完全或部分的食物剥夺对中华鳖(Pelodiscus sinensis)幼体补偿生长反应的影响:生长率的时间变化模式与体组成的变化

为了探究中华鳖（Pelodiscus sinensis）幼体的补偿生长能力,我们对中华鳖幼鳖（平均湿重9．56g）进行如下6种处理：饥饿0（对照）、1、2、3、4周,或者食物限制4周,即只投喂体湿重百分之一的食物;然后对各组进行饱食处理直到10周的实验结束为止。结果发现在饱食期的第一周各饥饿处理组的特殊生长率均显著高于对照组（P〈0．05）,但是终体重均没有赶上对照组。当饥饿或食物限制结束时,脂肪含量随着饥饿期的延长而降低,灰分和水分则表现出相反的变化趋势：脂肪含量显著低于对照（P〈0．05）,而灰分和水分则显著高于对照（P〈0．05）。蛋白含量则没有显著变化（P〉0．05）。实验结束时,除了灰分外（P〈0．05）,其他个体组成指标均恢复到对照组的水平。以上结果表明中华鳖幼体在饥饿胁迫下首先利用脂肪作为主要能源以维持生存,以及在该研究条件下完全的食物剥夺可以诱发其部分补偿生长反应．而部分食物剥夺则不能诱发此反应。     

Fast-growing transgenic common carp mounting compensatory growth

Compensatory growth is a phase of accelerated growth apparent when favourable conditions are restored after a period of growth depression. To investigate if F₂ common 'all-fish' growth hormone gene transgenic common carp ( Cyprinus carpio ) could mount compensatory growth, a 9 week study at 29° C was performed. The control group was fed to satiation twice a day throughout the experiment. The other two groups were deprived of feed for 1 or 2 weeks, respectively, and then fed to satiation during the re-feeding period. At the end of the experiment, the live masses of fish in the deprived groups were still significantly lower than those of the controls. During the re-feeding period, size-adjusted mean specific growth rates and mean feed intakes were significantly higher in the deprived fish than in the controls, indicating a partial compensatory growth response in these fish. No significant differences were found in food conversion efficiency between the deprived and control fish during re-feeding, suggesting that hyperphagia was the mechanism responsible for increased growth rates. The proximate composition of the deprived fish at the end of the experiment was similar to that of the control fish. This study is, to our knowledge, the first to report that fast-growing transgenic fish can achieve partial compensation of growth following starvation.     

Compensatory growth response in three-spined stickleback in relation to feed-deprivation protocols

Different protocols of food deprivation were used to bring two groups of juvenile three-spined sticklebacks Gasterosteus aculeatus to the same reduced body mass in comparison with a control group fed daily ad libitum . One group experienced 1 week of deprivation then 2 weeks on maintenance rations. The second group experienced 1 week of ad libitum feeding followed by 2 weeks of deprivation. The deprived groups were reduced to a mean mass of c . 80% of controls. The compensatory growth response shown when ad libitum feeding was resumed was independent of the trajectory by which the three-spined sticklebacks had reached the reduced body mass. The compensatory response was sufficient to return the deprived groups to the mass and length trajectories shown by the control group within 4 weeks. There was full compensation for dry mass and total lipid, but incomplete compensation for lipid-free dry mass. Hyperphagia and increased growth efficiency were present in the re-feeding phase, but there was a lag of a week before the hyperphagia was established. The consistency of the compensatory response of immature three-spined sticklebacks provides a potential model system for the analysis and prediction of appetite and growth in teleosts.     

