Food Conversion Efficiency Research Articles

Effects of dietary biofloc on growth, digestibility, protein turnover and energy budget of sea cucumber Apostichopus japonicus (Selenka)

Bioflocs are not only rich in various bioactive compounds but also proven to be sustainable protein sources of aquafeed. A 60-day experiment was conducted to evaluate the feasibility and capacity of dietary replacement of macroalgae Sargassum thunbergii with biofloc meal as an ingredient in the diet of Apostichopus japonicus. During the experiment, the sea cucumbers of initial wet weight ∼25.18 g were fed seven diets contained graded biofloc levels of 0%, 5%, 10%, 20%, 30%, 45% and 60% (referred as group B0, B5, B10, B20, B30, B45 and B60, respectively) in a recirculating aquaculture system. Each group contained 150 sea cucumbers that were equally allocated into 3 cylinder aquaria. The results showed that dietary supplementation levels of 20% and 30% biofloc significantly enhanced specific growth rate (SGR), food conversion efficiency (FCE) and protein efficiency ratio (PER) of sea cucumber. Based on the second-order polynomial regression models of SGR and FCE, it was concluded that 27.74−30.75% were optimal dietary replacement levels of biofloc. Apparent digestibility coefficients and digestive enzyme activities all showed remarkable trends of the first increase and then decrease as dietary biofloc level increased with relatively higher values in diet B30, which might have stimulated the digestion and absorption of nutrients to maintain faster growth of sea cucumber. There were significant differences in parameters estimated by time-based turnover model of δ15 N between the experimental diets, and the sea cucumbers in diets B30 and B45 exhibited faster nitrogen turnover rates. The average formula of energy allocation was 100C = 3.8G + 65.4F + 3.3U + 27.5R in the present study. The fluctuation in energy for growth and metabolism suggested that dietary biofloc modified their energy allocation strategy by balancing the energy accumulation of growth and energy consumption of feces, excretion and respiration. In conclusion, ca. 30% replacement of S. thunbergii with biofloc powder could improve growth performance of A. japonicus, by enhancing feeding utilization and digestibility, accelerating protein turnover and optimizing energy budget of sea cucumber.

Effects of flow velocity on growth, metabolism and nitrogen and phosphorus budget of Haliotis discus hannai Ino in a recirculating aquaculture system

To study the effects of different flow velocities on growth, metabolism and nitrogen (N) and phosphorus (P) budget of Haliotis discus hannai Ino in a recirculating aquaculture system, abalones (shell length: 45.71 ± 3.09 mm, body weight: 8.62 ± 0.75 g) were cultured at three different flow velocities with four replicates each: high (400 L/hr), medium (300 L/hr) and low (200 L/hr). At the end of the 70 days experiment, the survival rate, food intake and P utilization rate of abalones in the 200 L/hr group were significantly lower than those in any other group (p < .05), whereas the total ammonia nitrogen and nitrite nitrogen concentrations in the water were significantly higher than those in any other group (p < .05). The body weight specific growth rate, food conversion efficiency, abalone-harvested N and P outputs and N utilization rate were ranked as follows: 300 > 400 > 200 L/hr (p < .05). In the 300 L/hr group, the activities of hexokinase, pyruvate kinase and lactate dehydrogenase were significantly lower than those in the 400 L/hr group, whereas the activity of succinate dehydrogenase was significantly higher than that in the other two groups (p < .05). Aerobic metabolism was the main source of energy acquisition for abalones in the 300 L/hr group. In the 400 L/hr group, the expression levels of manganese superoxide dismutase and thioredoxin peroxidase significantly increased from Day 35 to Day 70, but they still were significantly lower than the values in the 200 L/hr group (p < .05). In the 200 L/hr group, the expression levels of catalase and heat shock protein 70 were significantly higher than those in any other group, and they significantly increased from Day 35 to Day 70 (p < .05). These results indicate that maintaining flow velocity at 300 L/hr will minimize oxidative damage due to deterioration of water quality, reduce the energy consumption required for organisms to resist the impact of water flow, improve the N and P utilization rates of the recirculating aquaculture system, and reduce the cost of culturing abalones.

