Hydroponic forage for ruminant feeding: A comprehensive review

The technology of growing forage crops without the support of soil, but in an aqueous medium is known as hydroponic forage (HPF). Unlike soil-based traditional cultivation, with HPF, the growth cycle of forage will be shorter (4-10 days), which can ensure round-the-year forage availability either from lowcost or hi-tech HPF devices. In addition, HPF is immune to weather fluctuations and is a climatically resilient agricultural practice. On the nutritional front, while the crude protein content is known to augment in HPF compared with original grain and conventional green forage; energy will be greater than green forage but lower than grain. In this backdrop, the present updated review discusses the zoo-technical attributes such as intake, rumen fermentation, nutrient digestibility, growth and feed efficiency, lactation, reproduction and health status of ruminants upon feeding varied species of cereal- and legume HPF. Tradeoffs between animal productivity and economic feasibility have been inconsistent in the literature on feeding HPF. Furthermore, the potential merits and pitfalls of HPF vis-à-vis economic delivery of nutrients for practical diet formulation are also highlighted along with the way forward to leverage the benefits of this technology in the context of tropical livestock production systems under changing climatic scenario.