Effect of cycles of feed deprivation on growth and food consumption of immature three-spined sticklebacks and European minnows

Individual juvenile three-spined sticklebacks Gasterosteus aculeatus and European minnow Phoxinus phoxinus , from sympatric populations, were subjected to four cycles of 1 week of food deprivation and 2 weeks of ad libitum feeding. Mean specific growth rate during the weeks of deprivation was negative and did not differ between species. The three-spined stickleback showed sufficient growth compensation to recover to the growth trajectory shown by control fish daily fed ad libitum . The compensation was generated by hyperphagia during the re-feeding periods, and in the last two periods of re-feeding, the gross growth efficiencies of deprived three-spined sticklebacks were greater than in control fish. The expression of the compensatory changes in growth and food consumption became clearer over the successive periods of re-feeding. The European minnow developed only a weak compensatory growth response and the mass trajectory of the deprived fish deviated more and more from the control trajectory. During re-feeding periods, there were no significant differences in food consumption or gross growth efficiency between control and deprived European minnows. The differences between the two species are discussed in terms of the possible costs of compensatory growth, the control of growth and differences in feeding biology.     

Changes in growth,appetite, food conversion efficiency and body composition in mice selected for high post-weaning weight gain on restricted feeding

Summary This study aimed to test the hypothesis that if animals were fed the same amount over the same time period, selection of the fastest growers would result in a change in the partitioning of metabolisable energy toward more protein and less fat deposition. Two mouse lines (S1 and S2) were selected for high 5 to 9 week weight gain corrected to mean 5 week weight. Appetite variation between mice was eliminated by feeding a fixed amount to each mouse daily. After 6 generations of selection, the lines were compared with an unselected control (C) on restricted and ad libitum levels of feeding for growth rate, appetite, food conversion efficiency and chemical body composition.Realised heritabilities of 5 to 9 week gain were 0.36+ 0.05 and 0.19±0.04 for S1 and S2 respectively. Nine week weights were increased by an average of 13% on both feeding levels. Most of this increase, particularly in S2, occurred before 5 weeks and was therefore outside the period of measurement used in selection. On ad libitum feeding, selection increased food intake per unit time by 6% but there was no increase per unit body weight. Food conversion efficiency (gain/food) increased by 12%. Compared with controls at 9 weeks, 3% more of the body weights of selected mice was fat and 1% less was protein. These differences were reduced but were still in the same direction when comparisons were made at the same body weight. Thus the expected change in energy partitioning toward greater protein and less fat deposition in the S lines did not occur.It was concluded that the increased growth and energy retention in the S lines was brought about by a reduction in maintenance requirement. To achieve the desired change in energy partitioning using a similar selection scheme, higher levels of dietary protein should be fed, and some measure of protein deposition rather than growth rate used as the selection criterion.     

Partial compensatory growth in hybrid tilapia Oreochromis mossambicus × O. niloticus following food deprivation

The capacity of hybrid tilapia Oreochromis mossambicus × O. niloticus [23.2 ± 0.2 g (mean ± SE)] to show compensatory growth was assessed in an 8‐week experiment. Fish were deprived of feed for 1, 2 and 4 weeks, and then fed to satiation for 4 weeks; fish fed to satiation during the experiment served as control. Water temperature gradually declined from 28.1 to 25.5°C throughout the experiment. Specific growth rate (SGR) decreased with progressive food deprivation. At the end of deprivation, body weight was lower in the deprived fish than in the control. Fish deprived for 4 weeks exhibited lower contents of lipids and energy in whole body, and higher moisture content and ratio of protein to energy (P/E) than those of the control; they also consumed feed faster than the control when normal feeding was resumed. All deprived fish showed higher food intake (FI) than that of the control during re‐alimentation; however, enhanced SGR was only observed in the fish deprived for 4 weeks. There were no significant differences in digestibility of protein and energy, food efficiency (FE) or energy retention efficiency between the control and deprived fish. At the end of re‐alimentation, deprived fish failed to catch up in body weight with the control, while content of moisture, lipids and energy, and P/E in whole body of the deprived fish did not significantly differ from that of the control. The results of the experiment revealed that the hybrid tilapia reared in freshwater showed partial capacity for compensatory growth following food deprivation of 4 weeks, and that growth compensation was due mainly to increased FI, rather than to improved FE.     

