Breed Standards for Composites

Help Support Steer Planet:

cbcr

Well-known member
Joined
Feb 17, 2011
Messages
332
I was reading some information the other day pertaining to the amount of heterosos that is retained in composite animals.

On a 2 breed Composite here is what it said:

2 breeds  50%  +  50%  = 50% heterosis
2 breeds  3/4  +  1/4    = 38% heterosis
2 breeds  5/8  +  3/8    = 47% heterosis

With this information and when you look at some of the breeds that are a 5/8 x 3/8 composite, do you feel that the breed registries have helped or hurt their breed by allowing such a varying amount of Angus influence to be used?  Do you think that they should have put a 5/8 x 3/8 composite limit with the 5/8 being the primary breed of that registry?
 

cbcr

Well-known member
Joined
Feb 17, 2011
Messages
332
Yea, but what this is referring to is the amount of heterosis in continued breeding of these animals and shows the amount of hybrid vigor as compared with an F1.

So if an F1 has 100% hybrid vigor, then mating 2 F1 50/50 composites you will retain 50% of the hybrid vigor, but breeding an F1 back to either breed would only result in 38% retained hybrid vigor.  But by mating a 1/2 blood composite to a 3/4 blood composite (which results in a 5/8 x 3/8 composite) you would have 47% retained hybrid vigor.

The main point of my question is, I have seen several comments on bulls especially and the consistency of their offspring if using an F1 bull as compared to a 5/8 x 3/8 composite.  Should the breed registries have set the standard for their Angus influenced cattle to be 5/8 of their breed and 3/8 Angus?
 

aj

Well-known member
Joined
Jul 5, 2006
Messages
6,420
Location
western kansas
Are you saying that a f1 bull bred to a bunch of cows has 50% of the expected heterosis of using a purebred bull on the same bunch of cows?
 

cbcr

Well-known member
Joined
Feb 17, 2011
Messages
332
No, an F1 has 100% heterosis.  So if you have say a 50/50 Simmental/Angus bull, if you breed him to say Shorthorn cattle, you will again have an F1 with 100% heterosis.

But if you bred a 50/50 Simmental Angus to another 50/50 Simmental/Angus you would only retain 50% of the hybrid vigor.

Again in the scenario above, if the 1/2 Shorthorn x 1/4 Simmental x 1/4 Angus was mated to another animal of the same breed makeup you would retain 62% heterosis.
 

Cabanha Santa Isabel - BR

Well-known member
Joined
Aug 15, 2012
Messages
605
Location
Rio Grande - RS - Brazil
cbcr said:
No, an F1 has 100% heterosis.  So if you have say a 50/50 Simmental/Angus bull, if you breed him to say Shorthorn cattle, you will again have an F1 with 100% heterosis.

But if you bred a 50/50 Simmental Angus to another 50/50 Simmental/Angus you would only retain 50% of the hybrid vigor.

Again in the scenario above, if the 1/2 Shorthorn x 1/4 Simmental x 1/4 Angus was mated to another animal of the same breed makeup you would retain 62% heterosis.

(thumbsup)
 
Top