Defining and measuring feed efficiency is something I have always struggled with. It’s definitely not as easy as science wants it to be. Science wants to break everything down into understandable bits and pieces. Unfortunately, that won’t work in the real world. The real world is made up of wholes with thousands of interactive pieces.
Before we continue, we need to understand that all beef animals fall into two basic categories. Some animals are destined to end up on the dinner table, while others are working in a cowherd to produce more beef animals. Ironically, success in both categories is dependent on the same thing – storing up energy in the form of fat. Beef does not provide an enjoyable eating experience until it has stored up enough fat to grade Choice or Prime. A cow is incapable of getting bred until she has stored up enough fat to come into estrous.
You cannot assume the animal that gains the most is the most efficient because you don’t know how much feed was required to achieve those gains. Therefore, the beef industry came up with ways to determine how much feed is required to produce a pound of gain. On the surface, this seems like the ideal way to measure feed efficiency. In reality, though, feed to gain ratios have done nothing but create taller and taller animals that are leaner and leaner. Animals that do the best in these tests are gaining pounds of skeleton and muscle – not fat. It takes much, much less feed to produce skeleton and muscle than it does to produce fat.
All beef animals must meet their maintenance requirements before any weight gain can take place. After the maintenance requirements have been met, nutrients will first be allocated to skeletal and muscle growth. After those needs have been taken care of, nutrients are made available for milk production in lactating animals. Fat deposition, which is by far the most important, cannot take place until all other needs have been met. A pound of fat requires 2.5 times more energy and feed than a pound of muscle or bone. Therefore, it takes substantially more pounds of feed to produce a pound of fat than it takes to produce a pound of muscle or bone.
Daughters of the so-called “feed-efficient” bulls will be tall, late-maturing, hard-keeping and difficult to get bred. Fertility is more a function of fleshing ability than of anything else. Cows must be storing up energy in the form of fat before reproduction is possible. Therefore, if you produce your own replacement heifers and if you are going to purchase bulls that have been tested for feed efficiency, we suggest you to select for bulls that performed the worst in the feed efficiency test. Their offspring will be early-maturing animals with great fleshing ability.
More and more seedstock producers are using GrowSafe systems to test their bulls for so-called “feed efficiency.” Without exception, these tests heavily favor tall, hard-keeping animals. Moderate-framed, early-maturing animals that have the propensity for fat deposition will never be able to compete with tall, late-maturing, hard-keeping animals in a traditional feed-efficiency test. Remember, it takes 2.5 times more energy (feed) to produce a pound of fat (body condition) than it does to produce a pound of muscle or bone.
In the name of feed efficiency,the beef industry has inadvertently created tall, lean cattle that take longer and longer to finish and are difficult to get bred. This has been going on for the past 40 years – and it continues to get worse every year.