The article analyzed the potential of increasing fodder productivity, seed quality, and control and the potential of fodder production in different aspects of open fields like using barren lands from salinity or water scarcity. Significant industrial development has been noticed in recent years for high-tech controlled environment fodder production, especially in the United States, Europe, and Australia. Many start-up industries evolved in the market with advanced technologies for large-scale hydroponic fodder production with artificial lighting. However, minimal research activities have been reported in terms of technological development like environmental control, optimization in energy and water use, automation, and control. There is an information gap in the potential of CEFP and their challenges from engineering aspects, especially the energy use in HVAC and lighting systems. The critical analysis of thermal environmental control techniques and challenges for CEFP is essential for researchers, industry, and producers. A comprehensive review would be beneficial for understanding the prospects and limitations of CEFP for various stakeholders.
Livestock units are expected to increase up to 50%, and arable land per capita will decrease by approximately 23% in 2050 compared with the number in 2012.CEFP would increase as the arable land demand for human food production with the increased world population. A critical analysis of thermal environment control for CEFP would benefit various stakeholders from academia to industry. Therefore, this article presents a comprehensive analysis of multiple aspects of CEFP for livestock production. Section 2 presents hydroponic growing methods and their application for CEFP, and different facility types are analyzed in Section 3. Section 4 includes the analysis of previous studies on nutritional aspects, including the pros and cons for livestock productivity. Indoor environmental requirements and techniques for sustainable barley fodder system production are presented in Section 5, and potential option and control techniques are presented in Section 6. Finally, Section 7 includes a comprehensive analysis of the prospect, challenges, and research needs to achieve sustainability goals for the CEFP. Hydroponics is a method of growing plants using nutrient solutions or water without soil. Different types of leafy vegetables and fodder could be produced using hydroponic systems. The growing system could be open systems, where the nutrient solution or water is not recycled, and closed systems recycle excess water from growing systems. The open hydroponic systems are not practically feasible due to wastage of water and nutrients.
An experiment study showed that using macro and micro-nutrients with water does not significantly affect the yield of wheat fodder grown hydroponically for seven days. So, hydroponic fodder grown in CE comes without fertilizers and chemicals, making it a sustainable solution for livestock production. Based on the solution/water feeding methods, six different hydroponic techniques are available for growing plants, such as nutrient film system , deep water culture system , aeroponics system , ebb and flow system , wick system , and drip hydroponic system. Fig. 3 describes the basic working principles for various watering methods for hydroponic production and their associated advantages and disadvantages. NFS, EFS, and DWCS are commonly used for leafy green production in CEA applications. The aeroponic system is the advanced form of the hydroponic system, which could be challenging for CEFP. Table 1 shows critical influencing indicators to develop a decision matrix for watering technologies in hydroponic production. The information presented in Table 1 is generated from Verner et al.. WS is relatively simple, with no energy demand components as no motor is required for water movement, but not suitable for large-scale production. DWCS system is also simple and less energy-intensive, but a large volume of water is needed for operation and is prone to water-borne diseases. In general, the hydroponic fodder production technique is slightly different from the techniques used for fruit and vegetable production. The standard technique for fodder production is spraying solution or water at certain intervals and draining excess water to the tank for recycling . However, the performance of these techniques for fodder production has not been extensively studied.
In general, the concept of the NFS is most promising for draining the water in a hydroponic fodder production system. The slope of the growing bed is a critical parameter in the NFS that needs to be optimized for better performance. Growing trays in NFS are positioned at some angle or slope to facilitate a nutrient solution to drain into the nutrient solution reservoir and recirculate. NFS with a 1.5% slope was found ideal for lettuce production, and a relatively steeper slope was found beneficial for tomato productivity. The impact of growing trays slope on the productivity of green wheat fodder in the NFS system was evaluated with two different light sources . The study reported that the highest yield of wheat fodder after seven days of cultivation could be achieved with growing trays sloped at 6.5%. Matos et al. designed a hydroponic fodder production system based on the concept of the DWCS, but the study did not evaluate the performance compared with other standard techniques. Fig. 5 shows a complete CEFP unit with NFT system with 8% slope and other cirtical components for automated production system. To our best knowledge, no research has been conducted to assess the performances of the various techniques for supplying nutrient/water for fodder production. Also, the water-saving potential of an innovative approach for CEFP needs to be investigated to minimize the possibility of molds and waterborne disease contamination with fodder. Greenhouses could be used for fodder production to minimize energy-intensive artificial lighting. FAO recently supported a project for hydrophobic fodder production and established 79 simple greenhouses structures across seven regions in Namibia. The project began in 2020, benefited around 3,350 households, and saved their livestock from dying. Different low-tech greenhouse structures are mainly used for fodder production based on local conditions and resources. A study reported that a high-tech greenhouse requires about 8-15 kWh of electricity to produce 600 kg of hydroponic maize fodder daily, which could be minimized using a low-tech net house. S´ anchez del Castillo et al. evaluated the effect of different densities for growing wheat and barley in a low-tech poly-covered greenhouse in Mexico.
