Dependence of residual milk in the udder of the cow upon total yield; its bearing upon supposed inhibition of secretion.

Abstract

In order to examine the influence of variations in yield upon the amount of milk remaining in the udder after milking, residual milk was determined in each of 10 cows following several normal milkings. By varying the interval since the last milking, a range of amounts of milk in the udder at the start of milking was obtained. The data reveal significant correlation between residual milk and total milk, both within and between cows. The regression coefficients are 0.1573 ± 0.0341 within cows and 0.3216 ± 0.0728 between cows. When intervals between successive milkings are unequal it is, therefore, incorrect to assume that yield at any milking represents the amount of milk secreted during the preceding interval. It is pointed out that the interpretation of data purporting to measure the inhibition of secretion caused by long intervals between milkings may consequently have to be greatly modified.