Provision of zinc to sheep by means of an intraruminal pellet

Abstract

A group of young wethers consuming a zinc-deficient diet (3.8 pg Zn g-1) had a 10 g zinc pellet inserted in their rumens. The pellet maintained plasma and wool zinc concentrations and plasma alkaline phosphatase activities for 7, 8.5 and > 10 weeks respectively, at levels equal to those of another group on a similar diet supplemented with 16 pg Zn g-1. The amount of zinc in faeces indicated that the pellets initially released 15 mg Zn day-1 and that after 7 weeks, when only 3 mg Zn day-1 was being released, the effective life of the pellet was finished. The pellet offers a simple method for testing the existence of zinc-responsive conditions in the field and would be adequate to overcome short-term deficiency caused by seasonal conditions or pregnancy. A third group of wethers on the deficient diet alone, showed a decline in plasma zinc from 0.7 ¦g Zn ml-1 to 0.25 ¦g ml-1 in 3 weeks, and both plasma alkaline phosphatase activities and wool zinc concentrations were lower than in the other groups after 7 weeks.