# Microalgal Proteins and Bioactives for Food, Feed, and Other Applications
## 1 Introduction
### Microalgae for Feed Applications  
The use of microalgae biomass in animal feed dates to the 1950s and it is considered an effective way to include valuable nutrients and vitamins, EAAs, PUFAs, polysaccharides, minerals and pigments into feed to increase its nutritional value [3]. Currently, about 30% of total microalgae biomass produced globally is used as feed, and approximately half of this consists of _Arthospira_ sp. biomass [94]. The incorporation of microalgae into feed can benefit the animal's physiology by improving their immunity and disease resistance, as well as through stimulation of probiotic bacteria in the gut/rumen. Other benefits described include reproductive performance, improvements of feed conversion ratios and improvement in the meat quality of pigs, rabbits, poultry and ruminants. However, the findings of different studies are highly influenced by the microalgae biomass composition and the amount included in the diets of animals [3]. Interestingly, [PERSON] and colleagues claim that the efficiency of microalgae biomass incorporation into the diet of mono-gastric animals is improved by the simultaneous addition of carbohydrate-active enzymes as feed additives [3]. In fish aquaculture, microalgae are used to feed larvae, and the main species used include _Nannochloropsis oceania_, _Chlorella vulgaris_, _Isocrlysis galbana_, _Pavlova_ sp., _Pluetooth ductylum tricornutum_, _Tetraselmis sucecia_, _Skeletonema_ sp., _Thalassiosira_ sp. and _Haematococcus pluvialis_[16]. Astaxanthin extracted from _Haematococcus pluvialis_ is widely used in salmon aquaculture as it gives salmon its typical \"pink\" color desired by the consumer [95]. Effects of the inclusion of microalgae biomass into the feed of different animals are summarized in Table 7.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & **Vitamin** & \
\begin{tabular}{c} **Vitamin Recommended** \\ **Daily Allowance (RDA)** \\ \end{tabular} &
\begin{tabular}{c} **Vitamin** \\ **[mg/100 g DW]** \\ \end{tabular} & **References** \\ \hline _Arthospira_ sp. & C & 60 mg & 10.1 & [91] \\ _Chorella_ sp. & C & & 10.4 & [91] \\ _Dunaliella salina_ & C & & 2500 & [92] \\ \hline _Nannochloropsis_ & D3 & 5 \(\mu\)g & 0.1 & [87] \\ _oceanica_ & D3 & 5 \(\mu\)g & 0.1 & [87] \\ \hline _Tetraselmis_ & E & 10 \(\mu\)g & 108.0 & [88] \\ _suceica_ & E & 10 \(\mu\)g & 20.0 & [93] \\ \hline _Anabena_ & K1 & 120 \(\mu\)g & 20.0 & [93] \\ _cylindica_ & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 6: _Cont._  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Species** & \begin{tabular}{c} **Animal, Duration of** \\ **Experiment** \\ \end{tabular} & \begin{tabular}{c} **Content of** \\ **Microalga in Diet** \\ \end{tabular} & **Findings** & **References** \\ \hline _Arthospira platensis_ & \begin{tabular}{c} Lambs \\ 6 weeks \\ \end{tabular} & 10–20\% & Increase of weight (10\%) & [96] \\ \hline _Chorella_ sp. & \begin{tabular}{c} broiler chicks \\ 4 weeks \\ \end{tabular} & 1\% & Increase of average daily gain (ADG) & [97] \\ \hline _Haematococcus pluvialis_ & \begin{tabular}{c} Rainbow trout \\ 30 days \\ \end{tabular} & 0.3\% & \begin{tabular}{c} Decreased serum glucose, \\ Triglycerides (TAG) and \\ cholesterol levels \\ \end{tabular} & [98] \\ \hline _Isocrlysis galbana_ & \
\begin{tabular}{c} _Silver fish_ \\ 80 days \\ \end{tabular} & 4.5–5\% &
\begin{tabular}{c} Increased fish growth performance \\ Increased content of omega-3 \\ fatty acids \\ \end{tabular} & [99] \\ \hline \hline \end{tabular}
\end{table}
Table 7: The effects of microalgae inclusion in the feed diet of different animals ( ruminants, fish and mono-gastric).