A release device such as a bolus having an outer shell containing magnesium and an inner core containing zinc for veterinary use

摘要

A release device comprising an inner, core portion and an outer portion comprising a thin shell portion, which outer shell portion at least partially covers the inner, core portion, each of the said inner and outer portions comprising respective metal alloy compositions. The metal alloy composition of the inner portion comprises at least 35 wt.% of zinc, by weight of the total metal alloy composition of the inner portion, and the metal alloy composition of the outer portion comprises at least 60 wt.% of magnesium, by weight of the total metal alloy composition of the outer portion. Thus, a zinc alloy core is at least partially covered by a thin corrodible magnesium alloy shell.