Occurrence of aberrant secretion in bovine virgin mammary glands and effect on phagocytic activities of neutrophils

A clinical examination of 224 virgin mammary glands in 56 heifers revealed aberrant secretion (AS) in 7 cases. The occurrence of AS was confirmed by l ight and transmission electron microscopy techniques. A cytological examina tion showed that total somatic cell counts in standardized volume lavages o f mammary glands with aberrant secretion (AMG) were statistically significa ntly higher than in normal gland (NMG) lavages (2.713 +/- 1.514.10(6)/ml; 0 .985 +/- 0.882.10(6)/ml; P < 0.05). In differential cell counts, macrophage s. were dominant in lavages from both types of glands (NMG, AMG). AMG lavag es, however, contained significantly more neutrophilic granulocytes (NG) (P < 0.05) and significantly fewer macrophages (P < 0.05) than NMG lavages. A n examination of the phagocytic function of NG showed a statistically signi ficant difference in relative numbers of NG that were phagocytizing bacteri al cells (Staphylococcus aureus) (NMG 67.6%; AMG 34.7%; P < 0.05). Differen ces in phagocytic index values were not statistically significant (NMG 3.16 +/- 0.50; AMNG 2.74 +/- 0.27; P > 0.05). Aberrant secretion in virgin mamm ary glands of heifers therefore seems to be a factor that weakens the resis tance of mammary glands to bacterial infections.