The evaluation of non-specific immune status of heifers in field conditions during the periparturient period

Abstract

-During the periparturient period, some impairment of immune defences were observed. Reference values for the different non-specific immune parameters in cows are not generally available, thus limiting the application of these parameters in dairy practice. This paper reports the data on the measurements of different parameters in the blood, and explores the possible influence of the herd on the non-specific immune status of the cow. Five herds located in Northern Italy were selected and overall 39 heifers were enrolled in the trial. Blood samples were taken 14 and 7 days before the expected date of calving, then at 7, 14, 21, 28, 45, 60, and 75 days after calving. The parameters assessed were N-acetyl-β-glucosaminidase (NAGase), lysozyme, nitric oxide, superoxide dismutase, haptoglobin, respiratory burst, and serum protein profile. After calving, a significant decrease of respiratory burst and nitric oxide concentration were observed in comparison with the pre-calving values but not with the post-calving samplings. Total proteins, β-and γ-globulins showed a progressive and significant increase in concentration after calving, in comparison with pre-calving values. The results of the study confirmed that a decrease of immune functions can be observed in commercial dairy herds in the first four weeks after calving. The amplitude of this phenomenon is not common to all animals and all herds, suggesting the possibility to reduce the impairment by improved management and genetic selection. heifers / periparturient period / blood / non-specific immunity

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

“…Overall, these data confirmed the results of a previous study on blood parameters [23], suggesting that the level of non-specific immune parameters could be influenced, in addition to heath status, by management and genetics. These latter aspects need more targeted studies to confirm this hypothesis and to define the role of bacteria.…”

“…We did not observe a significant decrease in RB in milk PMN post-calving, as happens in blood PMN [23]. However, the RB values from infected quarters at 7 d were lower, even if not significantly, than the values observed during the last part of the follow-up period.…”

“…The levels of RB in milk PMN 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 result was not in agreement with the results observed in blood, where a significant decrease was observed [23], but indirectly confirmed what was observed in experimental studies [15].…”

“…However, the low levels observed in blood globulins during the first month of lactation support the presence of an impairment of immune defences as described [13,23].…”

“…A detailed description of the results on blood parameters has already been published in this journal [23]. This paper reports the results concerning milk immune parameters, and compares the pattern of the non-specific immune parameters measured contemporarily in blood and milk in relation to the health status of the mammary gland.…”