Full Compensatory Growth Research Articles

Physiological responses associated with compensatory growth of Colossoma macropomum submitted to different feeding rates

Colossoma macropomum, popularly known as tambaqui, is the most commercially cultivated native species in South America. Our study aimed to evaluate a series of endpoints related to growth response and physiological parameters in C. macropomum juveniles submitted to different feeding rates (FR) and subsequent refeeding. Fish were fed at five different FR (2%, 4%, 6%, 8%, and 10% of body weight per day) for 30 days (restricted feeding phase) and then refed until apparent satiation for another 30 days (refeeding phase). Growth parameters increased with increasing FR. The FR for maximum growth was estimated to be 8.98% day −1. The reduction in FR negatively affected the activity of digestive enzymes, intestinal histomorphometry, proximal composition, plasma metabolites, and antioxidant capacity. However, after refeeding, these physiological variables were mostly restored. Our results indicate that a FR of 6% day−1 provided the best growth and feed conversion, while the full compensatory growth was achieved at 4% day−1 after refeeding. Collectively, our data suggest that a FR of 2% day−1 can trigger the catabolism of endogenous reserves, an impeding factor for compensatory growth.

Change and Regulation of Nutritional Metabolism in Silver Pomfret During Compensatory Growth.

Compensatory growth (CG) in fish is heavily influenced by nutrient metabolism. However, there are limited studies examining how nutrient metabolism is regulated during this process. For silver pomfret, an important commercial marine fish, it's crucial to establish effective starvation and re-feeding strategies to ensure good water quality and fast growth. To identify the complete compensatory growth model of silver pomfret, we conducted an experiment with a control group (normal feeding) and three starvation/re-feeding groups. We observed that the recovery of weight and condition factor in the 14-day starvation and 14-day re-feeding groups was significantly faster than other groups, indicating full compensatory growth. Thus, we selected this group for the next experiment. We performed untargeted metabolomics and transcriptome analysis of muscle tissue on Day 14, 21 and 28 (CG process), and examined the key regulatory genes of nutrient metabolism on Day 0, 7, 14, 21 and 28 (starvation and re-feeding process). Our data revealed that during starvation, silver pomfret first utilized carbohydrates and short-chain lipids, followed by proteins and long-chain lipids. After re-feeding, lipids accumulated first, resulting in rapid growth, followed by the recovery of protein content in muscle. During starvation, the expression of anabolic-related genes such as TER and CALR decreased, and catabolic-related genes such as TSC2 and MLYCD increased, promoting the AMPK pathway. During re-feeding, anabolic-related gene expression increased without AMPK inhibition. Our findings provide insights into the energy utilization strategies of fish and molecular regulation during compensatory growth in fish.

Metabolic turnover rate, digestive enzyme activities, and bacterial communities in the white shrimp Litopenaeus vannamei under compensatory growth.

The present work aimed to evaluate the effects promoted by a phase of compensatory growth on metabolic turnover rate, digestive enzyme activity, and bacterial biota of the Pacific white shrimp Litopenaeus vannamei kept under different feeding regimes. Three treatments were evaluated as follows: 70% feed restriction during 3 (T3) and 6 (T6) days, followed by a period of feeding to satiety, and a control treatment without restriction periods. The results showed a full compensatory growth in treatments T3 and T6 by day 35 of the bioassay. A significant increase in trypsin and lipase (T6) activities was observed during compensatory growth, whereas specific amylase activity was significantly lower in treatment T6 compared to T3 but not significantly different from the control group. To determine the metabolic turnover rate of nitrogen in muscle tissue, an analysis of nitrogen isotope values (δ15N) at natural abundance levels was performed. At the end of the experimental period, shrimp under feed restriction had lower metabolic turnover rates and longer nitrogen residence times (t 50) in muscle tissue, as compared to individuals in the control treatment. Regarding the changes in the bacterial communities in shrimp gut, no significant differences were observed at the phylum level, with Proteobacteria being the most abundant bacteria, followed by Actinobacteria. At family taxa level, Rhodobacteraceae presented the highest relative abundance in all treatments, whereas a decrease in Vibrionaceae was observed in treatments T3 and T6 when compared to control shrimps during compensatory growth. At the genus level, a decrease in Celeribacter, Catenococcus, and Epibacterium, and an increase in Ruegeria and Shimia, were identified in shrimp subjected to feed restriction when compared to control organisms during compensatory growth (day 14). At the end of the experimental period, the evaluated parameters showed similar results as those observed in the control treatment, suggesting a normalization of the metabolism and the physiological state. The present findings contribute to a better understanding on the physiological effects produced during compensatory growth in shrimp, which in turn could assist in the development of improved feeding strategies in benefit of the aquaculture industry.

