| Show variation in butterfat tests nothing unusual the purebred pure bred dairyman as well as aa the commercial dairyman la Is interested in the tests for butterfat upon their cattle quite frequently these tests testa are made either upon the entire herd berd or upon individuals of the herds when these tests are compared with tests testa made previously a wide variation or fluctuation to Is noted there are times when these teats are made within a few days of each other and the variation Is surprising such fluctuations are often looked upon with suspicion while it should be realized that it Is quite natural for cows to vary in their tests for butterfat in fact when this point Is investigated it Is found that cows vary more in their tests than la Is commonly thought some years ago the michigan agricultural college published a special bulletin containing the work of anderaon upon the variations in the percentage of butterfat of single of cows upon test the seven day tests I 1 ot of cows handled under ordinary herd conditions were studied as well as similar records upon 2000 cows entered in the advanced registry of their respective breeds any conclusions reached by these investigations can be looked upon as being indicative of the real condition as the number of milk ings studied Is large enough to W warrant at this it may be expected that 30 per cent of the cows in a herd will vary in the percentage of butterfat butter tat in the milk produced at individual bilkings mil kings in a seven day period 1 per cent or less fifty per cent of the cows during a S like period will vary in their tests from 11 to 2 per cent 14 per cent will vary from 21 per cent to 3 per cent while the remaining 6 per cent will show a variation between bilkings mil kings of more than 3 per cent from these facts IV we e may conclude that I 1 it t Is not surprising to have a cow test 3 per cent at one milking and test 6 per cent at th the e next milking I 1 have actually seen a cow test 18 per cent in the morning or ing and test over 6 per cent in the afternoon in a herd of cows the average variation of the entire herd test would be per cent based upon these figures B W fairbanks colorado agricultural college |
