A 10‐week feeding trial was conducted to evaluate the effects of supplementing different levels of dl‐methionyl‐dl‐methionine (AQUAVI® Met‐Met) in plant protein–based diets on Litopenaeus vannamei. The positive control (PC) and negative control (NC) diets were designed with 20% and 8% fishmeal respectively, and other six diets were formulated with graded levels of Met‐Met from 0.05% to 0.30% with a 0.05% increment on the basis of NC diet (MM 0.05–MM 0.3). Six replicates were randomly assigned to each diet with 50 shrimp each having initial weight of 0.98 ± 0.02 g. The variation of FM concentration from 20% to 8% and supplemented with graded levels of Met‐Met did not affect the survival rate, feed conversion ratio, protein efficiency ratio, whole body and muscle proximate compositions (p > 0.05). However, diets with ≤0.20% Met‐Met supplementation resulted in significantly increased weight gain and specific growth rate, after which both parameters reached plateau. Shrimp fed the NC diet showed significantly lower total essential amino acid (EAA) content in muscle (p < 0.05). Supplementation of Met‐Met significantly improved apparent digestibility coefficients of dry matter, crude protein, lipid, phosphorus and EAAs (p < 0.05). Based on broken‐line analysis, the methionine requirement for white shrimp was estimated to be 0.87% when using Met‐Met as methionine source.

This experiment was conducted to investigate the effects of dietary supplementation with Bacillus amyloliquefaciens CECT 5940 ( BA-5940 ) on growth performance, antioxidant capacity, immunity, and digestive enzyme activity of broiler chickens. A total of 720 one-day-old Arbor Acres male broiler chicks (average body weight, 45.87 ± 0.86 g) were randomly allocated to 5 treatments of 8 replicates with 18 chicks in each replicate. Broilers in the control group were fed a corn-wheat-soybean basal diet, the other 4 groups were fed the same basal diet supplemented with 500, 1,000, 1,500, or 2,000 mg/kg Ecobiol (1.27 × 10 9 CFU/g BA-5940) for 42 d, respectively. Broilers fed diets supplemented with BA-5940 showed a quadratic response ( P < 0.05) of average daily gain ( ADG ) and feed to gain ratio ( F:G ) during d 22 to 42 and d 0 to 42. The glutathione peroxidase ( GSH-Px ) and superoxide dismutase ( SOD ) activities in serum and liver, and total antioxidant capacity ( T-AOC ) in liver of broilers on d 42 increased linearly ( P < 0.05) with increasing levels of BA-5940, while malondialdehyde ( MDA ) level in serum decreased linearly ( P < 0.05). Concentrations of serum immunoglobulin ( Ig ) A and IgM on d 21, and IgM on d 42 increased linearly ( P < 0.05) as BA-5940 levels increased. Supplementation with increasing levels of BA-5940 linearly decreased serum tumor necrosis factor-α ( TNF-α ) levels on d 21 and 42, while increased interleukin ( IL )-10 concentration (linear, P < 0.05) on d 21. Meanwhile, the levels of IL-1β, IL-6, and TNF-α in the mucosa of jejunum and ileum were decreased (linear, P < 0.05) on d 42 as dietary supplementation of BA-5940 increased. Additionally, supplementation with BA-5940 also increased the activities of amylase (linear, P < 0.01), lipase (linear, P < 0.05) and chymotrypsin (linear, P < 0.01) in jejunal digesta, and lipase (linear, P < 0.05) in ileal digesta of broilers on d 42. To summarize, inclusion of BA-5940 in corn-wheat-soybean meal-based diet improved growth performance of broilers through improving antioxidant capacity, immunity, and digestive enzyme activity. Based on the results of this study, 1.1–1.6 × 10 9 CFU/kg BA-5940 is recommended for supplementation in broiler diets.