Chapter 18 - Waste-derived volatile fatty acids for sustainable ruminant feed supplementation

Abstract

Linear livestock production practice gives rise to a number of environmental, economic, and social issues including unsustainable feed provision, resource inefficiency, and climate impacts. Provision of dietary supplements in ruminants through bioconversion of organic waste/residues is a promising way to introduce the concept of circular bioeconomy to animal feed production. Volatile fatty acids (VFAs) are natural metabolites mainly generated from the bioconversion of fiber in the rumen of ruminants, and are used as an animal's energy source and precursor for the production of animal products. Considering that VFAs can also be produced from anaerobic digestion (AD) of different organic wastes, this chapter discusses the potentials applications of waste-derived VFAs such as acetic, butyric, and propionic acids as animal feed supplementation. In this regard, first, the effect of VFAs on energy provision, dry matter intake, weight gain, weaning age, ketosis and acidosis, milk yield and composition, hormones, gastrointestinal development, etc., in ruminants are analyzed. Then the potentials of different organic waste sources for the production of VFAs through AD are presented. Finally, the purification and concentration methods such as distillation and membrane separation, whichcan be applied for the production of animal feed grade VFAs solutions, are thoroughly reviewed.