Recessives are somewhat simple—if momma carries it, and daddy carries it, you have a 50-50 chance the calf will exhibit it. Those recessives noted as “lethal” cause death.
If you wish to avoid ever having a TH or HCA afflicted calf, just avoid using carrier bulls on any daughter of a known carrier.
What is “TH” recessive? Stands for “Tibial Hemimelia” (origin in Shorthorn breed)
Calf will exhibit abdominal hernia, distorted pelvis and rear legs, exposed brain and/or spine tissue.
Such calves if born alive tend to die soon after birth.
What is “PHA” recessive? Stands for “Pulmonary hypoplasia and Arasarca” (origin Maine-Anjou)
Calf will have small lungs, filled with fluid, and will lack lymphatic system develop.
Such calves tend to be stillborn; a certain percentage of such conceptions may abort prior to term.