Effects of a single-phase fasting period and subsequent re-feeding on compensatory growth, digestive enzyme activities, and antioxidant capacity of sobaity (Sparidentex hasta) and yellowfin seabream (Acanthopagrus latus)

Abstract An eight-week research was carried out to examine the influence of fasting (FA) and refeeding (RF) episodes on the compensatory growth responses (CGR) in sobaity (Sparidentex hasta, 10 g) and yellowfin seabreams (Acanthopagrus latus, 4.3 g) juveniles. Fish were fed with a commercial feed (contained 500 g kg−1 crude protein and 150 g kg−1 crude lipid) as following regimes: control (C, fish were fed three times every day), T1 (two weeks of feeding, one week of FA, and five weeks of RF), T2 (one week of feeding, two weeks of FA and five weeks of RF) and T3 (three weeks of FA and five weeks of RF). Two hundred and forty S. hasta juveniles were stocked into twelve 300-L tanks (20 fish tank−1), and 360 A. latus juveniles were allocated into other 12 tanks (30 fish tank−1). Each treatment was carried out in triplicates for each species, and each tank held only one of the species. The experiment was carried out for both species simultaneously. The weight and length of fish from the four groups were measured individually after the third week (after FA episode) and after eight weeks (after RF episode). After finishing the RF episode (eighth week), six fish of each tank were sacrificed with an overdose of 2-phenoxyethanol (1000 mg L–1), and the liver and the whole gut of the sacrificed fish were sampled, dissected, and then kept in a freezer (−80°C) until further analyses. Survival rate was decreased in S. hasta juveniles with increasing the FA period mainly due to their cannibalistic behavior, which was triggered by starvation, but it was not affected in A. latus. The fasted groups in both species significantly lost their weight after FA episodes. After five weeks of RF, S. hasta showed full compensatory growth response; meanwhile A. latus had a partial compensatory response (P<0.05). Hepatosomatic index value decreased after the FA period in both species, but it was restored to the normal level after RF phase. The activities of liver catalase, superoxide dismutase, glutathione-S-transferase, and glutathione peroxidase were increased in T2 group in S. hasta, but liver antioxidant enzymes were not affected in A. latus. In both species, the amount of the lipid peroxidation was significantly increased in the liver of fish groups subjected to T2 or T3 compared to T1 and control groups (P<0.05). Liver alanine aminotransferase (ALT) and alkaline phosphatase (ALP) in S. hasta fasted for two weeks were higher than the other groups. The activities of trypsin, chymotrypsin, α-amylase, and lipase in S. hasta fasted for a week (T1) were higher than control. In addition, the activities of trypsin and chymotrypsin in A. latus fasted for two or three weeks were lower than C and T1 groups. The activity of ALP was increased with increasing FA period in both species. The findings of the present study showed that single-phase FA episodes reduce survival and induce oxidative stress in S. hasta juveniles; meanwhile A. latus juveniles did not show complete compensatory growth after RF episode.

Effect of Fasting and Refeeding on Juvenile Leopard Mandarin Fish Siniperca scherzeri.

Simple SummaryThe development of live prey feed domestication techniques for the carnivorous leopard mandarin fish (Siniperca scherzeri) requires establishing nutritionally complete diets and research into optimal feeding regimes. Accordingly, the purpose of this experiment was to investigate the effects of varied feeding regimes for S. schezeri on compensatory growth. Individuals were divided into a daily feeding control group (C), a 5-day fasting group (F5), a 10-day fasting group (F10), and a 14-day fasting group (F14). The results demonstrated that after four weeks of treatment, all experimental groups experienced full compensatory growth and reached the control group weight. Therefore, this information will be valuable for effective management when fasting is necessary in S. schezeri aquaculture.To verify the effect of fasting on juvenile leopard mandarin fish (Siniperca scherzeri mean weight, 14.7 g), compensatory growth, body composition, and blood content of juveniles were investigated for six weeks following two-week feeding treatments: fed continuously (control), and fasted for 5 (F5), 10 (F10) and 14 days (F14). Full compensatory growth was evident after four weeks of food resupply in all fasting groups. Specific growth rate, feeding rate, and feed efficiency in all fasting groups were significantly higher than those of the control after the first 2 weeks of food resupply. At the end of fasting, the lipid content, ratio of lipid to lean body mass, hepatosomatic and viscerosomatic indices in all fasting groups, or total cholesterol content in F14 significantly decreased compared to the control. These results indicated that juvenile leopard mandarin fish subjected to 5–14 days of food deprivation could achieve full compensatory growth after feeding resumption for 4 weeks and that the morphological and biochemical indices, as well as body and blood composition, remained comparable to the control group after the completion of the study under our experimental conditions.

