AMINO ACID NUTRITION AND DIGESTIBILITY IN WHITELEG SHRIMP: WHERE DO WE STAND?

Moving from a formulation based on dietary crude protein (CP) to a formulation based on essential amino acid (EAA) was one of the major breakthroughs in formulation of animal feeds, allowing nutritionist to meet animal amino acid (AA) requirement while minimizing nitrogen (N) release into the environment. Although CP (N*6.25) value offers a good estimate of protein level, it does not allow to distinguish between N originating from AA and N originating from non-protein sources. Dietary AA instead of CP content is, therefore, increasingly used as a more reliable parameter to evaluate feed quality. Knowledge on AA requirements of pacific whiteleg shrimp (Litopenaeus vannamei) continue to increase in the recent years. Moreover, significant information on the digestibility of nutrients, including AA from practical ingredients for pacific whiteleg shrimp, has been produced during the last years, allowing nutritionists to formulate on a digestible basis. A major advantage of formulating in a digestible basis is that it makes possible to ensure more predictable shrimp performance, when changing feed recipes due to fluctuations in availability and prices of feedstuffs, such as fish meal.

The increasing availability of supplemental AA constitute a cost-effective strategy that helps nutritionists managing variability of nutrients in feed ingredients along with variability in price and availability of raw materials. Numerous research studies have demonstrated that substitution of fish meal with alternative protein sources in shrimp diets results in similar growth, survival, and feed conversion ratios, as long as nutrient composition, including AA profile, are balanced to cover animal requirements. We propose to review available data on AA recommendations and digestibility for whiteleg shrimp that will help making the process of least-cost formulation for shrimp more cost-effective.