Products of Solid-Phase Probiotic Bacilli Fermentation Increase Food Conversion Efficiency and Stimulate Chicken Growth

Poultry farming is one of the major directions in agriculture. Agricultural poultry has high growth speed, productivity and is resistant to the industrial environment. Our group carried out a study of probiotic preparations of Bacillus subtilis KATMIRA1933 and Bacillus amyloliquefaciens B-1895 strains. These preparations were made by solid-phase fermentation and tested for dynamical germination of rearing flock (Highsex brown). The research was conducted at SD “Svetliy”, structure department of PC “Agrofirm Vostok” (Volgograd region). Soybeans were used as the substrate for preparations. We investigated the influence of monocultural preparation and mixed bioadditives. The duration of the experiment was 120 days. It was shown that addition of the drugs to the poultry food leads to it’s live weight gain (max 19%) and decrease of food conversion factor (min 1.98). The increase of erythrocyte (max 6%), leukocyte (max 2%) and hemoglobin (max 13%) content and the concentration protein fractions in poultry blood (max 14%) was also noted. Simultaneous use of two strains decreases their physiological effects. Bacterial components of preparations did not disturb the natural intestinal microbiota of the fowl. The abundance of Bifidobacterium and Lactobacillus strains was constant. Since preparations based on soybeans are cheap and straightforward to produce, using them can be highly efficient in modern poultry and livestock farming.

Insect-based protein: future promising protein source for fish cultured

As one of the vital component feed used in fisheries, fishmeal (FM) is generally added to the fish diet to enhance fish growth, digestive performance and absorption of nutrients. This addition contributes significantly to the variable production cost in the aquaculture industry. Expanded production of carnivorous species requiring high protein, high-energy feeds will further tax global fish meal. Thus, research based on the low-cost budget for feed operating cost should be strategized to assist aquaculturists in enhancing fish productivity. Moreover, suitable alternative feed ingredients will have to be utilized to provide the essential nutrients and energy needed to fuel the growth of aquaculture production. To this effect, the use of insect-based protein sources to replace FM that often scarce, expensive, limited availability, and leads to high fish production costs is alternative ways and has been gaining momentum. Currently, Insects have been proposed as one of the potential future protein sources of protein because of the production of insects is highly sustainable. Farming insects is characterized by higher food conversion efficiencies, lower environmental impact, and higher potential to be grown on waste streams.

Study on the ecosystem construction of using ecopath model in inland waterway

In this paper, Ecopath with Ecosim 5.1 software is used to simulate the constructed water ecosystem of inland waterway. According to the characteristics of feeding relationship, the ecopath model of water ecosystem is divided into seven functional groups: phytoplankton, hydrophyte, zooplankton, herbivorous, omnivorous, polychaetes and detritus. By analyzing the important ecological parameters of the ecosystem, such as biomass, biomass / biomass, consumption / biomass, trophic level and ecological nutrient conversion efficiency, the software integrates the energy flow process of the ecosystem, the ratio of the total net primary production and the sum of all respiratory flows is 1.314, it’s indicating that the ecosystem is equilibrium. The research method of this paper can be widely used to evaluate the stability of the ecosystem of the domestic river.

