Influence of level and source (inorganic vs organic) of zinc supplementation on immune function in growing lambs

Droke, E. A.; Gengelbach, G. P.; Spears, J. W.

doi:1998.11.2.139

Article

Animal Reproduction and Physiology

Asian-Australasian Journal of Animal Sciences 1998;11(2): 139-144.
https://doi.org/10.5713/ajas.1998.139 Published online April 1, 1998.

Influence of level and source (inorganic vs organic) of zinc supplementation on immune function in growing lambs

E. A. Droke, G. P. Gengelbach, J. W. Spears

Abstract

Eighteen lambs were used to determine the effects of zinc (Zn) level and source on Zn status and immune function during both normal conditions and conditions of physiologic stress. Treatments consisted of a basal diet (27.6 mg of Zn/kg), and the basal diet supplemented with 25 mg of Zn/kg, added as either zinc oxide or zinc methionine. The basal diet was a corn-cottonseed hull-isolated soy protein-based diet (14% CP). Lambs were weighed and blood samples taken at 28-d intervals for determination of serum Zn and alkaline phosphatase activity. Weights and serum Zn were similar (p > 0.10) among treatments at all sampling days. To evaluate immune responses and Zn status during conditions of physiologic stress lambs were administered 100 I.U. of adrenocorticotrophin (ACTH) on d 112 and feed was with held for 48 h. Cortisol levels were elevated (p < .01) 5 h post ACTH injection, but had returned to initial levels after 48 h. Lymphocyte blastogenesis ([3H]-thymidine incorporation) on d 112 (prior to ACTH infection) and 114 was unaffected (p > .10) by dietary treatment. However, blastogenesis in response to pokeweed mitogen was greater (p < .0001), whereas the response to phytohemag-glutinin was reduced (p < .01) following ACTH administration and fasting. Antibody response to administration of porcine red blood cells was unaffected (p > .05) by dietary treatment. These results indicate that, given the Zn concentration of the basal diet, there was no enhancement of immune function by supplemental Zn, either before of after lambs were subjected to stress.

Keywords: Zinc; Zinc Methionine; Zinc Oxide; Immune Function; Lambs