Anti-trypsin activity in bovine colostrum: influence of animal-related factors, correlation with immunoglobulin G content, and changes during the first 5 days postpartum.

A characteristic of bovine colostrum is its anti-trypsin activity, which is hypothesized to protect bioactive compounds from proteolytic digestion, thereby facilitating their effective absorption. The present study aimed to investigate the influence of parity and breed on anti-trypsin activity in colostrum. Furthermore, the correlation between anti-trypsin activity and IgG content was assessed, along with the progression of anti-trypsin activity over the first 5 days postpartum. Anti-trypsin activity was measured in colostrum samples of 104 cows of 9 different breeds (dairy breed: German Holstein Friesian, n = 68; beef breeds: Aberdeen Angus, Charolais, Limousin, Galloway Simmental, Pinzgauer, Rotes Höhenvieh, Tiroler Grauvieh, n = 36). Colostrum samples were obtained less than 30 min after calving. The interaction between parity and breed was observed to influence anti-trypsin activity (P < 0.01). While primiparous German Holstein Friesian cows showed lower anti-trypsin activity compared to multiparous German Holstein Friesian, the opposite was true for colostrum samples of beef breeds. A weak positive correlation was found between anti-trypsin activity and IgG content in the 104 colostrum samples (rs = 0.23; P = 0.02). When the analysis was limited to samples with an IgG concentration of less than 50 g/L, a stronger correlation was observed (rs = 0.47; P < 0.001). No significant correlation was identified if only colostrum samples with an IgG concentration of ≥ 50 g/L were considered (rs = -0.003; P = 0.99). In 13 cows anti-trypsin activity was measured every 24 hours for 5 days postpartum regardless of breed or parity. This approach was chosen to test the robustness of the collected data when applied to a heterogeneous group. A marked decline in activity was recorded with increasing time since parturition. The activity between the different time points differed significantly (P < 0.01), except for the comparison between the measurements at 96 hours and those at 120 hours. These findings suggest that anti-trypsin activity in colostrum is influenced by the interaction of breed and parity. Anti-trypsin activity in colostrum decreases over time after birth. It seems to play an important role in bovine colostrum and transition milk of dairy and beef breeds.