Pros and cons of Ulva lactuca and Cladophora glomerata grown in freshwater as feed

The use of algae as alternative feeds has long time attracted interest. However, due to excessive accumulation and variation in some of its components, difficulty in harvesting, and the need for some processes (cleaning, rinsing, drying, etc.) before final use, it causes hesitations about their use as feed. The feed values of Ulva lactuca and Cladophora glomerata collected from the same region in two different years (2020-2021) were investigated. The comparison of Ulva lactuca and Clodophora glomerata in two successive yearsyielded significant differences (P < 0.05) for crude protein% (22.23-10.78 and 18.38-12.85), crude ash% (19.28-34.10 and 40.67-35.51), ADF% (13.41-12.39 and 19.61-22.13), NDF% (39.18-36.35 and 29.36-35.74), calcium% (11.75-1.49 and 38.47-1.35), magnesium% (1.02-13.54 and 1.76-8.61), potassium% (0.53-6.17 and 1.50-17.86), sulphur% (4.76-2.41 and 3.41-1.80), and nickel ppm (9.50-87.5 and 20.25-105.3). Significant differences were also detected between other nutrients, minerals, energy, and digestibility values (P < 0.05). It has been determined that some heavy metal and mineral amounts are at restrictive levels at the point of use as feed. Aluminum (4982.7-7459.3 ppm) and silicon (8882.3-1449.3 ppm) were found in Ulva lactuca and Cladophora glomerata, respectively (P < 0.05). Sulphur, aluminum, silicon, and nickel amounts are above the tolarable feed criteria limits. Cadmium and lead were determined to be above the limits allowed in the legal legislation. Their biosorbent properties cause them to be affected by the ecosystem, and undesirable accumulations appear as a restrictive situation. Therefore, it is necessary to systematically determine their contents and variations. It was concluded that they are important in terms of potential feed value but should be used in a controlled manner.

Automated summary

The use of algae as alternative feeds has attracted interest, but concerns exist due to the accumulation, variation, and processing requirements. The study found significant differences in feed values of Ulva lactuca and Cladophora glomerata collected from the same region in different years. The excessive levels of certain heavy metals and minerals pose restrictions on their use as feed.