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Published online by Cambridge University Press: 20 November 2017
Many references (review, Hemingway, 2000) indicate that giving supplementary dietary selenium (Se) and vitamin E during the dry period in amounts greater than accepted nutritional requirements can decrease the incidence, duration and severity of high somatic cell counts (SCC) and mastitis in dairy cows. Low dietary Se intakes and plasma Se concentrations are more frequent than those for vitamin E. As one example, Erskine et al. (1987) investigated two groups each of 16 herds each having either > 700 x 103 SCC /ml (High) or < 150 x 103 SCC /ml (Low). Mean contrasting plasma concentrations (μg /ml) were respectively 0.074 and 0.138 (P < 0.01) for Se with 4.2 and 4.8 (NS, adequate) for vitamin E. Supplementary dietary Se and vitamin E were given more frequently to the Low SCC herds. The present experiment investigated the effect of two multi-trace element/vitamin boluses (‘All-Trace’, Agrimin Ltd. DN20 0SP) which, inter alia, release 2 mg Se and 9 i.u. vitamin E /day giving a significant increase in glutathione peroxidase activity over an 8-month period (Allan et al., 1993).