Travlr
Well-known member
LOL... nice dodge...To some maybe, black and/or polled ae "defects". But being black or polled poses no health risks, or leads to disability or mortality. Inherited diseases, conditions, and abnormalities that are genetic, are all caused by recessive genes. If these were all dominant, there would be no cattle. That red and black color thing though is a good illustration. Black, BB is dominant over red bb. All red cattle are homozygous bb. Black cattle can be homo BB or hetera Bb.
Breed a BB to a Bb, and all calves will be black. 75% of them homo BB, and 25% hetera bb. ( red carriers)
Breed a Bb to a Bb, and 25% will be homo BB, black 50% will be hetera (red carriers) Bb black, and 25% will be bb red.
Breed a BB black to a bb red, and all calves will be hetera black, Bb.
Breed a Bb black to a bb red, and 50% wil l be Bb black, and 50% bb red.
So let's say bb represents a known genetic birth defect or disease, and you will understand why you shouldn't breed a carrier ( one copy of the b gene). And, you will see way that defect could only be tied to the recessive bb gene. If the defect were dominant,, ALL cattle, whether homo BB or hetera Bb, would have it. Only a calf from a cross between two hetrea Bb cattle, would stand a 25% chance of being normal.
This also illustrates why in breeding sons and daughters to mommas and daddies, is like playing Russian Roulette with 5 in the chamber. The exception would be, when using registered stock and all have been tested and certified to be non carriers.
Duck and weave... duck and weave...