The escalating global demand for protein in the feed market, coupled with the overexploitation of conventional sources such as soybean meal (SBM) and fishmeal, has intensified the exploration of alternative protein ingredients in aquaculture and animal feed.
Algae, renowned for their rich composition of micronutrients and macronutrients—abundant in protein, polysaccharides, vitamins, and minerals while low in fat—emerge as promising candidates.
Various algae species, including Caulerpa sp., Ulva sp., Coelastrella sp., Scenedesmus sp., and Spirulina sp., have gained recognition as potential substitutes for SBM in chicken feed due to their high protein content and adaptability to diverse growing conditions.
Nonetheless, the chemical composition of algae exhibits considerable variation between and within species, influenced by factors such as harvest season and environmental conditions, as highlighted in Algal Research by the authors—animal scientists and biotechnology experts based in Thailand.
The researchers emphasize that while most algae boast high protein content, they often exhibit lower digestibility. Green algae, in particular, containing cellulose as a cell wall component, significantly impacts nutrient digestibility and utilization, particularly proteins, in poultry. Hence, evaluating the nutritive value of a new ingredient becomes pivotal in determining its suitability for poultry feeds, a crucial consideration in feed formulation.
Their study aimed to assess the nutritional composition and digestibility of five algae species: Caulerpa lentillifera J. Agardh, Ulva rigida C. Agardh, Spirulina sp., Coelastrella sp., and Scenedesmus sp.
Methodology
The team employed microscopic analysis to evaluate the amino acid profiles and physical characteristics of these novel feed raw materials. Furthermore, they assessed the protein solubility and in vitro digestibility of the algae species by incubating samples with porcine pepsin and porcine pancreatin alongside a protease, lipase, and amylase enzyme solution.
The researchers stress the importance of digestibility as a critical indicator of the utilization rate of nutritive factors, acknowledging that while in vivo digestibility measurements provide the most accurate assessment, they are time-consuming, expensive, and often require a substantial number of experimental animals. In contrast, in vitro digestibility, employing purified digestive enzymes, offers valuable insights, serving as an effective and rapid predictor of potential nutritional quality.
Key findings
The results of the study reveal that Spirulina sp. boasts the highest protein content (44.44% of dry matter basis) and is rich in amino acids (Lys, Thr, and Trp). Furthermore, Spirulina sp. exhibits significantly higher protein solubility, digestibility, and digestible protein compared to other species (52.35%, 49–67%, and 20.70%, respectively). Conversely, Ulva rigida excels in energy digestibility and digestible energy.
Concluding, the authors suggest that Spirulina sp. stands out as the most suitable algae for alternative protein sourcing in poultry feed formulations among those assessed, but they emphasize the necessity for additional in vivo tests to validate their findings.
Source: Algal Research
Title: Investigation of nutritional profile, protein solubility and in vitro digestibility of various algae species as an alternative protein source for poultry feed