Feed deprivation over 16 days followed by refeeding until 75 days fails to elicit full compensation of Procambarus clarkii

A 75-day experiment was conducted with 6 different feeding regimes to evaluate compensatory responses in growth, physiological state, and muscle biochemical composition of juvenile Procambarus clarkii (1.37 ± 0.03 g). P. clarkii were deprived of feed for 0 day (control group), 2 (treatment 2), 4 (treatment 3), 8 (treatment 4), 16 (treatment 5), and 24 days (treatment 6) before being fed daily until day 75. Each feeding regime was tested in 10 replicate tanks with four crayfish in each tank. The growth (survival, SGRw, FCR, feeding rate, moulting frequency, HSI, PI, growth trajectory analysed using schnute model), digestive enzymes (trypsin and lipase), energy reserves and metabolites (alkaline phosphatase, total protein, total cholesterol, triglyceride, aspartate transaminase, and pyruvate kinase), antioxidant enzymes (superoxide dismutase, catalase, and malondialdehyde), and muscle biochemical composition (crude protein, crude lipid, ash, and moisture) were evaluated every 25 days. Results showed that P. clarkii in treatments 3 and 4 had similar growth as those in the control group but higher feeding rates at the end of the experiment, indicating that full compensatory growth occurred, while crayfish in treatments 5 and 6 only showed partial compensation. No compensation was observed in treatment 2. Furthermore, P. clarkii in treatment 4 had better feed utilisation efficiency, with a significantly lower FCR than those in other groups. The feed-deprivation period significantly influenced the physiological state of P. clarkii, with significantly lower values of variables of energy reserves and metabolites observed in treatments 5 and 6, except for alkaline phosphatase. Furthermore, P. clarkii in treatment 6 had significantly lower catalase activity but higher trypsin activity and malondialdehyde content than those in other groups. Muscle biochemical composition analysis revealed that P. clarkii in treatments 5 and 6 had significantly lower crude protein and lipid contents than other groups. The physiological state and muscle biochemical composition of crayfish varied over time (days 25, 50, and 75), with markedly increased activities or contents of total cholesterol, triglycerides, aspartate transaminase, catalase, crude protein and crude lipid observed in all treatments except the control group at the end of the experiment. Collectively, these results demonstrate that long-term feed deprivation (16 and 24 days) could only elicit partial compensation in growth, physiological state, and muscle biochemical composition of P. clarkii, while feed deprivation for 4 and 8 days followed by refeeding until day 75 could effectively trigger full compensation, particularly with respect to improve feed utilisation efficiency.

Full compensatory growth before harvest and no impact on fish welfare in Atlantic salmon after an 8-week fasting period

Individually tagged Atlantic salmon postsmolts (≈1200 g, 46 cm) reared in triplicate indoor holding tanks were fasted for 8 weeks at 12 °C and subsequently refed for 5 weeks, whereafter they were transferred to triplicate sea cages in a common garden setup together with a continuously fed control group until harvest size of ≈6100 g and 73 cm. At the end of the fasting period fish had lost 7.3% mass and the condition factor had decreased from 1.23 to 1.06. Furthermore, fasted fish were 544 g lighter and 3.8 cm shorter than fed controls, corresponding to a size difference of 50%. Following refeeding, feed intake gradually increased and surpassed the feed intake of controls. As such, fasted fish eventually showed compensatory growth and at harvest weight and length were similar to controls. At harvest, males were larger than females, and immature fish were larger than maturing fish in both treatment groups. The proportion of maturing fish was 25% higher in the fed control group. During the fasting period fish behaviours were video monitored, but no aggressions were observed. After the 8-week fasting period, fish welfare was scored based on the salmon welfare index model. Only minor deviations were found and at similar regularities between fasted and control fish. To assess potential long-term impacts on welfare status, vertebral deformities were quantified with radiology at harvest. Occurrence of vertebral deformities were low and similar between treatments. In conclusion, this study shows that Atlantic salmon are highly flexible with regards to growth patterns in response to food availability, and that a prolonged fasting period neither cause signs of reduced welfare in the short or in the long term.

