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Several studies have shown that food ration can affect the growth of cultured fish. Determining the optimal food ration would help to achieve better growth and also provide direct economic benefits due to reduced food wastage, which would lead to commercial success. Therefore, we studied the effects of ration levels on growth performance of 0+ juvenile yellowtail flounder to determine the optimal food ration. Two experiments were conducted; the first experiment as a preliminary using ration levels of 1%, 2%, 4%, 6% body weight per day (% bw day−1) held at 7.0 °C with a stocking density of 0.95 kg m−2 (45% bottom coverage). Results of this preliminary experiment indicated that fish fed with 1% bw day−1 had significantly lower growth (weight, length, body depth and specific growth rates (SGR)) than those fed with 2%, 4% and 6% ration. However, fish fed with rations of 1% and 2% showed significantly lower gross food conversion ratios (GFCR) than fish fed with 4% and 6% rations. Survival was not significantly affected by different ration levels. Based on these preliminary results, we used ration levels of 1%, 1.5%, 2% and 3% for the main experiment. Fish were held at 10 °C with a stocking density of 1.45 kg m−2 (34% bottom coverage). Results indicated that fish fed with 1%, 1.5% and 2% bw day−1 had significantly lower growth than fish fed with 3% bw day−1. GFCR was significantly different for all four rations. It was lower for 1% than 1.5%, 2% and 3% rations. Survival was not significantly different between any treatments. We discuss our results with emphasis on growth and economics (i.e., feed wastage) and stress the need to balance both components in a commercial operation. 相似文献
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We investigated if simplified routines based on blastomere morphology and fertilization success can be used as predictors of egg and embryo viability in Atlantic cod, and abnormal blastomere morphology is related to juvenile deformities. Egg morphology data from 312 families that were produced by hand stripping of gametes were used. Fertilized eggs from all families were separately incubated in 25 L incubators. Blastomere morphology and fertilization success were assessed at 16–32 cell stage. Embryo mortality was measured until hatch. Fertilization success showed a significant positive correlation with the proportion of normal blastomere and 74% of the variation in the incidence of blastomere abnormality was explained by fertilization success. Juvenile deformities were positively correlated with blastomere abnormality and 8% of the variation in juvenile deformities was explained by incidences of blastomere abnormality. To our knowledge, this is the first direct evidence showing that incidences of blastomere abnormalities may be related to cod juvenile deformities. Our results suggest that fertilization success and the occurrence of blastomere abnormalities could be easily adopted by commercial cod hatcheries for the early determination of egg quality. 相似文献
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Øyvind J Hansen Velmurugu Puvanendran Jens Petter Jøstensen Christian Ous 《Aquaculture Research》2011,42(7):1026-1033
Effects of two weaning diets that differed in phospholipid (PL) classes on growth, survival and deformities of cod larvae and early juveniles were evaluated. Cod larvae were fed rotifers until 21 days post hatch (dph) and then weaning onto dry diet started. One group of larvae were fed a control diet with low levels of phosphatidylcholine (PC), PE and phosphatidylinositol (PI) and the other group of larvae were fed with an experimental diet containing higher levels of PC, PE and PI. Larvae fed with the control diet were significantly smaller than larvae fed with the experimental diet at the end of the experiment. Swim bladder abnormalities were significantly higher in larvae fed with control diet at 35 dph than the larvae fed with experimental diet; however, no significant difference was evident at 42 dph. Vertebral deformities were significantly higher in larvae fed with control diet and scoliosis was significantly different between the treatments. Survival was also significantly higher in the experimental group. Our results indicate that dietary levels of PL, PC and PI may affect the cod larval growth, survival and deformities. More detail studies are needed to find out the optimal levels of these important PL classes in larval cod diets. 相似文献
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Jennifer Monk Velmurugu Puvanendran Joseph A. Brown 《Aquaculture (Amsterdam, Netherlands)》2008,277(3-4):197-202
We examined the foraging behaviour, growth and survival of Atlantic cod (Gadus morhua) larvae in two different colours of tank bottom; either beige (light hereafter) or black (dark hereafter) bottomed tanks with black walls. Results showed no significant differences in the growth, foraging behaviour, or survival of Atlantic cod larvae in response to tank bottom colour indicating that larvae could be reared in lighter bottom tanks without any detrimental effect to the larvae. Using a light bottom tank is also of greater benefit to the culturist as they provide better contrast to monitor the behavioural and morphological development of the larvae. 相似文献
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Phytate, the mixed salt of phytic acid (myo-inositol hexaphosphate), derived from plant-sourced feed ingredients is invariably present in practical diets for pigs. Typically, swine diets contain in the order of 3.0 g kg− 1 phytate-bound phosphorus (phytate-P) but phytate concentrations are subject to variation. Importantly, phytate-P is only partially utilised by pigs because they do not generate sufficient endogenous phytase activity. Phytate-degrading enzymes, via step-wise dephosphorylation of phytate, have the capacity to liberate phytate-P, thus enhancing P absorption and reducing P excretion, which are both nutritionally and ecologically beneficial consequences. The commercial introduction of microbial phytases in 1991 has greatly magnified the interest in the roles of phytate and phytase in pig nutrition.
