Use of digital Brix refractometer to estimate total protein levels in Santa Ines ewes' colostrum and lambs' blood serum

The current study aimed to estimate the total protein levels in Santa Ines ewes' colostrum and in lambs' blood serum by digital refractometry to determine the transfer of passive immunity to lambs under farm conditions. Nineteen ewes and 29 lambs were used. Ewes' colostrum and lamb blood serum samples were collected at 6, 12, 24 and 48 h postpartum to measure the total serum protein by digital Brix refractometer. The confirmation of lambs immunological status was performed by the zinc sulphate turbidity (ZST) test on blood samples collected from lambs 12 and 24 h postpartum. Total protein concentration in colostrum significantly decreased between 6 and 12 h postpartum (p < 0.05). This reduction was accompanied by a significant increase in lambs' total serum protein concentration (p < 0.05), indicating the occurrence of passive immunity transfer in the first 12 h of life of these newborns. These findings were confirmed by the ZST test, which showed a positive reaction in 82.75 % and 75.86 % of the samples after 12 and 24 h, respectively. In conclusion, digital Brix refractometer proved to be a valuable tool for estimating total protein concentration in Santa Ines ewes' colostrum and in lamb blood serum under farm conditions.