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You’re making genetic progress, but at what rate?

Lynsay Beavers and Brian Van Doormaal Published on 30 April 2015

These days, if you use A.I. sires as opposed to natural service, it’s practically impossible not to make genetic progress. The bulls offered by A.I. companies are of such caliber that, for the most part, genetic progress heads in one direction – upwards. However, the rate at which a herd makes progress is highly variable.

To reveal the different rates at which herds are making genetic progress, CDN examined a dataset including cows with an official LPI that were born in 2001, 2006 or 2011.

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Using these birth years gave the opportunity to analyze the rate of genetic progress in each herd across five- and 10-year periods.

Herds included in the analysis were restricted to those that had at least 10 cows with an official Lifetime Profit Index (LPI) in each of the three birth years. In total, the analysis involved approximately 193,700 cows from nearly 2,500 herds across Canada.

The fast, the average and the slow progressers

Herds were grouped into 10 groups (i.e., deciles) based on the annual rate of genetic progress achieved for LPI over the five-year period based on cows born in 2011 versus 2006.

Annual rates of genetic progress were graphed for this five-year period as well as for the 10-year period (i.e., cows born in 2011 versus 2001), as shown in Figure 1.

annual rate of progressThe average herd has experienced a faster rate of genetic gain over the most recent five-year period compared to the 10-year period. This is surely due to genomics to some degree, which has increased the rate of genetic progress in the breed.

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During the 10-year period, the top 10 percent of herds made around 20 points more progress per year than average herds.

During the five-year period, this doubled, with the herds in the top 10 percent making 40 LPI points more progress per year compared to herds with the average rate of LPI progress.

Female genomic testing was used twice as much in herds in the top 10 percent compared to average herds (12 percent versus 6 percent).

It’s likely that owners of the top herds genomic tested more animals because they realize the importance of genetic selection and may be involved with marketing genetics.

Nonetheless, female genomic testing is a tool used to accelerate genetic progress, and increased uptake by herds in the top 10 percent speaks to the willingness of these herd owners to seek out and utilize such tools to their advantage.

Figure 2 groups herds the same way as Figure 1 but shows progress for EBV milk over five- and 10-year periods.

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genetic rate of progressOnce again, it is clear there are certain herds making much faster genetic progress for this trait and that the annual progress achieved in these herds in the most recent five-year period far exceeds that achieved over the 10-year period.

Also noteworthy is the fact that in both Figures 1 and 2, herds in the bottom deciles made more progress per year for LPI and EBV milk over the 10-year period than the five-year period, meaning that the annual rate of progress has been slowing down so these herds are falling more and more behind.

Annual progress for key traits

Table 1 shows the annual genetic gain for key traits in an average herd as well as the average progress per year experienced by herds in the top and bottom 10 percent.

dairy cow annual genetic gainOnly LPI and its three components, as well as production yields and conformation, are included since rates of genetic progress for functional traits are quite slow in most herds with little difference across herds.

The average herd makes approximately 70 LPI points of progress per year, while a herd in the top 10 percent or bottom 10 percent would make approximately 40 points more or 40 points less gain per year, respectively.

By looking at the LPI components, it is clear that most of the annual rate of gain in LPI comes from progress for production and durability.

For the health and fertility, however, the average herd in Canada has virtually made no genetic progress for this component while the best herds have achieved an average gain of 1 point per year during the past five years.

The poorest herds for rate of progress for LPI actually lost ground for health and fertility at an average rate of nearly 2 points per year.

Genetic progress for production traits is variable from herd to herd, with the average herd gaining 77 kg EBV milk per year while the top 10 percent of herds for LPI gain achieve EBV milk gains of nearly 140 kg EBV milk.

Progress for herds in the bottom 10 percent is only 19 kg EBV milk annually. These extreme genetic differences surely translate into considerable production differences among herds, which translates to poorer profitability.

In terms of conformation, the average herd makes 0.8 EBV points of progress annually. Interestingly, even herds in the bottom 10 percent for LPI gain make 0.6 EBV points of progress for conformation each year. This shows that significant progress is made for conformation, even if progress for LPI is minimal.

Summary

Your herd is almost certainly making genetic progress, but there are real and significant differences among herds in the rate at which genetic progress is occurring.

Thanks to genomics, genetic progress has sped up in most herds in the past five years, which has contributed to the fact that annual rates of gain have been faster in the most recent five years compared to earlier years.

While the average herd has made more progress over the past five years, it is herds in the top 10 percent that are achieving gains at a much faster rate than others.

Herds in the top 10 percent for LPI gains are likely utilizing all tools available to them to maximize genetic progress, keeping them far ahead of the pack in terms of annual genetic gain.  PD

Lynsay Beavers is an industry liaison coordinator and Brian Van Doormaal is the general manager with Canadian Dairy Network.

—Excerpts from the Canadian Dairy Network website, January 2015

Lynsay Beavers
  • Lynsay Beavers
  • Industry Liaison Coordinator
  • Canadian Dairy Network

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