Experiments with iodinated casein on farms in England and Wales

Abstract

1. A field experiment in which ninety-seven farms co-operated has been carried out to find whether giving cows a daily dose of 20 g. of iodinated casein, incorporated with an additional allowance of concentrated food, could be used to increase milk yields for short periods on commercial farms. The results have been analysed statistically, and the causes of variation in the response to iodinated casein have been investigated. The farms supplied 1164 cows, and 1008 cows were finally included in the analysis. Not all of the seventy-eight pairs which were deleted were discarded, and some could legitimately be used in certain parts of the analysis.2. 4% of the cows refused the iodinated casein cube. The refusal rate was higher in the Channel Island cattle which are known to be fastidious feeders