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26 May 2021

ProCROSS releases ranking index

 

ProCROSS Rank with major revision for VikingRed and VikingHolstein is ready now. The Selection emphasis for the ProCROSS Rank (PCR) from each breeds’ native index is shifted in order to homogenize body size, enhance production, and improve udder conformation for ProCROSS cows.

With over 20 years of experience in crossbreeding, the ProCROSS company has released an updated ProCROSS Rank (PCR) index—a tool for use by dairy farmers and their consultants to select the best purebred bulls for their ProCROSS herds.

This update is for bulls in the VikingRed and VikingHolstein breeds and these two breeds, along with Coopex Montbeliarde, are used in the 3-breed rotation named ProCROSS.

 “ProCROSS is the most successful crossbreeding system because it utilizes the top-ranked bulls from each of three very compatible breeds in its rotation,” says ProCROSS Manager, Stephane Fitamant.  “However, the top bulls ranked purebreeding might assort differently for use in ProCROSS.”

 Two PCR variations are provided separately for each breed: PCRS is designed for dairy farmers who market milk solids and PCRL is for farmers who are most concerned with liquid volume of milk.

Motivation for revision

The national index for the VikingRed and VikingHolstein breeding programs—Nordic Total Merit (NTM)—was revised in August 2020.  Therefore, a revision for the PCR of the same breeds was also warranted.  

The NTM is a balanced breeding goal in which several trait groups are weighted based on their economic values and contribution to profitability.

 The recent update of NTM incorporates Saved Feed index, a new evaluation of feed efficiency, and exploits knowledge of future production conditions and incomes and expenses on farms.

“By using the NTM as the foundation for the PCR, all traits emphasized for selection in purebreeding will continue to have emphasis for PCR,” says Fitamant.  He continues, “The complementarity and strengths of the breeding programs of the three breeds each are expressed in high-ranking bulls for PCR.”  

 Those strengths for the three pure breeds of ProCROSS include:

 

Coopex Montbeliarde

VikingRed

VikingHolstein

Strength

Fertility

Adaptability

Calving ease

Longevity

Health

 

Production

Udder conformation

Moderate body size

 

 

Traits emphasized in the PCR

For both VikingRed and for Viking Holstein, the revised PCR favors bulls that transmit:

  1. More production (based on yield index for PCRS and based on liquid volume for PCRL)
  2. Higher udder conformation composite
  3. Homogenous body size

To make body size more homogenous in the ProCROSS cow, the PCR gives advantage to VikingRed bulls that transmit large body size.  For VikingHolstein, PCR favors bulls that transmit shorter stature.  

The traits emphasized in PCR align well with the body of knowledge regarding hybrid vigor and heritability—genetic parameters that vary from trait to trait.  Hybrid vigor comes in large doses for the health, fertility, and survival of dairy cows, but in smaller amounts for production and conformation.

On the other hand, heritability has opposite effect: production and conformation traits are considered moderately or highly heritable while health, fertility, and survival are lowly heritable. 

Therefore, ProCROSS farmers will experience large benefit in the use of PCR by simultaneously capitalizing on the additional emphasis in the highly heritable traits and the “free gift” of hybrid vigor for lowly heritable traits.

In concordance, dairy farmers with decades of experience milking ProCROSS cows have historically focused more of their selection emphasis on production and udder conformation.  A retrospective look at their bull selection decisions confirms the new objective for this PCR revision.

Expressions of PCR 

The average and standard deviation for PCR has been set to 500 and 30, respectively.  The higher the PCR index, the suitable the bull will be for ProCROSS.  

Each PCR evaluation is standardized to a roster of young bulls that serve as the breed base.  This means that even as the population of bulls improves over time, an average bull will maintain a PCR of 500.

The breed base is exclusive to the breed of evaluation.  Therefore, bulls should not be compared across breeds for PCR.