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Guernsey PTI Formula

(Updated April 2025)

(25*(PTAP/21.35))+(25*(PTAF/27.75))+

(9*(DPR/2.84))+(4*(CCR/3.43))+(4*(HCR/2.75))+

(10*(UDC/0.71))+(10*(FLC/0.99))+(6*(PL/2.89))+

(2.4*(PTA Strength/1.2))–(1.6*(PTA Stature/2))+

(3*(LIV/2.63))

UDC and FLC should be rounded to the nearest 10th prior to use in the PTI formula

Udder Composite (UDC)

((.17*(FU/1.3))+(.10*(RH/1.2))+(.10*(RW/1.3))+

(.15*(UC/1))+(.33*(UD/1.4))+(.15*(TP/1.2)))/0.71

Foot & Leg Composite (FLC)

((.36*(RV/0.6))+(.48*(FA/0.7))–(.16*(RL/0.7)))/0.99

To see your cows and heifers on these lists...

Requirements for appearing on genetic lists:

  • Active AI: bull must have semen available, recorded as Active with NAAB and be daughter-proven with a minimum amount of daughters on recorded test and classified.

  • Genomic young sires: bulls must be genomic tested with a valid Stud Code recorded at NAAB and NOT yet daughter-proven.

  • CPI/PTAT Cows: cows must have a calving recorded on DHI within the past 2 years, be purebred or GR, and scored GP-80 or higher.

  • CPI/PTAT Heifers: heifers must be under 2 years old and be purebred or GR.

  • Production recognition: cows must be purebred, GR, or PR. For Class Leaders, cows must meet a minimum requirement of test days.

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