The capacity of microbial phytases to enhance growth performance of pigs offered diets with inadequate P levels is well documented. However, in some instances, phytase has been shown to improve performance of pigs offered P adequate diets thus phytase-induced improvements in growth performance should not be attributed entirely to increased P availability. This raises the possibility that phytase is increasing the utilisation of nutrients other than P. These so-called ‘extra-phosphoric’ effects of phytase remain controversial, particularly in relation to protein and amino acid availability. There are conflicting opinions that are reflected in the inconsistent outcomes of studies to determine the effect of phytase on ileal digestibility of amino acids and protein utilisation in pigs. In phytase amino acid digestibility assays, it seems likely the choice of chromic oxide as the dietary marker has contributed to these ambiguous results, which may be further complicated when ileal digesta samples are taken from cannulated pigs fed on a restricted, twice-daily basis. In order to resolve this critical issue, there is an urgent need to assess the impacts of selection of dietary markers, methods of ileal digesta collection and feeding regimen relative on the outcomes of phytase amino acid digestibility assays in pigs.
However, inconsistent results from phytase studies in pigs are not confined to amino acid digestibility assays. Arguably, insufficient attention has been paid to dietary substrate levels in relation to phytase inclusion from both scientific and practical standpoints. Phytate analyses are not straightforward and there is a real need to develop more accurate and rapid methods to facilitate phytate determinations. The properties of phytate vary between (and within) feed ingredients where solubility of phytate may be critical; which, in turn, is a function of gut pH in pigs. Contemporary phytases have the capacity to degrade approximately 50% of dietary phytate at the level of the ileum, which may mean higher inclusion rates are warranted. Consequently, there is scope for the development of more effective ‘second-generation’ phytate-degrading feed enzymes and their possible introduction, coupled with a better scientific understanding of relevant fundamental issues, will ensure that phytate-degrading enzymes will contribute to viable and sustainable pig production to an even greater extent in the future. 相似文献
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We conducted a study to evaluate the effects of holding water temperature on the fecundity and egg quality of photo‐manipulated Atlantic cod broodstock. Adult cod Gadus morhua were distributed among several 25‐m3 tanks. Three separate photoperiods were used for each group to obtain three spawning per year (in May, July and December). While photoperiod was controlled, the temperature was not controlled and followed the ambient seasonal pattern. Due to the uncontrolled seasonal temperature used, each spawning group experienced different temperatures at a particular gonadal developmental stage. Otherwise, all groups were treated the same. Results showed that the May and July spawning groups released significantly more eggs per kg of fish (four and three times more respectively) than the December spawning group. The egg fertilization success and proportion of normal eggs were also higher in the May and July groups. Possible reason for the difference may be that the May and July groups experienced lower temperatures (4–7°C) during oocyte maturation and ovulation than the December group (7–9°C). Our results show the importance of using lower/natural temperatures during oocyte maturation and ovulation to obtain good quality eggs in photo‐manipulated cod broodstock. 相似文献
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Early introduction of an inert diet and unenriched Artemia enhances growth and quality of Atlantic cod (Gadus morhua) larvae 
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下载免费PDF全文 Ø.J. Hansen V. Puvanendran J.P. Jøstensen I.‐B. Falk‐Petersen 《Aquaculture Nutrition》2018,24(1):102-111
