By Joe C. Paschal, Professor Emeritus and Livestock Specialist
If Brahman breeders were asked about the greatest benefit in crossbreeding with Brahman cattle, most would respond “hybrid vigor” in the cross. Certainly, that seems to be the most often given response as the major benefit in crossing two or more breeds, especially with Brahman or Brahman influence breeds. Hybrid vigor is usually measured on a given trait like weaning weight, but it should be measured as the culmination of all growth and efficiencies of the crossbred individual. Hybrid vigor is the improvement in performance of the first cross compared to the average of the purebred parents. To be measured accurately, both parental breeds need to be sires and dams. In Bos indicus, there is be an impact on the level of hybrid vigor based on parental breeds. There are also instances when hybrid vigor does not improve performance in the cross, especially when the parental breeds excel in traits like milk production or marbling.
Hybrid vigor impacts traits most that are low in heritability and often more difficult to collect records for use in selection. Fertility is one of those. Using IVF and other assisted reproductive technologies makes it even more difficult to collect those records as we change the physiology of the female with hormones. In general, hybrid vigor is greatest for traits measured early in life and for those most affected by the environment. It is lower for growth and carcass traits but surprising high for longevity. Hybrid vigor can be classified as individual (or direct) and maternal, depending on its impact on the crossbred individual or the its crossbred dam. Individual hybrid vigor is exhibited by the crossbred animal for traits such as fertility, maternal ability, growth, and carcass traits.
When the crossbred is out of a crossbred dam, then maternal hybrid vigor has an enormous impact from initial fertilization through weaning and even yearling weight gain and efficiency. Maternal hybrid vigor acts on every pregnancy and every progeny and can have a lifetime of accumulated effects on them. We all recognize that and at Brahmans have excelled at improving the performance and efficiency of the Southern US cowherd for over 75 years thanks to the high levels of hybrid vigor in Brahman crosses, especially when the F1 Brahman cow is the dam.
The data in Table 1 provides unpublished data from Florida showing the value of crossbreeding in tropical and subtropical environments – more and heavier calves weaned. Hybrid vigor has one drawback. It cannot be transmitted intact from one generation to the next. The F1 exhibits the maximum (100%) hybrid vigor (direct and maternal – if a female) but unless crossed with a third unrelated breed, hybrid vigor is halved. Hybrid vigor will not “cover up” bad genetics in either breed. Many years ago, purebred breeders were encouraged to breed Brahman bulls to their lower performing non-Brahman cows to produce F1s that often were the foundation of the grading up of those breeds. It certainly sold Brahman bulls and improved the genetics, productivity, and efficiency of the commercial cow herds that purchased those F1s but the breed would have been better off breeding them to the higher performing females.
So, what is the “real benefit” of crossbreeding? Breed effects – the characteristics of the breeds that are selected to create the cross, in this case Brahman. Not the ears or the hump but the genetic impact of the breed. It is the additive genetics or breeding value expressed in the EPD and enhanced with the genomic information that ABBA now includes. That genetic value is transmitted intact from one generation to the next intact.
The breeding value includes all the traits preferred in the Brahman breed (and includes some not so preferred) but the more data that is on hand the better the results. Better to use to keep the good ones and to cull the bad ones. Genomics is just a part of the equation, whole herd reporting of accurate records in a timely manner will improve response to selection significantly. More importantly, that level of performance is not dependent upon crossing, it remains and increases generation after generation.
It benefits both (and most importantly) the purebred Brahman breeder who has the ability to breed cattle that fit their production goals efficiently and the commercial producer who likes to purchase high quality F1 Brahman females based on genetics rather than phenotype. Most other breeds have been using genomics to improve their EPD and many already have had Whole Herd Reporting for many years so when Brahmans are crossed with these breeds, they have the opportunity to express their true genetic potential as breeding females of Brahman descent, not simply F1 females. The distinction is similar to whether or not you off er Golden Certified Brahman F1 Females or simply Certified Brahman F1 Females. The rains will come, restocking will begin, be ready to offer high quality Brahman bulls and females and exceptional Brahman F1 females with documented Brahman genetics!
