For years, we’ve heard the rumors, speculation and accusations that hormones in beef are behind the trend toward young girls reaching puberty at younger ages. The idea seems far-fetched, as hormone levels in beef from implanted cattle are virtually indistinguishable from those in beef from non-implanted cattle. There's no real evidence, but since the cause or causes behind the trend toward earlier puberty remain a mystery, the rumor persists.
Now, though, researchers at North Dakota State University are conducting a trial to test the theory. NDSU animal science faculty members Eric Berg and Kim Vonnahme, and graduate student James Magolski, have begun the project with funding from the North Dakota Beef Commission and the State Board of Agriculture, Research and Education.
Their hypothesis is that consuming beef obtained from cattle receiving an estrogenic implant strategy during feedlot finishing does not alter the timing of puberty or the body composition post-puberty, compared with consuming non-implanted “natural” beef or a common meat alternative, tofu.
Because of the difficulty and ethical challenges in conducting such a trial in humans, the team is using 24 young female pigs, born within 12 hours of each other and from identical sire and dam genetic lines.
The researchers penned the 35-pound gilts individually and fed them a base diet containing no soybean meal to keep estrogen levels low. The base diet also serves as a control. Treatment groups receive either tofu, beef from implanted cattle or beef from non-implanted cattle, with each diet similar in protein content and calories. The team will take blood samples twice a week to measure hormone levels.
At onset of estrus, the team will slaughter the pigs and analyze reproductive tracts as well as muscle and fat samples to determine body composition and hormone levels.
It seems doubtful that this or any other scientific trial will show any link between implants and puberty in girls. Renowned meat scientist Gary Smith for example, posts on his “Where Food Comes From” blog that a pre-pubescent girl would need to consume 47,384 pounds of implanted beef per day to equal the estrogen levels in an adult woman.
It will be interesting to see how this trial turns out, and whether the results influence public perceptions. We’ll let you know as soon as we learn more.