TABLE 4.

Application of microalgal astaxanthin for animals feeding.

Application field	Animal	Algal species	Form of astaxanthin	Concentration of astaxanthin	Specific effects	References
Livestock farming	Weaned pig	H. lacustris	Astaxanthin extract	0.025 g kg-1 diet	1) Supplementation of astaxanthin in pig diet improved the shelf life of pork fat; 2) The growth performance of pigs fed the astaxanthin did not differ from pigs fed a control diet.	Szczepanik et al. (2022)
	Finishing pig	NA a	Astaxanthin	1.5 and 3.0 ppm of astaxanthin in diet	1) Dietary supplementation of astaxanthin in diet reduced the cholesterol content in the meat of finishing pig; 2) Dietary supplementation of astaxanthin in diet improved the carcass traits and meat quality of finishing pig	Yang et al. (2006)
	Heifer	NA	NA	0.25 mg astaxanthin per kg BW per day per animal	1) Dietary supplementation of astaxanthin increased the body weight gain and feed intake; 2) Feed conversion ratio was reduced by the supplementation of astaxanthin in diet.	Kumar et al. (2019)
Aquaculture	Rainbow trout (Oncorhynchus mykiss)	C. vulgaris	Algal biomass	Diet was supplemented with 4% algal biomass containing 0.2% carotenoids (30% astaxanthin)	1) Dietary supplementation of algal biomass did not significantly change the total feed intake and weight gain; 2) Accumulation of carotenoids (11.9 mg kg-1 dry muscle) in the muscle of fish was observed; 3) Compared with synthetic pigments, algal biomass is a slightly less efficient muscle coloring ingredient for farmed trout	Gouveia et al. (1997)
	Chinese mitten crab (Eriocheir sinensis)	H. lacustris	Defatted algal meal	Diet containing 1% defatted algal meal (64.80 mg astaxanthin/kg dry diet)	1) Malonaldehyde contents in the serum and the hepatopancreas of male crab were reduced to 3.92 nmol mL-1 and 1.64 nmol mg-1 protein; 2) The contents of astaxanthin and total carotenoids in the carapace of crab were improved; 3) Astaxanthin-rich algal meal significantly reduced the cost of feed formulation, improved the coloration, enhanced antioxidant and immune capacity of adult crab	Ma et al. (2019)
	Rotifer (Brachionus plicatilis)	H. lacustris	Defatted algal meal	Addition of defatted algal meal (containing 0.5% w/w astaxanthin) at a content of 125 mg L-1	1) The density of rotifer fed astaxanthin-rich algal meal was higher than that of control group; 2) When the addition of algal meal was 125 mg L-1, rotifer egg density was the highest; 3) The contents of astaxanthin and carotenoid in rotifer were improved to 0.60 and 0.76 mg g-1 (wet weight)	Li and Liu (2019)
	Rainbow trout (Oncorhynchus mykiss)	H. lacustris	Commercial algal biomass	Addition of algal biomass in diet at a content of 2.80, 5.60, and 11.20 g kg-1	Dietary supplementation of astaxanthin-rich algal biomass improved the fillet quality of rainbow trout via attenuating the oxidative stress and functions of antioxidant-relevant enzymes, thus protecting fish from arsenic toxicity	Milan et al. (2021)
	Post-larval white shrimp (Litopenaeus vannamei)	H. lacustris	Algal biomass	Algal biomass (astaxanthin content: 30 g kg-1 dry weight) was added in the diet at a content of 3.3 g kg-1	1) Astaxanthin-rich algal biomass increased the survival rate (72.08%) of post-larval white shrimp; 2) After the acute salinity stress, shrimp fed with algal astaxanthin had lower malonaldehyde content; 3) Dietary supplementation of astaxanthin-rich algal biomass increased the anti-oxidative ability and immune capacity of shrimp	Xie et al. (2018)
	Golden pompano (Trachinotus ovatus)	H. lacustris	Algal biomass	Content of algal biomass in diet was 0.3%	1) Compared to the fish in control group, the fish fed with astaxanthin-rich algal biomass had higher weight gain and specific growth rate; 2) Dietary supplementation of astaxanthin-rich algal biomass increased the protein content in the whole-body compositions; 3) Astaxanthin-rich algal biomass alleviated the inflammatory response of fish under acute hypoxia stress by activating Nrf2-ARE pathway to antagonize the NF-κB pathway	Xie et al. (2020)
Poultry farming	Broiler chicken	H. lacustris	Algal meal	Addition of 350, 1800, and 8,950 mg algal meal/kg feed (7, 36, and 179 mg astaxanthin/kg feed)	1) The contents of astaxanthin and total carotenoids in liver, kidney, intestine, and breast muscle increased; 2) Astaxanthin-rich algal meal supplement did not influence growth performance, feed intake or feed conversion ratio	Waldenstedt et al. (2003)
	Laying hens	H. lacustris	Astaxanthin extract	20, 40, 80, and 160 mg astaxanthin/kg diet	1) The increase of dietary astaxanthin did not significantly impact the egg weight, laying rate, feed consumption, eggshell strength, feed efficiency, or Haugh unit; 2) The scavenging abilities of hydroxyl radicals and superoxide anions were linearly increased with the increase of astaxanthin level; 3) Yolk color darkened linearly with the increase of astaxanthin level	Heng et al. (2021)
	Broiler chicken	H. lacustris	Astaxanthin powder	10, 20, 30, and 40 mg astaxanthin powder/kg feed	Dietary supplementation of astaxanthin to the broiler meat diet resulted in an improvement in the immune characteristics of broilers at normal and elevated environmental temperatures	Awadh and Zangana (2021)
	Laying hens	H. lacustris	Astaxanthin extract	20, 40, 80, and 160 mg astaxanthin/kg diet	Dietary supplementation of astaxanthin extracted from microalgae delayed the decrease in yolk index and yolk color during the storage at 4°C and 25 °C	Heng et al. (2020)
	Layers	NA	Astaxanthin	0.7, 0.9, 1.1 and 1.3 ppm of astaxanthin in diet	1) Dietary supplementation of astaxanthin in poultry diet had no significant effect on layer production performance; 2) Yolk colorness was linearly increased with the increase of astaxanthin content in poultry diet.	Yang et al. (2006)
	Layer hens	H. lacustris	Full fatted microalgae	Basal diet was supplemented with 0.08% and 0.32% of algae to provide 20 and 80 mg of astaxanthin/kg of diets	1) Dietary supplementation of astaxanthin resulted in the enrichment of astaxanthin and total carotenoids in the plasma and egg yolk of hens; 2) Egg yolk color was changed by the addition of microalgal astaxanthin in diet; 3) The increase of astaxanthin content in diet reduced the malondialdehyde content in liver and egg yolk	Magnuson et al. (2018)

^a NA means not available.