PRELIMINARY OBSERVATIONS IN THE USE OF A SUSTAINED RELEASE PELLET FOR ADMINISTRATION OF CHROMIC OXIDE TO SHEEP IN DIGESTIBILITY STUDIES

Abstract

Sustained release pellets of chromic oxide (Cr2O3) were administered to sheep every second day for 112 days, to serve as an external indicator in digestibility determinations of mixed rations. The pellets were made from a mixture of Cr2O3 and dental plaster in the ratio of 2:1. A pressure of 10,000 p.s.i. produced a pellet with a specific gravity of 2.8.Digestibility coefficients obtained by the Cr2O3 ratio method differed markedly from those obtained in a conventional digestibility trial and the apparent recovery of Cr2O3 from feces samples showed a coefficient of variation of 27 per cent. Recovery of pellets from the alimentary tracts of the slaughtered sheep showed that the disintegration time of the pellets was correlated with the proportions of alfalfa (r = −0.83), wheat straw (r = 0.36), and oat grain (r = 0.80) in the rations. Indications were that some pellets were lost by passing into the abomasum where immediate disintegration occurred, or by regurgitation, although the latter had not been noticed in this experiment.