Evaluation of colostrum quality and passive immunity transfer in donkeys of the Brazilian Nordestino ecotype via different methods

This study aimed to assess the quality of the colostrum and passive immunity transfer in donkeys of the Nordestino ecotype using different methodologies, as well as to correlate the most precise methods with the most accessible ones. Fourteen female Nordestino donkeys between 3 and 7 years old with a mean live weight of 185 ± 30 kg and their newborns were studied. The donkeys and their foals were subjected to colostrum and blood collection, respectively, at four experimental times, namely 0, 6, 12, and 24 h after delivery. The methods used to evaluate the colostrum and blood serum included radial immunodiffusion (gold standard), refractometry, the biuret test, and bromatology. The results were subjected to analyses of variance, regression, and correlation. The colostrum of the donkeys was of great quality immediately after delivery, with a mean immunoglobulin G (IgG) concentration of 8.71 g/dL. The colostrum samples showed a strong correlation between the results of the radial immunodiffusion test and the Brix refractometry analyses. Newborns of the Nordestino ecotype were found to be born agammaglobulinemic, with a progressive increase in IgG concentration after colostrum intake; a maximum value of 3.07 g/dL IgG was recorded 17.9 h after delivery. The blood serum analysis of the newborns also revealed a good correlation between the results of the radial immunodiffusion test and total proteins as measured by refractometry. In conclusion, the colostrum of female Nordestino ecotype donkeys is of great quality, ensuring the effective transfer of immunoglobulins to their newborns.