November 25, 2015

Turkey science: What’s on your plate?

by Bonnie Denmark

The 45 million turkeys that end up on the Thanksgiving table are nothing like their wild ancestors. In fact, they are very different from the typical Thanksgiving turkeys of even half a century ago, according to biologist and turkey expert Richard Buchholz of the University of Mississippi. Until the 1950s, Americans enjoyed a variety of turkey breeds developed over hundreds of years. These traditional turkeys were smaller and known for their beautiful plumes. But who cares about plume color when carving a roasted bird? Besides, colorful feathers make for unsightly dark pin quills that need to be removed by cooks. What consumers wanted was plentiful, cheap white meat and no dark pin feathers. Turkey farmers listened, going to great lengths to create a turkey tailor-made for the Thanksgiving platter.

People wanted a turkey with more white meat. (Wikimedia Commons)

For thousands of years, humans have used selective breeding, or artificial selection, to produce crops and animals with desirable characteristics. (Charles Darwin coined the term “natural selection” after the age-old practice of artificial selection. See our module Charles Darwin II for more on how selective mating happens both naturally and artificially to promote desired traits.) Selective breeding programs target inheritable phenotypes, that is, the physical traits an organism expresses. Through artificial selection, turkey farmers gave the American public just what they asked for. In the 1950s, Broad Breasted White turkeys hit the market, and today most turkey eaters have never tasted anything else. These birds are market-ready in a very short time and have disproportionately large breasts for abundant white meat. In addition, they have white feathers, so dark pin quills are not an issue. The downside is that achieving such a narrow purpose through artificial selection has come at the expense of many admirable qualities traditionally associated with turkeys.

A wild turkey in the eastern US. (Wikimedia Commons)

In the wild, turkeys are known as fast, curious, energetic, social birds who cleverly elude hunters. Turkeys naturally forage for a varied diet of nuts, seeds, berries, roots, insects, amphibians, and small reptiles. Broad Breasted Whites are confined to pens and are fed a constant bland diet of fortified corn-based food. They couldn’t forage if they wanted to – their beaks are clipped to be used more like shovels, and those who shovel their food most efficiently are selected to create the next generation. These birds were engineered for large size, quick growth, and light color. Period. This tightly focused breeding has led to less genetic diversity in Broad Breasted Whites, resulting in higher susceptibility to disease and the need for antibiotics. And they are notoriously stupid since their natural instincts have been bred out of them.

Professor Buchholz describes other collateral effects of the breeding that produced these bulked-up birds. Although Broad Breasted Whites sparked a turkey industry bonanza, their short life is not pleasant. The same traits that make them Thanksgiving platter-worthy render them unable to move comfortably or to reproduce except by artificial insemination. Further, they suffer myriad health problems such as heart, respiratory, joint, and eye problems. Even if they manage to escape slaughter, Broad Breasted Whites do not live long. Case in point: None of the six turkeys pardoned by Obama as of Thanksgiving of 2012 were still alive by Thanksgiving 2013. Three of the last four died within five months of their presidential pardon; the other one lived a mere 16 months. “The bird is bred for the table, not for longevity,” says Dean Norton, who is in charge of the sanctuary for pardoned turkeys.

A Broad Breasted White turkey receives a pardon from President Obama in 2009. (Lawrence Jackson, Official White House Photographer)

Before Broad Breasted Whites ruled the market, many domestic turkey strains such as Narragansetts, Bourbon Reds, and Standard Bronzes were found on farms and tables. These ancestors of the Broad Breasted Whites, known as “heritage turkeys,” have beautiful plumage and moist, flavorful meat but are smaller and take longer to reach market size than the industrial breed that makes up over 99% of supermarket turkeys. Heritage breeds have maintained greater biological diversity, so they are much hardier than their Broad Breasted White cousins. Raised slowly in pastures where they forage, socialize, mate, fly, roost, and engage in other normal turkey behaviors, the heritage varieties live twice as long as their dumbed-down, penned-up, factory-raised counterparts.

After nearing extinction in the 1990s, heritage breeds are making comeback as more people have joined the “Slow Food” movement. Misgivings over antibiotics in poultry along with concern for animal welfare have contributed to a renewed interest in heritage turkeys among people who care about where their food comes from. Heritage birds are pricier since they take longer to get to market, yet fans say they are well worth the extra cost and wait – heritage turkeys win hands-down in blind taste tests.

As for Buchholz, he tells Scientific American, “I am going to eat a nice Butterball® turkey…and I will enjoy him.” For the rest of us, there’s always tofurkey.

 

LEARN MORE

Listen to an interview with University of Mississippi professor of biology and turkey expert Dr. Richard Buchholz in the Scientific American podcast Taming the Wild Turkey.

For an introduction to how traits are passed down from one generation to the next, see our module Mendel and Inheritance.

Read Kimberly Crandell’s Did Science Build a Better Turkey? on the livescience website.

Written by

Bonnie Denmark holds an MA in linguistics and teacher certification in English, ESL, and Spanish. She has devoted her professional life to educational and accessibility issues as a computational linguist, multimedia curriculum developer, educator, and writer. She has also worked nationally and internationally as a language instructor, educational technology consultant, and teacher trainer. Bonnie joined the Visionlearning team as a literacy specialist in 2011, assisting the project by developing comprehension aids for science modules and creating other STEM learning materials.