Abstract:
In order to determine the optimal weaning time and transition duration for hybrid sturgeon (
Acipenser baerii ♀ ×
A. schrenckii ♂), thereby addressing critical feeding-technique challenges during seed rearing, we investigated the effects of different weaning strategies on growth performance, survival rate, and early changes in digestive enzyme activities. Two weaning transition strategies were applied to hybrid sturgeon larvae from 7 to 60 days post hatching (dph). For group W, the weaning transition period was 20 d, with the starting times of transition set at 15 dph (W15), 20 dph (W20), and 25 dph (W25), respectively. Group T started the weaning transition at 20 dph, with the transition periods set at 10 d (T10), 20 d (T20), and 30 d (T30), respectively. The results show that in W groups, W20 group exhibited a significantly higher survival rate than the other two W groups. As for growth, W20 group performed better and had significantly higher body mass than the other two W groups since 35 dph. The amylase activity of all hybrid sturgeon during the whole process showed a wave-like decreasing trend, and W15 group presented relatively higher averages. Lipase activity in W groups first increased, reaching their peak values at 40−50 dph, then decreased. Trypsin activity in W15 and W20 groups increased during 15−25 dph and then stabilized. W25 group showed a downward trend after reaching a peak value at 35 dph. The value of W20 group was significantly higher than that of the other groups at 60 dph. Pepsin activity increased in a wavelike manner during the experiment. W15 and W25 groups reached the peak values at 50 and 60 dph, respectively, and were significantly higher than the other groups. In T groups, the survival rate of T10 group was significantly lower than the other two T groups. T10 and T20 groups both showed significantly greater total length and body mass than the T30 group. The amylase activity in T group changed in a similar trend to that in W group, and T10 group had a higher average activity. The lipase activity showed an increasing trend, with T30 group being significantly higher than others at the experiment end. Trypsin activity fluctuated greatly between 20−30 dph and then stabilized. T10 group had a relatively high average. Pepsin activity first decreased and then increased, and that in T10 group was significantly the highest at the end of the experiment. In conclusion, starting weaning at 20 dph and a 20-day weaning transition time are the most appropriate weaning strategies for hybrid sturgeon at 17−19 ℃.