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The Study Of The Compensatory Growth And The RNA/DNA Ratio Of The Soft-shelled Turtles (Pelodiscus Sinensis)

Posted on:2012-07-05Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q S XieFull Text:PDF
GTID:1103330335974019Subject:Zoology
Abstract/Summary:PDF Full Text Request
This study systematically investigated the effect of different feeding regime on compensatory growth (CG) of juvenile soft-shelled turtles, Pelodiscus sinensis; the diel rhythm in RNA/DNA ratio (R/D) of soft-shelled turtles and the relation between the feeding strategy and the R/D; the change regulation in R/D of soft-shelled turtles under low protein nutrition stress and the relation between the R/D and the feeding and growth performance. These studies were adopted modern biologicl techniques, such as physiological ecological, nutritional, biochemical methods. The study was consisted of five sections as followed: The effects of the cyclical feed deprivation and refeeding, different starvation period, protein restriction with subsequent realimentation on CG in juvenile soft-shelled turtles were investigated; The diel rhythm in RNA/DNA ratio (R/D) of soft-shelled turtles and the relation between the feeding strategy and the R/D; The change regulation in R/D of soft-shelled turtles under low protein nutrition stress and the relation between the R/D and the feeding and growth performance. Results from the present study could make important contributions to promote the research work carried out the comparison for the CG among different species and understand the evolutionary significance of CG; We evaluated the diel variation of the R/D in this species and the effect of feeding strategy on this index, which could make sure the optimal sampling time and tissue for establish reasonable feeding strategy; R/D-Pr-SGR model can be used to evaluate nutrition value of formulate feed and the growth in the soft-shelled turtle species and to further perfect and develop growth evaluation system of aquatic reptiles, which would fill this subject crossing theory blank. The main results were as follows:1. An 8-week experiment was carried out to evaluate the CG of juvenile soft-shelled turtle, with the initial body weight of 17.61±0.46g, under four cyclical feeding regimes of feed deprivation and refeeding with the water temperature was 30.0±0.5℃. The deprivation and refeeding regimes included 1 day of deprivation followed with 6 days of refeeding (T1), 2 day of deprivation with 5 days of refeeding (T2), 3 day of deprivation with 4 days of refeeding (T3). The control group (C) fed apparent satiation daily throughout the whole experiment. At the end of the experiment, the final body weight, feeding rate and specific growth rate in group T1 and C were significantly higher than those of group T2 and T3. While there were no significant differences in feed conversion ratio among all groups. These results indicated that the turtles of group T1 show complete CG response mostly by enhanced the feeding rate. The optimal ratio of deprivation to refeeding period proportion may be below 1:6 and five cycles of deprivation and refeeding may be appropriate for the turtles.2. To ascertain CG capability of juvenile soft-shelled turtles, the turtles with an average body weight of 4.47g were treated with one of the following regimes: full food deprivation for 0 (group control), 3 (group T1), 6 (group T2), 9 (group T3), 12 (group T4) and 15 (group T5) days; and then the turtles in each group were fed to apparent satiation until the end of the 36-days experiment times. The result indicated that there was CG effect in juvenile Soft-shelled turtle following starvation, the T1 group of the completely CG which were obvious from significant increase of the feeding level and food conversion efficiency the early of re-alimentation phase. The T2 and T3 group showed partial CG, which was obvious from significant increase of the feeding level the early of re-alimentation phase. The T4 and T5 group of did not show CG, which were from long time full food deprivation.3. The effects of protein restriction with subsequent realimentation on compensatory growth (CG) of juvenile soft-shelled turtles were investigated. The turtles were fed five diets containing different crude protein content (T1: 29.24%, T2: 31.42%, T3: 34.19%, T4: 37.16%, C: 43.31%) while the energy content remained constant for 4 weeks (restriction period) and then re-fed a diet (43.31% crude protein) for 7 weeks (realimentation period). During the restriction period, feed conversion ratio (FCR) significantly increased in all protein-restricted groups (T1-T4) compared with the control group (C). At the end of the restriction period, body mass in groups T1 and T2 was significantly lower than the control. During the realimentation phase, the weekly body mass gain (WG) in group T1 was greater than that of the control from week 5 to week 10. FCR significantly decreased in group T1 compared with the control. No significant differences in final body mass between C and T1 groups were found at the end of the realimentation period. These results indicated that soft-shelled turtles receiving a diet in which protein was reduced from 43.31% to 29.24% (approximate 33% reduction) for 4 weeks achieved a 6-week complete CG response.4. The effect of starvation and feeding rhythm (feeding once daily at 8:00, feeding twice daily at 8:00 and 18:00) on the diel variation in R/D was studied in Soft-shelled turtles, Pelodiscus sinensis, under the photoperiod was 14L:10D. Sampling to investigate the diel variation in muscle and hepatic tissue of R/D of turtles was carried out for 48h. The amplitude F text analyzed suggested that there was significant diel rhythm in R/D of these tissues. The cosine rhythm software analyzed the rhythm parameter suggested the amplitude and mesor increased by feeding action, the acrophase in feeding once and twice group was ahead and postpone, respectively. The diel rhythm of R/D in feeding group did not complete accordance with the cosine rhythm. The correlation analysis indicated that the coefficient of correlation was 0.85 between the R/D ratio of hepatic tissue and that of muscle tissue. The chi-square value of two continual periods of hepatic tissue were lower than those of the muscle tissue, suggested that the better stability and reliability in hepatic tissue. The optimal sampling time was rhythm mesor and acrophase time.5. A 90-day experiment was carried out to determine the regulation of growth performance and R/D in Soft-shelled turtles, under low protein nutrition stress. Three protein contents diets (45%, 40%, 35%) were prepared and every 15d, a subsample of four individuals was taken, which were used to produce a range of specific growth rates (SGR) and relative weight gain ratio (Rw). An ultraviolet absorption assay was used to measure nucleic acid concentrations in muscle and liver tissue. The results were as followed: 1). The value of SGR and R/D were decreased with the dietary protein content decreased. The value of R/D in muscle were continuance higher than that of the liver tissue, suggested that the better stability and reliability in liver tissue; 2). The R/D and feeding rate (FI) present linear up trend, indicated the R/D and FI are positive correlation. Regression analysis revealed that the more significantly correlation in liver tissue; 3) The liver and muscle pf R/D, Pr and the SGR and Rw was obvious linear correlation, respectively, suggested that the possibility of the SGR and Rw was substituted by R/D. The relation and the degree of correlation between the different organizations of R/D differ with the SGR and Rw values, the degree of correlation in liver was higher than that of the muscle. The results showed that the SGR, Rw FI and R/D (the liver and muscle) of the soft-shelled turtles under low protein feed stress are gradually decline. The degree of correlation and stability between R/D and SGR (and Rw) in liver was higher than that of the muscle, which could be as a sensitive index under protein nutrition stress.
Keywords/Search Tags:Soft-shelled turtle, Compensatory growth, Diel rhythm, RNA/DNA, ratios
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