Spray-dried blood products
Spray-dried blood products are by-products obtained from swine and bovine slaughter plants. The whole blood is collected in chilling tanks and prevented from coagulating by adding an anticoagulant. The spray-drying process consists of rapidly drying the blood at an average inlet temperature of 440°F, resulting in a finely grained powder for use in swine diets (Almeida et al., 2013). Spray-dried blood cells and spray-dried plasma are produced by separating the fractions of blood, whereas spray-dried blood meal contains both blood cells and plasma.
Spray-dried blood products are protein sources of high-quality due to the high concentration of crude protein (75-90%) and lysine (NRC, 2012). Moreover, spray-dried plasma protein is widely used to stimulate feed intake of weanling pigs (DeRouchey et al., 2002). However, the use of spray-dried blood products requires to provide an adequate balance of branched-chain amino acids due to the high concentration of leucine but low concentration of isoleucine, particularly in spray-dried blood cells or blood meal (Kerr et al., 2004; Goodband et al., 2014). Also, the concentration of methionine is low in all spray-dried blood products. The inclusion of other protein sources or supplementation of diets with feed-grade amino acids is important to adjust the amino acid profile in diets with spray-dried blood products (Remus et al., 2013).
The use of spray-dried blood products may vary substantially in composition and quality according to source and processing methods. The application of heat is a critical step to eliminate pathogens but at the same time over-heating blood products may decrease lysine availability. In order to minimize the risk of disease transmission via feed ingredients, it is advisable to only use bovine-derived products or porcine-derived products that are tested and PCR-negative for Porcine Epidemic Diarrhea virus (PEDv).