Journal of Animal Science, Vol 68, Issue 1 206-213, Copyright © 1990 by American Society of Animal Science

JOURNAL ARTICLE

Effects of exogenous somatotropin on the concentration of minerals in the tissues of growing ram lambs

R. J. Boila, A. D. Kennedy and B. M. Belluk
University of Manitoba, Winnipeg, Canada.

Ten Suffolk ram lambs (mean BW 14.4 +/- 1.0 kg, 9 wk of age) were used to evaluate the effects of somatotropin (ST) on the concentration of minerals in tissues. Lambs were treated with daily injections of sterile saline (SAL; n = 5) or with bovine pituitary-extracted ST (.1 mg.kg BW-1.d-1; n = 5) for 13 wk. At slaughter at 22 wk of age, the liver, heart, kidneys, brain, spleen, lungs and testes were removed. Tissues were lyophilized, ground and analyzed for minerals. Daily treatment with ST had no influence on Ca, Na, K or the ratio of Na to K in tissues. Although P was lower (P less than .10) in the liver of ST lambs, the concentration of P remained within a normal range for sheep. The concentrations of both Mg (P less than .10) and Fe (P less than .05) were lower in the spleen of ST lambs. Splenic hypertrophy appeared to occur (P = .13) in ST lambs; the total splenic pool of Mg and of Fe did not differ (P greater than .10) between SAL and ST lambs. The concentration of several other minerals were lower in tissues of ST lambs: Cu in kidneys (P less than .10) and liver (P = .12); Zn (P less than .05) in liver, kidneys and lungs; and Mn in liver (P less than .05). By causing a reduction in the concentration of minerals in tissues, ST may increase the possibility of a metabolic insufficiency of a mineral. Exogenous treatment of animals with ST may modify the metabolic requirements for minerals and thereby increase dietary requirements.