“A weak bull is the most expensive investment a cattle farmer could make. Such a bull could prove to be an expensive mistake because his daughters will remain in the herd for 10 years or longer, well after the farmer has stopped using the bull” - Arthur de Villiers (Jnr), Bonsmara newsletter December 2009.
Crossbreeding is standard practice in cattle farming, and it is done all over the world. However, research has shown that in most cases the crossbreeding program lacks planning and is therefore not very efficient.
Crossbred bulls are the offspring of a crossbred mother with a purebred bull, or a crossbred mother with a crossbred bull. Purebred breeds were developed firstly through natural selection brought about by the environment, and secondly because of selection by humans to fulfil specific needs for milk, meat, adaptability etc.
Pure breeds can be developed through crossbreeding after many generations of purposeful breeding and selection for certain breed- and production characteristics; (this has been done in the case of the Bonsmara breed.) Farmers use crossbred bulls because they believe that crossbred bulls increase production as a result of hybrid vigour (=the phenomenon that the calf is better than the average of Sire and Dam); and because crossbred bulls are generally cheaper than purebred animals.
The question is whether a crossbred bull will indeed improve production?
The bull-component in a breeding herd is only about 3-4%, but the genetic make-up of every calf is, obviously, for 50% determined by the bull. Altogether 87% of the genetic make-up of a calf is determined by the bulls that were used in the previous 3 generations, as females from the various bulls are used as replacement heifers. This means that up to 90% of progress in a herd is brought about by the selection of the bull.
In separate trials the average weaning weight at 205 days of Angus, Brahman and Charolais showed the following results:
Purebred calves (within the same breed, i.e., Angus X Angus): 186 Kg
Calves out of purebred bull X purebred cow of different breeds (i.e., Angus X Charolais=F1): 200 Kg
Calves out of F1 cows X purebred bulls: 208 Kg
Calves out of F1 cows X crossbred bulls: 199 Kg
From these tests the use of crossbred bulls did not result in a higher weaning weight, and that crossbred cows weaned 13% heavier calves.