Sustained release delivery system for ruminant animals

Ten in vivo trials were conducted to study the slow release delivery system. Trials 1, 2, 5, and 6 involved the use of one ruminally fistulated steer and were designed to study the effect of the following variables on the rate of release of slow release delivery system (SRDS), paper weight (Kg basis) within one paper type, paper weights among different paper types, and different covering types (coarse vs dense vs none) used to cover the exposed ends of SRDS(s). Twenty-four nonfistulated mature Angus, Herferd, and Angus-Herferd cows were used for trial 3 to investigate the effect of diet and animal variation on the rate of release of cromium oxide from SRDS. Fecal samples were collected every other day and analysed for cromium. Trial 4 involved the use of 24 nonfistulated heifers to study the release of Rumensin® from SRDS(s). Daily gain, hay consumption, and feed efficiency were recorded for each animal and compared with responses of control animals and animals receiving orally administered Rumensin®. Trials 7, 8, 9, and 10 were employed using six ruminally fistulated Jersey females. In trials 7 and 8, the effect of diet and animal variation among and within animals, on the rate of release of SRDS's (containing waterproof membranes) were studied. Trial 9 was conducted to evaluate consistency of release of Ciba-Geigy A-72662 (a systemic fly insecticide) from a SRDS. Fecal samples were collected from each animal on alternate days during the first and last two weeks of the trial and once a week per animal during other weeks. Trial 10 was employed to measure the release of Ciba-Geigy A-72662 from a modified SRDS design. Fecal samples were collected once a week per animal. Fecal samples from trials 9 and 10 will be analyzed for ovacidal properties.

Weight of paper (Kg basis) had a significant effect (P<.001) on rate of exposure of SRDS(s). There was a trend for thinner paper (13.6 Kg basis) to degrade at a faster rate than thicker paper (31.8 Kg basis). Moreover, there was a relatively large amount of variation in rate of exposure between different paper types and weights (Kg basis). Covering type also had a significant effect on rate of exposure of SRDS's (P<.01). The interaction of covering type and basis was highly significant (P<.001). Day also had a significant curvilinear effect on the rate of exposure of SRDS (P>.0002). Hence, the rate of paper membranes exposed per day decreased as the time SRDS(s) remained in the animal increased.

No cromium oxide was detected in the feces collected from animals in trial 3. However, Rumensin® was successfully released from SRDS(s). Daily gain for animals receiving Rumensin® via SRDS was similar to heifers fed Rumensin® in supplement (.87 Kg/day vs .86 Kg/day). Rumensin® treated groups (either by SRDS or by supplement) had increased gains within the range experienced by other workers. Rumensin® treated heifers were also more efficient than heifers who received no Rumensin® (4.88, 3.70, and 5.59 pound hay/pound gain).

Diet (fescue-legume vs fescue) had no effect on the rate of exposure of SRDS (P>.1). Additionally, there was no variation among and within animals on the rate of exposure of SRDS(s) (P>.1).