This is an abbreviation of unit 3 from the Advanced Equine Nutrition course. The complete text, a video, and quiz questions are available with The Horse’s Advocate membership. You can also purchase them separately. Note: Passing the Basic Equine Nutrition Course is required before starting the Advanced Course.

Unit 3 – Energy Flux: The Flow Of All Life

The First Law Of Thermodynamics

The First Law of Thermodynamics states that energy is neither created nor destroyed. It can only change from one form to another.

Energy flux refers to the change of form from energy chemically stored within the food horses eat. It also includes the water they drink and the air they breathe (all called substrates). Additionally, it denotes the speed at which this energy transitions through the body into carbon dioxide and water (called waste). It includes all the processes in between (eating, digestion, metabolism, and elimination). What comes into the horse must equal what goes out. Adjustments occur based on what is placed into or removed from storage. Many call this energy balance.

In math, balance is equal parts on either side of the equal sign. These days, the term balance is overused. However, in terms of energy, balance is an irrefutable law of physics. This law occurs throughout our universe. It applies to you and your horses. Let’s take a look at this through the lens of feeding horses.

Key Points:

1. The 1st Law Of Thermodynamics – energy can’t be created or destroyed but can only change form. In nutrition, it is stated as calories in = calories out.
2. Energy flux is the movement of energy through the body. It changes from chemical energy in food to electrical energy in the cells.
3. Multiple factors can affect calories in (starvation, abundance) and calories out (metabolic problems).
4. Horse owners need to “adjust the dials” to balance energy in and energy out.
5. The third Law Of Thermodynamics, also called entropy, states that energy is essential. Energy allows things in the universe to keep their form and function. No energy = no life.
6. Glycolysis is the beginning of energy production as glucose is broken down within the cells.
7. The Krebs cycle breaks down the end product of glycolysis and fat to create abundant electrical energy.
8. Cellular fuels include air, water, sugars, fats, and amino acids. They enter the body or are made within it. They are stored as glycogen or body fat as a buffer against a sudden or long-term need for energy.
9. Energy in = energy used, stored, or excreted.
10. An abundance of food plus decreased metabolic efficiency leads to reduced energy flux, resulting in disease, breakdowns, and premature death.