RESPONSES OF SHRIMP TO NOVEL METHIONINE SOURCE IN CLEAR AND GREEN WATER SYSTEMS  

Karthik Masagounder* and Cláudia Figueiredo-Silva
Evonik Nutrition & Care GmbH, Rodenbacher Chaussee 4, 63457 Hanau-Wolfgang, Germany
Email: karthik.masagounder@evonik.com
 

Fish meal is still one of the major protein ingredients used in shrimp feed, with its inclusion level ranging from 5 to 30%, depending on the region and life stage of shrimp. When fish meal is replaced with plant protein sources such as soybean meal, methionine becomes the first limiting amino acid which brings the need for supplemental methionine in commercial feed. Unlike in fish feed, use of supplemental amino acids in shrimp feed is practiced only in limited parts of the world. One of the concerns that the shrimp feed producers have is leaching of supplemental amino acids. Shrimps are slow eaters and masticate feed externally which lead to leaching of nutrients including methionine. In this context, Evonik Industries has developed a novel methionine source called Met-Met (DL-Methionyl-DL-Methionine; AQUAVI® Met-Met), which has much lower water solubility comparing to other methionine sources commercially available. The objective of this paper is to provide an overview of studies showing the bioavailability of Met-Met relative to DL-Met in clear water system, and then show the responses of shrimp to Met-Met under green water system. Studies in the clear water system showed that the bioavailability of Met-Met relative to DL-Met is about 200% with values varying between 172 and 298% for the specific growth rate of shrimp. This bioefficacy value was validated in a follow-up study by feeding shrimp with high (26%) or low (10%) fish meal diet. The study showed that shrimp fed the low fish meal diet produces similar performances as that of high fish meal diet when the diet was supplemented with 0.18 to 0.28% DL-Met or just 0.09% Met-Met. Shrimp fed the low fish meal diet with no methionine supplementation produced lower growth rate. The better bioefficacy of Met-Met over DL-Met likely stems from its lower water solubility and better synchronicity with the amino acids released from intact protein sources. Studies run under green water system showed significant improvement in growth performances of shrimp when fed diets containing supplemental Met-Met. Results indicate that shrimp responded exponentially to the increasing levels of Met-Met with 95% of maximum growth obtained at 1.05%-1.30% Met+Cys level in the diet (on as-is basis). Overall, results show significant improvements in the growth performances of shrimp fed supplemental methionine to meet methionine and Met+Cys requirements, under both clear and green water systems. Results further demonstrate that Met-Met is the right choice of supplemental methionine source available today for shrimp industry to minimize dependency on fish meal.