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Natural Food (natural + food)
Selected AbstractsReproductive performance, lipids and fatty acids of mud crab Scylla serrata (Forsskål) fed dietary lipid levelsAQUACULTURE RESEARCH, Issue 14 2007Veronica R Alava Abstract Natural food (NF, control), artificial diets (AD) containing total lipid levels of 10%, 12% and 14% (AD10, AD12 and AD14) and their combinations (AD10+NF, AD12+NF and AD14+NF) were fed for 112 days to pond-sourced eyestalk-ablated mud crab Scylla serrata (625±6.4 g) in tanks in order to determine their effects on reproduction and lipid profiles in broodstock tissues and zoeae. Crabs fed NF had the highest number of spawning followed by crabs fed AD10+NF and AD14+NF. Higher offspring production (number of zoeae) was obtained from crabs fed NF and AD+NF than from AD. As dietary total lipid levels increased, total lipid of broodstock ovaries, hepatopancreas, muscle and zoeae correspondingly increased in which AD+NF promoted higher levels than AD. Increased dietary total lipid levels enhanced lipid classes such as triacylglycerols and phosphatidyl choline levels in zoeae, all higher in crabs fed AD+NF than in AD. The major fatty acids in zoeae, particularly 16:0, 18:0, 18:1n-9 and 20:4n-6, 20:5n-3 and 22:6n-3, were higher in crabs fed AD+NF than in AD, the contents corresponding to broodstock dietary total lipid levels. A 10% total lipid in AD in combination with NF was sufficient to provide the essential lipids in crabs in the improvement of larval production and quality. [source] Avian productivity in urban landscapes: a review and meta-analysisIBIS, Issue 1 2009D. E. CHAMBERLAIN There is an urgent need to thoroughly review and comprehend the effects of urbanization on wildlife in order to understand both the ecological implications of increasing urbanization and how to mitigate its threat to biodiversity globally. We examined patterns in comparative productivity of urban and non-urban passerine birds, using published estimates from paired comparisons, and by reviewing and developing explanations in terms of resources, competitors, predators and other specifically urban environmental factors. The most consistent patterns were for earlier lay dates, lower clutch size, lower nestling weight and lower productivity per nesting attempt in urban landscapes; these were supported by a formal meta-analysis. Nest failure rates did not show consistent patterns across the species considered. We suggest that food availability is a key driver of differences in passerine demography between landscapes. In urban habitats, human-provided food may improve adult condition over winter, leading to earlier lay dates and, in some species, to higher survival and higher breeding densities, but paucity of natural food may lead to lower productivity per nesting attempt. We demonstrate that additional comparative research is needed on a wider range of species, on the effects of natural and human-provided food availability, and on the differences in survival and dispersal between urban and non-urban populations. Importantly, better-targeted research and monitoring is needed in areas that are at greatest threat from urbanization, especially in the developing world. [source] Population trends of Rooks Corvus frugilegus in Spain and the importance of refuse tipsIBIS, Issue 1 2008PEDRO P. OLEA Anthropogenic food from refuse tips can affect population dynamics in birds, especially gulls, but the evidence is mostly circumstantial. We combine analyses of long-term population data and natural experiments to show a positive effect of refuse tips on the growth of the Spanish breeding population of Rooks Corvus frugilegus. In this isolated population of around 2000 breeding pairs, monitored since 1976, birds in colonies less than 10 km from tips fed largely on refuse, particularly during periods of lowest natural food availability. Three lines of evidence support the hypothesis that the supply of refuse influenced breeding numbers, suggesting that this population is limited by food: 1) between 1976 and 2003, the two population nuclei that had access to tips increased 2.1 and 3.7 times more than that without a tip nearby; 2) annual colony growth between 1996 and 2003 was strongly correlated with the availability of tips when other potentially important variables were taken into account; 3) the number of breeding pairs in refuse-foraging colonies declined rapidly after the closure of the local tip and recovered only when a supply of refuse