Just to clarify. In terms of commodity production, perhaps the term I should have used was mainstream production. I still believe that hybrid vigour is imperative in commercial beef production. The big gains in fertility, longevity, disease resistance, and some gains in growth rate and feed conversion (read solar energy into protein) cannot be ignored.
It is possible to produce consistent, quality product through crossbreeding, in fact this is what chicken and pork and grains have done.
The argument about where the genes come from and buying versus raising replacements are largely management dependent. It is true that there is an environmental effect that gives an advantage to "home raised" replacement females.
By keeping related females and breeding them to related bulls, we will fix genes in the subpopulation, and will also see some inbreeding depression, however when crossed on an outside sire, the progeny will express major hybrid vigour. The challenge is the hybrid vigour you may lose in the cowherd (read fertility, longevity). It is possible to counterbalance this somewhat with different breeding schemes, but you have to manage the herd appropriately to do this.
There is some good stuff out of USDA MARC. http://sol.marc.usda.gov/
Hope this helps clarify a bit.
It is possible to produce consistent, quality product through crossbreeding, in fact this is what chicken and pork and grains have done.
The argument about where the genes come from and buying versus raising replacements are largely management dependent. It is true that there is an environmental effect that gives an advantage to "home raised" replacement females.
By keeping related females and breeding them to related bulls, we will fix genes in the subpopulation, and will also see some inbreeding depression, however when crossed on an outside sire, the progeny will express major hybrid vigour. The challenge is the hybrid vigour you may lose in the cowherd (read fertility, longevity). It is possible to counterbalance this somewhat with different breeding schemes, but you have to manage the herd appropriately to do this.
There is some good stuff out of USDA MARC. http://sol.marc.usda.gov/
Hope this helps clarify a bit.
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