RESUMEN
BACKGROUND: Recent data indicate that almost 60% of colostrum samples do not have enough antibodies to provide adequate protection for the calf. Thus, the aim of this study was to determine the influence of the level of production of cows on the content of immunostimulating components of protein fraction of colostrum. The observations were conducted on two farms that keep dairy cows. One of the farms was selected to represent a typical performance level for the mass population of dairy cows in Poland, about 5500 kg of milk per cow per year (LI) and the second one was characterized by a higher level of production, about 8000 kg (HI). RESULTS: Based on the data obtained, 100% of the samples collected from LI had an immunoglobulin G (IgG) content >50 gL-1 , in the first collection. In the case of HI, 63% of the samples had an IgG content >50 gL-1 , with a distribution in the range of 10.7 to 72.7 gL-1 . The colostrum of LI cows was characterized by a higher content of lactoferrin, lysozyme, α-lactalbumin, and ß-lactoglobulin compared to the milk of HI cows. CONCLUSIONS: The immunostimulating components of colostrum declined rapidly in subsequent milkings or with the increased productivity of the cows. The concentration of IgG was negatively correlated with the performance level of cows, which means that high-producing cows had colostrum with a low concentration of IgG. © 2018 Society of Chemical Industry.