Molecular breeding and industrialization of forage sweet sorghum

Sorghum ( Sorghum bicolor (L.) Moench) is the world’s fifth major crop and a C4 model plant. Sweet sorghum is a variant of grain sorghum with implications in biofuel industry and stress biology because of it remarkable traits including high biomass production, high concentration of soluble sugars in its juicy stem, and strong abiotic tolerance. In recent years, there is a new demand to develop sweet sorghum into a forage crop, which requires the tailor-made modification of its major biological characteristics. Compared to silage maize, sweet sorghum possesses higher levels of directly fermentable reducing sugars and the ability to accumulate high biomass under low-input production systems. In addition, it is tolerant to drought and more efficient in utilization of solar radiation and nitrogen-based fertilizers than maize on marginal lands which are not optimal for food production. These traits collectively make sweet sorghum more attractive than silage maize with huge potential as a forage crop. Yet, due to the relatively short history of sweet sorghum breeding, the development of new varieties adapting to various phenological requirements is restricted, and the rapid deployment of sweet sorghum for forage production is limited. Here we summarize the current status of forage sweet sorghum breeding in China. A suit of sweet sorghum traits, such as plant architecture (leave, and stem), flowering time and maturity, leaf senescence and accumulation of juice and sugar as well as drought and salt tolerance are identified, and recent progression in dissecting their genetic basis reviewed. It is suggested that newly developed cutting-edge technologies such as genome editing and whole-genome selection are needed to harness the genetic improvement of sweet sorghum. Feeding experiments with improved varieties showed that sweet sorghum is an important component of the livestock diet for increasing the palatability and nutrient conversion efficiency. The production-scale demonstration project, forming a production pipeline from sweet sorghum hybrid production, cultivation, distillation and feeding of livestock and cycle of manures, showed that forage sweet sorghum based bio-industry sets a model for circular economy in rural areas. Future forage sweet sorghum breeding and approaches to develop its bio-industry are discussed.

Growth and nutrition of Agelastica coerulea (Coleoptera: Chrysomelidae) larvae changed when fed with leaves obtained from an O3-enriched atmosphere.

A series of laboratory no-choice assays were performed to test changes in the feeding, growth, and nutrition of leaf beetle (Agelastica coerulea) larval instars on O3-treated leaves of Japanese white birch (Betula platyphylla var. japonica). Larvae fed with O3-treated leaves grew and developed significantly faster throughout their developmental cycle than the corresponding controls. The growth rate (GR) and consumption index (CI) were mostly decreased with age for both control and O3-treated leaves. Efficiency of conversion of both ingested and digested food (ECI, ECD) showed an increase from the 2nd to the 4th instar, after which they decreased significantly and reached the lowest value in the last larval instars (7th). GR, CI, ECI, and ECD were greater and approximate digestibility (AD) was lower in larvae fed with O3-treated leaves than those fed with control leaves. This indicated that the greater rate of growth on fumigated leaves was due primarily to a greater rate of consumption (i.e., O3 increased the "acceptability" of the host more than "suitability") and efficiency in converting food into body mass. Overall, larval performance seemed to have improved when fed with O3-treated leaves in these assays. This study suggests that insects may be more injurious to O3-treated plants and warrants further investigations on birch-beetle interactions under field conditions.

Age-dependent food utilisation of Acheta domesticus (Orthoptera: Gryllidae) in small groups at two temperatures

Insects hold potential as a sustainable source of animal protein. In recent years a new and rapidly growing industry of insect-based foods has emerged. The house cricket, Acheta domesticus (L.) (Orthoptera: Gryllidae), is one of the most important insect species being produced commercially in the USA for feed and food. However, the price of cricket powder remains much higher in comparison with other animal sources of protein. This study seeks to contribute to reduce cricket production costs by determining food conversion efficiency at different ages as a mean of establishing an optimal harvesting age. Two temperature treatments of 27 and 29 °C consisting of 27 groups of five crickets each were monitored weekly to measure food consumption and growth for a period of 10 and 9 weeks respectively. Data were used to calculate efficiency of conversion of ingested food (ECI) for each week and treatment. Crickets at 27 °C produced more biomass and adults were significantly larger than those developing at 29 °C. The peak individual weekly biomass gain was observed at the end of 8 weeks at 27 °C (87.9±8.1 mg) (mean ± SEM) and at the end of 6 weeks at 29 °C (51.4±7.1 mg). Mean ECI values during weeks 1 to 8 at 27 °C (20.7, 22.6, 22, 20.8, 21.6, 20.9, 20, and 16.5%) and weeks 1 to 6 at 29 °C (18, 24.4, 19.9, 18.9, 21.1, and 16.4%) did not differ significantly. Decline of ECI values was better explained by the increase in adult proportions than by mortality. The optimal age to harvest based on food consumption and cricket biomass gain ratios was at the end of 8 weeks at 27 °C and at the end of 6 weeks at 29 °C. An economic analysis resulted in slightly higher profits ($ 1.04 USD) per g of hatchling/year at 27 °C.

