Dietary differences can confound animal studies
Scientists then went on to develop multiple standardized diets for animal facilities and laboratories, leading to the production of various standardized pellet foods for laboratory rats and mice. “It became very clear that nutrition was going to be one of the key components in improving rigour and reproducibility,” Watts says.
. But those diets still encompass a lot of variation. And they don’t exist for many common animal models. Several were developed for reasons of cost and practicality, rather than to mimic an animal’s natural habits. So careful documentation of the experimental set-up is crucial to improving the replicability of experiments, says David Allison, a biostatistician at Indiana University Bloomington who worked on teasing out the differences between the NIH and Wisconsin primate studies. Including details about the diet used in a study can help future researchers to “decide whether they want to replicate it and how to interpret the results”, he says.Across various species, researchers have found that variations in food can yield unexpected results, ranging from small deviations that “don’t really inform the science” to data with profound implications for the conclusions, says Allison. For instance, in one long-running study Allison was involved in, rats developed bladder stones owing to an adulterant in some batches of food bought from a commercial supplier. That meant that they didn’t have animals from which to draw statistically significant conclusions and had to go back to the drawing board to work out why it happened and fix the problem before continuing the experiment. And in another, they had a similar situation when the animals developed skin lesions because of excess vitamin A. Although these issues didn’t affect Allison’s conclusions, the observations “made our experiments not as pristine as we wished”, he says. “It’s an issue that often comes up in longevity studies, because the animal is being fed the same foods for so long.” Even in short-term studies — and even with standardized diets — experimental complications crop up. In 2018, dietitian Caroline Tuck at La Trobe University in Melbourne, Australia, was studying short-chain fermentable carbohydrates known as FODMAPs, which can exacerbate conditions such as irritable bowel syndrome in humans. When researching diets with different FODMAP levels in mouse models, she realized that standardized laboratory diets vary widely in their levels of protein and micro- and macronutrients. “Standard chow can be so many different things,” says team member Giada De Palma, a microbiome researcher at McMaster University in Hamilton, Canada. To assess the impact of the various foods, the team fed four groups of mice different commercial foods for three weeks, and found significant differences in the microbial diversity in the caecumThe specific composition of mouse chow can affect the rodents’ behaviour and physiology.Tuck and De Palma emphasize that no one diet was better than the others. But, given the differences, they recommend that scientists using pelleted feeds consider whether the composition might affect their research question. “It’s really about considering it at the design phase of an experiment,” says Tuck, “rather than as an afterthought or just using whatever is routinely used in the lab.” Furthermore, Tuck says, researchers should report the specifics in their studies. “When publishing, we talk about when the animals had access to food and water, but actually listing exactly what the diet was is really important as well.” Careful documentation also helped to solve the question of whether caloric restriction helped rhesus monkeys to live longer. When retracing their steps, researchers at the NIH and at Wisconsin found that the contrasting findings could have been caused, in part, by the quality of the food, the timing of administration and the animals’ own choices . For example, monkeys at the NIH had access to food throughout the night, whereas those in Wisconsin had their afternoon fruit snack removed at the end of the day.Another route to improving reproducibility is to focus on animal welfare and encompass more variety in the diet, says Robyn Crook, a behavioural neuroscientist at San Francisco State University in California. “There’s a lot of value that comes from not having a standardized diet,” she says. Consistent data from animals that “are homogeneously extremely stressed and deprived” are not useful to research. “There’s only so much you can standardize about the life of a rat or a mouse before you start to negatively impact welfare. And then you negatively impact science as well,” she says. Gribble agrees. “Some lab diets are not even close to what those animals would be eating in the wild,” she says. “It’s not the nutritional profile that those organisms have adapted to, so that alone could change results.”
United States Latest News, United States Headlines
Similar News:You can also read news stories similar to this one that we have collected from other news sources.
Ukrainian soldiers are now using powerful electric bikes to take out Russian tanksELEEK and Delfast are making a difference in the Ukraine war by providing Ukrainian soldiers with electric bikes that they can use to destroy Russian tanks.
Read more »
The Kardashians Roll Into Italy for Kourtney Kardashian-Travis Barker WeddingThe celebration is reportedly being held at a Middle Ages castle overlooking the Gulf of Portofino.
Read more »
Pep talk from caddy helped secure PGA Championship crown, says ThomasA pep talk from his caddy made all the difference for Justin Thomas as he collected his second major title after staging an incredible comeback to win the PGA Championship on Sunday.
Read more »
'I study animals, here are 4 dating tips I've learned from them'I decided to apply animal behavior principles directly to my personal life—specifically my dating life.
Read more »
A’s attendance woes reaching historic, embarrassing stageIt was revealed that only 1,452 fans showed up to one A’s game last month.
Read more »
What Is Dietary Fat?Everything you need to know about dietary fat and why including it in your diet is important for good health
Read more »