Table 1.

Antibody titers before challenge (Mean value)

Group	5 days old	10 days old	17 days old	24 days old
1	2.32 ± 1.242	21.73 ± 7.406	364.41 ± 37.253a	851.34 ± 58.734a
2	2.32 ± 1.221	22.75 ± 7.306	477.76 ± 31.132a	1316.26 ± 87.820b
3	2.12 ± 1.226	19.69 ± 6.121	471.73 ± 4.436a	1612.38 ± 69.443b
4	2.11 ± 1.222	2.63 ± 8.481	2.12 ± 2.855b	2.23 ± 1.212c

^{a, b, c} The difference between data with the same letters in the same column is not significant (P > 0.05). The difference between data with different letters in the same column is significant (P < 0.05).