wbvs58
Well-known member
A good case for only using registered bulls where the pedigree and genetic status is known. For example take one defect such as AM, it would not matter one bit how many carriers of AM cows were in a herd as long as the bull you used was AM free. If you were to work on 25% of the herd were carriers of AM from previous use of a carrier bull, this is on the assumption that 50% of the progeny of that bull were carriers and then 50% of those calves would be steers and if you kept all the heifers it would still only be 25% of your cows as carriers. With the new bull free of AM after keeping all his heifers in one generation you are down to 25% of 25% that are carriers in your herd which is 6.25% so the carrier staus is quickly eliminated in a commercial cow herd with little or no damage done.GAR Precision 1680 is still in the database, but it does show that he is a carrier of AM and NH. Lots of use with BW and WW data submitted on over 8000 progeny.
Correct me if I am wrong, but the use of AI bulls vs walking bulls does not necessarily mean an increased risk of a genetic issue. Genetic defects can naturally originate in an animal or can be inherited from one or both parents. Stands to reason that a bull with heavy use has a higher risk of a defect presenting itself in progeny - not due to the fact that he has AI use, but from the fact that more progeny/use increases the probability of detection (not existence) of the defect. A bull purchased for in herd natural use could have a genetic mutation/defect that is never detected. But he might be spreading that defect in half his calves who also spread the defect for years.
Take two scenarios - an AI bull with heavy use that has a defect which is soon detected, a test developed, and an effort to locate and remove the defective animals is underway. Or a natural service bull that sires 50 calves per year - half carrying the defect. 5 calves kept and sold as breeding stock each year. Which scenario presents the higher risk long term?
Pedigree registered with a reputable breed society is a pretty powerfull tool in dealing with any recessive defect that may crop up. Heavy use of outstanding bulls and cows will continue to be used in the seedstock industry and commercially and I am sure there will be more defects show up in the future but you look to taking these small risks to look for these improvements you are after. Isn't that what we are all after in breeding cattle, the next generation better than the previous. We are in a very good position to deal with it.
Precision seems to be the one that is demonised the most, Travlr will always bring up his name when this subject is brought up as exhibit A. I would like to make it clear that Precisions influence on the Angus breed has not been wiped out it is present in many of the top Angus lines today. Any carriers have been been dealt with by removing to the commercial herd and live their life out as productive commercial cows. They will still be on the Angus database though. No herds wiped out, no big pits dug to bury animals.
Ken