Rendered Ingredients Significantly Influence Sustainability, Quality And Safety Of Pet Food

By:  Meeker and J. Meisinger, J. Anim. Sci. 2015.93:835–847, condensed by Steve Boyles, OSU Extension Beef Specialist

The United States currently produces, slaughters, and processes approximately 112 million pigs, 32 million cattle, and 8.5 billion chickens annually. The current volume of raw material rendered in the United States and Canada is nearly 25 million tons.  Meat consumption worldwide is expected to increase to about 100 pounds per capita by 2030. This large increase is mostly due to the increase in meat consumption by people in developing countries.

A DESCRIPTION OF RENDERING:  Rendering is one of the oldest forms of recycling and is the basis for improved sustainability of animal agriculture. Byproducts from food animal agriculture are rendered into many useful products. For instance, meat and bone meal, meat meal, poultry meal, hydrolyzed feather meal, blood meal, fish meal, and animal fats are some of the primary products resulting from the rendering process. The most important and valuable use for these animal byproducts is as feed ingredients for livestock, poultry, aquaculture, and companion animals.  Medical supplies are also extracted.

So-called “offal” is safely consumed in many countries around the world by humans. Historically, much more of an animal was consumed by humans with much less “waste”. This animal offal is the primary raw material for rendering operations, with additional amounts coming from condemned or fallen animals, material generated from restaurants (such as fryer grease), grocery stores (such as bones, fat, and scrap from meat cutting or leftovers from the deli), and butcher shops.  “Fallen animals” or livestock that die outside of slaughter facilities amount to only 3.75% of all rendering raw material.

All rendering processes involve the application of heat, the extraction of moisture, and in North America generally do not incorporate cooking under pressure except for feathers and other high keratin-containing products. Temperatures between 239 to 295°F for an average of 40 minutes or more are used in the rendering process.  The range of temperatures and times used in current rendering protocols in the United States and Canada were deemed sufficient to destroy the avian influenza virus. The temperature/time to kill porcine epidemic diarrhea virus as determined by the National Pork Board are well below that used in the rendering process.

CONSUMER AWARENESS AND PET FOOD:  Rendered fats and oils such as tallow, lard, poultry fat, and fish oil provide a supplementary source of energy, flavor, texture, and nutrients in pet foods. Whereas energy is commonly derived from the carbohydrates in grain, animal fats provide a concentrated source of calories and remain more stable and palatable than the more unsaturated vegetable oils.  Cats digest protein less efficiently than dogs and require higher amounts of it in their diet.  Calcium and phosphorous, are essential minerals for dogs and cats and are readily available in rendered products. The high availability of phosphorus in rendered products is another contribution to sustainability because phosphate rock is nonrenewable and is running out worldwide.

SUMMARY:  The byproducts from food animal production can be rendered into safe and nutritious pet food ingredients. Feeding animals is a greater value use for byproducts than other alternative uses such as energy or fertilizer; therefore, feeding byproducts to animals improves the sustainability of the industries from which the byproducts are derived. There should be a place in pet food or livestock feed for ingredients that have nutritional value and are safe for animals.


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