OSU Researcher Examines Facts about Hormones and BeefMon, 05 Nov 2012 13:08:38 CST
In the latest Poultry Practices Newsletter from the Oklahoma State University Extension Service, Josh Payne, Ph.D., Area Animal Waste Management Specialist, compares the levels of hormone exposure from treated beef and other common food sources.
Hormone use in US meat production, or the lack thereof, is a controversial and often misunderstood subject. For example, hormones are not used in poultry or swine production but growth hormones are sometimes used in beef production to produce a leaner meat product more efficiently. Questions exist in the public sector regarding the safety of consuming hormone-implanted beef. In short, the use of supplemental hormones in beef production has been scientifically proven as safe for consumers and is approved by the US Food and Drug Administration (FDA). In an effort to better understand the use of hormones in beef production, letís explore the science supporting these facts.
Hormones are products of living cells naturally found in both plants and animals that often stimulate cellular activity. There are six hormones approved for use in beef production. Three are natural hormones (testosterone, estradiol, and progesterone) and three are chemically similar synthetic hormones (trenbolone acetate, zeranol, and melengestrol acetate).
Growth hormones in beef are primarily administered using a small pelleted implant that is placed under the skin on the back of the ear. The implants are designed to release the hormone slowly over time into the bloodstream. This ensures that hormone concentrations remain constant and low. Since the ear is discarded at harvest, the implant does not enter the food chain. Implants work by enhancing the secretion of natural growth regulating hormones and through stimulation of other cellular mechanisms in tissues. This, in turn, increases feed efficiency, protein deposition and growth rate. Implanted calves usually result in a 10-20% increase in average daily gain (growth rate) compared to non-implanted calves.
Moreover, because of the increased feed efficiency, less feed is required which decreases production costs by 5-10%.
Since implant doses are low, the use of implants in cattle has very little impact on hormone levels in beef. Table 1 illustrates that 500 grams (~ 1 lb) of beef from an implanted steer contains approximately 7 nanograms of estrogen compared to 5 nanograms of estrogen from non-implanted beef. Furthermore, there are many common foods that are naturally much higher in estrogenic activity than implanted beef.
For example, 500 grams of tofu contains 16,214,285 times the estrogenic activity compared to the same amount of implanted beef. To gain additional perspective on the minuteness of these measurements, nanograms are equivalent to one billionth of a gram. One gram is roughly equal in weight to 1 small paper clip. If we were to divide the same paper clip into 1 billion tiny pieces, one of those tiny pieces would equal 1 nanogram.
Table 1. Estrogenic activity of common foods (Nanograms of estrogen for animal products and isoflavones for plant products per 500 grams of food):
Soy flour defatted 755,000,000
Pinto beans 900,000
White bread 300,000
Beef from implanted steer 7
Beef from non-implanted steer 5
Some consumers question whether consuming beef implanted with hormones can cause cancer or early puberty in children. Hormone implanted beef has never been implicated in adverse health effects in humans. Height, weight, diet, exercise and family history, however, have been found to influence the age of puberty. Furthermore, the amount of estrogen consumed in implanted beef is negligible compared to the amount the human body produces each day (Table 2). The average non-pregnant woman produces 513,000 nanograms per day. The average manís body produces 136,000 nanograms per day. An average child will produce 41,000 nanograms of estrogen per day.
Table 2. Estrogen production in humans and potential estrogen intake from implanted beef:
Item Estrogen amount
Pregnant woman 19,600,000 nanograms/day
Non-pregnant woman 513,000 nanograms/day
Adult man 136,000 nanograms/day
Pre-pubertal children 41,000 nanograms/day
500 g of beef from implanted steer 7 nanograms
Regarding potential environmental concerns associated with growth hormones, the FDA has determined that the use of natural hormones in beef does not pose a risk to the environment as the amounts administered to calves are much lower than amounts naturally produced by adult cattle. Regarding synthetic hormones, extensive environmental risk studies have been conducted and the FDA has determined that the use of these hormones will not significantly impact the environment.
Most of the beef produced in the US spend most of their lives in a pasture and are then finished in a feedlot where they are given a grain-fed diet. Beef that are finished in a feedlot with the aid of growth hormones require less total land mass, less feed crops and create fewer greenhouse gasses per pound of beef produced compared to non growth hormone pasture-based finishing systems.
Consumers who prefer to purchase naturally produced or organic beef raised without growth hormones should be prepared to pay a premium. Implanted beef reduce the cost and resources required in beef production and that results in lower costs that are passed on to the consumer.
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