Evaluation of Brix refractometry for the estimation of colostrum quality in jennies.

Abstract Donkey placenta does not allow the passage of immunoglobulins, thus foals are born hypo-gammaglobulinemic and an adequate intake of high-quality colostrum in the first 24 hours of life is crucial for the surviving. The study aims to assess the relation between colostrum IgG concentration evaluated by the single radial immunodiffusion (SRID) test and the Brix refractometer in donkeys in order to establish a cut-off value for high quality of colostrum based on Brix refractometry. Colostrum was collected at foaling, and at 6, 12, 24 hours after foaling from the left and the right half of 9 Amiata jennies. A total of 72 colostrum samples were analyzed. A Friedman test with a Dunn’s test for multiple comparison was used for assessing the differences between the left and right half at each sampling time. No differences were found between the left and right halves; the average value was used to analyze the effect of sampling time on the IgG concentrations and Brix values. The relationship between colostrum IgG concentrations (SRID test) vs Brix value and Brix value vs time were analyzed using two different mixed linear models. A strong statistically significant relation has been found between IgG concentrations and Brix value (R2=0.84). The relation between IgG concentrations and Brix refractometer showed a cut-off point of 17% Brix score for the identification of high-quality colostrum. Brix value (%) decreased continuously from 16.29 by 0.29 x hour. Jennies and donkey foals’ management may be greatly improved using this simple and cheap device.