Growth performance, apparent digestibility coefficients and digestive enzyme activities of Pacific white shrimp, Penaeus vannamei fed low fishmeal diets supplemented with DL‐methionine and phytase

An eight‐week growth trial and a four‐week digestibility trial was undertaken to assess the impact of DL‐methionine and phytase supplementation on growth performances, apparent digestibility coefficients (ADC), phosphorus retention and digestive enzyme activities of Penaeus vannamei. Five treatment groups in three replicates fed with a control diet (fishmeal 200 g/kg), and four low fishmeal (50 g/kg) diets with soy protein concentrate‐soybean meal protein viz., SPC1 (without supplementation), SPC 2 (DL‐methionine), SPC 3 (Phytase) and SPC4 (DL‐methionine and phytase). SPC 2 had significantly improved (p < .05) the weight gain (5.79 ± 0.12), FCR (1.53 ± 0.06) and SGR (3.21 ± 0.06) than other low fishmeal diets, but not significantly different to that of SPC 4 and control. SPC 2 also showed significantly higher protease activity. P retention was significantly higher in SPC 2 than SPC 1, SPC 3 and control, however, not significantly different from SPC 4. Faecal phosphorus load was significantly reduced in SPC 2 than SPC 1 and control. Protein digestibility was significantly higher in SPC 2 and SPC 4, whilst phosphorus digestibility was significantly higher in SPC 4. Thus, it is concluded that the supplementation of DL‐methionine is essential for the overall better performances of P. vannamei in low fishmeal diets and phytase for improving phosphorus digestibility.