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Guernsey PTI Formula

(Updated April 2020)

(25*(PTAP/18))+(25*(PTAF/25))+ (15*(DPR/2.3))+(10*(UDC/.90))+(10*(FLC/1.03))+

(6*(PL/2.4))+(3*(PTA Strength/0.9)) – (3*(PTA Stature/1.8))+(3*(LIV/2.3))

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

Udder Composite (UDC)

(.15*(FU/1.33))+(.10*(RH/1.24))+(.10*(RW/1.22))+(.15*(UC/.84))+(.33*(UD/1.53))+(.15*(TP/1.05))-(.02*(TL/1.11)) /0.71

Foot & Leg Composite (FLC)

((.36*(RV/.42)) + (.48*(FA/.49)) – (.16*(RL/.65))) / 0.68

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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