Date Full Report Received


Date Abstract Report Received



Primary Investigator:
Co-Investigators: Brian Kerr, Pedro Urriola
Rendering is a process of grinding, heating, partial separation of fat, and drying of a wide array of inedible animal and carcass tissues, including blood, feathers, muscle, bones, fat, and offal. In the U.S., the rendering industry processes over 20 million tonnes of raw animal components into various protein, fat, and mineral products. Of the 4 million tonnes of animal derived protein products produced annually, about 85% are utilized as animal feed ingredients, and is an essential role that the rendering industry plays for achieving environmental and economic sustainability of animal agriculture Animal protein by-products are concentrated sources of energy, amino acids, and minerals which have been used in swine feeding programs depending upon price relative to competing ingredients. Although several studies have determined the digestible and metabolizable energy and the digestible AA and P content of animal protein by-products, the types and number of sources of these by-products evaluated in these studies has been limited.

The objectives of this study were to first contact rendering companies, feed ingredient suppliers, feed companies, and commercial poultry and swine production operations to obtain a variety of animal protein by-products. Geographic locations and sources of these by-products were selected over an extended period of time to represent the inherent variability in chemical composition of a wide variety of products among and within rendering plants to create a comprehensive and robust database. From this data base, 13 samples of animal protein by-products were then selected to conduct a digestibility experiment in growing pigs to determine DE and ME of these feedstuffs, and then develop DE and ME prediction equations based upon animal protein by-products chemical composition.

The results of the survey indicate there is substantial variation in the energy and nutrient composition among animal protein by-products, and there is also substantial variability within an animal protein by-product. These differences are not however, unique to animal protein by-products as similar variation is noted in other alternative feedstuffs utilized in swine feed formulations, such as corn co-products, which also have a moderate amount of variation in nutrient content. The results of the animal metabolism experiment showed that there was also substantial variation in the DE and ME of these animal protein by-products, with a range in DE from 5,367 to 2,567 kcal DE/kg of DM, and a range in ME from 4,783 to 2,340 kcal ME/kg DM. Prediction of DE and ME from the analyzed energy and nutrient components was possible, with the GE or ash content of the animal protein by-product accounting for approximately 85% of the DE and ME variability. The use of typical nutrient components commonly used in rendering plants and feed manufacturing for quality control (CP, EE, and ash), may also be used to predict DE and ME content of animal protein by-products, but they resulted in less accuracy than using GE or ash.