[The usefulness of the refractometer in the assessment of colostrum and various factors affecting serum gamma globulin levels in newborn calves].

The effects of a number of factors on the concentration of gamma globulins in the serum of newborn calves were studied in 181 calves from six different dairy farms as was also the use of the refractometer test in controlling the ingestion of colostrum. The refractometer test was found to be reliable in controlling the concentration of gamma globulins in the serum of calves up to the sixth day of life. The factors 'time the first colostrum was ingested', 'amount of first colostrum ingested' and the 'concentration of gamma globulins in the colostrum' were found to account for 23.5 per cent of the variations in serum gamma globulin concentration; this became 42.4 per cent when the 'system of administration' and the 'farm-bound factors' were also taken into account. The first colostrum is best ingested when it is offered in a pail or bottle provided with a nipple. Calves of heifers were found to show a lower concentration of gamma globulins in the serum than did calves of older cows.