Gut microbes limit growth in house sparrow nestlings (Passer domesticus) but not through limitations in digestive capacity.

Recent research often lauds the services and beneficial effects of host‐associated microbes on animals. However, hosting these microbes may come at a cost. For example, germ‐free and antibiotic‐treated birds generally grow faster than their conventional counterparts. In the wild, juvenile body size is correlated with survival, so hosting a microbiota may incur a fitness cost. Avian altricial nestlings represent an interesting study system in which to investigate these interactions, given that they exhibit the fastest growth rates among vertebrates, and growth is limited by their digestive capacity. We investigated whether reduction and restructuring of the microbiota by antibiotic treatment would: (i) increase growth and food conversion efficiency in nestling house sparrows (Passer domesticus); (ii) alter aspects of gut anatomy or function (particularly activities of digestive carbohydrases and their regulation in response to dietary change); and (iii) whether there were correlations between relative abundances of microbial taxa, digestive function and nestling growth. Antibiotic treatment significantly increased growth and food conversion efficiency in nestlings. Antibiotics did not alter aspects of gut anatomy that we considered but depressed intestinal maltase activity. There were no significant correlations between abundances of microbial taxa and aspects of host physiology. Overall, we conclude that microbial‐induced growth limitation in developing birds is not driven by interactions with digestive capacity. Rather, decreased energetic and material costs of immune function or beneficial effects from microbes enriched under antibiotic treatment may underlie these effects. Understanding the costs and tradeoffs of hosting gut microbial communities represents an avenue of future research.

Effect of Temperature on Growth, Energy Budget, and Physiological Performance of Green, White, and Purple Color Morphs of Sea Cucumber, Apostichopus japonicus

AbstractAs an intertidal species, Apostichopus japonicus is subject to diel and seasonal temperature fluctuations. Color variation is a distinct characteristic of A. japonicus, and a new color morph, purple A. japonicus, was recently found on the coast of Rushan, Weihai City. This study was conducted to compare the performance of green, white, and purple color morphs of A. japonicus at different water temperatures to help improving aquaculture technology and management. In this study, green, white, and purple color morphs of juvenile A. japonicus (1.5 ± 0.1 g) were cultured at 10, 14, 18, 22, and 26 C for 60 d, according to the suitable temperature range for sea cucumber growth. Temperature was shown to have a significant effect on growth, energy budget, and physiology of sea cucumbers (P &lt; 0.05). Specific growth rates, feed conversion efficiencies, and the proportion of energy allocated to growth of all three color morphs were optimal at 18 C. Activities of the enzymes related with oxidative stress, immune response, and digestion were determined. Superoxide dismutase (SOD) and trypsin activities generally reached a maximum in all three color morphs at 18 C. The purple color morph of A. japonicus was higher in growth rate, food conversion efficiency, and proportion of energy allocated to growth than green and white color morphs at 18 and 22 C, consistent with its higher trypsin and SOD activity, indicating the mutual effect of growth and physiology. At 18, 22, and 26 C, the green color morph had the highest level of lysozyme activity and purple color morph had the lowest, indicating possible infection by external pathogens of green color morph, which might be caused by high temperature. These results suggested that the optimum temperature for culture of the three color morphs was approximately 18 C, the purple had a better adaption to high temperature, and the green and white color morphs may be more susceptible to thermal stress than the purple color morph.

Pigeonpea genotypes affect the growth, food utilization and nutritional indices of spotted pod borer, Maruca vitrata Fabricius (Lepidoptera: Crambidae)

