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Monthly Archives: February 2018

Genetic indexes: can one size fit all?

Indexes are important genetic selection tools. They combine all significant genetic traits into one package – and get producers away from setting minimum criteria for specific traits. That allows you to focus on creating a next generation of cows that are the right fit for your environment.

A global industry standard index like TPI has certainly helped dairy producers improve their herds. The one-size-fits all TPI index places 46% of the total weight on production traits, 28% on health and fertility traits and 26% on conformation traits.

However, an index like this assumes all farms face the same challenges within their herd. It assumes everyone has the same farm goals and milk markets. It simply serves as a general overview for a one-size-fits-all genetic plan.

Consider your goals

When you set your own, customized genetic plan, you can divide the weights as you see fit. To decide which production, health or conformation traits to include, consider your farm’s situation and future goals. How are you paid for milk? In a fluid milk market, you’ll likely put more emphasis on pounds of milk as compared to those who ship milk to a cheese plant. Are you expanding or at a stable herd size? If you’re looking to grow from within to expand your herd, you’ll want to put more emphasis on Productive Life and high fertility sires than the producers who are at a static herd size and able to cull voluntarily.

Your farm’s scenario is unique. With different goals, environments and situations, it’s evident there is no such thing as a one-size-fits-all index.

Make progress where it matters

Just 42 TPI points separate the 100th and 200th ranked genomic bulls on Holstein USA’s December 2017 Top 200 TPI list. Does a separation that small mean these bulls offer similar genetic benefits? Of course not!

To illustrate why, let’s compare three different genetic plan scenarios. One focuses on high production, one on high health, the other on high conformation. The tables below show the sires, traits and genetic averages for the top five Alta sires that meet each customized genetic plan. Notice the extreme amount of progress, and also the opportunity cost for using each particular index.

When high production is the goal, your genetic plan may be set with weights of 70% on production, 15% on health, and 15% on conformation. A team of bulls fitting that plan averages 2400 pounds PTAM and 171 pounds of combined fat and protein.

High Production: 70-15-15MilkProteinFatPLDPRSCSPTATUDCFLCTPI
AltaMONTOYA2089791058.02.22.792.091.840.932864
AltaAKUZAKI264078798.10.72.992.072.520.752747
AltaSPRITE253984884.2-0.83.032.332.131.532684
AltaEMBOSS260777974.5-0.53.071.311.470.812589
AltaWILLIE212375916.82.22.911.972.100.632766
240079926.30.82.961.952.010.932730

When health is the focus, a 30% production, 60% health, 10% conformation genetic plan might make sense for you. That team of bulls delivers averages of +9.5 PL, +5.0 DPR and 2.75 SCS. That’s more than four points higher for DPR than the high production group! However, you give up nearly 1100 pounds of milk and 41 pounds of components to get those high health numbers.

High Health: 30-60-10MilkProteinFatPLDPRSCSPTATUDCFLCTPI
AltaDEPOT910376311.47.02.480.680.801.002693
AltaKALISPELL1727527710.04.22.751.371.571.362734
AltaROBSON83555898.64.72.861.521.351.422802
AltaNITRO129554938.34.42.732.081.991.492871
Alta49ER181061709.04.62.931.071.441.032702
13155278.49.55.02.751.341.431.262760

Lastly, if your genetic goal is to improve conformation, the team below provides an average 2.47 for PTA Type, 2.86 Udder Composite, and nearly two points for Foot & Leg Composite. With that much emphasis on the conformation traits, you’ll sacrifice on pounds of milk, fat and protein, and give up some productive life and fertility.

High Conformation: 25-25-50MilkProteinFatPLDPRSCSPTATUDCFLCTPI
AltaSCION109848798.72.42.762.803.332.112786
AltaDRAGO162156857.22.43.052.962.792.562799
AltaPACKARD77048699.93.82.402.742.391.762839
AltaCR53137867.02.32.941.692.772.042669
AltaDPORT173558697.73.02.962.163.031.162749
115149788.12.82.822.472.861.932768

Now, compare those different genetic plan averages side-by-side. You can see that a mere 38 points separate these groups on TPI average. However, the genetic values for the production, health and conformation traits are extremely different.

MilkProFatPLDPRSCSPTATUDCFLCTPI
High Production: 70-15-15240079926.30.82.961.952.010.932730
High Health: 30-60-10131552789.552.751.341.431.262760
High type: 25-25-50115149788.12.82.822.472.861.932768

15 bulls in the Top 5

Most of the bulls above rank similarly for TPI. But not one bull appears in more than one of the customized genetic plan top-5 lists. With 15 bulls in the top five, it’s clear to see there’s no such thing as a perfect bull. There is, however a perfect genetic plan. It’s the one you customize for your farm to match your current situation and future goals.

