50 Years of Simmental_May/June.qxp_NATION~1.QXD 4/26/18 8:43 AM Page 2
As ASA celebrates 50 years, we look to the past, and how it shapes our future. This month’s issue is the fifth installment in a year-long series, focused on
Golden Memories Coordinated by Emme Troendle In 1996 and 1997, Dr. Bruce E. Cunningham, Director of Research and Education for ASA, wrote a series of articles entitled “Pondering Performance,” focusing on the new and innovative multi-breed genetic evaluation and the inclusion of Canadian data. This article, originally published in the May 1997 issue of the Register summarizes the multifaceted components that went into the genetic evaluation.
PONDERING PERFORMANCE By Bruce E. Cunningham, Ph.D.
The American Simmental Association (ASA) and the Canadian Simmental Association (CSA) will be releasing their first Multiple Breed International Cattle Evaluation (MB-ICE) with the Fall 1997 Sire Summary. The MB-ICE is the result of a two-year research project conducted by the ASA, the CSA and the Animal Breeding Group at Cornell University. Compared to the current National Cattle Evaluation procedures used by the ASA and CSA, the MB-ICE has the following features: 1) Breed of Founder Effect — The phrase, breed of founder, is used to indicate that a random sample of animals from various breeds are not needed to evaluate breed differences. The breed of founder effects are developed by tracing pedigrees and determining the breed(s) represented in the most distant animals (founder) in each pedigree. A time trend is included in the breed of founder effects to account the genetic trend that may be present in each sampled breed. The MB-ICE system uses two sources of information to evaluate breed differences in the ASA and CSA data: a) estimates derived from the published crossbreeding studies in the scientific literature; and b) the actual information in the ASA and CSA data base. If the data contain numerous of animals with any fraction of Angus breeding, the literature estimates of the difference between Angus and Simmental will have little impact on the final estimate. For other breeds that are not represented as well as Angus, Hereford, or Brahman, the literature values have a significant influence on the final estimates.
2) Heterosis Effect — Heterosis or hybrid vigor is produced when crossing parents with different breed backgrounds. For traits such as birth weight or weaning weight, heterosis provides an increase in performance that is not part of the animal’s breeding value. In the MB-ICE, heterosis affects a calf’s performance for the direct heterosis expressed by the calf and in case of weaning weight, the maternal heterosis expressed by the dam. 3) Continuous Age of Dam Effects — The MB-ICE system provides age of dam adjustments using the cow’s age in months based on her breed background and the sex of her calf. The age of dam effects will be estimated directly by the MB-ICE system so no records will be adjusted for age of dam prior to the evaluation. For crossbred cows, the age of dam effects will be weighted averages of the breeds represented in the dam. 4) Merging of data files from the ASA and CSA: The Fall 1997 Sire Summary will combine the data bases from the ASA and the CSA into a single International Evaluation. Using the MB-ICE, EPDs for birth weight, weaning weight, yearling weight, maternal milk and maternal weaning weight will be directly comparable among all animals in the ASA and CSA data bases regardless of their breed background or country of origin. The ASA and CSA provide EPDs for calving ease and maternal grandsires using a threshold model. The calving ease system will remain a purebred Simmental evaluation. The current base for the separate Simmental, Simbrah, and Canadian Simmental evaluations is all purebred animals born in 1986. For the MB-ICE, the base will be set by summing to zero the estimated values for Simmental, Angus, Hereford and Brahman genes represented in calves born in 1991. The base for the calving ease system will be defined as all purebred Simmental calves born in 1991.
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