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Growing Phase (growing + phase)

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Life Sciences	100%

Selected Abstracts

Alternate oils in fish feeds

EUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 3 2007
Jana Pickova
Abstract Nearly half of the fish consumed as food worldwide are raised on fish farms rather than caught in the wild, as shown by FAO statistics. The increasing aquaculture of predatory carnivorous fish demands new sources of feed constituents, particularly oils at the moment. Common terrestrial plant oils contain only traces of the long-chain polyunsaturated fatty acids. In connection with fish feed, especially the lack of n -3 "marine fatty acids" is obvious. Recommendations on the required amounts of the fatty acids DHA (22:6n -3) and EPA (20:5n -3) exist from 1994. When plant oil-based diets are fed during the growing phase and replaced by a fish oil-based diet during a period prior to slaughter, most of the beneficial lipid composition of fish in terms of human dietary recommendations is restored. Little attention has been focused on the fish welfare in connection to substitution of dietary oil sources, and studies are still scarce. New fish diets will rely heavily on the use of alternate ingredients such as plant oils also for carnivorous cold-temperate water fish species. In the future, an addition of synthetic or GMO-produced "marine" fatty acids is a possible scenario. The aim of this review is to highlight some plant oils used in fish feeds, with special emphasis on compounds other than fatty acids. We also include some results from an ongoing study, where the effect of dietary soy oil on gonad maturation in Atlantic cod (Gadus morhua) is indicated. [source]

Effects of temperature and food quality on anuran larval growth and metamorphosis

FUNCTIONAL ECOLOGY, Issue 5 2002
D. Álvarez
Summary 1Anurans exhibit high levels of growth-mediated phenotypic plasticity in age and size at metamorphosis. Although temperature and food quality exert a strong influence on larval growth, little is known about the interacting effects of these factors on age and size at metamorphosis. 2Plasticity in growth rates, maximum larval mass, mass loss, larval period and size at metamorphosis was examined in Iberian Painted Frogs (Discoglossus galganoi Capula, Nascetti, Lanza, Bullini & Crespo 1985) under different combinations of temperature and diet quality. 3Temperature and diet had strong effects on the maximum size reached by tadpoles throughout the premetamorphic stages. Larval body mass varied inversely with temperature. The effect of diet depended on temperature; larvae fed on a ,carnivorous' diet (rich in protein and lipids) achieved a larger size than larvae offered an ,herbivorous' diet (rich in carbohydrates) at 17 °C but not at 12 or 22 °C. 4Larval period was insensitive to diet composition, and varied only with temperature. Primarily the interacting effects of food quality and temperature affected size at metamorphosis. Size at metamorphosis varied inversely with temperature under the plant- and the animal-based diets. However, the carnivorous diet resulted in bigger metamorphs at 17 and 22 °C, but did not influence final mass at 12 °C. Maximum size over the larval period explained most of the variation in mass loss after the premetamorphic growing phase. [source]

The relationship between plasma leptin concentrations and the distribution of body fat in crossbred steers

ANIMAL SCIENCE JOURNAL, Issue 2 2003
Tomoya YAMADA
Abstract The objective of the present study was to examine the relationship between plasma leptin levels and fat distribution in crossbred steers. Twenty-four crossbred steers (Japanese Black × Holstein) were used in this study. Six steers belonged to the growing phase (11 months of age), and 18 steers to the finishing phase (from 21 to 28 months of age). Plasma leptin levels correlated positively with body fat weight (r = 0.807, P < 0.01), body fat percentage (r = 0.802, P < 0.01), visceral fat weight (r = 0.807, P < 0.01), visceral fat percentage (r = 0.780, P < 0.01), subcutaneous fat weight (r = 0.745, P < 0.01), subcutaneous fat percentage (r = 0.734, P < 0.01), intermuscular fat weight (r = 0.793, P < 0.01), intermuscular fat percentage (0.775, P < 0.01), renal fat weight (r = 0.694, P < 0.01), renal fat percentage (r = 0.642, P < 0.01), subcutaneous fat thickness (r = 0.755, P < 0.01), intermuscular fat thickness (r = 0.721, P < 0.01), beef marbling score (r = 0.706, P < 0.01) and the crude fat content of Musculus longissimus thoracis (r = 0.592, P < 0.01). The location of fat deposits did not affect the correlation values. However, when steers were divided into growing (n = 6) and finishing (n = 18) groups, there was no significant correlation between plasma leptin levels and the carcass characteristics related to fat deposition (fat weight, fat percentage, carcass traits) in either group. These results suggest that plasma leptin levels in crossbred steers positively correlate with body fat content and carcass traits when these parameters vary widely. [source]

Can management practices in rice fields contribute to amphibian conservation in southern Brazilian wetlands?

AQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 1 2010
Iberê Farina Machado
Abstract 1.Rice field expansion is one of the activities associated with the disappearance of 90% of the wetlands in southern Brazil. Worldwide, rice agriculture has been recognized as having considerable potential value for many aquatic species. Nevertheless, management practices in such systems must be ameliorated and better investigated. 2.This study evaluated the potential role of rice fields as refugia for amphibians, and whether different hydrologic management practices after rice cultivation could contribute to wetland amphibian conservation in southern Brazil. 3.Six collections were made in six rice fields with different management practices after cultivation (three dry and three flooded) and three natural wetlands. The amphibians were sampled through six random 15-min visual transects per collection in each rice field and the natural wetlands. 4.In total, 2139 anuran individuals were observed in rice fields (798) and Reserva Lake (1341), comprising 12 anuran species distributed among five anuran families. Anuran richness and abundance varied over the rice cultivating cycle, and they were higher in the growing phases than in the fallow phases. The mean anuran richness and abundance was higher in Reserva Lake than in flooded and dry rice fields. 5.The different management practices adopted after the harvesting period (presence or lack of surface water) did not influence the anuran richness and abundance. It did, however, influence species composition. 6.The difference in species composition between the management practices adopted is an interesting result in terms of biodiversity conservation. Rice producers could maintain part of their agricultural land flooded during the fallow phase as a strategy to preserve a higher diversity of anurans. These results should be taken into consideration in wetland conservation plans in southern Brazil; however, the percentage of each agricultural land that should be kept flooded should be decided by Brazilian agricultural and conservation policies. Such a strategy would reconcile agricultural/economic needs with the conservation of biodiversity in southern Brazil, where more than 90% of wetland systems have already been lost. Copyright © 2009 John Wiley & Sons, Ltd. [source]