## 4 Applications of _Chlorella vulgaris_ in Food, Feed, and Medicine
### Applications in Feed  
_C. vulgaris_ has garnered significant attention as a valuable ingredient in animal feed due to its high protein content, essential fatty acids, and other bioactive compounds [123]. It is incorporated into livestock, poultry, aquaculture, and pet feeds, offering benefits such as enhanced growth, improved immune function, and better resistance to diseases [34; 128]. In livestock and poultry feed, _C. vulgaris_ is typically incorporated as a protein-rich supplement, providing all essential amino acids needed for animal growth and development [129; 130]. The most common inclusion level may range from 0.1% to 5%, depending on the species and production goals, with formulations often in powdered or pelletized forms to ensure easy mixing with traditional feed ingredients like corn and soybean meal. Studies have shown that supplementation with _C. vulgaris_ in diets for chickens, pigs, and cattle improves weight gain, feed-conversion efficiency, and overall growth performance [31; 128; 131]. Moreover, it has been observed to enhance the nutritional quality of animal products by increasing beneficial fatty acid content in meat and eggs [132; 133]. In aquaculture, _C. vulgaris_ is used as a powdered or microencapsulated feed additive, particularly for species such as tilapia, carp, and salmon [131]. These formulations are usually added in combination with fish meal or plant-based feeds, and microalgae can be utilized directly as feed for the cultured organisms or indirectly as feed for other live-feed organisms, such as rotifers and _Artemia_[134]. The direct use of _C. vulgaris_ as a feed for fish is primarily limited to herbivorous plankton feeders, such as cypririids and cichlids. However, the indirect use of _C. vulgaris_ as feed for live-feed organisms is more widespread, particularly in the culture of marine finfish larvae, which rely heavily on live feed during their early stages of development. The inclusion of _C. vulgaris_ in aquaculture feeds typically ranges from 5% to 20% of the total diet, depending on the target species and production objectives [20; 36]. At these levels, _C. vulgaris_ has been shown to significantly enhance growth rates, feed efficiency, and pigmentation in fish [135]. The carotenoids present in _C. vulgaris_ improve skin and flesh pigmentation, which is a key factor in enhancing the aesthetic quality of fish--an impor \begin{table}
\begin{tabular}{c c c} \hline \hline
**Compound** & **Benefit** & **Reference(s)** \\ \hline Protein & Excellent plant-based protein source for dietary supplementation & [4] \\ \hline Amino Acids & Complete protein profile, supports muscle and tissue health & [4] \\ \hline Polyunsaturated Fatty Acids & Contribute to heart health and anti-inflammatory effects & [3] \\ \hline Polysaccharides & Immunomodulatory properties, antioxidant benefits, support gut health & [3; 25] \\ \hline Vitamins & Nutritional fortification supports energy metabolism, promotes eye health & [102] \\ (B-complex, beta-carotene) & & \\ \hline Minerals & Enhances dietary intake, supports bone health and metabolic processes & [102] \\ (iron, magnesium, calcium) & & \\ \hline Chlorophyll & Antioxidant properties, acts as a natural food colorant, detoxifies & [25] \\ \hline Carotenoids (lutein, beta-carotene) & Antioxidant benefits support skin and eye health, enhance cognitive function & [44; 59] \\ \hline Dietary Fiber & Modulates glucose absorption, improves insulin sensitivity, enhances satiety & [3; 7; 127] \\ \hline Antioxidants (chlorophyll, carotenoids, polyphenols) & Neutralizes free radicals, reduces oxidative stress, extends food shelf life & [34] \\ \hline Antimicrobial Compounds (peptides, fatty acids) & Inhibits growth of harmful microorganisms, reduces reliance on synthetic preservatives & [21] \\ \hline Bioactive Compounds & Cholesterol management, improves glucose metabolism, potential anti-diabetic properties & [96; 124] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Nutritional compounds in _Chloella vulgaris_ for food and their associated benefits.