Valutazione della conta differenziale delle cellule del latte in relazione allo stato sanitario della mammella

In dairy herd management, somatic cell counting is largely used as an indicator of mastitis. Differential cell counts been indicated as a more accurate method for mastitis identification. Little is known, though, about the expected profile in healthy milk samples. This cross-sectional study explored the inflammatory profiles in milk from 2 dairy herds known to be affected by mammary gland infections from different Staphylococcus aureus strains, and 1 herd known to be free of contagious milk pathogens. Milk sampling was performed on 50 animals. Somatic cell counts and bacteriological examination were performed as described on NMC guidelines. Relative percents of lymphocytes (L), macrophages (M), polymorphonuclear cells (PMN); and their ratios were assessed through milk cytology. Results confirmed that herd A was free from contagious pathogens, herd B was positive for a coagulase negative strain of S. aureus, and herd C was positive for S. aureus. In all herds, healthy quarters as well as subclinically mastitic quarters were found. When cytology results were grouped by herd, the inflammatory profiles resulted markedly different. Our results suggest that milk immune response can vary from herd to herd. We do not know, though, if the differences are given to different genetic background, or from different stimulus from the different pathogen strains. Further studies must be done to determinate if a sole factor could be implicated, or if this differences are given to a combination of those factors.