To go into a lengthy discussion on the genetics of ‘hybrid vigour’ would take pages. However, to simplify, the following breeds were evolved and bred for that very reason, to combine the traits of the Bos indicus (adapted to hot conditions), such as the Afrikaner and Brahman, with those of the Bos taurus (for higher fertility, meat traits, etc.) of European origin, such as the Hereford and Shorthorn.
The Bonsmara, Brangus, Hugenoot and others took years of painstaking selection and recordings of different bulls and cows used in the breeding of these bulls, which would breed ‘pure’. Again the methods in detailed analysis would take pages, but the effect of hybrid vigour is there to be seen!
Added to this, many of the top breeders of the above mentioned breeds follow a type of ‘line’ from previous results of breeders that had what we call the ‘X-factor’. Other breeders may follow another ‘line’ and, as commercial breeders have all the data of these ‘lines’ and they buy bulls from different lines, it could actually result in ‘hybrid vigour’ within the same breed! So why cross-breed?
The pure breeds available are of such a high standard, all with their breeders’ societies in place to ensure only the best bulls are available to commercial breeders, and which, in turn, are available to the feedlots. The term ‘simplifying management’ referred to in the story is also debatable.