USDA research links degraded fats in feed to growth losses

A comprehensive review of 15 years of collaborative research between the USDA’s Agricultural Research Service (ARS) and the University of Minnesota identifies the effects of using alternative fats and oils on livestock productivity. These insights provide a valuable tool for livestock producers and feed mills.  The information helps them assess the nutritional and economic value of adding fats and oils to animal diets.

Livestock producers are continually faced with challenging economic decisions. They must carefully evaluate how various feed choices impact animal performance. This refers to how efficiently animals convert dietary energy into weight gain. Lipids, such as fats and oils derived from plant and animal sources, are commonly added to feed to supply vital energy.

To maximize resource efficiency, fats and oils from the food service industry are often recycled, processed, and incorporated in livestock feed. With this practice, the livestock industry helps reduce food waste, lower environmental impact, and promote sustainability.

Unfortunately, heating fats and oils, particularly during frying, degrades their nutritional value. This degradation leads to ‘rancidity’ and the production of compounds that can negatively affect metabolic processes in the animal and ultimately reduce their rate and efficiency of growth. Consequently, swine and poultry producers have questioned the nutritional, caloric, and economic value of using recycled fats and oils in animal diets.

"We’ve been listening to the concerns of the livestock industry and conducted studies to address these issues," said Brian Kerr, animal scientist with the National Laboratory for Agriculture and The Environment, in Ames, IA. "Our research provides essential scientific data on lipid quality, nutritional value, susceptibility of these lipids to oxidation, and the subsequent effects on feed intake, growth rate, and efficiency in swine and poultry."

For example, when researchers evaluated these degraded fats and oils in broilers and pigs, they found that various levels of lipid oxidation products in livestock diets reduce feed intake and growth by up to 25% in pigs and up to 10% in broiler chickens. In short, the more damaged the oil, the worse the animals performed.