Tag Archives: testosterone

HORMONES IN BEEF: part one of three (exerpted from my book)

8 Mar

One of the flashpoints in any discussion of beef consumption is the use of hormones; or more specifically, growth hormones. Exactly what are they and why are they used?  And more to the point, are they as dangerous as some people claim?

Language is an interesting thing. You can use words to create emotional responses. Like “hormone-free” beef. There’s no such thing. It’s impossible.

Why? Because all animals—like all human beings—produce natural hormones in their metabolisms. In fact, every multicellular critter (cattle, people, dogs, birds, vegetables, whatever) creates its own natural hormones. If you’re worried about hormones in beef, what you need to look for is are the terms no added hormones or no hormones administered.

What exactly is a hormone? It’s a chemical released in one part of your body that affects another part. Hormones like estradiol, progesterone, and testosterone (aha, those “low T” ads) are naturally present in beef, and also in pork, poultry, milk, eggs and fish. But guess what? Plant foods like potatoes and wheat contain significant levels of progesterone, and some oils and plants also contain testosterone. Milk products provide about 80% of the progesterone, 30-40% of the testosterone and 60-70% of the estrogens in our diet. Meat and fish, about 5% of the progesterone, 20-30% of the testosterone and 15-20% of the estrogens in our diet.  

When people talk about when they talk about hormones in beef is really the administration of a growth hormone to stimulate weight gain in young cattle. There are several reasons for this. People who eat beef prefer (and have come to expect) tender meat. This means eating the meat of younger animals, because the meat of a younger animal is naturally more tender than that of an old animal (obvious, really). For this reason, beef cattle are usually slaughtered at a very young age (from about 18 months to two years). Most male cattle are neutered when they’re young (a process that turns bulls into steers); female cattle (heifers) are spayed. Neutered steers and spayed heifers produce fewer natural hormones than older animals (same with humans), so small amounts of certain hormones are given to them to help them grow.

Most cattle finished in the conventional way are given growth promotants via ear implants. These are small pellets placed underneath the skin in the middle one-third of the ear—a place where there’s no way they could accidentally be included in products intended for human consumption, and no risk of hormone residues entering the meat. The pellets dissolve gradually over 60 to about 120 days, and must be completely depleted before slaughter. Feedlot operators must verify that the pellet is “dead” at least 30 to 45 days before the animal is killed.

Ear implanting

Ear implanting

After the pellet is implanted, its active ingredients are slowly released into the animal’s bloodstream, increasing its blood hormone level just enough to stimulate additional growth in muscle. Implanted animals grow faster, are leaner, and use feed more efficiently. Since the conventional cattle feeding business is defined by very narrow margins affected by seasonal swings in feed costs, the use of implants more than pays for itself in delivering larger, leaner cattle. Note this comment, however, from an implant information sheet: “All growth implants . . . show the greatest improvement in gains and efficiency on higher energy diets.” So the type and quality of feed is critical.

Implants increase weight gain by 5 to 23 percent and improve feed efficiency from 3 to 11 percent. Essentially, the animal grows larger faster, and so can be slaughtered younger. The hormones used are identical (either natural or synthetic versions) to the hormones cattle naturally produce. Today, both the United States and Canada have approved three natural hormones (estradiol, progesterone, and testosterone) and three synthetic hormones (zeranol, trenbolone, and melengesterol) to help cattle feed efficiently, bulk up faster, and develop leaner meat. Note that melengesterol is administered via feed, not implant.

Implants work by speeding muscle growth and reducing fat deposition. Comparing an implanted animal with an animal of the same weight that has not been implanted, the implanted animal will be leaner. But since beef grades are primarily based on the degree of marbling (measured as the amount of internal fat in the rib-eye muscle), implanted cattle will generally need to be fed longer, so that they have time to put on more muscle and marbling.

In the United States, hormone implants are regulated by the Food and Drug Administration. The Food Safety Inspection Service of the USDA tests for synthetic hormone residues in meat, but they don’t test for natural hormone residues. It can’t be done . . . animals produce natural hormones throughout their lives. It’s simply not possible to differentiate between hormones occurring naturally, and those from implants. This means that to some extent, the use of growth-promoting hormones cannot be regulated.

Next post: Part Two – Are Hormone Implants Safe?… The Politics