| The loach, Misgurnus anguillicaudatus, is a small freshwater economic fish in our country and iswidely distributed in Japan, Korea, Taiwan and eastern coasts of Asian. The loach has high nutritionalvalue and easily domesticated, however, there were large amount of death of fry and juvenile loach duringlarge-scale farming. The purpose of this study was to determine the growth and physiologicalcharacteristics of the openings feeding period and juvenile loach during starvation and in order to offertechnique help for loach industrialization cultivation.1. Effect of different feeds on the growth and survival of the loachWhen the water temperature was27±1degree, we fed the loach on eight kinds of bait that werecombined as follows: the production of water filter (A, which contains green algae, diatoms and rotifers),Fish meal (B), Egg yolk (C), Blank (D), Egg yolk and the production of water filter (E), Egg yolk and Fishmeal (F), Beer yeast (G) and Blood meal (H). We studied the effect of each food group on the loach growthand survival. Results were as follows:(1) The SGR in combining group C and E were higher than those in other combining groups, and therewere significant difference between them (P<0.05). The SGR in control group were lower than those inother groups, and t there were significant difference (P<0.05).(2) The lengths in group C and group E were longer than those in other groups, and t there weresignificant difference (P<0.05). The length in control group was shorter than those in other groups, andthere were significant difference t (P<0.05).(3) The mortality rates in group A, group C, group E and group H were significant lower than those incontrol group (P<0.05), but there were no significant differences between these groups (P>0.05). Themortality rate in group B was higher than those in other groups, and the different was significant (P<0.05).The results indicated that group C and group E are suit for the loach growth and survival.2. Effects of delayed feeding on feeding ability、growth and survival of Misgurnus anguillicaudatuslarvae(1)This study investigated the influence of delayed initial feeding on feeding、growth and survival of Misgurnus anguillicaudatus larvae, the experiment were conducted at different initial feeding time asfollows: delayed0d、2d、3d、4d、5d、6d、7d and absolutely hungry group. The results showed that:(2)when the temperature was27℃±1℃, the larvae of Misgurnus anguillicaudatus of3d old began tofeed, complete yolk absorption was noticed at4d after hatching, the mix vegetative period was2d, and theinitial feeding rate was36%; The highest initial feeding rates reached98%, and appeared on the5d afterhatching, the point of no return (PNR) was8～9d after hatching.(3)The total length of Misgurnus anguillicaudatus larvae of groups of delayed feeding0d and1dwere presented the positive growth, at11d after hatching, there were no significant difference（P>0.05）between the total length of two groups,and the length of groups of delayed2d and3d were presented asignificant reduced. Under the absolutely hungry condition, the larval total length of Misgurnusanguillicaudatus presented the positive growth between3d old and5d old, subsequently appeared negativegrowth..(4)At11d old, the survival rates of the groups of delayed0d and1d were separately82.67%and89.33%,and there were no significant difference（P>0.05）,with the feeding time delayed, the survival ratesobviously reduced, and all of larvae died11d old in the absolutely hungry group.3. The compensatory growth of juvenile loach after starvationThis paper studied the dynamic changes of compensatory growth under0days’(control group),7days’(S7group),14days’(S14group) and21days’(S21group) starvation and refeeding at26士1℃. Theresults indicated that:(1) At the end of starvation, the weight loss of treatment group was significantly lower (P<0.05) thancommon group and were10.58%,20.13%and24.91%, respectively. The weight gain of all treatment groupafter refeeding was significantly higher (P<0.05) than common group and the body weight of S7, S14andS21were73.57%,70.33%and56.64%, respectively. SGR in all treatment group were significantly higher(P<0.05) than common group. After refeeding, the body weight of S7group has no significantly difference(P>005) with common group, however, the body weight of S14group and S21group were significantlylower (P<0.05) than common group.(2)The effects of histology and morphology of loach (Misgurnus anguillicaudatus) after starvationand refeeding wered studied by paraffin section.The morphology research shows that: the juvenile starved for14d and21d, the gut is shrunken,and the hepatopancreas is atrophied and turmeric colo; Thehistology research shows that: there were no significant different between the control group and the fishstarved7d, the fish starved14d and21d,both the diam of intestine and the height of epithelial cell werelower than the control group, and there were significant difference(P<0.05) between them. the hepatic cellsare shrinkage, and the fat reducing. After refeeding, both the diam of intestine and the hight of epithelialcell were recovering, but still lower than the control group(P<0.05), the hepatic were also recovering insome degree, but they can not reach the normal level. |
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