Effect of walking exercise and nutritional plan on goat performance

This study evaluated the effects of walking exercise and nutritional plan on metabolic variables and the growth of stabled goats. Thirty-six goats [body weight (BW) = 21 ± 0.3 kg] were allocated in individual pens, and the treatments were randomly assigned to the animals in a 2 × 2 factorial design. The treatments consisted of walking exercise (7,5 km/day) or not and two nutritional plans [90 % (0.9M) or 170 % (1.7M) of the maintenance requirements] for 50 days (first period) . Further, all animals were fed a diet that met 170 % of their maintenance requirements and were not subjected to exercise for more 35 days (second period). There was no interaction effect between walking and nutritional plan for any of the studied variables. Walking exercise did not affect rib-eye area (REA; P = 0.13) or subcutaneous fat thickness (SFT; P = 0.11), but reduced body weight (BW) in the first (P = 0.03) and second (P = 0.03) periods. The animals in the 0.9M nutritional plan group exhibited lower REA and SFT values than those in the 1.7M group. This was accompanied by a decrease in plasma triiodothyronine concentration (T3; P = 0.03) in the animals that received the 0.9M plan in the first period. Exercise and nutritional plan, respectively, did not change (P ≥ 0.17) the plasma concentration of growth hormone (P = 0.31; P = 0.17), the gene expression of growth hormone receptors (GHR; P = 0.85; P = 0.79), insulin-like growth factor 1 (IGF-I; P = 0.87; P = 0.77), insulin-like growth factor 1 receptor (IGF1R; P = 0.55; P = 0.63) or peroxisome proliferator-activated receptors alpha (PPARα; P = 0.90; P = 0.92). In the second period, the BW and REA of the goats in the 0.9M group remained lower than those observed in the 1.7M group (23.33 vs. 30.37; P < 0.0001). Plasma T3 levels returned to values similar to those obtained with the 1.7M plan at the end of the second period (1.20 vs. 1.23; P = 0.03). Walking reduces the BW of goats without changing rib-eye area, subcutaneous fat deposition on the Longissimus muscle or gene expression. Nutritional restriction through a diet that meets 90 % of the maintenance requirements reduces weight gain but does not induce a full compensatory growth in goats.

Compensatory growth, plasma hormones and metabolites in juvenile Siberian sturgeon ( Acipenser baerii , Brandt 1869) subjected to fasting and re‐feeding

A 7‐week study was conducted to investigate the effect of different fasting and re‐feeding regimes on compensatory growth and some physiological parameters of juvenile Siberian sturgeon (Acipenser baerii). Fish (46.5 ± 0.5 g) were fed on a diet (containing 450 g/kg crude protein and 20 MJ/kg digestible energy) according to four feeding regimes in triplicate including: control group (C, fed everyday), W1 (2 weeks of feeding followed by 1 week of fasting and 4 weeks of re‐feeding), W2 (1 week of feeding followed by 2 weeks of fasting and 4 weeks of re‐feeding) and W3 (3 weeks of fasting followed by 4 weeks of re‐feeding). The fasted groups including W1 (119.6 ± 2.1 g), W2 (118.0 ± 1.7 g) and W3 (108.5 ± 4.8) significantly lost their weights during fasting phase and did not attain the final weight of the C (137.3 ± 1.7 g) after re‐feeding phase. The re‐feeding phase increased the specific growth rate in the fasted groups compared to the C (p < .05). After the fasting phase, concentrations of T₃, T₄, glucose, total protein and triglyceride in plasma of fasted groups were decreased, but levels of total cholesterol, aspartate aminotransferase, alkaline phosphatase and lactate dehydrogenase increased compared to the C. After re‐feeding phase, except for glucose level, all mentioned metabolites were restored in the plasma of W1 group, but total protein level and aspartate aminotransferase concentrations in plasma were not restored in W2 and W3 groups. Overall, our finding demonstrated 4 weeks of re‐feeding was too short to induce full compensatory growth in A. baerii juveniles.

