Passage and interactions of large plastic particles applied into lactatingcows

Two trials were performed on two lactating cows. In the first trial the die t consisted of 5.4 kg maize silage, 3.7 kg lucerne hay and 5.3 kg mixture ( in DM), the mean milk yield was 17.09 kg. Plastic particles of 6, 8, 10 and 12 mm were used, 50 particles of each size. In the second trial with simil ar diet the mean milk yield was 22.12 kg, only particles 6 and 10 mm (768 a nd 172 pieces, respectively) were applied separately or together. The speci fic gravity of particles, which were applied orally, was 1.25 +/- 0.05 g/cm (3). The aim was to determine the recovery and retention time of individual particles, in the second trial the interaction of 6 and 10 mm particles wa s also evaluated. Mean cumulative faecal recovery of 6, 8, 10 and 12 mm par ticles in the first trial was: 98.7, 98.7, 96.0 and 82.7%, total mean reten tion time was 39.7, 41.4, 44.5 and 58.4 hours, respectively. In the second trial the highest interaction between 6 and 10 mm particles was found when 28 hours had elapsed after application, when the cumulative faecal recovery was 60.3 and 54.8%, respectively.