THE INFLUENCE OF SHOCK-FREEZING ON IMMUNOGLOBULIN G PRESERVATION IN COLOSTRUM AND THE TRANSFER OF PASSIVE IMMUNITY TO NEWBORN CALVES

Abstract

This article presents a comparative assessment of conventional and shock-freezing technologies for colostrum, focusing on the preservation of immunoglobulin G (IgG) and indicators of passive immunity transfer in calves. In a controlled experiment, 20 newborn Holstein heifer calves were allocated into two groups (n = 10) and fed colostrum frozen using different technologies. Colostrum quality was assessed by refractometry, and IgG concentration in colostrum as well as serum IgG in calves were determined by radial immunodiffusion; blood samples were collected 48 hours after birth. The results showed that, with initially identical colostrum quality (23.50 ± 0.10 %Brix), shock-freezing resulted in a higher IgG concentration after thawing compared with conventional freezing (57.80 ± 1.45 g/L vs 52.35 ± 3.31 g/L, p <0.01), with a trend toward higher %Brix values (23.35 ± 0.28 vs 21.07 ± 0.45, p = 0.12). Shock-frozen colostrum also had higher total solids (28.96 ± 0.63% vs 27.16 ± 1.55%, p = 0.04) and protein (22.68 ± 0.47% vs 20.19 ± 0.89%, p <0.01). However, the key endpoint—serum IgG concentration in calves at 48 hours—did not differ significantly between groups (22.29 ± 4.24 vs 21.12 ± 3.85 mg/mL, p = 0.18), and passive transfer was successful in all cases (IgG > 10 mg/mL). By two months of age, growth performance and blood biochemistry were comparable between groups (p >0.05). Thus, when high-quality colostrum is used, both freezing technologies ensure adequate passive immunization, whereas shock-freezing may be considered a technological improvement for colostrum banks due to better preservation of IgG and the protein fraction after thawing.