Abstract:
Intra-ruminal controlled release devices (CRDs) are plastic winged capsules containing an active ingredient which is slowly extruded by a spring-loaded plunger. More recently the technology has been used to administer mineral markers (Parker, 1990), as well as n-alkanes (Dove et al. 1991) to ruminants in order to estimate faecal output.. The CRD delivery rate used in calculations is usually determined by the manufacturer on a batch subsample utilising plunger travel and matrix ingredient concentration following a period suspended in the rumen of test steers. If rumen-fistulated animals are not available then plunger displacement and a delivery rate estimate can only be calculated following slaughter and CRD recovery.
