Table 5 Effects of dietary threonine levels on activities of tryspin, chymotrypsin, alpha-amylase and lipase in intestine of sub-adult grass carp^d

Trypsin, U/g protein

177.2 ± 10.2^a

239.9 ± 12.5^b

252.6 ± 12.1^b

291.2 ± 16.8^c

286.1 ± 10.0^c

294.0 ± 10.6^c

Chymotrypsin, U/g protein

1.03 ± 0.09^a

1.00 ± 0.08^a

2.29 ± 0.15^c

1.58 ± 0.14^b

1.45 ± 0.14^b

1.48 ± 0.12^b

alpha-amylase, U /mg protein

2.46 ± 0.12^a

2.51 ± 0.19^a

2.84 ± 0.09^b

2.75 ± 0.06^b

2.73 ± 0.04^b

2.77 ± 0.04^b

Lipase, U/g protein

19.11 ± 1.29^ab

20.97 ± 1.77^bc

22.71 ± 2.00^c

22.55 ± 2.41^c

21.06 ± 2.34^bc

17.93 ± 1.26^a