Crossbreeding effects in dairy cattle: the Illinois Experiment, 1949 to 1969

A crossbreeding project involving the Holstein and Guernsey breeds was conducted at the Illinois Agricultural Experiment Station from 1949 to 1969. All surviving male calves, 989 of the 1061 born, were sold within 2 or 3 d following birth. All surviving female calves born in the first four generations, 723 of the 788 born, were given an opportunity to conceive and produce milk. Those female calves born in the fifth generation (152 of 166 born) were placed in the University herd or sold to commercial dairy farmers. On a basis of a total of 2015 calves born, crossbreds had a 15.6% greater survival rate to sale or 1 wk of age than purebreds. Of the 778 surviving females born in the first four generations, 18.4% more crossbreds than purebreds calved once, and 24.5% more crossbreds than purebreds calved twice. For weight at 18, 24, 30, 36, and 48 mo of age, crossbreds exceeded purebreds by 5.0, 7.0, 4.4, 3.6, and 5.3%, respectively. Crossbreds were 9.3 d older at calving than purebreds and had an average calving interval than was 9.4 d longer than that for purebreds. For yield of milk, fat, protein, and SNF, crossbreds exceeded purebreds by 8.0, 8.5, 7.5, and 3.0%, respectively. The measures of survival, growth, milk yield, and reproduction were approximately combined into an index of income produced per cow. On a basis of income per cow per lactation, crossbreds exceeded purebreds by 14.9%. On a basis of income produced per cow per year, crossbreds exceeded purebreds by 11.4%.