I write frequently about the need to breed grass-efficient cattle, and typically smaller-framed cattle because they have the potential for greater intake relative to their size and greater efficiency of beef production per acre.
The question many people want to ask is "What is the right size?"
That's the wrong question.
The answer should be cattle need to be the size that is the most reproductively efficient and effective on your operation, preferably with high-stock-density grazing to build the land and dramatically increase your production.
Further, we should always have been producing cattle based on reproductive- and environment-adapted factors, cattle that can get fat and reproduce on grass, plus cattle that have rapid growth within the appropriate frame size. This is not something we can learn or get from feedlot tests. Grain is not the same as grass. This is the rancher's job.
I saw a brief description of how to think about this and how to do it the other day from Johann Zietsman, the Zimbabwean pioneer of ultra-high-density (UHDG) grazing and breeding cattle to match. This goes well with my blog from October 2, Two things you need to know about intensive grazing.
"The optimum size is when 90% of heifers calve at 2 years, achieve 90% reconception and wean calves 40-50% their own weight," Zietsman said.
How can you do this? Zietsman answered with these seven concepts.
1. Understand that there is a negative correlation between frame size and relative intake that is the determinant of grass conversion efficiency, body condition and practical fertility.
2. Do not confuse frame size and weight. We do not want tall cattle. We want cattle that are heavy relative to their frame size (8-in-5 packages). The smaller and heavier the better !
3. Genetic change comes through the bull. To identify a good bull you first need to identify a good cow. Culling cows has more economic than genetic value.
4. Only use exceptional bulls. Make a bull obsolete (use extensively) as quickly as possible.
5. Use appropriate selection criteria. Do not worry about inbreeding. Concentrate desirable genes.
6. To progress we need drastic changes.
7. Do not become too clever. Forget about EPDs, genomics, etc.
8. The breeder's role is to accelerate natural selection.
Another thing Zietsman says that I think is critically correct is that reproduction is a survival trait, therefore it is highly heritable. If cattle fit their environment, they will be highly reproductive.
There are only two ways to get good body condition, which we all know is critical to rebreeding success: Feed for it or breed for it. The choice is yours.
To better understand what Zietsman is saying, I highly recommend buying his book, Man, Cattle and Veld.