Estimate how your herd’s mean pulmonary arterial pressure changes over generations based on bull selection strategy. Thresholds adjust for your grazing elevation.
Your operation
How strict are you on PAP when selecting bulls?
AI sires you're considering
Enter each bull's measured PAP, EPD, or both. If entering an EPD, also enter its accuracy — a low-accuracy EPD is heavily shrunk and carries much less predictive weight in the projection.
Projected herd mean PAP
Results after 5 generations
Cutoffs: ≤49 mmHg (mild), ≤45 mmHg (moderate), ≤40 mmHg (strict) reflect common producer screening thresholds. Elevation adjustments reflect that cattle at higher altitude naturally test higher due to reduced atmospheric oxygen.
Why change is slow: Beef cattle generation intervals average 4–6 years. Cows are typically not selected on PAP, so only the sire half of the genome changes each generation. Realistic per-generation response is 1–3 mmHg under consistent selection.
EPD accuracy: PAP EPD represents expected progeny deviation in mmHg. A positive EPD means progeny average above the genetic base — that bull raises herd PAP. The possible change (from AAA) = 2.267 × (1 − accuracy): at acc = 0.70 that’s ±0.68 mmHg; at acc = 0.30 it’s ±1.59 mmHg. Breed avg PAP EPD = +1.16 mmHg (Angus); top 10% = −1.02; top 1% = −2.77. Projections cap at the biological floor of ~35 mmHg.