Microalgae application in feed for ruminants

Growing human population and increasing demand for food of animal origin require a more proactive approach in livestock production. Ruminant production could be a promising panacea in this regard. Besides the strength in population, the utilization of unproductive land and nutrients from feed resources such as pasture, crop residues, agro-industrial by-products, etc., that are not in competition with humans for use as food further emphasizes the potential role of ruminants in feed security now and in the future. Microalgae are yet another nonconventional ingredient that are not only unutilized by humans but promising when applied in feed for ruminants. They are of different classifications and constitute a wide range of different substances ranging from proteins, carbohydrates, and lipids to minerals, vitamins, and antioxidants, which confirm their effectiveness as feed constituents for animal production. However, comparison may be difficult due to differences in microalgae type, quantity used, feed type, diet structure, nutrient composition, and duration of use; this chapter evaluates the use of microalgae in ruminant feeding and the effect on different aspect of ruminants.