Laboratory evaluation of 11 pigeonpea genotypes for resistance to spotted pod borer, Maruca vitrata Fabricius was conducted from the beginning of third instar to the pre-pupal stage of the insect on flowers of these pigeonpea genotypes. The nutritional indices such as CI (consumption index), AD (approximate digestibility), ECI (efficiency of conversion of ingested food) and ECD (efficiency of conversion of digested food) were worked out. Larval weight gain was significantly the highest on MN 1 (67.16 mg) and the lowest on AL 1747 (20.45 mg). Total weight of food consumed per larva was significantly the highest on MN 1 (119.16 mg) and the lowest on AL 1747 (56.16 mg). The relative growth rate was the lowest on AL 1747 (118.89%) and the highest on MN 1 (373.11%). Third instar larvae reared on MN 1 showed significantly the highest ECD and AD values (71.55 and 79.65%, respectively) compared with other genotypes. Significantly the lowest value of ECD and AD was observed in AL 1747 (54.71 and 66.96%, respectively). The highest (56.77%) and the lowest (36.51%) ECI of third instar larvae were recorded in MN 1 and AL 1747, respectively. Of the 11 genotypes tested, MN 1 was the most nutritive whereas, AL 1747 was the least nutritive than the others for M. vitrata larvae.

Impact of elevated temperature and carbon dioxide on insect performance indices of Spodoptera litura fabricius

Effect of rise in minimum temperature (4 & 5°C) and carbon dioxide (CO2) concentration (400 & 500 ppm) was studied on food consumption and nutritional indices of Spodoptera litura on cabbage. The food consumption, consumption index (CI) and approximate digestibility (AD) showed a respective increase of 20, 8.9 and 4.7 per cent with elevated CO2 concentrations while efficiency of conversion of ingested food (ECI), efficiency of conversion of digested food (ECD), relative consumption rate (RCR), larval weight gain and pupal weight decreased by 8.50, 27, 26.6, 24.59 and 20.97 per cent respectively. Food consumption, CI, AD, ECI and pupal weight values increased by 43.23, 50.83, 22, 19.66 and 11.93 per cent with increase in minimum temperature by 5°C whereas ECD, RCR and larval weight gain decreased by 20.28, 35.89 and 25.16 per cent. Present studies indicated that under elevated temperature and CO2 regimes, the damage caused by S. litura on crops would increase.

Physiological responses to elevated temperature across the geographic range of a terrestrial salamander.

Widespread species often possess physiological mechanisms for coping with thermal heterogeneity, and uncovering these mechanisms provides insight into species' responses to climate change. The emergence of non-invasive corticosterone (CORT) assays allows us to rapidly assess physiological responses to environmental change on a large scale. We lack, however, a basic understanding of how temperature affects CORT, and whether temperature and CORT interactively affect performance. Here, we examined the effects of elevated temperature on CORT and whole-organism performance in a terrestrial salamander, Plethodon cinereus, across a latitudinal gradient. Using water-borne hormone assays, we found that raising ambient temperature from 15 to 25°C increased CORT release at a similar rate for salamanders from all sites. However, CORT release rates were higher overall in the warmest, southernmost site. Elevated temperatures also affected physiological performance, but the effects differed among sites. Ingestion rate increased in salamanders from the warmer sites but remained the same for those from cooler sites. Mass gain was reduced for most individuals, although this reduction was more dramatic in salamanders from the cooler sites. We also found a temperature-dependent relationship between CORT and food conversion efficiency (i.e. the amount of mass gained per unit food ingested). CORT was negatively related to food conversion efficiency at 25°C but was unrelated at 15°C. Thus, the energetic gains of elevated ingestion rates may be counteracted by elevated CORT release rates experienced by salamanders in warmer environments. By integrating multiple physiological metrics, we highlight the complex relationships between temperature and individual responses to warming climates.

Study on food consumption parameters of Spodoptera litura (Fab.) (Noctuidae: Lepidoptera) on different Bt cotton hybrid plant parts

The food utilization efficiency of Spodoptera litura (Fab.) on squares, flowers and bolls of Bt-II cotton hybrids was reduced compared to Bt-I hybrids. Bt-II cotton hybrids were found to be superior over Bt-I hybrids. Among the twelve hybrids tested the least consumption index (C.I.) on squares, flowers was recorded on RCH-2 Bt-II (5.30), (5.36) respectively, and least growth rate (G.R.) was recorded in NCS-950 Bt-II on squares, flowers (0.083) and (0.080) respectively. The lowest E.C.I was noticed in NCS-950 Bt-II (1.51) on squares. On flowers the least E.C.I was recorded in RCH-134 Bt-II (1.54) where as on bolls the E.C.I was least in NCS-954 Bt-II (1.51). The least E.C.D on squares was noted in NCS-954 Bt-II (17.75) on flowers least was in RCH-134 Bt-II (18.50), on bolls it was (20.14) in NCS-954 Bt-II which was least. The Approximate digestibility was recorded least in NCS-145 Bt-II (40.36) on squares, on flowers the least A.D. was noticed in RCH-134 Bt-II (48.73), whereas on bolls it was RCH-134 Bt-II recorded least A.D. as 47.91 compared to other hybrids.

