As there is no consensus on the efficacy of purified amino acids in shrimp feed, two approaches were conducted to determine the methionine requirement in practical diets for Litopenaeus vannamei. The first approach used intact proteins in producing both a deficient and a replete diet that was then co-mixed in creating varying levels of methionine using intact protein. The second approach was to use the deficient diet supplemented with graded levels of pure methionine. Hence, three main diets were made, including a deficient basal diet (B, 0.48% methionine, Lentil meal-based, AGT Food and Ingredients, Inc. Saskatchewan, Canada), a dipeptide Met (Met-Met)-supplemented diet (M, 0.85% methionine), and a replete diet containing CPC (C, 0.84% methionine, Corn Protein Concentrate, Empyreal 5 TM Cargill Corn Milling, Cargill Inc., Blair, Nebraska, USA). Ten experimental diets were produced by blending the deficient diet with the replete diet resulting in graded levels of methionine namely B100, B70:M30, M100, B90:C10, B80:C20, B70:C30, B60:C40, B40:C60. B20:C80, and C100, Test diets were then fed to shrimp (15/aquaria) in 60 randomly-assigned aquaria (55.8 L) with a mean initial weight of 0.23 ± 0.0001g over a a six-week growth trial. All diets were formulated to be isonitrogenous and isolipidic (36% protein and 8% lipid, as is), with the basal diet formulated with fishmeal and lentil meal as primary protein sources and whole wheat as a carbohydrate source. Significant differences (p<0.05) were observed in weight gain as well as whole shrimp body amino acids namely Cysteine, Glycine, Threonine, and Taurine. The optimal dietary methionine requirement of L. vannamei, estimated by a two-slope broken-line regression analysis model based on weight gain% was 0.58% of the dry diet (corresponding to 1.61% of dietary protein on a dry-weight basis). Such findings are crucial in formulating cost-effective practical diets and utilizing intact proteins or purified amino acids for juvenile L. vannamei.
You may want to workin a sentence with the range of levels for both diet sets. Maybe where you talk about the Basal and two replete diets…
Hence, three main diets were made, including a deficient basal diet (0.?? % methionine, Lentil meal-based, AGT Food and Ingredients, Inc. Saskatchewan, Canada), a dipeptide Met (Met-Met)-supplemented diet (??? % methionine), and a replete diet containing CPC (??? % methionine, Corn Protein Concentrate, Empyreal 5 TM Cargill Corn Milling, Cargill Inc., Blair, Nebraska, USA).