Effects of cyclical short-term food deprivation and refeeding on compensatory growth and gene expression of SOD, GPX and HSP70 in Schizothorax wangchiachii

The present study evaluated the effects of cyclical short-term food deprivation and refeeding on growth performance, body composition, and gene expression of SOD, GPX and HSP70 in Schizothorax wangchiachii.The experimental design included four feeding protocols for eight weeks: feeding every day of the week (control), starvation for one day and refeeding for six days per week (S1F6 treatment), starvation for two days and refeeding for five days per week (S2F5 treatment), and starvation for three days and refeeding for four days per week (S3F4 treatment). The results showed that no significant difference in final body weight, specific growth rate and feed conversion efficiency were observed among the treatments (P > 0.05).The feeding rate significantly increased with the duration of food deprivation per week compared to the control (P < 0.05). The expression levels of HSP70 showed no significant differences in the gill, liver and spleen of S.wangchiachii subjected to different feed restriction regimes(P > 0.05), but in the kidney, the expression levels of HSP70 were significantly downregulated in S1F6 and S2F5 compared to the control(P < 0.05). The expression levels of SOD and GPX in the examined tissues were not affected by the different feed restriction regimes(P > 0.05). In conclusion, full compensatory growth was observed in S.wangchiachii under eight cycles of food deprivation and refeeding. Hyperphagia was the main mechanism of compensatory growth of S.wangchiachii.

The effects of a temporary lysine restriction in newly weaned pigs on growth performance and body composition1.

A serial slaughter study was conducted to determine the effects of a temporary Lys restriction immediately following weaning on growth performance and body composition. One hundred forty-four Yorkshire × Landrace × Duroc pigs (initial BW: 6.9 ± 0.2 kg) were randomly allocated to one of three dietary treatments (six pens per treatment with eight pigs per pen; four barrows and four gilts). For a 3-wk restriction period, pigs were fed diets that were 110% (Control) of the estimated required standardized ileal digestible (SID) Lys for nursery pigs or 20% (Lys20) or 40% (Lys40) below the estimated required SID Lys. Thereafter, all pigs were fed a common grower diet containing 120% of the estimated required SID Lys for 6 wk (recovery period). During the restriction period, ADG and G:F decreased with decreasing dietary Lys concentration (linear; P < 0.01). At the end of the restriction period, BW and whole-body protein concentrations decreased (linear; P < 0.01) and carcass lipid concentrations increased (linear; P < 0.01) with decreasing dietary Lys concentration. During the first 3 wk of the recovery period, ADG and G:F increased (linear; P < 0.05 and P < 0.01, respectively) and whole-body protein concentration at week 3 of the recovery period decreased (linear; P < 0.01) with decreasing dietary Lys concentration. There were no dietary treatment differences in whole-body lipid concentration after 3 wk of the recovery period. During the second half of the recovery period (weeks 7 through 9), there were no differences in ADG or G:F; after week 6, there were no differences in final BW (50.3 ± 0.5 kg) or whole-body protein (16.9 ± 0.2%) or lipid (14.9 ± 0.7%) concentrations. In conclusion, newly weaned pigs previously fed a Lys-limiting diet for 3 wk immediately after weaning achieved full compensatory growth with no differences in BW or body composition after a 6-wk recovery period. Reducing dietary Lys concentration early after weaning is a potential means to reduce the cost of (early) nursery diets without impacting overall growth and carcass composition.

Effect of feed deprivation on compensatory growth in juvenile rock bream Oplegnathus fasciatus

A feed-deprivation study was conducted for 9 weeks with four feeding regimes, estimating compensatory growth and proximate composition of rock bream Oplegnathus fasciatus (56.0 ± 0.9 g). Feeding regimes included continuous feeding (control), feed-deprivation for 1 week (S1) in week 3, for 2 weeks (S2, weeks 2–3), and for 3 weeks (S3, weeks 1–3). Following 3 weeks, fish were on a continuous feeding regime for the remaining period. Complete compensation was achieved in S1 and S2 after resuming feeding for 3 weeks and 6 weeks. Although specific growth rate, feeding rate and feed efficiency in S3 were higher than in the control during the feeding resumption period, S3 fish did not catch up the body weight of control fish by the end of the experiment. At the end of the feed-deprivation period, the ratio of lipid to lean body mass and the levels of protein, lipid, and energy in S1, S2 and S3 were lower than those in the control. After feeding resumption for 6 weeks, protein and lipid contents in S3 were significantly (P < 0.05) lower than those in the control. Rock bream with single-phase feed-deprivation for 1–2 weeks could exhibit full compensatory growth after feeding resumption for 3–6 weeks under our experimental conditions.

