Abstract
Cholesterol is an indispensable nutrient in crustacean aquaculture, particularly for species like the Pacific white shrimp (Penaeus vannamei), which lack the metabolic pathways for de novo synthesis. Historically, marine ingredients like fish meal, commonly included in shrimp feeds, provided adequate levels of cholesterol. However, the drive towards sustainable aquaculture practices necessitates reducing reliance on fish meal due to cost, availability, and environmental concerns. Replacing fish meal with alternative protein sources, primarily plant-based, often results in diets deficient in cholesterol, compromising shrimp growth, survival, and overall health. Consequently, supplementation with purified, synthetic cholesterol has become a standard practice to meet the established dietary requirements (ranging from 0.05% to 1.0% depending on species and life stage, with 0.05-0.5% often cited for P. vannamei). While effective, synthetic cholesterol represents a significant cost factor in feed formulation, prompting a search for more economical and natural alternatives.
This review evaluates the potential of whole egg powder as a multifunctional ingredient capable of replacing synthetic cholesterol in shrimp diets. Whole egg powder is a nutrient-dense ingredient that provides high-quality protein, essential amino acids, energy-rich lipids, vitamins, and vital phospholipids. Moreover, it’s manufactured through a gentle spray drying process that guarantees quality and high digestibility of proteins and essential amino acids. Crucially, it is also a natural source of cholesterol. This inherent cholesterol concentration suggests that incorporating egg powder into shrimp feed formulations could significantly contribute to, or potentially fully satisfy, the shrimp’s dietary cholesterol requirement, thereby reducing or eliminating the need for expensive synthetic supplementation. The primary driver for exploring egg powder as a cholesterol alternative is economics. Egg powder is generally reported to be a more affordable ingredient compared to both high-quality fish meal and purified cholesterol. Replacing synthetic cholesterol with the cholesterol naturally present in egg powder could lead to considerable savings in feed production costs, enhancing the economic viability of shrimp farming operations. Beyond cholesterol, egg powder offers additional nutritional benefits. It provides a balanced amino acid profile, although potentially lower in certain limiting amino acids like methionine, lysine, and arginine compared to premium fish meals, requiring careful formulation. Furthermore, egg powder is rich in phospholipids, particularly phosphatidylcholine (PC), which are known to be essential for larval and juvenile shrimp growth, survival, and stress resistance. The phospholipid requirement for penaeid shrimp is estimated to be between 1.2-1.5%, often met by adding lecithin sources. Egg powder can contribute significantly to meeting this requirement.
Based on its natural cholesterol content, affordability relative to synthetic cholesterol, and additional nutritional contributions (protein, phospholipids, bioactive compounds), egg powder shows significant potential as a cost-effective alternative for cholesterol supplementation in P. vannamei diets. Its use could alleviate the economic burden associated with purified cholesterol while contributing to overall shrimp nutrition and health. However, successful implementation requires formulation to balance its different nutrients. Further research, including dedicated feeding trials with P. vannamei, is ongoing, and it’s crucial to determine the optimal inclusion levels of egg powder for effective cholesterol replacement, evaluate its impact on growth performance and health, and fully realise its potential as a sustainable and economical ingredient in shrimp aquaculture.