| Amur sturgeon (Acipenser schrenckii) is a characteristic of large economic speciesin Heilongjiang River and now become an important culture fish. In recent years, as thedevelopment of the sturgeon breeding industrialization in China, Amur sturgeon wasdistributed in aquaculture at the national level, and achieved a certain economic benefits.Because of the breeding range increased, raising the temperature first rather cold wateraquaculture development of wide-temperature culture up to now, part of the breedingarea for a summer of hard problems, certain economic losses caused to farmers. Thispaper for the study of juvenile Acipenser schrenckii were fed at different cultivationtemperature (15℃,18℃,21℃,24℃,27℃) to study the change rules of watertemperature on growth performance and physiological mechanism using morphological,biochemical and immunological methods. Through studying the effect of watertemperature on the growth, digestion and immune function of juvenile Acipenserschrenckii, discussing the optimum growth temperature range of juvenile Acipenserschrenckii. The study results are as follows:1. Effects of temperatures on feeding and growth of juvenile A. schrenckiiThe specific growth gain (SGR) and relative weight gain (RWG) significantlyincreased with the increasing temperature between15℃-24℃(P <0.05), andreaches the maximum at24℃. Result of analyzing the relations between temperatureand SGR showed：SGR=(-0.0346)T2+1.6447T-14.33(P <0.05，R2=0.8494),according to analyze the pertinence between SGR and temperature，the result showed the maximum SGR of juvenile Acipenser schrenckii is23.77℃. The feed coefficient(FC) was decreased significantly and reached the minimum at24℃, and then greatlyincreased. Result of analyzing the relations between temperature and FC showed：FC=0.0178T2-0.788T+9.258(P <0.05，R2=0.8057), according to analyze the pertinencebetween FC and temperature， the result showed the minimum FC of juvenileAcipenser schrenckii is22.13℃. In addition, the feed ration (FR) increasedremarkablely with the temperature increasing (P <0.05). The growth rate in thedifferent temperature group were in the order of group24℃>21℃>27℃>18℃>15℃. Taken together, the optimal feeding and growth temperature range is21℃-24℃for juvenile Acipenser schrenckii.2. Effect of temperatures on digestive enzyme of juvenile A. schrenckiiThe culture temperature had significant effects on the protease activity in theforegut(P <0.05) of juvenile Acipenser schrenckii, the protease activity in the foregut ofthe group24℃and27℃were notablely lower than the group15℃(P <0.05),and the water temperature had no striking effects on the protease activity in the midgutand hindgut（P>0.05）. The temperature had no striking effects on lipase activity inintestinal tract (P>0.05), and the lipase activity of midgut was higher than the hindgutand foregut in every temperature group. The temperature had no striking effects onamylase activity in intestinal tract (P>0.05), and the amylase activity were in the orderof midgut> hindgut> foregut. Taken together, under the conditions of low culturetemperature (15℃), the intestinal protein digestion and absorption are mainlyconcentrated in the foregut of juvenile Acipenser schrenckii, and under the conditions ofhigh culture temperature (24℃-27℃), mainly concentrated in the midgut andhindgut. In addition, the fat absorption ability in the foregut of juvenile Acipenserschrenckii is better than the midgut and hindgut. Intestinal carbohydrate absorption injuvenile Acipenser schrenckii is mainly concentrated in the midgut. 3. Effects of temperatures on oxidation resistance and activities of immuneenzymes of juvenile A. schrenckiiThe water temperature had significant effects on the total antioxidant capacity(T-AOC), alkaline phosphatase (AKP), acid phosphatase (ACP), catalase (CAT) andnitric oxide synthase (NOS) activity and nitric oxide (NO) content in the liver ofjuvenile Acipenser schrenckii (P <0.05), and water temperature had significant effectson the T-AOC, AKP, ACP, and NOS activity in the serum of juvenile Acipenserschrenckii (P <0.05). The water temperature had no striking effects on the lysozymeactivity, total superoxide dismutase (T-SOD) activity and malondialdehyde (MDA)content. Under the low-temperature environment (15℃-18℃), the juvenile fishhave the ability of immune and antioxidant, is due to as good adaptation of Acipenserschrenckii for low temperature environment. The experimental results showed that, thejuvenile Acipenser schrenckii have strong immune related enzyme activity when thetemperature in21℃-24℃. So within this temperature range of juvenile fish havestrong immune function.Taken together, the optimal growth temperature range is21℃-24℃forjuvenile Acipenser schrenckii. In the temperature range juvenile Acipenser schrenckiican reaches the maximum growth rate and survival rate, and have strong digestive andantioxidant capacity. |
PDF Full Text Request