[Determination of polyethylene during the process of measuring feed passage rate in sheep].

In a trial with rams, application of polyethylene powder (PE) as a marker for determination of feed passage rate through the digestive tract and three methods of its determination in feed and feces were tested. PE with particle size 0.4 mm and specific weight 0.924 was administered to animals in feed and its excretion was studied during the period of 10 days in two experimental diets based on secondary sources of wood, and in one control diet. PE formed 3.9% (D-2), 3.5% (D-1) and 4% (control) of the diet dry matter and was determined by gravimetric method; for mineralizing organic matter in the sample, nitric acid (Chandler et al., 1964), mixture of sulphuric and nitric acid (Kemmink and Dijkstra, 1968) and sodium hydroxide (Boling et al., 1967) were used. The most suitable was the method using sodium hydroxide, by which 81.23% (D-2), 84.78% (D-1) and 86.6% (control) of PE recovery was determined in feces samples.