The USDA Agricultural Research Service (ARS) and the University of Minnesota collaborated to produce a comprehensive review of 15 years identifying the effects of using alternative fats and oils on livestock productivity which could be a valuable for livestock producers and feed mills for assessing the nutritional and economic value of animal diets.
Livestock producers are continually faced with challenging economic decisions and must carefully evaluate how various feed choices impact animal performance in reference 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 to help reduce food waste, lower environmental impact and promote sustainability.
Unfortunately, heating fats and oils, particularly during frying, degrades their nutritional value and 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.'
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. The more damaged the oil, the worse the animals performed. Results also showed that understanding how much oxidized compounds vary in heated oils, along with how much lipid is already in the diet, can help manufacturers of animal feed compare diets and predict animal performance.
The study and analysis is giving the livestock industry a strong scientific foundation to guide future decisions for producers, feed mill managers and farmers to assess the caloric and therefore economic, value of lipids and make informed decisions on whether to use these alternative energy sources in animal feed based on quality indices.
The full study is available in the Journal of Animal
Science.