The effect of long-acting injectable selenium formulations on blood and liver selenium concentrations and liveweights of red deer (Cervus elaphus)

Aim: To evaluate the efficacy of a new long acting injectable selenium (Se) formulation to increase the Se status and prevent Se deficiency in red dee r. Methods: Groups of weaned red deer (four stags and six hinds/group) grazing pastures containing < 30 mg Se/kg DM were injected subcutaneously with eit her 0.5, 1.0 or 2.0 mg Se/kg as a new formulation of BaSeO4 (Deposel Multid ose), 1.0mgSe/kg of a current formulation (Deposel), or not treated. Blood Se concentrations and liveweight were measured nine times at intervals over 377 and 270 days, respectively. Results: Both formulations of Se elevated blood Se concentrations from 105 nmol/l pre-injection for at least 377 days with peak levels of 1894, 1395 a nd 818 nmol/l for high, medium and low doses of Deposel Multidose, respecti vely, at 73-141 days, and 1508 nmol/l at 73-141 days for the medium dose of Deposel, which persisted at similar levels for the duration of the study. Deposel Multidose produced fewer and less severe subcutaneous tissue reacti ons than Deposel. Pastures contained 10 to 30 mg Se/kg DM. There was no sig nificant difference in growth rate between treated and control deer. There was a significant (p <0. 01) linear relationship (y = 1.25x + 71.6, R-2=0.8 6) between blood (x) and liver (y) Se concentrations in the range of 120 - 2100 nmol/l for blood concentrations, and 200 - 3000 nmol/kg for liver conc entrations. Conclusion: Injections of BaSeO4 in both formulations studied were effectiv e in increasing the Se status of deer but the new formulation produced fewe r and less-severe tissue reactions. Young growing red deer appear less sens itive to Se deficiency as measured by weight gain, than sheep and cattle, s uggesting that reference ranges for those species are not appropriate for d eer. There was a linear correlation between blood and liver selenium concen trations.