Effects of Chlorella vulgaris and Probiotic Dietary Supplementation on Performance, Apparent Digestibility, and Gut Morphology of Post-weaning Piglets

In intensive swine production, piglets are separated from the sow at weaning, joined with other litters, and abruptly transitioned from milk to dry feeding at an early age (typically 21−28 days). Thus, weaning is the most stressful phase of the pig’s productive life. Consequently, at this stage, piglets often show a decreased growth and increased digestive disturbances. As such, they may benefit the most from the supply of highly digestible or bioactive nutrients and probiotics in order to promote gut health, which will have a determining impact on adequate digestive capacity, performance, and overall health. Microalgae have been considered a sustainable and functional feedstuff of potential use in piglet diets.1,2 Indeed, depending on culture conditions, many microalgae species can present high crude protein contents, such that their biomass may partially replace widely used conventional feedstuffs such as soybean meal.2,3 Other species could also be an interesting source of lipids, particularly of omega-3 polyunsaturated fatty acids that have beneficial effects on piglet health and performance.4,5 Microalgae use mainly CO2, nitrogen, and phosphorus and are capable of generating large biomass production with solar radiation as the only energy source, without the direct requirement of arable land. Nevertheless, the effects of microalgae on piglet physiology and the impact on production performance at weaning remain understudied, limiting support for broader industrial applications. Among the microalgae available commercially, C. vulgaris is particularly promising for swine nutrition due to its high protein, antioxidant, and vitamin contents.3 Most studies have addressed C. vulgaris, or other Chlorella species, for aquaculture applications,6,7 and to date, only a few studies have addressed the effect of dietary inclusion of Chlorella sp. on weaning piglet performance. In thisregard, Hintz & Heitman8 used a biomass derived from a semicontrolled cultivation of predominantly Chlorella and Scendesmus; Yap et al.9 explored the use of an unidentified Chlorella sp.; and Yan et al.10 utilized a fermented C. vulgaris product. Recently, Martins et al.11−13 conducted an extensive study with a defined C. vulgaris, in spray-dried powder, autotrophically grown in photobioreactors, and fed to weaning piglets in metabolic cages. Martins et al.13 also highlighted the importance of testing their findings in growth trials with ad libitum feeding and group housing where animal performance better approximates that of commercial conditions. If adequately used by piglets, this microalga may supply high-quality protein, essential fatty acids, or antioxidant compounds and vitamins.