Does the perfect genetic index exist?

Total merit indexes like NTM (Nordic Total Merit), NM$ index, TPI and NVI among others are important genetic selection tools. They combine the traits that are of economic importance for dairy business into one package. The indexes differ by the traits covered and by the weight allocated to the specific traits. NTM places 53% of the total weight on health and reproduction traits, 30% on production and 17% on Conformation and workability traits. 
By relying on the total merit index, dairy farmers get an easy tool to rank and benchmark bulls that they use to create a next generation of cows for their herd. Such a standard index assumes that there are the same market conditions and that the challenges that dairymen face are the same. Total index serves as general overview for a genetic plan. However, you might want to develop your own, customized genetic plan that fit your herd. While doing so, you might want to adjust the weights to fit your farm’s situation and your future goals. With VikRank tool - CustomVik, you can adjust the weights in NTM as you wish and can easily select the bulls that fit perfectly to your goals and environment. 
If we look at the top 20 VikingHolstein bulls ranked on NTM, only six index units separate Top 1 and Top 20 bulls. However, that does not mean that the genetic benefits that are delivered by the top ranking NTM bulls are exactly the same, as each of the high-ranking bulls has its own profile. 
To demonstrate that, let’s consider three different scenarios of the genetic plan: one with focus on Production, one with focus on Health and the last one with focus on Conformation. 

Scenario 1 – High Production (70% production – 15% Health & Reproduction– 15% Conformation & Workability)

When high production is your primary goal, the genetic plan could be set with 70% of weight on Production traits, 15% on Health & Reproduction, and 15% on Conformation & Workability. Top 5 bulls in this scenario have 10,575 kg milk (305 days), 448.7 kg Fat and 368.8 kg Protein. 

Scenario 2 – High Health (20% production – 70% Health & Reproduction– 10% Conformation & Workability)

In the genetic plan where health is in focus, the genetic plan may be set with 20% of weight on Production, 70% on Health & Reproduction traits and 10% on Conformation & Workability. The team with Top 5 bulls in this scenario have six index units higher for Daughter Fertility, nine index units higher for Calving Maternal, 23 days longer productive life (first three lactations). This team of bulls offers significant higher disease reduction than ‘High Production’ group. The daughters of the bulls in ‘High health’ group would have less disease compared to breed population average: 
  • 32% less mastitis
  • 18% less early reproductive disorders
  • 11% less late reproductive disorders
  • 20% less ketosis
  • 16% less other metabolic disorders
  • 33% less sole ulcer
  • 8% less sole hemorrhage & digital dermatitis. 
However, in ‘High health’ scenario you have to give up 230 kg milk and 24.2 kg solids to get better health figures. 

Scenario 3 – High Conformation (25% production – 25% Health & Reproduction– 50% Conformation & Workability)

In the genetic plan where conformation is in focus, the genetic plan could be set with 25% of weight on Production, 25% on Health & Reproduction traits and 50% on Conformation & Workability. The team with Top 5 bulls in this scenario have index 117 for Frame, 114 for Feet & Leg index and 122 for Udder conformation, which are much higher values than the bulls in the other two groups. When that much weight is set on the conformation traits, you will compromise on production (53 kg less milk, 12 kg less solids compared to ‘High Production’ group), and sacrifice some productive life (20 days less than ‘High health’ group), reproduction and health.

All Top 5 bulls in each of the three scenarios have high NTM.  If we compare those different genetic plan averages, we can see that the average NTM is nearly the same, 34 units for ‘High production’ 33.6 units for ‘High health’ and 31.6 units for ‘High conformation’ group.  However, the genetic values for the production, health and conformation traits are quite different.
There are three bulls that are present in more than one list. VH Brook is the only bull that is present in Top 5 bulls in all three scenarios: Top 1 in ‘High production’, Top 3 in ‘High health’ and Top 2 in ‘High Conformation’. VH Brook has a profile that fits all three goals. VH Badger is Top 2 in High production scenario and Top 4 in High Health scenario. These two bulls with gNTM +37 are right now the top ranking NTM bulls for VikingHolstein. VH Garbro (gNTM +28) is Top 4 in both ‘High production’ and ‘High conformation’ scenarios. NTM includes all economically important traits and serves as general overview for a genetic plan. With NTM as a tool, you can easily rank the bulls, identify the best performing bulls and get the estimation on how much value the bulls would create for your dairy business. 

Your unique genetic plan
To develop the genetic plan that fits your business perfectly, you should consider your herd goals, future plans and the market situation and based on that decide how much emphasis to place on different traits, like production, health and conformation. With the VikRank tool - CustomVik, you can easily adjust the weights in the total merit index to match your business goals and based on that determine the best sires for your unique goals.

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