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Natural Diet (natural + diet)
Selected AbstractsFood competition between 2+ tench (Tinca tinca L.), common carp (Cyprinus carpio L.) and bigmouth buffalo (Ictiobus cyprinellus Val.) in pond polycultureJOURNAL OF APPLIED ICHTHYOLOGY, Issue 3 2003Z. Adámek Summary Natural diets of tench (Tinca tinca L.), carp (Cyprinus carpio L.) and bigmouth buffalo (Ictiobus cyprinellus Val.) were studied to determine food competition among them in polyculture stocks of two different densities. Tench diet consisted mainly of zooplankton (43.8%) and bottom sediments (21.2%). In contrast, carp diet consisted mainly of bottom items including plant debris and detritus (68.8%), which dominated over zooplankton (19.1%). In bigmouth buffalo, most food bulk comprised zooplankton (80.7%). Thus, the resulting food competition (i.e. similarity) was most pronounced between tench and carp (60.8%) and between tench and bigmouth buffalo (47.4%). When comparing growth performance of the three cultured species, the ratios between stocking and harvesting size were: in normal stocking density (392 kg ha,1) 1.72, 3.67 and 2.13, and in doubled stocking density (777 kg ha,1) 1.07, 2.33 and 2.16 in tench, carp and bigmouth buffalo, respectively. [source] Effect of prepared diet and vitamins A, E and C supplementation on the reproductive performance of cage-reared bighead carp Aristichthys nobilis (Richardson)JOURNAL OF APPLIED ICHTHYOLOGY, Issue 1 2000By C. B. Santiago Twenty-month-old bighead carp, Aristichthys nobilis (Richardson), were fed prepared dry diets for 20 months in cages in Laguna de Bay, Philippines, to determine the effect on reproductive performance. The experimental diets were similar in composition except for the combinations of vitamins being tested. Diet 1 was supplemented with vitamins A, E and C; diets 2, 3 and 4 each lacked one of the supplementary vitamins; and diet 5 did not include any vitamin supplementation. Bighead carp that relied solely on natural food without a prepared diet served as a control. The total of six treatments each had two replicates. Results showed that the onset of gonad maturation was 2,3 months earlier in the fish that were fed the prepared diets regardless of vitamin supplementation, when compared with the fish that were fed natural food (control). Moreover, the prepared diets enhanced egg hatchability which was significantly higher in fish that were fed diet 1 (+ vitamins A, E and C, 80.5 ± 18.1%) and diet 3 (, vitamin E, 78.5 ± 1.1%) than in those fish that were fed natural food (control) (36.5 ± 31.3%). Mean number of 3-day-old larvae was highest in fish fed on diet 1 (34 525 ± 1732), followed closely by fish that were fed diet 3 (32 420 ± 3909). A low number of 3-day-old larvae was obtained from fish fed the natural diet (14 490 ± 4331) as well as in fish that were fed diet 2 (, vitamin A, 14 347 ± 4863), diet 4 (, vitamin C, 21 407 ± 5840) and diet 5 (, vitamin A, E and C, 12 191 ± 1439). Other criteria for reproduction such as relative fecundity, fertilization rate, and hatching rate did not differ significantly (P >,0.05) among treatments. The addition of vitamins also had no significant effects on weight gain of adult fish. [source] The intraruminal papillation gradient in wild ruminants of different feeding types: Implications for rumen physiologyJOURNAL OF MORPHOLOGY, Issue 8 2009Marcus Clauss Abstract Browsing and grazing ruminants are thought to differ in the degree their rumen contents are stratified,which may be due to different characteristics of their respective forages, to particular adaptations of the animals, or both. However, this stratification is difficult to measure in live animals. The papillation of the rumen has been suggested as an anatomical proxy for stratification,with even papillation indicating homogenous contents, and uneven papillation (with few and small dorsal and ventral papillae, and prominent papillae in the atrium ruminis) stratified contents. Using the surface enlargement factor (SEF, indicating how basal mucosa surface is increased by papillae) of over 55 ruminant species, we demonstrate that differences between the SEFdorsal or SEFventral and the SEFatrium are significantly related to the percentage of grass in the natural diet. The more a species is adapted to grass, the more distinct this difference, with extreme grazers having unpapillated