Jill said:
If you'll reread what I wrote, I said IF the bull isn't dominant, we have a bull here that will throw calves anywhere from 40-100 all depends what the cow is, that is what I call a nondominant bull and in those cases the cow does determine the size of the calf.
If being non-dominant = inconsistent, I would agree. And you could be right anyway.
When I think of dominant, I think of 1 gene overriding the other. For example... 1 black gene + 1 red gene = black. That's dominant. IDK if that is exactly what's going on with birth weights. It might be, but I'm very skeptical if that is the case.
Consistent means that an animal produces similar results at least most of the time.
I don't know how many different genes effect birth weight, but an animal has 2 sets of every gene. Every sperm cell gets 1 gene or the other gene from every single set. Every sperm cell is a different mix of genes from the sires gene pool. I know that MMI tests 128 sets of genes for Marbling... that's a lot of sets for 1 trait. I assume that multiple sets effect birth weight. If it's 1 set, which I doubt, a sperm can produce 2 different possibilities. If it is mutiple sets beyond 2, which is likely, a sperm cell can produce an unreal amount of possibilities.
Inconsistency usually occurs because of mating animals with varying genetics (crossbreeding, outcross genetics, different types, etc.). I may be wrong, but I'm guessing that the bull probably has birth weight genetics that are all mixed up in his gene pool. Even if the animal is a purebred, you still have an 1/8 or 1/16 (depending upon the breed) of something else mixed in & no 2 animals from the same breed are exactly a like either.
Consistency occurs when you concentrate animals with extremely similar traits for multiple generations & line breeding is one of the best ways to do that.
My dad told me that several geneticists that he spoke with claimed that 3 generations (7/8) wasn't enough to consider an animal a "purebred" & it would take at least 4 generations (15/16) before an animal would begin to become consistent for "most of the traits" of a breed. They say most, because even after 4 generations, some traits still wont breed true. That's why we have black & polled purebred Maines, Limi's, Gelbveih's, Simmi's, etc., because 4 generation animals wont produce results exactly like a fullblood animal would. That is why I am highly skeptical of any thing called "calving ease" that is not at least a 3 or 4 generation calving ease animal. Just too much variation can occur. Just because that bull calf weighs 65 lbs. doesn't mean that a significant portion of his aren't going to sire 90+ lbers. Lowline Angus are multiple generations of animals from a pretty limited gene pool, so that's why their birth weight & other traits should be very consistent.
On the other hand, the cow offers 50% of the genes, so she's at least 50% of the equation. And that's not factoring in her nutrition & her ability to convert, and that plays a role too. Just like show heifers that were fed hard during pregnancy will often have bigger calves. Again, I agree that the cow does play a significant role.
So to make a long story shorter, I agree with you, if dominant = consistent. And if not, you could be right. I'm not a geneticists, so I can't say with 100% certainty & probably even geneticists may not even know for sure.
