Sustained release of chromic oxide in the rumen of sheep from a CR2O3-paper pellet

Abstract

SUMMARY1. Pellets of Cr2O3-paper were administered to sheep to reveal the excretion pattern of Cr2O3 in the faeces.2. Two sheep fed on long hay and pelleted hay for each of two 28-day periods were given a Cr2O3-paper pellet daily at 9 00 hrs. during the 15th to the 24th day inclusive in each period.3. Total faeces were collected at hourly intervals during the 15th to the 28th day. Dry weight and concentration of Cr2O3 of each fraction was determined.4. A balance between input and output of Cr2O3 and a minimal standard J deviation of the concentration of Cr2O3 in the faeces between hourly collections was reached in 3 days with long hay and in 2 days when the hay was given as pellets.5. The decline in the concentration of Cr2O3 in the faeces started the day after the administration of pellets was discontinued.6. Grinding and pelleting of the hay resulted in a doubling of the standard deviations of the concentration of Cr2O3 in the hourly faeces collections during the period of input-output equilibrium.7. A pattern of a diurnal cyclic trend was apparent in the concentration of Cr2O3 in the hourly faeces collections, but it varied between animals and between diets.8. Pellets of Cr2O3-paper are suggested to facilitate the administration of Cr2O3 to ruminants.9. The effect of sampling frequency and animal replication on estimation accuracy is discussed.