Evaluation of passive transfer in goat kids with Brix refractometer and comparison with other semiquantitative tests

The aim of this study was to evaluate the passive transfer (PT) status of goat kids by Brix refractometry and compare the results with other semiquantitative tests (total protein - TP, glutaraldehyde coagulation test - GCT, and gamma-glutamyltransferase - GGT) and immunoglobulin G (IgG). The study was conducted on 75 goat kids born from 47 Saanen goats. The blood samples were collected from the kids on day 0 (presuckling) and on the 1st, 2nd, and 3rd days after birth. The Brix% and TP concentrations were measured with refractometers, and GGT activity was measured using a dry chemistry system. The duration of the GCT was determined in the first 60 min. The serum IgG concentration was measured by goat IgG ELISA kit. On the 1st and 2nd days, serum Brix% in the kids was measured as 9.33 ± 0.17% and 9.17 ± 0.14%, respectively. In the 1st and 2nd day serum samples of the kids, IgG was 817.76 ± 37.34 mg/dL and 1173.29 ± 47.81 mg/dL, respectively, and GGT was 1298.07 ± 133.29 IU/L and 692.26 ± 79.86 IU/L, respectively. The Brix refractometer was found to be more sensitive for detection of PT status in kids on the first and second days after birth, such as TP and GCT, whereas GGT, as an early indicator of PT, was useful only on the first day after birth. We conclude that the Brix refractometer could be used to determine the PT status in goat kids and Brix measurements lower than 8.6%, 9.2%, and 9.3% indicate failure of PT in 1-, 2-, and 3-day-old kids, respectively.