dorsal and ventral mucosa. The relative SEFdorsal as anatomical proxy for stratification, and the difference in particle and fluid retention in the rumen as physiological proxy for stratification, are highly correlated in species (n = 9) for which both kind of data are available. The results support the concept that the stratification of rumen contents varies among ruminants, with more homogenous contents in the more browsing and more stratified contents in the more grazing species. J. Morphol., 2009. © 2009 Wiley-Liss, Inc. [source] Toward Improved Public Confidence in Farmed Fish Quality: A Canadian Perspective on the Consequences of Diet SelectionJOURNAL OF THE WORLD AQUACULTURE SOCIETY, Issue 2 2010Anthony P. Farrell Marine fish oils (MFO) are used in salmon diets to mimic the natural diet, to ensure that essential fatty acid requirements for good fish growth and health are met, and to provide salmon flesh with an omega-3 highly unsaturated fatty acid content that can benefit human health. However, an extensive use of MFO in formulated salmonid diets is perceived as an unsustainable use of wild marine fish stocks. In addition, MFOs have a background level of persistent organic pollutants (POPs) unrelated to aquaculture practices. This review considers recently completed studies using alternative lipid sources of terrestrial origin as replacements for MFO and shows that the composition of conventional finfish diets can be altered to reduce the reliance on MFO while concurrently maintaining fish health as well as reducing background levels of POPs. A challenge still ahead is the need for a concerted and sustained outreach to ensure that the public is aware of such improvements to seafood quality so that the preoccupation of the news media with presenting negative images of fish culture to the public is combated. [source] Enamel ridge alignment in upper molars of ruminants in relation to their natural dietJOURNAL OF ZOOLOGY, Issue 1 2010T. M. Kaiser Abstract Although it is generally thought that dental design reflects mechanical adaptations to particular diets, concrete concepts of such adaptations beyond the evolution of hypsodonty are largely missing. We investigated the alignment of enamel ridges in the occlusal molar surface of 37 ruminant species and tested for correlations with the percentage of grass in the natural diet. Independent of phylogenetic lineage, species that were either larger and/or included more grass in their natural diet showed a higher proportion of enamel ridges aligned at low angles to the direction of the chewing stroke. Possible explanations for this design are a potential alignment of grass blades in parallel to the molar tooth row, a potential increased proportion of a propalinal (anterior,posterior) chewing movement in grazers as opposed to a strictly transversal chewing stroke in browsers and the general distribution of forces along the occlusal surface during the chewing stroke. The latter will be less heterogenous (with less force peaks) with an increasing proportion of low-angle enamel ridges. While the validity of these explanations will have to be tested in further studies, the enamel ridge alignment represents a clear signal that deviates from an arbitrary distribution and hence most likely represents a functional adaptation. [source] Convergence in the macroscopic anatomy of the reticulum in wild ruminant species of different feeding types and a new resulting hypothesis on reticular functionJOURNAL OF ZOOLOGY, Issue 1 2010M. Clauss Abstract The reticulum is the second part of the ruminant forestomach, located between the rumen and the omasum and characterized by honeycomb-like internal mucosa. With its fluid contents, it plays a decisive role in particle separation. Differences among species have been linked to their feeding style. We investigated whether reticulum size (absolute and in relation to rumen size) and size of the crests that form the mucosal honeycomb pattern differ among over 60 ruminant species of various body sizes and feeding type, controlling for phylogeny. Linear dimensions generally scaled allometrically, that is to body mass0.33. With or without controlling for phylogeny, species that ingest a higher proportion of grass in their natural diet had both significantly larger (higher) rumens and higher reticular mucosa crests, but neither reticulum height nor reticulum width varied with feeding