Serum responsiveness to recombinant bovine somatotropin in buffalo: a three-month lactation study using an acid-stripping ELISA for screening.

The misuse of recombinant bovine somatotropin (rbST) to increase milk yield involves buffalo not just cows. Screening methods to identify rbST-treated cattle have already been proposed. However, there have been no studies on prolonged periods with a high number of animals. In this study, we developed a new enzyme-linked immunosorbent assay (ELISA) to measure the serum responsiveness towards rbST, based on an acid-stripping procedure and relatively simple integral calculation dilution curves. We also applied the analysis to 640 serum and 96 milk samples collected from 16 buffalo treated with rbST and 16 controls, over a period of approximately three months. Its suitability as a screening method, in compliance with EU law, was also assessed. A bi-factorial approach was also evaluated, including the measurement of insulin-like growth factor 1 concentration in serum. Results showed that our ELISA could be used on its own for screening purposes, without the need to assess other biomarkers.