The low-cost hydroponic systems made of locally available materials are common in developing countries. In Malawi, hydroponic fodder has been produced in a simple poly-covered greenhouse with wooden frame shelving for trays. The major challenge in low-cost fodder production systems is controlling or adjusting the temperature, humidity, and air circulation, especially during the dry, hot summer months. The yield and type of fodder grown in these low-tech facilities are highly dependent upon the season and climatic condition of the locality/region. Modular farms are flexible and self-contained systems that allow growing fodders or vegetables without soil or sunlight. Hydroponic fodder could be grown in stackable vertical trays in warehouse-like structures or shipping containers with the help of artificial lighting. Grov Technologies in Utah, USA, has designed different vertical growing units for warehouse-type facilities to grow with advanced technologies like the Internet of Things , cloud, robotics, and machine learning for lighting and spectrum management to maximize potential yield. They claimed that their olympus tower could produce 2,300 to 2,700 kg of sprouted wheat or barley grass per day using less than five percent of water and replacing 35 to 50 acres of land compared to traditional farming. Similarly, two young farmers set up a warehouse hydroponic facility to produce high-quality green fodder for livestock in the Canary Islands in Spain. An 80 m2 facility could produce 1,000 kg of barley per day, providing a continuous supply of green fodder for 300 goats. The report indicates that the system could save 90% more water than traditional methods. Other industries have also been marketing the stackable vertical farming system to grow fodder in indoor spaces like warehouse-type structures or retrofitted abandoned buildings to grow livestock fodder. Agritom based in Australia, claimed that their custom type machine could produce from 100 kg to 1,200 kg of fodder per day, with a footprint ranging between 4.5-29.0 m2. HydroGreen is a local chain ag-tech company founded by farmers in South Dakota in the USA, manufacturing a fully automated vertical growing system that produces high-quality nutritional green fodder. They reported that about 2,700 square foot buildings could replace about 600 acres of land and produce 5.0 tons of fodder daily using a fraction of the water used in traditional crop production.
Fodder Tech, a company based in Utah, manufactures and markets different sizes and modular fodder production systems. The stackable vertical farming system could produce 9,000 kg of fresh fodder per day. A fully automated shipping container type system is becoming popular for growing fodder under extreme climates. Many companies are marketing the shipping containers type systems with a production capacity range of 50-2,500 kg per day, depending on the size of units. Agritom is currently marketing nine different sizes of the container system with LED lighting systems having rated production capacity per day between 50 kg to 2,250 kg. They reported that a 30 m2 system could produce 1,000 kg of green fodder per day compared with 1.0 hectares of land required in the traditional farming system. Fodder Tech is marketing various sizes of shipping containers with a capacity range from 50 kg to 900 kg per day. Table 2 summarizes some current industry leaderships for manufacturing and marking the CEFP systems. It is often said that the need for green fodder for livestock is as important as the need for good nutritious food for humans. Green fodder is always considered an inevitable,hydroponic barley fodder continuous, and economical source of nutrients for livestock from normal production perspectives. Compared with other available dry roughages, fodder is a natural, highly palatable, and digestible feed enriched with micro-nutrients resulting in improved nutrient digestibility, health, and performance of animals. Therefore, ensuring continuous and secured fodder supply is considered a major driver of sustainable and profitable livestock production. Hydroponics is a successful growing technique that offers a constant supply of green fodder all year round, even in all sorts of worse climatic conditions for sustainable livestock production. These plant materials and fodders are abundant in protein and energy, easily digestible, and utilized by most animals. It is reported that sprouted barley produced in hydroponic systems contained higher fiber, protein, and minerals than the barley grain. The nutritive value of animal feed could be analyzed in terms of dry matter , crude protein , crude fiber , ether extract , ash content , neutral detergent fiber , and acid detergent fiber . Thadchanamoorthy et al. showed that at 10th day after planting, the nutritive value of sprouted maize were greater compared to maize grain.Usually, when compared with respective grain/seed, hydroponic fodder has fewer contents of organic matter and non-fibrous carbohydrates,whereas increased contents of CP, NDF, ADF, and Ca.
This shift of nutrients is good for dairy animals from an animal nutrition perspective. Moreover, another study also revealed that hydroponic wheat fodder increased the DM, CP, EE, CF, K, and Na contents by 5.0%, 44.0%, 132.5%, 176.9%, 150%, and 320%, respectively, compared with conventional wheat fodder. Another study evaluated the yield and nutritional value of three barley cultivars that were harvested on the 6th, 8th, 10th, and 12th days. The study reported that the DM content of barley grain was 93.6% on the 6th day and decreased to 91.1% on the 12th day, whereas CP remained the highest on the 12th day of harvesting. Also, hydroponically produced green fodder exhibits various enzyme activities that break down complex proteins into albumin, globulin, and amino acids, resulting in higher protein quality . Studies also revealed that germination accelerated amylase and lipase activity in hydroponic fodder, increasing sugar and fatty acid content. The fatty acid concentrations in hydroponic fodder, particularly ω-3, ω-6, and stearic acid, increased linearly with the growing period. The sprouting process can significantly increase vitamins A, E, and β-carotene content compared to their grain. One study showed a 700% increase in vitamin E in fodder from grain; however, it is suggested to exercise caution about these numbers—while these numbers indicate a significant increase, based on dairy cow intake requirements, they may not be high from a biological perspective.