Genotype, Phenotype, DNA, and Progeny Testing
We at Underwood Farms continue to seek what knowledge we can regarding cattle breeding. Most recently, we have been reading old genetics texts such as Animal Breeding Plans by Lush and Animal Breeding by Hagedoorn.
We now have sufficient knowledge to understand that most Hereford breeders are not sufficiently knowledgeable of breeding to legitimately contribute to the advancement of the breed. If fact, we note that breeders overall have contributed to fashions based upon faulty theories that have set back the breed by decades at least twice in the 20th century.
First, there was the pursuit of the “comprest type” of cattle. Essentially, breeders selected for small, square cattle. Reading Sanders book on Hereford History, published in 1914, we can understand the thought. Breeders were looking for prime beef that would finish in the shortest amount of time. Smaller, early maturing animals produced great beef faster than larger animals. Over a 20-year period from 1878-1898, prize-winning steers declined from average weights of more than 3,000 pounds to averages of approximately 2,000 pounds. Over the next 40 years, prize winners declined almost another 1,000 pounds. In the days of the early fat cattle shows in the late 1870’s, one of the more coveted prizes was for the heaviest steer.
Just as pursuit of size alone in the mid-1800’s was in error, pursuit of a lack of size in the 1920’s-1940’s was also likely in error. By the late 1960’s the focus was once again on size, almost regardless of other characteristics. By the late 1980’s growth had switched from size to growth, although the two factors are highly correlated.
Today, the focus is in on growth and carcass quality. Today’s trend leaders are using ultrasound for marbling and muscling and using DNA analysis to find animals with markers for tenderness, marbling, and efficiency.
We at Underwood Farms do not disparage science, and we use the tools at our disposal to improve our herd. We ultrasound our cattle, and we recently began collecting hair samples of our cattle for DNA analysis.
It does occur to us, however, that tenderness and marbling are likely correlated to scores of markers, and it could be possible to find a tender animal and locate a homozygous marker in the animal that would in turn be correlated to tenderness. Perhaps a few markers would have to be studied before one was found, but such backwards-looking science could produce markers that provide true correlation. The primary beneficiary of such a correlation would be the owner of the animal, with the DNA test company also benefiting. Coincidentally, we have heard that the only known bull with all tenderness and marbling markers is owned by one of the owners of a DNA testing company.
Therefore, in addition to all testing that we can perform, we also slaughter and eat meat. Taste-testing still plays a large role in our breeding operation, and it likely always will.
Jim Lents and other breeders that are students of genetics have taken heed of the warning that cattle breeders place excessive attention on phenotype and too little attention on genotype. To paraphrase Hagedoorn, plant breeders years ago began looking at the results of the crop rather than individual plants. Breeding decisions based upon the merit of the crop rather than individuals was most important. Cattle breeders focus on individuals, and breed progress is not achieved. Arguably, the breed regresses.
Further, cattle breeders focus on the best individuals, whereas at least equal focus should be on the worst individuals. Still be selecting individuals and not considering consistency of progeny, phenotype is overweighted. Further, because of the positive influence of many heterozygous genes, breeders inadvertently select for heterozygous cattle. At some point, cattle become as heterozygous as possible, variability is maximized, and consistency is lost.
We at Underwood Farms have the most varied herd of Hereford cattle among all breeders of which we are aware. We have old family lines from 50+ years ago, miniatures, today’s favorites, favorites from the 1970’s, and many others. According to our query of the AHA database, we have the broadest range of Hereford EPD’s in the nation. Our herd has such variance because we are still in the process of accumulating and refining the seed stock which will become the foundation of the Underwood Farms herd. Some pieces of our breeding plan are likely in place, but we learn daily, and all of the pieces are not yet in place.
While the individual Hereford cattle we own vary tremendously, the cattle as a whole are likely more homozygous than most other herds. Some of our cattle have been linebred for more than 50 years by single breeders. We have linebred our cattle since our herd began in 2000.
Only time will tell if we are able to assimilate the right set of genetics from the enormous variety offered in Herefords and contribute to the breed.
August 19, 2007