Management of &amp;lt;i&amp;gt;Helicoverpa armigera&amp;lt;/i&amp;gt; (Lepidoptera: Noctuidae) by Nutritional Indices and Botanical Extracts of &amp;lt;i&amp;gt;Millettia ferruginea&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;Azadirachta indica&amp;lt;/i&amp;gt;

The development of hosts that are resistant and evaluation of botanical extracts to H. armigera Hubner (Lepidoptera: Noctuidae) is crucial for sustainable management, yet very limited in Ethiopia. Therefore, this study was done to identify alternative methods to insecticide control through host consumption study and botanical extracts. The performance of third-fifth larval stages of H. armigera on three host plant varieties including chickpea, tomato and faba bean and botanical extracts against the third larval instars and oviposition deterrence was studied under laboratory condition (22°C ± 2°C, 55% ± 5% RH, 12:12 L: D photoperiod). Significant differences were found in the efficiency of conversion of ingested food (ECI%) (F = 80.06; df = 6, 2; p < 0.05) and efficiency of conversion of digested food (ECD%) (F = 175.91; df = 6, 2; p < 0.05) values of H. armigera reared on the three host plant varieties of the whole larval instars. The minimum relative consumption rate (RCR) (11.271 ± 0.328) and maximum approximate digestibility (AD) (177.9 ± 1.928) values of the whole larval instars were on Dagaga and Koshari, respectively. The values of relative growth rate (RGR), ECI% and ECD% of the whole larval instars were highest on chickpea varieties and lowest on tomato Koshari. Among chickpea varieties, Habru was relatively resistant to larval instars of H. armigera. Botanical extracts at 50% neem oil (NO), 5% birbira seed extract (BSE) and 5% neem seed extract (NSE) (18.4%) resulted superior in larval mortality however, statistically not different. At both 5% and 2.5% concentration level of botanical extracts the minimum larval mortality was recorded from neem leaf extract (NLE). Maximum numbers of eggs were laid on control treatments and the minimum eggs were on 5% BSE. The deterrent effect of 50% neem oil was stronger (ODI = 17.66%) than that of 5% BSE (ODI = 14%) which is statistically similar value with 5% NSE (ODI = 13%). In conclusion, the result indicated that use of Habru chickpea variety with 50% NO was very effective in controlling both the larvae and deterring the adults of H. armigera from egg lying. These measures could be important in the wider managements of H. armigera by integrating host resistance and botanical extracts.

Effects of chronic ammonia nitrogen stress on the feeding and digestive enzyme activities of sea cucumber ( Apostichopus japonicas Selenka)

