Bonsma Basics

August 24, 2021

By Keaton Dodd

Dr. Jan C. Bonsma
Image Credit: TLBAA

Many fellow cattle producers are aware of the incredible work performed by Dr. Jan Bonsma and its impact on the beef cattle industry long term.

For those who may be new to the business or are just not as familiar with him or his work, his blog can help lay out some of his basic selection pressures and leads you to where you can find more information on him and his teachings’.

Dr. Jan C. Bonsma, originally of South Africa, spent most of his life studying cattle and traveling the world teaching fellow ranchers his applied practices in animal selection for longevity and production efficiency. Truly a visionary, Bonsma found his passion in breeding cattle and spent his life mastering the skill of visually evaluating cattle for functional efficiency.

Dr. Bonsma’s principles were first introduced to Brandon back in 2011 by a fellow Brahman breeder from Louisiana, Mr. Louis Dooley. Over the years, we have implemented many of the important traits of emphasis taught by Dr. Bonsma and have seen it pay dividends to our herd in the form of functionality and long-term profitability. In 2020 with permission from the Wortham Foundation, we were allowed to print a copy of Dr. Bonsma’s Wortham lectures so we could make them available to other ranchers looking to make improvements.

Lessons in Livestock Ecology

To understand Jan Bonsma and his teachings regarding beef cattle, we must first take a look at his definitions of livestock ecology and the four main ecological regions.

Bonsma states, “Animal ecology is the science which explains the interaction between the animal and it’s total environment.”He also breaks things down into four major climatic zones: Scorching (Hot and Dry), Muggy (Hot and Wet), Keen (Cold and Dry) and Raw (Nice temperatures, moderate humidity. He goes on to describe in detail examples of what breeds and species fit best in these environments.

This should make sense to many Brahman breeders, because we are very aware of our breeds superior production in the warmer and more humid areas of the globe, where in a place like the Midwest, or Rocky Mountains there are probably some Bos Taurus breeds that would have the adaptation advantage. This is a prime example of a Genotype-Environment Interaction and is one of the most important considerations to make when selecting the right cattle for your respective operation.

Figure 2. Illustration of the four major climatic zones of Bonsma’s livestock ecology teachings.
Drawing digitally re-created by Rachel Cutrer, 2020.

Judging for Functional Efficiency

Dr. Bonsma uses an awesome quote to open the chapter of Judging cattle for functional Efficiency which states, “At the moment of conception the complete genetic potential of that animal is fixed.” That is why proper selection of an animal with a desirable phenotype (physical appearance) and genotype (genetic makeup) is mandatory for success and profitability. From the point of conception on, the only thing that impacts the appearance of an animal are environmental factors like nutrition, climate, etc. Let’s not forget too, that choosing animals that fit the environment they are expected to produce in is just as important, or more important than anything else.

His first topic of discussion was the concept of Secondary Sex Characteristics. Let’s describe that in terms everybody will understand: we want bulls to look like men, and cows to look like ladies. He continues into more details by describing how hormone activity ultimately influences the masculinity and femininity in your breeding herd and in turn impacts fertility. When discussing a bull, we see courser hair, increase in muscling in the crest, shoulder, shank and stifle. For a female on the other hand, the ovarian hormones produced help give that cow a feminine appearance and progress the development of her udder.

How to identify a fertile female from a sub-fertile female:


  • Feminine featured in the head and neck
  • Brisket small (not full)
  • Lots of capacity
  • Finer / shiner hair coat
  • Wide hip
  • Dewlap / brisket fold

Sub-Fertile (not fertile)

  • More masculine look, especially in the head and neck
  • A bigger, more pronounced brisket
  • Heavier front end
  • Less capacity
  • Longer, heavier bones
  • No dewlap / brisket fold
  • Coarse hair, especially down the top and on her poll
  • Short from hooks to pins

Pictured above, a female who was still producing at 21 years of age here at BRC. She is an excellent example of a cow following Bonsma’s teachings on functional efficiency. She is feminine, has a slick coat, is widest through her midrib, and even has the dewlap fold.
Brisket fold that is present in fertile cows.

How to select for high fertility in bulls

Using the Bonsma principles of judging for functional efficiency is also easy to do in bulls, with practice.

Fertile bulls:

  • Darkening of the hair around the hump and crest
  • Sleek hair coat
  • Well developed neck crest / hump
  • Large, muscular upper front limb
  • Adequate testicular size with an even descent
  • Acceptable sheath length, size and shape
BRC Dutton 376/8
BRC Dutton 376/8 is a bull we feel follows along with Bonsma principles very well. Look at the darkening over his hump and shoulders. Everything from his muscular hump and forelimb to his slick shine hair coat follows Bonsma princples. Also note, of extreme importance, his tight sheath and correct sheath shape and angle.

Low fertility bulls:

  • Have a feminine head / appearance
  • Lacking in masculine features in the head, neck and fore limb
  • Under-developed or uneven testicle size and descent
  • Mammary development
  • Loose, pendulous, droopy sheath with large opening
Example of a bull with a loose, pendulous sheath that is a sign of poor fertility. *This is a sample photo, this is not a bull owned or bred by BRC.

Where do you go from here?

This is just the tip of the iceberg for an overview of Dr. Jan Bonsma’s principles and how they can be applied to beef cattle.

For anybody interested in applying an in-depth approach to cattle selection for longevity and functionality, I would highly encourage you to look over Dr. Bonsma’s books. We send a free copy to anyone who buys cattle from us, because we think it’s that important to educate our customers.

One of these books, “The Wortham Lectures” is available in on Amazon thanks to our reprint and The Wortham Foundation’s generosity. It is available at cost – $3.99. We use it as a guide frequently on the ranch with desirable results. Some of his other works are very hard to find but searchable on eBay or similar sites.

As seedstock producers, we are always trying to stay ahead of the curve when it comes to genetics technologies, and that has certainly led to huge improvements across the industry over the years. Still, we as producers must not forget to spend time also studying and selecting on phenotypes that more frequently see success in our ecological environment.

Through selection of cattle that meet the criteria Bonsma put into place for each gender, we as producers can create a practical, user friendly method to develop a cow herd that maintains functionality, fertility, and ultimately long-term profitability.

Find us at to learn more about Bonsma and see his teachings through our cattle genetics.

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