Effects of Food Deprivation and Feeding Ratio on the Growth, Feed Utilization and Body Composition of Juvenile Olive Flounder Paralichthys olivaceus

The effects of food deprivation and feeding ratio on the growth, feed utilization and body composition of juvenile olive flounder Paralichthys olivaceus were investigated in 810 juvenile fish averaging 6.4 g in weight randomly distributed in 27 400-L flowthrough tanks. A 3 [food deprivation: 8-week feeding without food deprivation (8W), 7-week feeding after 1-week food deprivation (7W) and 6-week feeding after 2-week food deprivation (6W)] × 3 (feeding ratio: 100%, 95% and 90% of satiation, hereafter denoted by 100, 95 and 90, respectively) factorial design was applied. The weight gain of the fish was significantly affected by both food deprivation and feeding ratio. The weight gain of the fish under the 8W-100 treatment was higher than that of those under the 7W-95, 7W-90, 6W-100, 6W-95 and 6W-90 treatments, but did not differ from those of fish under the 8W-95, 8W-90 and 7W-100 treatments. The specific growth rate (SGR) and the feed intake of the fish were affected by both food deprivation and feeding ratio. However, the feed conversion ratio (FCR) was unaffected by both food deprivation and feeding ratio. The protein efficiency ratio (PER) was affected by the feeding ratio, but not by food deprivation. The protein retention (PR) was affected by food deprivation, but not by feeding ratio. Juvenile olive flounder subjected to 1-week food deprivation at 100% satiation (7W-100 treatment) achieved full compensatory growth.

Effects of Dietary Nutrient Content, Feeding Period, and Feed Allowance on Juvenile Olive Flounder Paralichthys olivaceus at Different Feeding Period and Ration

We examined the effects of dietary nutrient content, feeding period, and feed allowance on compensatory growth, food use, chemical composition, and serum chemistry of juvenile olive flounder Paralichthys olivaceus. We placed 720 juvenile fish into 24 400-L flow-through round tanks (30 fish per tank). A 2 × 2 × 2 factorial design (diet: control (C) and high protein and lipid (HPL) × feed ing period: 8 and 6 weeks × feed allowance: 100% and 90% of satiation) was applied. Fish were hand-fed twice daily, based on the designated feeding schedule. Weight gain and food consumption were affected by both the feeding period and feed allowance, but not by diet. The food efficiency ratio was not affected by diet, feeding period, or feed allowance, but the protein efficiency ratio and protein retention were affected by diet and feeding period, respectively. We found that the full compensatory growth of fish was not achieved at a restricted feeding allowance.

Short-term cycles of feed deprivation and refeeding promote full compensatory growth in the Amazon fish matrinxã (Brycon amazonicus)

Developing nutritional strategies that can reduce production costs for the fish industry without affecting productive performance is paramount to make the activity sustainable. We investigated if short-term cycles of feed deprivation and refeeding elicit compensatory growth in matrinxã (Brycon amazonicus) juveniles, using three feeding protocols for 60 days (Phase 1): two levels of deprivation (feed deprivation for two days and refeeding for three — D2R3, or four days — D2R4) and a control level (daily feeding). Following, all fish groups were fed daily at satiation for 15 days (Phase 2). At Phase 1, matrinxã achieved full compensatory growth in both deprivation levels by increasing feed intake and feed efficiency. Overall, deprived fish consumed 40% (D2R3) and 36% (D2R4) less feed than fish fed daily. In Phase 2, growth was similar for all fish. Feed intake increased in both deprived fish, but feed efficiency did not differ among groups and was lower than in Phase 1, indicating a reduced efficiency in feed utilization when food was freely available. We propose that intermittent cycles of feeding represent an effective means to reduce production costs.