Think back to the examples above. Think about TPI (46% production, 28% health, 26% conformation). If your main goal is to increase milk production in your herd, emphasizing too much on the health and conformation traits will mean you sacrifice pounds of milk and total components in the next generation of your herd.

Alternatively, maybe you really want to improve the longevity and fertility of your herd. In that case, an index that focuses on conformation will cost you 1.4 months of productive longevity and more than two points of pregnancy rate in the next generation!

Bringing it together

Sticking to an industry standard index like TPI could get you the best ranking bulls for that index only. But that index doesn’t necessarily match your needs. If you’re looking for a more focused approach, keep these points in mind to make the most progress toward your farm’s goals:

  1. There’s no such thing as a “one-size-fits-all” genetic index.
  2. Work with your trusted Alta advisor to set your own, unique, customized genetic plan. Consider your farm’s goals, future plans and milk market as you decide how much emphasis to place on the production, health and conformation traits.
  3. Maximize progress toward your genetic goals by using a group of the best sires to match your unique genetic plan.
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The high value of low heritability

Most of us misunderstand heritability. In simple terms, for any given trait, heritability tells us how much of the difference in actual performance is due to genetics, as opposed to management or the environment.

To better understand, think about two cows in two different herds. How much of the difference in their milk production is due to genetics? How much is due to management or environment? It turns out about 30% of the milk production difference is due to genetics, while 70% is due to management and environment. Therefore, milk has a heritability of 0.30.

What about pregnancy rates? Management and environment account for the 96% majority of variation between daughters. So the influence of genetics is minor, at just 4%. Thus, Daughter Pregnancy Rate (DPR) has a heritability of 0.04.

We commonly refer to the health traits like Productive Life (PL), DPR and Somatic Cell Score (SCS) as the lower heritability traits. Many producers believe that low heritability equates to less, or slower, genetic progress. However, in spite of lower heritability, it would be wrong to conclude that DPR, PL or SCS are insignificant as a result.

Perspective is important

In genetics, accuracy shows through when we evaluate results within one herd. In that herd, if we evaluate within a specific lactation group, and then within a specific time of freshening, we find a contemporary group. By evaluating within one contemporary group, we reduce the impact of management and environmental differences.

The overall heritability for health traits like DPR and PL is low. When we break our evaluations down into contemporary groups, that’s when we find the true genetic differences.

The proof is in the numbers

Take this real-life example from a 1,500-cow dairy with very good reproductive performance. We’ve separated out first lactation cows into four groups, based on their sire’s DPR. It’s clear to see that the high DPR sires create daughters that become pregnant more quickly than the daughters of low DPR sires.

Table 1# of cowsAverage Sire DPRActual preg rate
Top 25% - High DPR1742.327%
Bottom 25% - Low DPR137-1.120%
difference3.47%

The same goes for Productive Life. Despite the low heritability at less than 9%, PL can make a real, noticeable difference in your herd.

This table compares how long the daughters of the industry’s best ten PL bulls and daughters of the industry’s bottom ten PL sires will last in a given herd. You can see that a higher percentage of high PL daughters, represented by the dark blue bars, remain in a herd than their low PL counterparts.

Graph showing the real effect that Productive Life plays on how long cows last in a herd

When you select for the lowly heritable PL, you will certainly create healthier, longer-living cows in your herd.

Focus on the economics

As a progressive dairy producer, don’t let confusion about heritability prevent you from using the right genetic tools to improve your herd. Health traits are economically important, and making improvement in these areas can have a huge impact on your bottom line.

Many traits have a high heritability, but no economic importance. In other words, we can make a lot of progress for these traits very quickly, but it will not make a more profitable cow.

A couple examples of high heritability traits are coat color and polled. Both of these traits have a heritability of 100 percent because they are completely controlled by genetics. However, even if we can make cows red or polled in one generation, what is the economic value of that?

By comparison, the economic value of more fertile cows that last longer because of fewer metabolic problems, fewer cases of mastitis, and less calving difficulty is clear to see. These genetic features make a more profitable production unit for each and every farm.

Selection secrets for healthier cows

When you set or reevaluate your genetic plan, take the following tips into account to maximize progress in the direction of your goals.

1. Define your goals

To set the right goals, first identify the most common reasons for culling in your herd. Is it reproduction, milk production, mastitis? This information gives you the basis for the genetic decisions you make going forward.

2. Choose your tools

Health traits offer dairy producers some powerful tools to help correct for low reproduction, metabolic problems, etc. Identify how important each of these trouble areas are to you. Place a proportionate emphasis on these traits when choosing the group of sires to use on your dairy.

3. Customize the solution

Industry standard selection indexes put different and continually changing weights on health traits. So don’t assume they reflect your individual goals and needs. Work with your trusted Alta advisor to make sure your genetic plan is customized to match your current situation and future goals.

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