Comparison of blood and milk non-specific immune parameters in heifers after calving in relation to udder healthRenata Piccinini, Enrica Binda, Michela Belotti, Giuseppe Casirani and Alfonso Zecconi
Università degli Studi di Milano, Dipartimento di Patologia Animale, Igiene e Sanità Pubblica Veterinaria, Sezione di Malattie Infettive, via Celoria 10, 20133 Milano, Italy
(Received 4 October 2004; accepted 22 February 2005)
Abstract - A practical protocol to study udder immune status in field conditions was planned with the aim to assess different non-specific immune parameters in milk samples from dairy heifers during the periparturient period. Five herds located in northern Italy were selected and overall 39 heifers were enrolled in the trial. Milk samples were taken at 7, 14, 21, 28, 45, 60, and 75 days after calving. The parameters assessed were N-acetyl--glucosaminidase (NAGase), lysozyme, respiratory burst (RB), somatic cell counts (SCC) and serum protein profile. SCC and NAGase were higher in the first sampling after calving, while lysozyme showed large variations during the observation period without a definite trend. The levels of RB observed in the first two weeks after calving, even if lower, were not statistically different from the values observed in samples taken over the following weeks. This study confirmed that the levels of immune components in milk are different from what is observed at blood level in the same cow. A significant decrease in RB in milk polymorphonuclear leukocytes (PMN) post-calving was not observed; milk PMN from healthy cows showed low RB levels, while the values from infected quarters were significantly higher. Significant differences between healthy and infected animals were also observed for milk NAG, lactoglobulin and albumin. These data suggest that udder immune response could be influenced both by the cow immune status and by external factors such as pathogens and management. Therefore, the reduction in immune defences, particularly in heifers, is not unavoidable and methods to boost PMN activity should be explored.
Key words: heifers / periparturient period / blood milk / non-specific immunity
Corresponding author: Alfonso Zecconi firstname.lastname@example.org
© INRA, EDP Sciences 2005