Early Diet Dilution with 40% Rice Hull Induces Lower Body Fat and Lipid Metabolic Programming in Peking Ducks

This study was conducted to evaluate the effect of early diet dilution with 40% rice hull on growth performance, carcass characteristic and composition of meat-type ducks, and to reveal the possible mechanism for decreased body fat deposition. 160 1-day-old White Peking ducks with initial body weight of <TEX>$44.5{\pm}1.0$</TEX> g were allotted to two treatments with 8 replicate pens per treatment and 10 ducks per pen (5 male and 5 female). Ducks were fed with the experimental starter diets diluted with 0% (control, RH0), 40% rice hull (RH40) during 8 to 14 d of age, respectively. Thereafter, all ducks were fed with grower diet. Ducks fed with RH40 diet from 8 to 14 d of age increased (p<0.05) feed intake, decreased (p<0.05) body weight, body weight gain and adjusted feed intake (excluded rice hull), abdominal fat, skin with fat, and fat content in carcass, and reduced (p<0.05) activities of hepatic malic dehydrogenase, glucose-6-phosphate dehydrogenase and fatty acid synthetase. When diet dilution was withdrawn in the re-fed period from 15 to 42 d of age, full compensatory growth of body weight, breast meat and leg meat weight were attained. However, ducks were still less (p<0.05) carcass fat content and showed continually lower (p<0.05) hepatic lipogenic enzyme activities at the market age in RH40 ducks than the control. These results indicated that diluting diet with 40% rice hull during 8 to 14 d of age might be a suitable method to improve feed efficiency, and to reduce carcass fat deposition in the production of meat-type ducks.

Compensatory Growth of Grower Olive Flounder (Paralichthys olivaceus) with Different Feeding Regime at Suboptimal Temperature.

Compensatory growth of grower olive flounder (Paralichthys olivaceus) was determined at suboptimal temperature (13.0±1.9°C). Fifteen fish averaging 201.1 g per tank were distributed into 18 of 300 L flow-through tanks. Six treatments were prepared in triplicate: fish were hand-fed with an extruded pellet to apparent satiation once a day for 16 weeks (16 WF); and the other five groups of fish were hand-fed for 15, 14, 13, 12 and 10 weeks after 1-, 2-, 3-, 4- and 6-week feed deprivation, referred to as 15 WF, 14 WF, 13 WF, 12 WF and 10 WF, respectively. A linear relationship between body weight of fish and feed deprivation was observed: Y (Body weight of fish) = −1.81X (Weeks of feed deprivation)+201.07, R2 = 0.83. Weight gain of grower olive flounder in 15 WF, 14 WF, 13 WF and 12 WF treatments was comparable to that of fish in 16 WF treatment, but lower than that of fish in 10 WF treatment. Specific growth rate of fish in 15 WF treatment was higher than that of fish in 16 WF, 14 WF and 10 WF treatments. Feed consumption of fish was not affected by feeding regime. Feed and protein efficiency ratios of fish in 15 WF treatment were higher than those of fish in 13 WF, 12 WF and 10 WF treatments. Grower olive flounder could achieve full compensatory growth when fish were daily fed for 12 weeks after 4-week feed deprivation at suboptimal temperature.

Bone morphogenetic protein 15 and growth differentiation factor 9 expression in the ovary of European sea bass ( Dicentrarchus labrax): Cellular localization, developmental profiles, and response to unilateral ovariectomy

Vertebrate oocytes actively contribute to follicle development by secreting a variety of growth factors, among which bone morphogenetic protein 15 (BMP15/Bmp15) and growth differentiation factor 9 (GDF9/Gdf9) have been paid particular attention. In the present study, we describe the cellular localization, the developmental profiles, and the response to unilateral ovariectomy (a procedure implying the surgical removal of one of the ovaries) of protein and mRNA steady-state levels of Bmp15 and Gdf9 in the ovary of European sea bass, an important fish species for marine aquaculture industry. In situ hybridization and immunohistochemistry demonstrated that the oocyte is the main production site of Bmp15 and Gdf9 in European sea bass ovary. During oocyte development, Bmp15 protein expression started to be detected only from the lipid vesicle stage onwards but not in primary pre-vitellogenic ( i.e. perinucleolar) oocytes as the bmp15 mRNA already did. Gdf9 protein and gdf9 mRNA expression were both detected in primary perinucleolar oocytes and followed similar decreasing patterns thereafter. Unilateral ovariectomy induced a full compensatory growth of the remaining ovary in the 2-month period following surgery (Á. García-López, M.I. Sánchez-Amaya, C.R. Tyler, F. Prat 2011). The compensatory growth elicited different changes in the expression levels of mRNA and protein of both factors, although the involvement of Bmp15 and Gdf9 in the regulatory network orchestrating such process remains unclear at present. Altogether, our results establish a solid base for further studies focused on elucidating the specific functions of Bmp15 and Gdf9 during primary and secondary oocyte growth in European sea bass.

