Compensatory growth after various levels of dietary protein restriction in rainbow trout, Oncorhynchus mykiss

This study was conducted to determine the effects of various levels of dietary protein restriction for 3weeks (phase 1) on compensatory growth, nutrient utilization, body compositions and organ indices of rainbow trout (Oncorhynchus mykiss) during a nine-week realimentation phase (phase 2). Five experimental treatments consisted of four protein restricted diets including 15, 22.5, 30 and 37.5% protein (RP15, RP22.5, RP30 and RP37.5 respectively) and the control diet 45% (C45). All diets were prepared to be isoenergetic at levels of 22.5MJkg -1 gross or 16.3MJkg -1 digestible energy. Each of five treatment groups was tried in triplicate groups of 75 fish with an average initial weight of 62.06±0.38g. Protein restriction in phase 1 linearly decreased specific growth rates of weight and length (SGR W and SGR L), body weight and length as well as feed utilization. The restriction induced a linearly increasing trend in protein retention efficiency, feed intake, organ indices such as viscera, pyloric caecum and hepato-somatic, whole body lipid and lipid/lean body mass whereas it induced a decrease in whole body moisture and protein at the end of phase 1. Protein restriction, except RP37, caused a significant increase in SGR W during phase 2 compared with C45, being most pronounced in the first 3weeks. Repeated measures ANOVA revealed a convergence in trajectories of ln body weight and length at the end of the experiment, suggesting that a complete catch up occurred in body mass and structure. There was also replenishment in distorted organ indices and body compositions, except protein which was still less in R15 than C45. More efficient utilization of feed and dietary protein by previously protein restricted fish during phase 2 appears to be the reason of the compensatory growth. At the end of the experiment, protein restriction was found to be effective in reduction of N loss. © 2012 Elsevier B.V..National Council for Scientific ResearchThis study was supported partly by The Scientific and Technological Research Council of Turkey under grant no. VHAG-2117 and the Mediterranean Fisheries Research Production and Training Institute, Antalya, Turkey . We would like to thank İ. Dal, M.A.T. Koçer, Ş. Ege, A. Yılayaz, Ö. Yeşilçimen, R. Uysal and F. Kardeş for their contributions over the experiment and laboratory analysis. -

Effect of various lengths of single phase starvation on compensatory growth in rainbow trout under summer conditions (Oncorhynchus mykiss) [Yaz koşullari{dotless}nda tek fazl{dotless} farkl{dotless} uzunlukta açl{dotless}k süreleri·ni·n gökkuşag {dotless} alabal{dotless}g {dotless}nda (oncorhynchus myki·ss) telafi· büyümesi·ne etki·si·]

This study was conducted to determine the effects of various lengths of starvation periods on following compensatory growth (CG) in rainbow trout under summer conditions (18.1°C and day length of 12.5-14.5 hours). Five treatments with triplicate tanks were as follows: control (C) fed to satiation over 84 days; one (S1), two (S2), three (S3), and four (S4) weeks of starvation; and then refeeding for the remaining eight weeks of the experiment. Starvation periods induced hyperphagia during refeeding but only S1 and S2 were able to catch up with C. Repeated measures of analysis of variance suggested a convergence in body mass but not in body length (structure). Organo-somatic indices of the starvation groups were significantly reduced at the end of starvation periods and restored to levels of the control fish within the first two weeks of the refeeding period. Broadly speaking, starvation longer than one week significantly reduced apparent digestibility of dry matter, lipid, and energy compared with the control group but did not affect protein and ash, and a complete recovery in the digestibility coefficients occurred within two weeks of satiation feeding. There was a linear increase in body moisture and a decrease in lipid and lipid/lean body mass ratio with the severity of starvation periods, but these divergences largely disappeared at the end of refeeding. During the starvation period, the protein synthesis rate (estimated using RNA/DNA ratio in the muscle and liver) reduced but in subsequent refeeding period, it increased in starved fish. The findings of the present experiment suggest that an application of single starvation episodes to elicit CG as a management tool in summer conditions should not be longer than two weeks. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey

