Effect of administration of vitamin E and selenium during the dry period on mammary health and milk cell counts in dairy ewes

The effect of parenteral administration of two subcutaneous injections of v itamin E and Se (5 mg and 0.1 mg/kg of body weight, respectively) during th e dry period on the mammary health and milk somatic cell counts of 25 dairy ewes was investigated. Supplementation reduced somatic cell counts (5.4 vs . 6.0 log(10)) during the subsequent lactation but had no effect on the inc idence of clinical mastitis (4% vs. 6%) and intramammary infections (9.0% v s. 11.3%). Furthermore, the administration of vitamin E and Se was associat ed with differences in differential cell counts of milk samples (macrophage s, 48.8% vs. 38.4%; polymorphonuclear neutrophils, 40.1% vs. 50.7%; and eos inophils, 0.7% vs. 1.4% for control ewes and ewes receiving supplements, re spectively). The administration of these supplements also increased erythro cyte glutathione peroxidase activity (139.5 vs. 86.3 U/ml of packed cell vo lume) and the percentage of blood neutrophils that reduced nitroblue tetraz olium after bacterial extract stimulation (48.6% vs. 38.7%). Parenteral adm inistration of vitamin E and Se to ewes during the dry period appeared to h ave influenced mammary gland status during the subsequent lactation and par ticularly total and differential milk cell counts.