Four hundred (Arbor Acres) one-day-old broiler chickens were randomly divided into five groups with four replicates (pen) (10 males and 10 females). The five treatments used in the present study consisted of the following: (1) 4% FM; (2) 6% wet fermented soybean meal (WFS); (3) 5% soybean meal (SBM); (4) 5% wet strengthened fermented soybean meal (WSFS) (which contained 70 kg fermented soybean meal, 30 kg commercial bacterial protein, 1.8 kg L-lysine, 1 kg DL-methionine and 30 g threonine; to enhance the CP and AA concentration resembled the nutrient content of FM: CP 52%, lysine 5.0%, methionine 1.7%, and threonine 2.0%); and (5) 4.5% dry strengthened fermented soybean meal (DSFS). All FS products were added to the feed on the same DM basis. The experimental diet (mash form) was formulated based on NRC (1994) (Table 3); the feeding trial lasted 35 days with the feeding period divided into two periods, namely, the starter period (0–3 weeks) and the growth period (3–5 weeks). Birds were floor-fed (width and length of each treatment: 160