Effect of intermittent feeding on growth in early juveniles of the crayfish Cherax quadricarinatus

Three experiments were conducted with juveniles of the crayfish Cherax quadricarinatus to investigate the effect of intermittent feeding regimes on growth and the ability to tolerate the shortage of food. In experiment 1, stage III juveniles were assigned to one of seven intermittent feeding groups (from FS1: 1 day fed/1 day non-fed to FS7: 7 days fed/7 days non-fed) and two control groups, continuously fed (CF) and continuously starved (CS) animals; this experiment comprised a short-term intermittent feeding period until the first molt, followed by a continuous feeding period. In the experiment 2, stage III juveniles were assigned to one of three intermittent feeding groups (FS2 to FS4) and one control group (CF); it consisted of a prolonged intermittent feeding period, until the end of the experiment. In the experiment 3, stage VI and VII juveniles were assigned to one of three intermittent feeding groups (FS2 to FS4) and one control (CF); it also consisted of a prolonged intermittent feeding period. The red claw crayfish juveniles were able to tolerate periods of intermittent feeding and underwent compensatory growth after continuous feed was re-established. The ability of crayfish to tolerate intermittent feeding was influenced by developmental stage and duration of the intermittent feeding period. Stage III juveniles survived, but decreased growth, when subjected to prolonged intermittent feeding. However, they showed full compensatory growth when the intermittent feeding period was short and followed by continuous feeding. On the other hand, stage VI–VII tolerated 60 days of prolonged intermittent feeding without any change in growth and survival. The hepatosomatic index (based on wet weight) values of the treatments and the control were similar, suggesting that intermittent feeding may not be considered a nutritional stress condition. The relative pleon weight (based on wet weight) values of the treatments and control were similar suggesting low use of nutrients from the muscle to increase the chance for survival. The juveniles of C. quadricarinatus can tolerate relatively long periods of low food availability and this is an important adaptation for their survival in changing/unpredictable environments and an attribute favorable for the production of the species.

Effect of Dietary Protein and Lipid Levels on Compensatory Growth of Juvenile Olive Flounder (Paralichthys olivaceus) Reared in Suboptimal Temperature

Effect of dietary protein and lipid levels on compensatory growth of juvenile olive flounder (Paralichthys olivaceus) was determined in suboptimal temperature (). Five hundred forty fish averaging 79.2 g were randomly distributed into 27 of 300 L flow-through tanks (20 fish/tank). Nine treatments were prepared in triplicate: fish were hand-fed with control (C) diet for 10 weeks (10WF-C); four fish groups were starved for 1 week and then fed with C, high protein (HP), high lipid (HL) and combined high protein and high lipid (HPL) diets for 9 weeks, referred to as 9WF-C, 9WF-HP, 9WF-HL, 9WF-HPL, respectively; and other four fish groups were starved for 2 weeks and then fed with C, HP, HL and HPL diets for 8 weeks, referred to as 8WF-C, 8WF-HP, 8WF-HL and 8WF-HPL, respectively. Weight gain and specific growth rate of fish in 9WF-HP, 9WF-HPL, 8WF-HP and 8WF-HPL treatments were higher than those of fish in 9WF-HL and 8WF-HL treatments. Feed efficiency of fish in 8WF-HP treatment was higher than that of fish in 9WF-C, 9WF-HL and 8WF-HL treatments. Protein efficiency ratio of fish in 10WF-C, 8WF-C, 8WF-HP and 8WF-HPL treatments was higher that that of fish in 9WF-HL and 8WF-HL treatments. Juvenile olive flounder subjected to 2-week feed deprivation could achieve full compensatory growth with dietary supplementation of protein or combined high protein and high lipid.