How Cows Choose What They Eat

While it seems safe to assume that the answer to “what do cows eat?” would be “grass,” it turns out there is a lot more going on when it comes to cows and their diet. Last month, On Pasture ran a story featuring Dr. Fred Provenza of Utah State University. After 30 years of research, he has gained some valuable insights into the contributing factors of why animals choose what they eat, and this knowledge could prove valuable as guidelines for livestock land management.

Here’s what Fred discovered: Food Choosing is a Learned Behavior

  • Animals learn what to eat from their mother

  • They learn from their herd mates

  • They learn from their own experiences consuming nutrients and toxins

Animals will naturally forage to mix a diet that has the perfect balance of elements for their individual needs. In one study, steer grazing on phosphorus deficient land started eating dead rabbits in the pasture to naturally supplement their diet with phosphorous in the rabbit bones.

8 Behavior Principles from Dr. Fred Provenza (via On Pasture)

  1. Behavior Depends on Consequences
    Think positive and negative reinforcement: Positive consequences increase the likelihood of an animal repeating a behavior and negative consequences decrease the likelihood of an animal repeating a behavior. Positive consequences have fewer negative side effects.

  2. Mother Knows Best
    The greatest influence on a cow’s food choices is its mother. First learning what to eat and where to eat is is passed from mother to calf through generations.

  3. Early Experiences Matter Most
    The behavior of animals changes throughout their lives based on experience. Animals are more likely to try new things, including foods, early in life. Experience can change the an animal’s physiology, neurology, the structure of its body even gene expression.

  4. Animals Must learn How to Forage
    Believe it or not animals actually have to learn how to eat. Young animals acquire foraging skills more quickly early in life than older animals.

  5. Animals Avoid Unfamiliar Foods
    Animals don’t naturally gravitate toward eating new foods; it can be risky if they are toxic. Given the option, they generally avoid trying new foods and opt for familiar, nutritious foods.

  6. Palatability Depends on Feedback from Nutrients and Toxins in Food
    As stated earlier, animals had an internal feedback loop based on the nutrients and toxins released into their body during digestion. The compounds are absorbed and travel to the cells and organs of the body. Signals are then sent back to the brain to tell it how well a food meets the animal’s nutritional needs. The brain then pairs the food’s flavor with it’s benefits, toxicity or lack of benefits to the body. Nutrients increase palatability while toxins decrease it. These changes in food preferences are part of the feedback loop and are automatic.

  7. Variety is the Spice of Life
    Giving animals access to a variety of foods on pastures allows them to learn to naturally manage their own nutrient needs. Fred also discovered that when we make pastures that are just grass, and we move the cattle when just the grass is eaten, we’ve created cows that don’t know things besides grass could be grazed.

  8. Everybody is an Individual
    Every cow is different and nutrient needs as well as toxin tolerances will naturally vary.

On Pasture Author, Kathy Voth notes, “One of the things I like best about Fred’s research is that it points out importance of asking questions, even when everyone else thinks the answer is obvious. Because he did this research we now have options and opportunities with our livestock that we never would have had otherwise.”