عنوان مقاله [English]
Introduction Humate material was used as feed additives in poultry nutrition. The biochar as a useful fertilizer in agriculture industry is a humate material that increases growth of plants. This fertilizer can as an additive be use in the poultry and animals feed, due to has many minerals material and two organic acid (humic and fulvic) in its compound. In poultry industry for egg production, reduce cost of diet is an important goal. The biochar as a dietary additive is easily derived from burn organic material and agriculture byproduct. In recent years, several studies have been conducted to determine the effect of humic acid as an additive on performance poultry. In a study, dietary supplementation of laying hens with humic acid improves the performance and egg shape index. Investigating the effect of biochar as replacement of dietary mineral supplements on performance and egg shell quality of laying hens is rare. The one of the properties of vitamin C (VC) is chelating properties, and with this property, it increases the intestinal absorption of minerals in birds. Therefore, in case of the above, this study was therefore conducted to investigate the effects of biochar (as a humate material) in five levels and vitamin C in two levels as replacement of dietary mineral supplements on performance and egg shell quality of laying hens.
Materials and Methods The current experiment was conducted to evaluate the effects of biochar with vitamin C as replacement of mineral supplement in diet of laying hen. A total of 400 laying hens of Bovans strain, were randomly assigned to 10 experimental groups in a 5×2 factorial treatment arrangement with five replications and eight laying hens in each replicate during three 30-day periods. Factors tested included biochar levels (0, 25, 50, 75, and 100% replacement with mineral supplements of diet) and vitamin C levels (0 and 100 mg/kg of diet). The feed intake, feed conversion ratio and daily weight gain were determined. The shape index was calculated by using egg height and egg width. The egg specific gravity was evaluated by floating eggs in soluble of water and salt with different density. The egg breaking strength was measured by resistance meter.
Results and Discussion Replacing biochar levels from 25 to 100% mineral supplement of diet, with and without vitamin C, had no effect on performance characteristics (feed intake, feed conversion ratio and daily weight gain) and egg shell quality traits (shape index, egg specific gravity and egg breaking strength) in total of period of the experiment (50 to 61 weeks of age). But Feed intake in the first period showed that treatments containing biochar at 25 and 50% levels of dietary mineral supplement without vitamin C, compared to the same treatments but with vitamin C and level 75% biochar without vitamin C, increased feed intake. In general, the addition of vitamin C to 25 and 50% biochar levels during this period reduced feed intake, while adding it to 75% level improved feed intake. In the third period, the egg shape index decreased with the addition of vitamin C. The reason of no effect of significant biochar on performance and egg shell quality can be due to different sources and amounts of biochar in poultry diet. The reason of had no effect of significant vitamin C on performance and egg shell quality can be having some reasons. The one of these reasons is bird environmental temperature. The use of vitamin C in laying hens diet that they are under heat stress improves their performance. Whereas, this study performed in normal environmental temperature. The second reason is vitamin C chelating properties, that this vitamin with these properties can be increased absorption minerals in birds intestinal. But due to digestive tract advanced of laying hens, maybe decrease its properties.
Conclusion The present study shows that biochar in all of levels had similar cost with control group, and it had no effect on performance and shell quality. Interaction biochar and vitamin C had no improved performance, egg shell quality traits and cost of diet during 50 to 61 weeks of age, too. Therefore, biochar due to low cost for its produce and its available and with no adverse effects on performance and egg quality traits of laying hens, can be replace with dietary mineral supplements in all of levels.