type. The height of the reticular mucosa crests represents a dietary adaptation in ruminants. We suggest that the reticular honeycomb structures do not separate particles by acting as traps (neither for small nor for large particles), but that the structures reduce the lumen of the reticulum during contractions , at varying degrees of completeness in the different feeding types. In browsing species with rumen contents that may be less fluid and more viscous than those of the reticulum, incomplete closure of the lumen may allow the reticulum to retain the fluid necessary for particle separation. In grazing species, whose rumen contents are more stratified with a larger distinct fluid pool, a more complete closure of the reticular lumen due to higher crests may be beneficial as the reticulum can quickly re-fill with fluid rumen contents that contain pre-sorted particles. [source] Observations on the Macroscopic Anatomy of the Intestinal Tract and its Mesenteric Folds in the Pampas Deer (Ozotoceros bezoarticus, Linnaeus 1758)ANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 4 2008W. Pérez Summary We described the macroscopic anatomy of the intestines and their peritoneal folds of five adult pampas deer (Ozotoceros bezoarticus), a cervid species considered to ingest a high proportion of grass in its natural diet. The mean (±SD) body weight was 17 (±2) kg. The small intestine and the caecocolon measured 495 (±37) cm and 237 (±24) cm in length, respectively, with an average ratio (small intestine:caecocolon) of 1.9 (±0.1). The ascending colon had two and a half centripetal gyri, a central flexure and two centrifugal gyri. The spiral ansa, which was similar to an ellipse, was fixed to the whole left face of the mesenterium. Apart from the peritoneal folds described in the Nomina Anatomica Veterinaria, three additional, hitherto not described folds were found: a fold that fixed the caecum to the proximal ansa of the ascending colon, one that joined the terminal part of the proximal ansa to the last centrifugal gyrus of the spiral ansa of the ascending colon, and one that linked the ascending duodenum to the proximal ansa of the ascending colon. When compared with published data from other cervids of different feeding niches, it appears that, among cervids, the ratio of small intestine to the caecocolon length does not reflect the natural diet. [source] Activities of glucose phosphorylation, glucose-6-phosphatase and lipogenic enzymes in the liver of perch, Perca fluviatilis, after different dietary treatmentAQUACULTURE RESEARCH, Issue 2001B Borrebaek Abstract Glucose phosphorylation was increased and the activity of glucose-6-phosphatase was decreased in the liver of perch Perca fluviatilis after feeding previously fasted fish with a high protein/low carbohydrate diet as well as with a diet containing 23% carbohydrate. Activity of the low affinity hexokinase IV (or D), also called glucokinase (GK), was not observed in the liver of perch on the natural diet, fasted perch or perch after feeding with the high protein/low-carbohydrate diet (< 0.2% CHO). How ever, hepatic GK-activity appeared after feeding with the carbohydrate containing diet. By contrast, the activity of hepatic high affinity hexokinase (HK), which was very low in fasted fish, was strongly increased after feeding with the low-carbohydrate as well as the carbohydrate-containing diet. Apparently, HK rather than GK is the hexokinase isoenzyme that is consistently regulated inversely to glucose-6-phosphatase. Activities of the lipogenic enzymes glucose-6-phosphate dehydrogenase, ATP-citrate lyase and malic enzyme were increased by feeding, particularly with the high protein/low carbohydrate diet. Very high levels of hepatic glycogen were observed after both diets. The results are in accordance with the hypothesis that the hepatic high affinity isoenzyme (HK) has a particular anabolic role. [source] The use of alternative diets to culture juvenile cuttlefish, Sepia officinalis: effects on growth and lipid compositionAQUACULTURE NUTRITION, Issue 3 2010A. FERREIRA Abstract The effects of feeding three natural frozen diets, grass shrimp (Palaemonetes sp.), crayfish (Procambarus clarkii) and fish (Sardina pilchardus) and two semi-humid artificial diets (based on fish or shrimp powder) to the cuttlefish, Sepia officinalis, were analysed. Growth rate and feeding rate [FR; % body weight (BW) day,1] and food conversions (FC, %) were determined. Cuttlefish fed shrimp grew larger (3.8% BW day,1) and had the highest FC, followed by those fed crayfish, and sardine. The highest FR was obtained for cuttlefish fed crayfish (10.5% BW day,1). Although both artificial diets were accepted, none produced growth. Digestive gland-to-body weight ratio (DG/BW ratio) was calculated for animals fed each diet. A positive correlation (r = 0.94) between cuttlefish ingestion FR and DG weight was obtained. Mortality occurred mainly during the last week, and some cannibalism occurred among cuttlefish fed artificial diets. Finally, lipid composition of diets, DG and mantle of each group were analysed. Sardine diet was characterized by high levels of triacylglycerol (TG), whereas the main difference between shrimp and crayfish was the higher n -3/n -6 ratio found in shrimp. Changes in the lipid composition of DG were related to diet, but did not correlate with growth data. A strong loss of TG in the DG of artificial diets groups was notable. No differences in mantle lipid composition among the natural diets were found, but artificial diet groups showed higher contents of neutral lipids in their mantle respect to natural diets. According to results obtained, crayfish (P. clarkii) could be used as an alternative prey for rearing S. officinalis compared with shrimp. Artificial diets showed the worst effects in growth and mortality as well as the stronger influence on DG and mantle lipid composition of cuttlefish. [source] Growth performance of weaning red abalone (Haliotis rufescens) fed with Macrocystis pyrifera plantlets and Porphyra columbina compared with a formulated dietAQUACULTURE RESEARCH, Issue 15 2009Jorge Hernández Abstract A feeding experiment was carried out to evaluate two natural diets versus a formulated feed on the performance of weaning red abalone Haliotis rufescens. Four treatment diets were then investigated: a formulated diet; plantlets from culture Macrocystis pyrifera, Porphyra columbina from natural beds; and a mixed diet consisting of a blend of fresh P. columbina together with the formulated diet. This study was performed in a shallow aquaculture system with a horizontal water flow. After 90 days, significant differences were observed between treatments. The highest growth was obtained with Porphyra (3.3 mm month,1), followed by the mixed diet (2.6 mm month,1), then Macrocystis (2.1 mm month,1) and lastly the formulated diet (1.4 mm month,1). Moreover, after the diets were tested for stability and remnant nutrients after a 12-h water immersion, a positive trend appeared to be related to the protein/energy (P:E). It is concluded that fronds of P. columbina resulted in the best diet for weaning H. rufescens under horizontal water flow systems, even if apparently the water stability of the formulated diet had a negative impact on abalone performance, particularly due to a poor nutrient retention capacity. Therefore, formulated diets should be improved before being recommended for weaning red abalone. [source] Quality of wild-captured saithe (Pollachius virens L.) fed formulated diets for 8 monthsAQUACULTURE RESEARCH, Issue 11 2009Håkon Otterå Abstract Fish farms may attract wild fish that feed on waste feed from the cages. Saithe, Pollachius virens L., are particularly numerous around salmon cages in northern Europe and may obtain a significant proportion of their diet from waste feed. It has been claimed that these fish are of inferior quality to saithe that feed on natural diets; differences are said to include soft muscle tissue and a different taste. In order to document such changes in quality we performed a feeding experiment. Young wild saithe were collected and fed either a lipid-rich salmon diet or a lean cod diet for 8 months. All fish were individually tagged and growth was monitored throughout the experiment. Parameters related to flesh quality were measured. Diet clearly influenced the growth rate of the fish, and many fish reached a very high hepatosomatic index when fed on a salmon diet. However, many fish had a low feed intake and thus a low rate of growth. There were some differences in skin and muscle colour, pH and in sensory parameters between wild-caught and artificially fed saithe at the end of the experiment. Those fed the cod diet were more similar to wild saithe than those fed the salmon diet. [source] | |||||||||||||