Comparison of Hach Method with Kjeldahl Method for Determining of Crude Protein Contents of Some Animal Feeds

The aim of present study was to evaluation of Hach method for determining of crude protein contents of some animal feeds. Twenty one samples of animal feeds and digesta, including a variety of forages, concentrate feeds and mixtures and digesta ruminal samples and 0.025, 0.05, 0.075, 0.1, 0.175 and 0.2 mg ammonium chloride were chosen and their nitrogen and protein contents were measured using Kjeldahl, as the reference method and the Hach Methods and compared with each other. There was no significant difference between the methods in terms of crude protein content estimation of different feed samples and different amounts of ammonium chloride. The regression between the crude protein contents measured by the two methods was linear and showed a significant correlation (r=0.99). Modifing the digestion method of the original Hach method accelerate the method and it makes possible to analysis more samples without any negative effects on the obtained results. According with the reslt of this experiment the protein content of some analyzing samples in animal nutrition laboratories can be accurately measured through the Hach method.