Wednesday, June 18, 2014

U.S. Meat Animal Research Center (USMARC) Symposium: 50 Years of Service to the Beef Industry

BIF put together a well respected host of speakers to review the last 50 years of research at the US Meat Animal Research Center.

Larry Cundiff
The Germplasm Evaluation Program was initiated in 1969 after several planning meetings from 1967 to 1969. Because of the quarantine facilities in Canada, the Germplasm Evaluation Program worked very closely with Ag Canada to obtain semen on imported continental bulls. G.E. Dickerson designed the programs to address questions about breed differences and to maintain heterosis among breeds. Over 8 cycles of the program, 37 breeds have been evaluated. In a 7 year period the MARC had amassed a large cow herd as they were trying to evaluate cows from each breed late into their productive years. One of the first lessons was the problems of breeding imported bulls to 2 and 3 year old cows, as calving problems frequently occurred. No one breed was able to excel at all economically important traits in the early years of the Germplasm Evaluation Program. Logically, crossbred animals performed well for multiple traits. The program strove to group breeds into biological types. In the early 1980's the center began to estimate adjustment factors to put EPDs from multiple breeds all on the same scale. Due to the changes in breed averages, the biological types of many of the breeds have changed since the first Germplasm Evaluations. Cundiff believes that one of the great successes of the program was getting information to the cattlemen in a timely fashion. The Germplasm Evaluation Program and the leaders of breed organizations impacted which breeds where chosen for introduction into and became popular in the United States beef industry.

Mark Thallman
In 1998 scientists at MARC evaluated what the goals of the Germplasm Evaluation Program should be. The population is now used as the main source of samples for genomics research. The new approach of the program no longer seeks to evaluate exotic breeds that are not used within the industry, but instead focuses on breeds that are widely used within the current beef industry. The program has also added the focus of looking at genetic parameters (heritability) of new or important traits. In the current Germplasm Evaluation, 14 breeds are sampled and since 2006 the program has sampled 794 sires. They produce an average of 10 animals per each sampled bull. The design of the project creates purebreed animals, first generation crosses of two breeds, and second generation crosses of four breeds. They have maintained purebred herds of Angus, Hereford, Charolais, and Simmental for many years, and the program is working on building purebred herds for other breeds. The Germplasm Evaluation Program no longer uses cycles, but now uses a continuous program. The program has sequenced 180 purebred bulls and 81 crossbred bulls. Some of the recent research has shown that heterosis is maintained at a higher level than previously assumed. Composite bulls likely retain more heterosis effects than previously assumed.

Steven Kappes
The field of genomics stands on the population genetics work by Wright, Fisher, and Haldane, selection index work of Hazel and Lush, mixed model work of Henderson, application of BLUP to field data by Van Vleck, Willham, Quaas and Pollak, nucleic acid hereditary work of Avery, MacLeod, DNA structure by Watson and Crick, and PCR by Mullis. Various maps of the bovine genome have been created such as cytogenetic maps, physical maps (RH and FISH), and linkage maps. Researchers originally assumed that mapping production traits would be simple, all that would be needed is finer resolution maps. In 2003 we knew that single gene (marker) selection was worse than single trait selection. There are hundreds of genes which influence a trait, thus the infinitesimal model was a good approximation. These DNA markers needed to be incorporated into EPD predictions. The motto of the animal genomics community was "We need more markers, we need more animals." (These practices have currently been implemented in the industry, but this was not so in the late 1990's and early 2000's.) The first step in sequencing the bovine genome was creation of a bacterial artificial chromosome (BAC) library. This was done on L1 Domino 99375, as he was a line bred bull. His daughter, L1 Dominette 01449, was used to generated 60% of the sequence for the bovine reference genome. In the second phase of the sequencing project researchers sequenced 6 other breeds to identify single base pair markers called single nucleotide polymorphisms (SNPs). Previously, researchers used 150 repeat markers, now there are 750,000 markers in a single assay. Researchers now used all available SNP markers simultaneously in a genomic selection prediction model. For milk protein predictions in dairy, the pedigree estimate provided the same amount of information as 7 progeny, and the SNP genotypes provide the same amount of information as 34 progeny. The gain in information is even stronger for lowly heritable traits, for pregnancy the SNP genotypes provide the same amount of information as 131 progeny.

Ronnie Green
The ground on which the MARC currently stands is considered excellent crop land. When the land was purchased by eminent domain to manufacture ammunition for World War II, many people assumed that the land would go back to the private domain after the war effort. But, after the Korean War, several people saw the possibility of the land as a research center, modeled after other military institutions that had been turned into research institutions. The history of MARC and the Beef Improvement Federation have been intrinsically intertwined.

Bill Rishel, Dave Nichols, Burke Teichert, and Chuck Folken
This panel of producers discussed the impact of the MARC research which included work on food security, heterosis, and genomics. Dave Nichols expressed his excitement about new genomic predictions. He stated that genomic tests were the most influential development in beef genetics since the publication of EPDs.
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