Evaluation of controlled‐release devices for providing chromium sesquioxide and zinc in Huacaya alpacas at pasture

• Published in: Australian veterinary journal Vol. 96; no. 11; pp. 458 - 463
• Main Authors: Judson, GJ, McGregor, BA, Ellis, KJ, Howse, AM
• Format: Journal Article
• Language: English
• Published: Melbourne Wiley Publishing Asia Pty Ltd 01-11-2018; Wiley Subscription Services, Inc
• Subjects: Alkaline phosphatase; alpaca; Blood; Chromium; chromium sesquioxide; controlled‐release device; Dry matter; Excretion; Pasture; Sheep; Species; Zinc; Zinc oxide; Zinc oxides; controlled-release device; zinc; alpaca; sheep; chromium sesquioxide
• ISSN: 0005-0423; 1751-0813
• DOI: 10.1111/avj.12759

Objective
To assess the effectiveness of controlled‐release devices (CRDs) for providing zinc and for estimating faecal output in alpacas and sheep at pasture.
Methods
The study groups of 10 alpacas and 10 sheep at pasture were paired within species and allocated at random to receive by mouth either one CRD containing chromium sesquioxide designed to function for at least 21 days or two CRDs, one containing chromium sesquioxide and the other zinc oxide designed to release over a nominal 60‐day period. Faecal concentrations of chromium, zinc and ash, blood and plasma concentrations of zinc and plasma activity of alkaline phosphatase (ALP) were measured over a period of 117 days after treatment.
Results
The mean faecal chromium excretion profiles suggested that the CRDs performed in a similar manner in both species, releasing chromium for nearly 30 days in alpacas and for slightly more than 30 days in sheep. Using a common predetermined release rate of chromium from the CRDs, the daily faecal outputs of alpacas and sheep were estimated to be 0.54 kg dry matter and 0.33 kg dry matter, respectively. The CRD containing zinc oxide provided after 1 week an estimated daily release rate of 40 mg zinc with a lifetime of between 60 and 70 days in both species. The additional zinc did not elicit a response in blood zinc concentrations or in plasma ALP activity.
Conclusion
The CRDs were retained in the gastrointestinal tracts of the alpacas and sheep and both types functioned as expected. The CRD delivering chromium sesquioxide at a known release rate provided an estimate of faecal dry matter output over a period of almost 3 weeks and the CRD formulated to deliver supplementary zinc did so at the nominal release rate over a period of approximately 60 days in both species. These data indicated that the standard sheep CRD is applicable for use in alpacas.