Comparison of blood and milk non-specific immune parameters in heifers after calving in relation to udder health

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-β-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.heifers / periparturient period / blood milk / non-specific immunity

Assessment of subclinical mastitis diagnostic accuracy by differential cell count in individual cow milk

“…This statistical procedure allows to represent the evolution of the proportion of true positive cases (also called sensitivity) as a function of the proportion of false positives cases (corresponding to 1 minus specificity), and to evaluate a binary classifier test to diagnose a disease. In our case disease was defined as a milk sample with >200,000 cells/mL (Piccinini et al 2005;Zecconi et al 2018). Table 2 describes the parameters calculated to evaluate DSCC diagnostic test and the abbreviations used in the text.…”

“…However, the progressive decrease of mean SCC in dairy herds worldwide is further affecting in SCC accuracy as a subclinical mastitis marker. Currently, a level of 200,000 cells/mL is considered the threshold to identify subclinical mastitis (Piccinini et al 2005;Zecconi et al 2018), but udder inflammation was observed even below 100,000 cells/mL (Zecconi et al 2006;Merle et al 2007;Piccinini et al 2007;Baumert et al 2009;Schwarz et al 2011), and nearly half of contagious pathogens have a SCC below 100,000 cells/ml (Zecconi et al 2003;Zecconi 2010).…”

Somatic cell count as a decision tool for selective dry cow therapy in Italy

“…SCC was also used to define udder health status. A value of SCC >200,000 cells/mL was used to define subclinical mastitis (Piccinini et al 2005), and by Italian Breeder Association nationwide to define subclinical mastitis in MTR.…”

Characterization of Bioactive Recombinant Human Lysozyme Expressed in Milk of Cloned Transgenic Cattle

“…The content of lysozyme in human milk ranges from 3 to 3000 µg/ml, and the typical concentration is about 200–400 µg/ml [16], [17]; however, only trace amounts are found in the breast milk of ruminants. Bovine milk typically contains only 0.05–0.22 µg/ml of lysozyme [16], [18]. In addition, its activity is 1/10 of lysozyme from human breast milk [16], [19].…”