PDF HTML阅读 XML下载 导出引用 引用提醒 慢性氨氮胁迫对刺参摄食与消化酶活性的影响 DOI: 作者: 作者单位: 山东省海洋生物研究院, 山东 青岛 266014 作者简介: 胡炜(1978-),男,高级工程师,主要从事刺参生理生态学研究.E-mail:mail24@163.com 通讯作者: 中图分类号: S917 基金项目: 山东省科技发展计划项目（2014GNC111022）；山东省农业良种工程项目（2014-2018）；山东省现代农业产业技术体系刺参产业创新团队建设项目（SDAIT-22-01，SDAIT-22-05）；山东省自然科学基金项目（ZR2014CQ056）；山东省星火科技示范项目（2015XH006）. Effects of chronic ammonia nitrogen stress on the feeding and digestive enzyme activities of sea cucumber (Apostichopus japonicas Selenka) Author: Affiliation: Marine Biology Institute of Shandong Province, Qingdao 266014, China Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以刺参（ Selenka）为研究对象，探讨氨氮胁迫浓度为0 mg/L、2 mg/L、4 mg/L、6 mg/L、8 mg/L、10 mg/L时14 d内刺参摄食情况与消化道内3种不同消化酶活性变化。刺参规格分别为小[S，体重（15.13±0.02）g]、中[M，体重（28.42±0.32）g]、大[L，体重（60.14±0.88）g]。结果显示：（1）随着氨氮浓度的升高，实验刺参存活与生长逐渐与对照组出现显著差异。当氨氮浓度高于2 mg/L时，刺参末体重与特定生长率随氨氮浓度升高有显著下降趋势；当氨氮浓度为8~10 mg/L时，3种不同规格刺参均出现了吐肠、化皮，直至死亡，氨氮浓度为10 mg/L时中规格刺参存活率最低，为81.3%。（2）当氨氮浓度低于10 mg/L时，氨氮胁迫对3种规格刺参摄食率（FR）影响差异不显著，而全部实验组的食物转化率（FCE）均显著低于对照（<0.05）。（3）氨氮胁迫对3种不同规格刺参消化酶活性的影响存在差异。随氨氮浓度升高，蛋白酶活性呈降低趋势，氨氮浓度8 mg/L和10 mg/L时全部实验组刺参蛋白酶活性显著低于对照（<0.05）；脂肪酶和淀粉酶活性随氨氮浓度升高呈先升后降趋势，在2 mg/L时出现峰值；当氨氮浓度为6 mg/L时，小规格刺参的消化道淀粉酶活性降低到0.30 U/mg（prot），与对照出现显著差异（<0.05），中规格刺参在同一氨氮浓度胁迫下的消化酶活性变化显著高于其他规格。研究表明，氨氮胁迫会对刺参摄食、消化与生长产生不利影响，在氨氮浓度4 mg/L以下刺参消化酶活性短期可被显著诱导上调，高氨氮浓度对消化酶活性起抑制效应并可导致生理紊乱，此响应存在体重规格上的差异。 Abstract:This study was conducted to evaluate the effects of chronic ammonia nitrogen (N) stress (concentration gradient:0 mg/L, 2 mg/L, 4 mg/L, 6 mg/L, 8 mg/L, 10 mg/L) on the feeding and activities of three types of digestive enzymes (protease, amylase, lipase) in sea cucumbers ( Selenka) of three different sizes (initial body weights:15.13±0.02 g, 28.42±0.32 g, and 60.14±0.88 g) over a 14-day period. The results obtained were as follows. (1) With an increase in ammonia-N level, the survival and growth of sea cucumbers were significantly different from those in the control group. When the ammonia-N level was higher than 2 mg/L, the final body weight and specific growth rate of sea cucumbers show a marked downward trend with an increase in ammonia concentration. As the ammonia-N level increased to 8 and 10 mg/L, all sea cucumbers of the three different sizes appeared evisceration, with skin ulceration until death. When the ammonia-N level was 10 mg/L, the survival rate of medium-sized sea cucumbers reached 81.3%, the lowest among the three sizes. (2) When the ammonia-N level was lower than 10 mg/L, the effect of ammonia-N stress on the feeding rate of sea cucumbers of all three weights was not significant (>0.05), whereas the food conversion efficiency of all the experimental groups was significantly lower than that of the control group (<0.05). (3) There were significant differences in the digestive enzyme activities of the three-sized sea cucumbers under the stress of ammonia-N. With an increase in ammonia concentration, protease activities decreased. When the ammonia-N level was 8 mg/L and 10 mg/L, the protease activities of all the experimental groups were significantly lower than those in the control group (<0.05). With an increase in ammonia concentration, the activities of lipase and amylase initially increased and then decreased, peaking at 2 mg/L. When the ammonia-N level was 6 mg/L, the amylase activity of the small-sized sea cucumbers decreased to 0.30 U/mg protein, which was significantly different from the control group (<0.05). When the ammonia-N level was from 6 mg/L to 8 mg/L, the activity of lipase in the three-sized sea cucumbers was markedly affected, being significantly lower than that in the control group (<0.05). Under the same ammonia concentration, the activities of digestive enzymes in the medium-sized sea cucumbers were significantly higher than those in the other sizes. These results indicate that ammonia-N stress can affect the feeding and digestive enzyme activities of sea cucumbers. Therefore, in the process of sea cucumber breeding, particularly in large-scale seed culture, it is preferable to control the concentration of ammonia-N in the water environment to within 4 mg/L. 参考文献 相似文献 引证文献