Balıkhane artıklarının alternatif yem kaynağı olarak gökkuşağı alabalığı ( Oncorhynchus mykiss W.,1792 )'nın beslenmesinde kullanım olanakları

Possibility of feeding rainbow trout fOncorhynchus mykiss W., 1792) with fish longer by-products as an alternative feed source. In this study three experimental groups each two with replicates were used, first group feed with wet, second one dry and third one mixture of wet feed and dry feed. At the begining of the experiment mean weights of the fish according to groups were respectively 55.288+11.052 g (n= 80), 56.063+14.513 g (n= 80) and 54.875+14.227 g (n= 80). Study lasted 180 days (December 6, 1996-June 9, 1997). At the end of the study mean live weights were 262.550+76.022 (n= 80), 341.400+61.659 (n= 80) and 312.700;plusmn;92.807 (n= 80) respectively. In term of spesific growth rates (first group feed with wet % 0.886, second one dry % 1.004 and third one mixture of wet feed and dry feed % 0.967), the differences among the groups were insignificant, but feed conversion ratio (first group feed with wet 6.092, second one dry 1.583 and third one mixture of wet feed and dry feed 3.321) and daily feed consumption (first group feed with wet % 4.912, second one dry % 1.466 and third one mixture of wet feed and dry feed % 2.927) were significant (P;lt;0.01). When the groups were compared from economical point of view the most pavourable one was the wet feed group which were followed by mixed feed and dry feed groups. As a ratio net profit mean feed cost was the lowest in the first group because of free supply of byproducts (% 0), which was followed by third (% 22.95) and second groups (% 41.44). during the study was no mortality this indicates that wet feed or by products had not any health hazardous effects.In conclusion it seems to possible to recommend using fish processing by products as a wet feed for rainbow trout.Bu çalışma, üç deneme grubundan oluşmuştur. Bunlar yaş yem, pelet yem, yaş yem + pelet yemdir. Araştırmada kullanılan balıkların gruplara göre ortalama başlangıç ağırlıkları sırası ile 55.288+11.052 g (n= 80), 56.063+14.513 g (n= 80) ve 54.875±14.227 g (n= 80) olup, her grup iki tekerrürlü olarak tanklara yerleştirilmiştir. Çalışma 180 gün sürmüştür. Çalışma sonunda ortalama canlı ağırlıklar, gruplara göre, sırasıyla; 262.550+76.022 g (n=80), 341.400±61.659 (n= 80), 312.700±92.807 g (n= 80) olarak saptanmıştır. Spesifik büyüme oranları bakımından (yaş yemle besleme % 0.886, kuru yemle besleme % 1.004, yaş yem + kuru yemle besleme % 0.967) gruplar arasındaki farklılık önemsiz, yem değerlendirme değerleri (yaş yemle besleme 6.092, kuru yemle besleme 1.583, yaş yem + kuru yemle besleme 3.321) ve günlük yem tüketimleri (yaş yemle besleme % 4.912, kuru yemle besleme % 1.466, yaş yem + kuru yemle besleme % 2.927) bakımından ise önemli bulunmuştur (P0.01). Grupların ekonomik yönden karşılaştırılmasında, yaş yem olarak kullanılan balıkhane artıklarına para ödenmediğinden, en iyi net kar yaş yemle beslenen grupta gerçekleşmiş, bunu yaş yem + pelet yemle beslenen grup ve kuru yemle beslenen grup izlemiştir. Net gelirin yüzdesi olarak, ortalama yem gideri en iyi 1. Grupta % 0 (balıkhane artıklarına para ödenmediği için) çıkmış, bunu 3. Grup % 22.95 ile ve 2. Grup % 41.44 değeri ile takip etmiştir. Deneme süresince gruplarda ölümün görülmemesi, yaş yemin balıkların sağlık durumlarını olumsuz yönde etkilemediğini göstermiştir. Sonuç olarak, incelenen bütün özellikler bakımından yapılan değerlendirmelerden, balıkhane artıklarının yaş yem olarak gökkuşağı alabalığına verilebileceği sonucuna varılmıştır