was restored. The effect of tips on colony growth was stronger when the availability of natural foraging habitat around the colonies was low, suggesting that anthropogenic food acts as a buffer against shortage of natural food. Artificial food supplementation may be an effective tool to increase the breeding population of target species, especially those facing a reduction of their foraging habitats. The potential effects on bird species of Directive 1999/31/CE, which is enforcing a massive closure of tips in Europe, are discussed. [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] How different provisioning strategies result in equal rates of food delivery: an experimental study of blue tits Parus caeruleusJOURNAL OF AVIAN BIOLOGY, Issue 4 2002Fabrizio Grieco Food provisioning in birds requires a considerable amount of time and usually has to be traded-off against other parental and non-parental activities. I investigated experimentally the rate at which blue tit Parus caeruleus parents deliver food to their brood after a change in food availability. The main argument behind this study is that parents enjoying an additional food source may use less time for self-feeding and therefore use more time for food provisioning. This could increase the rate at which food is brought to the nest. However, a prey choice model that takes the energetic needs of the parent into account allows for the possibility that the food-supplemented parents would deliver the same amount of food by increasing prey size (through an increase in prey selectivity) and reducing visit rate. The field data indicate that the parents changed provisioning strategy when food-supplemented: they fed the chicks natural food less frequently, but brought larger larvae. On the whole, delivery rate of natural food was the same or lower than in controls. The results suggest that food-supplemented parents used the time saved to increase their degree of food selectivity. When the gains from an increased delivery rate are not worth the increased costs (mainly resulting from an increased visiting rate), the parent with low energetic need may increase selectivity to provide the same amount of food to the brood as the unmanipulated parent, but at a lower cost. [source] GROWTH OF CULTURED ABALONE, HALIOTIS FULGENS, USING NATURAL ALGAL DIETSJOURNAL OF PHYCOLOGY, Issue 2001Article first published online: 24 SEP 200 Pérez-Estrada, C. J.1,2, Serviere-Zaragoza, E.1, Mazariegos-Villareal, A.1, Reynoso-Granados, T.1 & Monsalvo-Spencer, P.1 1Centro de Investigaciones Biológicas del Noroeste (CIBNOR). P.O. Box 128, La Paz, Baja California Sur. 23000. México; 2Universidad Autónoma de Baja California Sur. Carretera al Sur km. 5.5 o 23080 o La Paz, B. C. S. Algal diets have been evaluated and used extensively for the aquaculture of abalone, especially in Japan. In other areas little is known about the nutritional value of the algae that the local abalone consume. In Mexico, regional hatcheries use Macrocystis pyrifera as a main source of natural food. Kelp availability, year round, has not generally been a problem for abalone aquaculturists. Most difficulties occur during severe storms, which may prevent access to kelp beds. El Niño also caused widespread destruction of M. pyrifera. In this study, growth rates of juvenile green abalone Haliotis fulgens, 31.7 " 1.5 mm shell length and 2.5 " 0.2 g body weight were evaluated during 136 days. Juveniles were fed with some of the algae used in regional hatcheries, Macrocystis pyrifera, Egregia menziesii, Eisenia arborea, Porphyra sp. and Ulva sp. Shell length growth rates varied between 2 mm day-1 for Ulva sp. and 18 mm day-1 for M. pyrifera. Body weight rates ranged from no growth for Ulva sp. to 14 mg day-1for E. menziesii. The percent of survival was between 46 and 75 %. Ulva sp. showed the lowest protein content followed by E. menziesii, E. arborea, M. pyrifera and Porphyra sp. [source] The effect of protein levels on growth, postprandial excretion and tryptic activity of juvenile mullet Mugil platanus (Günther)AQUACULTURE RESEARCH, Issue 4 2010Cristina V A De Carvalho Abstract The objective of the present work was to determine the optimum dietary protein level for juvenile mullets. Five isocaloric diets were formulated to contain increasing levels (300, 350, 400, 450 and 500 g kg,1) of crude protein (CP) corresponding to 18.7 MJ metabolizable energy kg,1. All diets were tested in triplicate. Each experimental unit was composed of a 50 L tank with 50 juveniles (mean ± SE initial weight and length equal to 1.17 ± 0.02 g and 4.34 ± 0.03 cm respectively). Diets were offered five times a day until apparent satiation for 35 days. No significant difference (P>0.05) was observed in survival rate, feed efficiency and body composition between treatments. However, weight gain, feed consumption and specific growth rate were higher in fish fed the 350 g kg,1 CP level than those fed the highest protein content diet (500 g kg,1 CP). The amount of postprandial ammonia excreted by mullet was linearly related to protein intake. Intestinal tryptic activity was inversely proportional to the percentage of dietary CP. It is likely that diets containing <350 g kg,1 CP will be needed for on-growing mullet, especially when reared in ponds with abundant natural food. [source] Diurnal feeding pattern and gut content of milkfish Chanos chanos (Forsskål, 1775) cultured semi-intensively during the wet and dry season in brackish ponds in the PhilippinesAQUACULTURE RESEARCH, Issue 1 2008Kai-Jens Kühlmann Abstract To improve feeding management and reduce feed cost in semi-intensive grow-out culture of milkfish (Chanos chanos, Forsskål 1775) in brackish ponds, the relative shares of natural food (NF) and supplemental feed (SF) ingested by the fish were microscopically quantified from their completely dissected digestive tracts sampled during 24-h cycles in wet (June,September) and dry (December,April) seasons. Particles from rice husk, indigestible to milkfish, were used as internal markers to quantify supplemental feed. Significantly (P<0.05) more NF than SF (1.4±0.2 vs. 0.4±0.1 g kg,0.8) and SF than NF (1.4±0.8 vs. 0.6±0.3 g kg,0.8) were found during the first month of the wet and the first 3 months of the dry season respectively. Diurnal feeding patterns on SF were significantly higher at morning hours during the dry compared with the wet season. The feeding pattern of milkfish is likely to be affected by the different weather and pond conditions in both seasons. Developing a season-specific pond fertilization management to enhance NF availability in semi-intensive milkfish culture can help to improve the economical and ecological performance of milkfish culture. [source] Changing of fat content and fatty acid profile of reared pike (Esox lucius) fed two different dietsAQUACULTURE RESEARCH, Issue 1 2006Balázs Kucska Abstract Fat content and fatty acid profile of two pike yearling groups grown on two different diets were compared. The groups originated from culture on artificial feed. One group (cultured pike fed first pellet then prey-fish (PF)) was fed with natural food, live prey-fish, while the other one (cultured pike fed exclusively pellet (PP)) by trout feed through a 3-month experimental period. Growth of pike was lower with PP than with PF. The trout feed resulted in an increase of the fat content of fillet and the formation of abdominal fat depots. Feeding of natural food decreased the fat content. The proportion of the saturated fatty acids in fillet was higher in the (PF) group. The n-6 fatty acids (arachidonic C20:4n-6 and docosatetraenic C22:4n-6 acids) were lowest in PP-fed pike. Regarding total n-3 fatty acids ratio there was no significant difference between the groups, but the level of ,-linolenic (C:18:3n-3) acid showed significant difference among groups. [source] Promotion and contribution of biota in low water exchange ponds farming blue shrimp Litopenaeus stylirostris (Stimpson)AQUACULTURE RESEARCH, Issue 1 2002Luis R Martinez-Cordova Abstract An experimental study was conducted during 20 weeks in Bahia Kino, Sonora, Mexico, in order to evaluate the feasibility of promoting biota in low-water exchange ponds farming blue shrimp, Litopenaeus stylirostris. The effect of that promotion on the production parameters of cultured shrimp as well as on the water quality parameters was evaluated. Treatments consisted of: (i) ponds fed formulated food (FF), and (ii) ponds fed formulated plus promoted natural food (NFF). Phytoplankton, zooplankton and benthos were effectively promoted during some weeks of the culture period. Growth and feed conversion ratio (15.16 g and 1.79 respectively) were significantly better in treatment NFF than in treatment FF (13.89 g and 2.02 respectively). Differences in some of the water quality parameters were observed among treatments. Phosphates (0.15 mg/L versus 0.53 mg/L), and total ammonia-N (0.09 mg/L versus 0.12 mg/L) presented greater concentrations in treatment FF than in the NFF. [source] | |||||||||||||