| A typical feature of fish and poikilotherms is that they are capable of starving for long periods. Starvation affects metabolic activity and during this period essential processes are maintained at the expense of accumulated endogenous energy reserves, which results in a loss of body weight, and reduce of growth rate. Growth rates of fish may be highly variable and, in many cases, appear to be limited by food availability. When food supplies are increased following a period of starvation or restricted feeding, fish and other animals may display a growth spurt, often referred to as catch-up, or compensatory growth. The physiological basis of compensatory growth is incompletely understood, but starved and starved-refed animals may be not only considerably impacted on growth performances, but also on the other biochemical and physiological aspects. The conducted experiments were to investigate effects of starvation and refeeding on the compensatory growth performances, oxygen consumption, muscle composition and blood constituents in Salevlinus malma.The experimental fish, initial body weight was 275.5 + 33.9g, were reared in outdoor cages (1.5 x 2.0 x 0.7m) with flowing water supply (1.5-2.0m/s, 2-8 V). Five treatments were designed as 0,5,10,15,20 days of starvation period, the starved fish refed for 15 days by fresh rainbow trout after certain period of food deprivation treating. Two duplicates were designed and the initial density was 6 fish/cage for each treatment. The growth rate, weight gain, feeding rate, food conversion ratio, muscle composition (fat, protein, moisture, glycogen) and blood constituents (plasma total protein, albumin, globulin, triglycerides, total cholesterol, high density lipoprotein cholesterin and blood glucose) were measured after treating by starvation and refeeding respectively. The oxygen consumption was tested every 2 days during the starvation period and every 5 days during refeeding period.refeeding period. The results:(1) The starvation and refeeding significantly influenced Salevlinus malma on growth performances and food intake. The complete compensatory growth performances were observed in 5d and 10d group, furthermore, the over-compensatory growth responses were found in 15d and 20d group compared with the control. The weight losses were significant higher in 10d, 15d, and 20d group after starving-treatment (p<0.05), and no significant difference detected in the 5d group compared with the control (p=0.395). The weight gain and specific growth rate (SGR) were considerable higher in 15d and 20d group after refeeding-treatment (p<0.05), but there were no differences between the control and the 5d group (p=0.340). Compared with the control, significant higher and lower feeding ratio (FR) was detected in 5d and 15d group respectively during the refeeding period (p<0.05), whereas no significant differences were found in lOd and 20d group (p=0.984,0.985). Compared with untreated fish in the control, treated fish in other four groups showed remarkably higher food conversion efficiency (FCE) during refeeding period (p<0.05).(2) Starvation and refeeding affected oxygen consumption (OC) of Salevlinus malma significantly. During the first 10 days starvation, the OC decreased rapidly from 217.7 mg.kg-1.h-1 to 167.5mg.kg-1.h-1, and then maintained stable levels during the last 10 days. During refeeding period, the OC of all treated groups increased rapidly and reconverted to the level of the control within 10 days.(3) The starvation and refeeding significantly impacted on the muscle composition of Salevlinus malma. The moisture and protein content in muscle of treated fish did not show significant differences (p=1.000,0.996,0.998,0.767-1.000,0.978,0.884,0.998) compared with untreated ones though fluctuating values were observed. The muscle lipids, muscle glycogen and hepatic glycogen content decreased respectively in all treated groups during the period of starving-treatment. During the refeeding period, the content of muscle glycogen reconverted to the normal level in... |
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