Abstract
The objective was to conduct a collaborative study to evaluate the dry matter contents in feeds in six feed analysis laboratories from institutions linked to the National Institute of Science and Technology in Animal Science (INCT-CA). Six feeds were evaluated: sugarcane, corn silage, elephant grass, soybean meal, citrus pulp, and corn mixed with urea (9:1). It was asked to each laboratory that the samples were analyzed for eleven days, consecutive or not, with three replicates per sample per day of evaluation. There were variations among laboratories, days of analysis and interaction effect of material and laboratory. Comparative evaluation between the average contents produced by the laboratories and the Karl Fischer method indicated that 11.1% of the assessments were found accurate. The variation of results among laboratories accounted from 54.1 to 79.2% of the total random variation. It was found that the repeatability represented 6.24 to 26.45% of reproducibility. There are Horwitz ratios less than 2 for all materials tested. It was noticed that 52.8% of the assessments show variations of the estimates as a function of days in which analysis was performed. High inter-laboratory variability was checked through the evaluation of questionnaires sent to laboratories to elucidate the main procedures used in each laboratory, which can possible explain the great variation of the estimates obtained here.
analytical methods; collaborative study; feed analysis; Karl Fischer titration
