We read with great interest last month’s article, “Crossbred bull fix’” by Miranda Reiman of Certified Angus Beef (CAB). The hypothesis of the article was that using composite (F1) bulls had a number of disadvantages compared to purebred bulls and straightbreeding. Her reasoning was that composites (F1): had unpredictable calf crops; less reliable EPDs, which included lack of genomics; and could not be purchased in bulk. I would like to address these points.
Crossbreeding beef cattle offers two primary advantages relative to the use of only one breed: 1) crossbred animals exhibit heterosis (hybrid vigor), and 2) crossbred animals combine the strengths of the various breeds used to form the cross. The goal of a well-designed, systematic crossbreeding program is to simultaneously optimize these advantages of heterosis and breed complementarity.
Heterosis or hybrid vigor refers to the superiority in performance of the crossbred animal compared to the average of the straightbred parents. Heterosis may be calculated using the formula:
% Heterosis = [(crossbred average - straightbred average) ÷ straightbred average] x 100