This issue of our newsletter/blog deals with the use of the hormone estrogen in beef cattle production. In keeping with our mission, we want to discuss why and how the practice of supplementing estrogen in beef production is used and, of course, is the meat from implanted cattle safe to eat. As consumers or beef producers, we want to be comfortable and confident that we can answer the questions to our own satisfaction. The following information should help you do that.
Basics of estrogen supplementation for beef cattle:
- When: calves are generally supplemented during the feeding phase at feedyards, but can be implanted prior to weaning or as stocker calves on the ranch.
- Process: time release tablet is placed under the skin of the ear so no part of the implant enters the food chain.
- What: Estrogen/Estradiol. Estradiol is the same hormone therapy used in human therapies, including birth control pills.
- Effect: increase in growth, measured by ADG (average daily gain) and increase in feed efficiency (amount of gain per pound of feed consumed)
- Safety: all implants have use and time restrictions required by USDA and FDA. Withdrawal periods are legal requirements and added safety precautions which should insure consumer confidence. See charts below for level comparisons in beef, other foods, and humans.
|Table 5. Estrogenic activity of common foods.|
|Food||Estrogenic activity in
nanograms/lb of food
|Beef from pregnant cow||636|
|Beef from implanted cattle||10|
|Beef from non-implanted cattle||7|
|Adapted from Preston, 1997.|
|Table 6. Estrogen produced, nanograms per day.|
|3 oz implanted beef||1.9|
|Adopted from Preston, 1997|