Determinação da fibra bruta em alimento volumoso e concentrado utilizando a autoclave e o analisador de fibras

Abstract

The analysis of the fiber content of foods is of great importance for animal feed, especially for herbivorous animals, and there are several methods to quantify the fiber content of foods and the oldest method is the analysis of crude fiber. With the objective of optimizing the execution time of the analysis and reducing the manpower, alternative methods were developed to the oficial method that replaces the fiber analyzer with reflux for equipment such as the autoclave and the fiber analyzer that uses the filter bag technique. The objective of the present work was to compare the results of the analysis of the crude fiber (CF) of a roughage, Brachiaria brizantha grass cv. Marandu (marandu grass) and a concentrate ration, composed of beef cattle feed, by the filter bag technique using an autoclave and fiber analyzer (TECNAL, model TE-149). Non-woven fabric (TNT) with a grammage of 100g/m² was used to make the filter bags, so that they were 5 cm long by 5 cm wide, which corresponds to an area of 25 cm². The amount of sample that each bag received obeyed the ratio of 20 mg of DM/cm2 of surface. Five replications were performed for each food evaluated in each method: autoclave and fiber analyzer. No significant differences were observed for the analysis of crude fiber from marandu grass using the autoclave and the fiber analyzer. The experimental design used was completely randomized, with two treatments (two methods) and five replications in each treatment. The results were submitted to analysis of variance and the means were compared by the F test at 5% probability, using the statistical program R 3.4.2. No significant differences were observed for the analysis of crude fiber from marandu grass using the autoclave and the fiber analyzer. However, when comparing the analysis of crude fiber in the concentrate ration by the two methods, a significant difference in values was observed, with a higher value for the fiber analyzer. It is concluded that the analysis of crude fiber in roughage using the autoclave or the fiber analyzer produces similar results. However, in concentrated rations, the use of a fiber analyzer, without a pressurized environment, overestimates the crude fiber content, and the use of an autoclave is recommended for this type of sample.