Other methods of analyzing pet food protein and amino acid digestibilityhave drawbacks compared to the cecectomized rooster assay.

A surgical procedure, similar to a human appendectomy, turns roosters into aneffective, efficient model for dogs’ and cats’ digestive systems, which helpswith pet food nutrition research. The technique, called the precision-fedcecectomized rooster assay, allowed Kelly Swanson, PhD, University of Illinois– Urbana-Champaign animal nutrition professor, to compare the digestibility ofchicken meal to raw, steamed and retorted chicken.

How the cecectomized rooster assay helps pet food analysis

“We and others in the pet food industry not only analyze protein quality(amino acid profile) of ingredients, but use the cecectomized rooster assay toassess amino acid digestibility,” he said. “Knowing both protein quality anddigestibility are needed to accurately formulate diets and ensure thatdogs/cats are meeting their needs.

“Although the current study only tested specific ingredients, one can use thisassay to test complete diets that are processed in various ways,” he said. “Ifdone in that manner, one could compare how extrusion compares to retort,pasteurization, freeze-drying, etc. It could also be used to test kibble dietsformulated using chicken meal versus fresh chicken.”

Other methods of analyzing pet food protein and amino acid digestibility havedrawbacks compared to the cecectomized rooster assay. For example, estimatesof digestibility that use fecal analysis aren’t accurate because the bacteriaand other microorganisms, or microbiota, in dogs’ and cats’ large intestinesalter the results, Swanson said. Cat and dog microbiota eat some of thenutrients in the animals’ food too, masking the true digestibility of the petfood.

“In addition to avoiding the bias provided by large intestinal microbiota, thececectomized rooster assay allows one to test individual ingredients,” hesaid. “This is not possible in dog or cat studies where complete diets must befed, and the ingredient in question is only a proportion of the diet.”

Likewise, in vitro studies of nutrient digestibility can’t match thececectomized rooster assay, Swanson said. In vitro lab experiments focus onspecific ingredient categories, such as soy- or chicken-based proteins, sothose procedures aren’t accurate for other ingredients. This makes itespecially difficult to test novel pet food ingredients.

“Therefore, we believe that the cecectomized rooster assay is the best choicefor testing the amino acid digestibility of novel protein sources or thoseundergoing different processing conditions,” he said.

Effects of cecectomized rooster assay on the birds

For decades, scientists have used the cececomtized rooster assay as a model ofnot only dog and cat digestion, but also that of humans and livestock.Although differences exist between mammals’ and birds’ anatomy and metabolism,biologists have found that the cececomtized rooster assay provides a goodestimate for dogs, cats and other animals’ digestion.

The roosters themselves experience few health issues from the surgical removalof their two cecum, or ceca, said Swanson. Roosters need a brief recoveryperiod before the studies begin, then the birds can be housed and cared forjust like other roosters in animal research facilities.

“In regards to animal welfare, the rooster assay is a good example of the 3R’sof research: reduction, replacement and refinement,” said Swanson. “Itreplaces the need for work in dogs and cats, is a refined and accuratetechnique, and requires a small number of animals (four or five birds peringredient tested) due to its accuracy.”

Source: Petfood Industry News

Image: Bigstock

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