Studies of Magnitudes in Star Clusters , X . Spec - Tral Type B and the Local Stellar System by Harlow Shapley

A word should be said as to the theoretically important question whether the reciprocal crosses differ in their results. No consistent difference is observable. Eight of the 31 F, cows (indicated by an asterisk in table 1) had Guernsey dams while 23 had Holstein dams. In their first lactation period the cows with Guernsey dams gave less milk but more butter-fat, average 6953 pounds of milk, 287 pounds of butter-fat. But in the second lactation period, three cows with Guernsey dams give a little more than the average amount of milk with exactly the average amount of butter-fat. It seems unlikely, therefore, that any sex-linked factors are concerned in the case.