The effects of two weaning diets and different weaning protocols on growth, survival, skeletal deformity and gut morphology of Atlantic cod larvae were studied in four groups from 16 to 45 days posthatch (dph). Cod larvae in groups 1 (early weaning with control diet) and 2 (early weaning with experimental diet) were used to evaluate the effects of different polar lipid content of weaning diets on larval and juvenile performance. Cod larvae in groups 2, 3 (early weaning with experimental diet + cofeeding with Artemia) and 4 (earlier weaning with experimental diet and earlier cofeeding with Artemia) were used to evaluate the effects of early introduction of dry diet and Artemia. From 45 to 170 dph, cod juveniles from all four groups were reared using a standard feeding protocol. No significant differences in growth, survival, deformities and gut morphology were found between cod larvae and juveniles from groups 1 and 2. Cod larvae fed on cofeeding regime with Artemia nauplii (groups 3 and 4) were bigger and had lower frequencies of jaw and neck deformities and higher foregut microvillus circumference than cod larvae from group 2. Our results demonstrate the importance of proper weaning protocols in producing better quality cod juveniles. 相似文献
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Mohammad Reza Abdollahi Faegheh Zaefarian Hayley Hunt Muhammad Naveed Anwar David G. Thomas Velmurugu Ravindran 《Journal of animal physiology and animal nutrition》2019,103(1):146-161
A 21‐day experiment was conducted to investigate the effects of wheat particle size, insoluble fibre source and whole wheat (WW) inclusion on the gizzard musculature, intestinal architecture and nutrient utilisation of broiler chickens. The following seven treatments, all in mash form, were tested: control diet using finely ground wheat (Fine); control diet using medium‐ground wheat (Medium); control diet using coarsely ground wheat (Coarse); fine diet diluted with 10 g/kg lignocellulose (LC); fine diet diluted with 30 g/kg oat hulls (OH); fine diet diluted with 30 g/kg wood shavings (WS); and ground wheat in the fine diet replaced with 50 and 100 g/kg WW during the second (day 8–14) and third (day 15–21) weeks of the study respectively. Except for the LC diet, all treatments increased (p < 0.05) the thickness of the caudodorsal thick muscle of gizzard compared to the fine diet. The highest (p < 0.05) caudoventral thin and cranioventral thick muscle diameters in the gizzard walls were achieved with the OH and WS diets. Feeding OH, WS and WW diets improved (p < 0.05) starch digestibility compared with the fine diet, while medium, coarse and LC diets had no effect (p > 0.05). All diets containing fibre sources (LC, OH and WS) reduced (p < 0.05) the energy digestibility compared to the fine diet. Birds fed OH and WS diets gained the lowest (p < 0.05) weights. Feeding LC, OH, WS and WW diets increased (p < 0.05) the feed per gain compared with the fine diet. The current results suggest that there is a potential for coarse particles, insoluble fibre sources and WW feeding to improve the gizzard musculature and digestibility of some nutrients, with the effect being more pronounced with the inclusion of structural fibre sources. 相似文献
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Faegheh Zaefarian Aaron J. Cowieson Katrine Pontoppidan M. Reza Abdollahi Velmurugu Ravindran 《动物营养（英文）》2021,7(2):268
Accurate knowledge of the actual nutritional value of individual feed ingredients and complete diets is critical for efficient and sustainable animal production. For this reason, feed evaluation has always been in the forefront of nutritional research. Feed evaluation for poultry involves several approaches that include chemical analysis, table values, prediction equations, near-infrared reflectance spectroscopy, in vivo data and in vitro digestion techniques. Among these, the use of animals (in vivo) is the most valuable to gain information on nutrient utilization and is more predictive of bird performance. However, in vivo methods are expensive, laborious and time-consuming. It is therefore important to establish in vitro methods that are reliable, rapid and practical to assess the nutritional quality of feed ingredients or complete diets. Accuracy of the technique is crucial, as poor prediction will have a negative impact on bird performance and, increase feed cost and environmental issues. In this review, the relevance and importance of feed evaluation in poultry nutrition will be highlighted and the various approaches to evaluate the feed value of feed ingredients or complete diets will be discussed. Trends in and practical limitations encountered in feed evaluation science, with emphasis on in vitro digestion techniques, will be discussed. 相似文献