1. Different concentrations of zinc-methionine (Zn-Met) were given to pigeon squabs, and the resulting effects on growth, immune functions and intestinal microflora were investigated from hatching to 28 d of age. A total of 180 artificially hatched pigeon squabs were randomly allotted to each of three treatments with three replicates of 20 squabs. The three treatments given were either one ml (2 mg/ml) Zn-Met, one ml (10 mg/ml) Zn-Met or one ml 0.9% NaCl solution. 2. The results showed that Zn-Met improved the growth performance of squabs. The average daily and average weekly weight gain was significantly greater in squabs treated with Zn-Met than in the control group. 3. The group given 2 and 10 mg supplemental Zn-Met had heavier thymus, spleen and bursa of Fabricius than the control group at d 28. 4. Maternal antibody titres against Newcastle disease haemagglutination inhibition and alpha-naphthyl acetate esterase were significantly higher in squabs treated with supplemental 2 and 10 mg Zn-Met compared to the control group at d 14 and d 28. 5. Additionally, the squabs given supplemental 2 mg Zn-Met exhibited significantly higher Bacillaceae, Lactobacillus, Enterococcus and Bifidobacterium populations at d 14 and d 28, but lower Escherichia coli populations at d 28 compared to the control group. On the contrary, Lactobacillus, Enterococcus and Bifidobacterium populations were significantly decreased with 10 mg Zn-Met at d 28. 6. This study indicates that supplementation with Zn-Met has a positive effect on growth performance, immune function and regulation of intestinal flora in pigeons. An inclusion level of 2 mg seems to be better than 10 mg Zn-Met per day per bird.

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The aim of the present study was to optimize the solid state co‐fermentation requirements of soybean meal (SBM) by Bacillus subtilis and B. licheniformis and assess the application effects on the feeding of koi carp. The soluble protein conversion rate (SPCR) was the highest when co‐fermented by B. subtilis and B. licheniformis with the mixed ratio 1:2 (V/V, marked as SL1:2). As the results of response of surface methodology showed, the optimal co‐fermentation requirements by SL1:2 were at inoculums size 5% under the duration of 60 h at 30°C and with the substrate/water ratio 1:1. The highest SPCR was 50.22% ± 2.06%, and the anti‐nutrient factors in fermented soybean meal (FSBM) decreased significantly (p < 0.05). Six isonitrogenous diets were formulated. Fish meal (FM) was partially replaced by 0%, 30% and 60% of FSBM in the treatment groups, and FSBM replaced by SBM as controlled group. When FM was replaced by 0% and 30% of FSBM, the effects of FSBM on protease activity, immune activity and antioxidant activity of Koi were higher than that of the same proportion of SBM. Meanwhile, the effects of FSBM on the feeding of koi carp could reduce the dosage of 10% SBM at the same proportion. As the results show, FSBM used in aquaculture effectively reduced feed expenditure, improved economic and environmental benefits, and prevented the deterioration of water quality.