plus 50% mineral supplement, 4) control diet whit 75% Biochar plus 25% mineral supplement, 5) control diet whit 100% Biochar plus mineral supplement. Birds and feeds were weighed at days 1, 21, and 42 on a cage basis. The body weight gain, body weight, feed intake and feed conversion ratio were determined. The meat lipid oxidation was evaluated by thiobarbituric acid-reactive substances assay described previously. The pH of meat was measured with a pH meter by homogenizing 5 g of sample with 25 ml of distilled. To estimate the water holding capacity, one g of the meat samples were put in tissue paper inside a tube and centrifuged (for 4 min at 1500 g). Then meat samples were dried at 70˚C for 24 h. Cooking loss was determined via the difference between raw weight and cooked weight, and expressed as a percentage of the original weight. The drip loss was determined as the percentage of weight loss of meat samples under standardized conditions. Color values L∗ (lightness), a∗ (redness), and b∗ (yellowness) were determined with a previously described digital imaging method. The hue angle (arc tangent of b*/a*), and chroma (saturation index) √ (a*2 + b*2) were also determined. The crude ash of bone samples was analyzed according to standardized methods.

 In the whole period of experiment, the replacement of mineral supplements with Biochar  could not make a significant difference on body weight, feed intake, food conversion rate (FCR), European Production Index, bone ash. Meat pH of birds fed 75% Biochar was higher than in all treatments and dripping loss of 75% Biochar was significantly lower than other treatments but here are no significant difference between other treatments. Brightness and yellowness were not affected by the experimental treatment, but the redness index was higher in 75% and 50% Biochar than in other treatments. Therefore, Biochar can replace dietary mineral supplements due to the presence of humic substances and the presence of mineral elements in its composition. Also, due to the low price of Biochar, the use of this substance instead of dietary mineral supplements, makes the use of minerals more desirable and reduces the cost of the diet of broilers. In the present study, the use of Biochar and its substitution with dietary supplements, due to its mineral content and humic acid, improved meat quality of broilers. Despite the lack of a significant difference between the price of a diet ration and a diet containing Biochar, it seems that the use of Biochar can replace dietary minerals and reduce the economic costs of the diet, which is an important issue in the poultry industry.The lack of altered bone ash in broiler chickens fed Biochar containing humic acid in this experiment was probably due to the adequate and balanced levels of calcium and phosphorus in the diet and therefore due to the lack of effect of humic acid in Biochar . This result may be due to adequate supply of minerals in treatments containing Biochar compared to control group treatment that has made no change in bone ash from control group.

 In conclusion, the use of Biochar at 75% level without affecting the performance, improved the meat quality (meat pH, redness color index and dripping loss percentage) of broiler chickens.