Effects of drying method and rearing temperature on broiler manure nutrient content

Abstract

There is no universally accepted method for preparing poultry manure samples prior to chemical analysis for nutrient content. Proper sample preparation and optimization of the techniques for manure chemical analyses are the keys to the determination of precise rates for land application to crops and pastures. This study was conducted to determine the effect of bird-rearing temperature (RT) and pre-analysis drying methods on broiler manure nutrient content. Four drying methods, air drying (AD), freeze drying (FD), oven drying at 65°C (OD65), and oven drying at 105°C (OD105) were evaluated on manure of birds grown at 16, 21, and 26°C. The results were compared with analysis of the fresh broiler manure with no drying (ND). All drying treatments resulted in highly significant nitrogen (N) loss (21%–27%) compared to ND at all rearing temperatures. However, there were no significant differences in total N loss among the four drying methods examined in this experiment. There was significant loss of NH4-N with OD105 for all RT, but no pattern was observed among other drying methods and RT with regard to NH4-N and organic N. The effect of drying methods on broiler manure nutrient content followed the same trend for all the rearing temperatures. The greatest loss of phosphorus (P), calcium (Ca), magnesium (Mg), potassium (K), iron (Fe), manganese (Mn), and zinc (Zn) were observed with freeze drying. We recommend fresh broiler manure analysis for the determination of total N and NH4-N after a proper mixing to obtain a homogeneous paste. For analyses of P, Ca, Mg, K, Fe, Mn, and Zn in the broiler manure, ND, AD, and OD65 generally resulted in lower reduction of these nutrients.