Saturday, August 20, 2016

ASA Fall Focus: Nuts and Bolts of Animal Breeding

Wade Shafer

What is the science of animal breeding? Shafer cited Wikipedia, saying, "The scientific theory of animal breeding incorporates population genetics, quantitative genetics, statistics, and recently molecular genomics and is based on the pioneering work of Sewall Wright, Jay Lush, and Charles Henderson."
He highlighted the work of Sewell Wright, Jay Lush, and Henderson, and Lenoy Hazel. Not only is animal breeding about the genetic value of animals, it is also about the economic value of those animals.

Animal breeding is where the rubber meets the road. "It is one of the most practical sciences."

Simmental has the slogan of "Visual analysis tells you what an animal appears to be, his pedigree tells you what he should be, his performance and progeny tells you what he actually is."

In 1971, Vaniman used Paul Miller, a dairy genetics at ABS, to produce the first sire summary using Boeing Airlines computers.  The foreword said that sire summaries would revolutionize beef breeding.

In 1982, ASA signed a long term contract with John Pollack and Dick Quass at Cornell University to deliver and advance genetic evaluation. This was the largest BLUP evaluation at the time. Best Linear Unbiased Prediction, BLUP, was developed in the 1950s and 1960s, but wasn't able to be deployed at a large scale till the 1980s when computer technology caught up. The contract with Cornell was exclusive, mean Cornell only did genetic evaluation for Simmental.

Simmental has also benefited from a close relationship with Montana State University and the cattle industry in the state of Montana.

Shafer pointed out stalwarts in the breed. He pointed out gathers such as Jerry Lipsey and Ropp. Steve McGuire has been the shepherd of the data.

Glimpse of the future, through the past. Shafer highlighted the career development of Dorian Garrick at Cornell. Red Angus is a partner of the Simmental Association. Red Angus worked with Colorado State University, with Bourdan and Brinks leading the way. They had a productive graduate student, especially with computers, named Bruce Golden.

In 1997, the Simmental Association and Cornell University teamed up to produce the first multi-breed genetic evaluation. Originally, this was deveoped to do a better job of predicting cattle, such as half bloods, that were being used in the grading up process.

In 2001, the National Beef Cattle Evaluation Consortium was federally funded through an earmark to support genetic evaluation.

In 2007, six breeds tried to join together to start a joint genetic prediction. This never materialized. In 2010, the Red Angus Association of America and the ASA created a joint genetic prediction. This ultimately lead to the creation of International Genetic Solutions. "An unprecedented collaboration between progressive breed associationss to enhance beef industry profitability." IGS now contains 12 breed associations, with 17 million animals, with 340,000 new records each year.

Theta Solutions is a company created by Dorian Garrick and Bruce Golden to advance the technology of genetic prediction. Theta Solutions software is called BOLT for Biometric Open Language Tools.

Lauren Hyde and Jackie Atkins

What are our selection decisions? How many bulls should I use? Should I use old bulls or young bulls? Which replacement females should I keep?

The speed of genetic change (hopefully progress) is
Directly proportional to:

  • Accuracy of selection
  • Selection intensity
  • Genetic variation

Inversely related to:

This is called the key equation. 

Accuracy of selection is the strength of the relationship between the ture breeding values and their predictions for the trait under selection. Accuracy increases when we use EPDs from BLUP. If using phenotypes, the accuracy is based on the heritability of the trait (which is much lower that using EPDs). 

If the BIF accuracy is 0.1, the change in weaning weight is 8 pounds. If the BIF accuracy is 0.25, the improvement in weaning weight is 12 pounds. 

Selection intensity is how choosy we are when we are selecting animals. Are we keeping everything or selecting at random or are we choosing the very top animals? Selection intensity is the difference between the average and the selected parents, divided by the variability (standard deviation) in the trait.

It is hard to change amount of genetic variation in a herd.

Generation interval is the average age of the parents when the progeny are born, In cattle this tends to vary between 4 to 6 years.

Trade-offs
Accuracy vs. generation interval
Decrease in generation interval causes decrease in accuracy and vice versa.
Quick turnover of herd sires mean we have fewer progeny per sire and less accurate predictions.

Selection intensity vs risk
Selection risk is that the true genetic merit of replacements is significantly worse than expected. With fewer sires we increase the intensity but increase our risk. With more sires we decrease our risk but we also decrease our selection intensity.

Male selection can be more important than female selection. We can be more choosy when selecting bulls and we have more progeny per bull.

You are not supposed to do single trait selection. But, selecting on an index is not single trait selection. ASA recommends that producers use indexes to select for increased profit.


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