Effects of mixed feeding schedules on growth performance, body composition, and nitrogen- and phosphorus balance in rainbow trout, Oncorhynchus mykiss

Background. Reducing feed cost and the pollution originating from feed have been principal matters in fish nutrition. Mixed feeding schedules have been proposed as one of the methods to reduce both of them and successfully tested in many fish species. The aim of the present study was to determine the mixed feeding schedules′ suitability for culture of rainbow trout. Materials and methods. Five different feeding schedules were tried by alternating the presentation of a low-protein (28.1%) diet (A) and a high-protein (49.9%) diet (B). The feeding schedules employed were 1A/1B, 1A/2B, 1A/3B, 2A/2B, and 2A/3B where the numerical values refer to the number of days each diet (A and B) was offered continuously. Fish given diets A and B continuously served as controls. Totally, seven dietary treatments were tested in triplicate for 10 weeks. Results. The fish maintained on the different mixed feeding schedules exhibited lower weight gain than those fed continuously on the high-protein diet (P < 0.05). The fish reared on schedule 1A/3B (1 day diet A alternated with 3 days diet B) had similar specific growth rate (SGR), feed conversation ratio (FCR), and protein efficiency ratio (PER) to those fed diet B continuously and was best among all mixed feeding schedules. However, the most cost-effective treatment was 2A/2B. In addition, this group compared to B resulted in significant increase and reduction of phosphorus retention and discharge, respectively (P < 0.05). The treatments significantly effected body moisture, fat- and ash levels (P < 0.05), but not protein. Conclusion. The study shows that mixed feeding schedules are promising for use in rainbow trout culture as they result in feed cost saving and reduced phosphorus discharge in the effluents

Preliminary Assessment of Dietary Mannanoligosaccharides on Growth Performance and Health Status of Gilthead Seabream Sparus auratus

WOS: 000305292100006PubMed ID: 22779212A feeding trial was performed to assess the potential beneficial effect of two levels of mannanoligosaccarides (MOS) on the growth performance, feed utilization, hematological parameters, and liver histopathology of gilthead seabream Sparus auratus (also known as gilthead bream). Mannanoligosaccarides were added at the rates of 2 and 4 g/kg to a fish-meal-based control diet, and each diet was given (twice daily [midmorning and midafternoon] to apparent satiation) to triplicate groups of gilthead seabream growers (mean weight = approximately 170 g) in sea cages. The trial lasted 12 weeks, and the average ambient water temperature ranged from 19.6 degrees C to 24.7 degrees C during the experimental period. At the end of the experiment, fish attained market size (350-450 g) and their health status was evaluated by blood analysis and liver histology. There were no differences in survival rates among fish fed experimental diets. However, there were significant improvements in both growth and feed utilization among fish fed diets supplemented with MOS. Hemoglobin (Hb) and hematocrit (Ht) levels and erythrocyte, leukocyte, and thrombocyte (Thr) counts were unaffected by any dietary MOS. The levels of Hb (g/dL; mean +/- SD) and Ht (%; mean +/- SD) were 11.0 +/- 2.5 and 45.6 +/- 6.7 for the control group, 11.1 +/- 1.7 and 39.3 +/- 8.0 for the 2-g/kg group, and 11.2 +/- 1.9 and 40.2 +/- 8.4 for the 4-g/kg group. The mean Thr count ranged from 47.6 to 53.8 x 10(3)/mm(3). Despite the apparently higher Thr counts for fish fed diets supplemented with MOS, these differences were not significant. Moreover, no histopathological differences were observed in liver tissue cross sections between control and treatment groups. These results suggest that supplementation of diets with MOS had no significant effects on general fish health