Effects of lactoferrin feeding on growth,feed intake and health of calves

Abstract

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.     

西伯利亚鲟在高温下饥饿后的补偿生长

在高温(29±1)℃下将西伯利亚鲟幼鱼(21.61±0.03)g饥饿0(对照)、6、12和18d后恢复摄食3周, 研究摄食、生长和鱼体组成的变化。结果表明, 经过不同程度饥饿的鱼体重均显著低于对照组(P0.05), 而饥饿18d(S18组)的鱼体重显著低于对照(P0.05)。在饥饿过程中,鱼体脂肪含量和肝脏肝糖原含量下降的同时, 各饥饿组的灰分含量上升, 但仅S18组与对照差异显著(P0.05)。结果表明, 西伯利亚鲟在高温下表现出完全补偿现象, 且是通过同时提高摄食率和饲料效率来实现补偿生长的, 因此在夏季高温时对鲟鱼进行一段时间适度的饥饿可以在不影响生长和体成分的前提下节约饲料成本, 减少因过量投饵而引起的环境污染。       

Growth and body composition changes in mice selected for high post-weaning weight gain on two levels of feeding

Summary Two lines of mice were selected for high post-weaning weight gain (3 to 6 weeks) adjusted for 3 week weight. One line (F) was grown on freely available food and the other (S) on a feeding scale set at the same level for all mice. Food intake of the S line averaged 80% of the F line. The realised heritabilities after 6 generations of selection were 0.38±0.06 and 0.33±0.07 for the F and S lines, respectively. In generation 7, mice from the F and S lines and from an unselected control line (C) were compared on both free and set levels of feeding from 3 weeks to 9 weeks of age. Measurements taken were growth rate, appetite, food conversion efficiency (weight gain/food intake) and body composition (fat, protein, ash, water). The F and S lines grew more rapidly and efficiently than the C line on both levels of feeding, each line performing best on the level of feeding on which it was selected. The average genetic correlation between growth rates of the same line on the two feeding levels was 0.54±0.10. The F line grew 19% faster and was 9% more efficient than the S line on free feeding but the S line grew 15% faster and was 15% more efficient than the F line on set feeding. Relative to the C line, food intake per day on free feeding was 4% higher in the F line and 6% lower in the S line. There was no difference between the lines in food intake/g body weight. The rate of deposition of all body components increased in both selection lines. In the F, S and C lines respectively, efficiencies of gains in body components (10²x gain/food) were 1.79, 1.31 and 1.06 for fat, 1.53, 1.63 and 1.22 for protein and 5.88, 6.45 and 4.98 for protein + water. Apparently energy lost as heat was reduced in both the F and S lines. The partitioning of energy retained was altered in favour of more fat in the F line and more protein in the S line.     

Effects of lactoferrin feeding on growth, feed intake and health of calves

Lactoferrin (LF) exhibits a broad spectrum of anti-microbial properties and may have regulatory functions in the immune system. In the present study, 40 calves (20 males, 20 females) were used to examine the effects of supplemental bovine LF added to colostrum and milk replacer (at 0.16%) on health, weight development and feed intake during a 70-day experimental period. The calves were allocated to a treatment group (n = 20) and a control group (n = 20); the groups were balanced in terms of sex, live weight and date of birth. Body weight and feed intake were measured at regular intervals. Blood and colostrum samples were collected to determine the content of IgG. In addition, colostrum and milk replacer samples were analysed for their LF concentrations. Significantly higher IgG values were observed in the LF treated than in the control group during the entire feeding experiment from week 2 to week 6. Calves receiving LF had less days of disease with less serious cases of diarrhoea than the control group. Body weight and feed intake were not significantly different between the treatments; in male calves LF-treated animals tended towards higher weight gains. This study indicates that LF is advantageous for health and may therefore be a beneficial supplement in the diets for neonatal calves.