Investigation on endosymbionts of Mediterranean flour moth gut and studying their role in physiology and biology

The bacterial flora of flour moth and their role in the physiology of Ephestia kuehniella (Zeller) (Lepidoptera: Pyralidae) were investigated. The gut flora of E. kuehniella was isolated on Luria Bertani Agar (LBA), followed by incubation at 28 °C respectively for 48–72 h. The isolates were identified using 16S rRNA sequencing. Altogether five bacterial species of different genera were identified as Bacillus infantis, Streptomyces cacaoi, Janibacter sp., Stenotrophomonas sp. and Acinetobacter sp. The fourth instar larvae reared on artificial diet without any antibiotic showed higher efficiency of conversion of digested food (ECD) and efficiency of conversion of ingested food (ECI) (16.068 ± 0.568% and 14.455 ± 0.448%), respectively. Approximate digestibility (AD) and Consumption index (CI) of the fourth instars larvae were higher on artificial diets containing tetracycline. The higher activity of alpha-amylase and general proteases were observed in the midgut of larvae reared on artificial diet containing antibiotic chloramphenicol. Total protein and lipid value were higher respectively in larvae that were reared on artificial diet containing streptomycin sulfate and artificial diet containing tetracycline. It seems that antibiotics had no significant effect on enzymatic activities of E. kuehniella. The larvae performed well in tetracycline treatment as per larval developmental duration compared with other treatments. Therefore, the gut bacteria do not seem to play a crucial role in the survival and development of the E. kuehniella. However, the question of adaptation of this pest species to hosts rich in protease inhibitors, such as flour has to be examined and ascertained.

Early development of the ectoparasite Caligus rogercresseyi under combined salinity and temperature gradients

One of the pathogens causing the highest economic impacts on the Chilean salmon industry is the ectoparasite copepod Caligus rogercresseyi, whose abundance is strongly influenced by environmental variables (e.g. salinity and temperature). Infested fish with sea lice reduces appetite, food-conversion efficiency and increase stress level, which results in decreased growth. The skin wounds, caused by the ectoparasite feeding, leave fish exposed to secondary infections and antiparasitics treatment expenses are high. To evaluate the impact of environmental variables on the early development of C. rogercresseyi, egg strings were obtained from mature females (reared in laboratory conditions) and exposed to different combinations of salinity (14, 20, 26 and 32 PSU) and temperature (6, 9, 12, 15 and 18°C). The hatching success and time, pelagic life time, survival and size of nauplius I, nauplius II and copepodid were quantified. Our results indicate that salinity and temperature have a significant effect on the hatching success of this parasite. Salinities between 26 and 32 PSU result in a hatching success of 100%, whereas lower salinities (14 PSU) reduce hatching success by 60% (at all experimental temperatures) generating an increase in mortality of these early developmental stages. A temperature reduction from 18°C to 6°C in culture conditions significantly extended the incubation time of C. rogercresseyi by 50%. Specifically, temperature had a higher impact on nauplius I and nauplius II larvae, increasing development times to 50 and 100 h respectively, when temperature was decreased to 6°C. Although combination of salinity and temperature have a significant effect on hatching time and survival in C. rogercresseyi, the combination of these variables had no impact on the size of nauplius I, nauplius II and copepodid stage. Thus, the effects on the survival and pelagic life time of the early stage of C. rogercresseyi, might substantially affect the fitness of the species under fluctuating conditions of salinity and temperature.

The effects of oat bran and soy flour on humoral immune response in rats fed hypercholesterolaemic diets

Previous studies have demonstrated the immunological and hypercholesterolaemic effects of soluble dietary fibre and soy protein in rats. In this study, we evaluated the effects of oat bran and soy flour on humoral immune response in Wistar rats fed hypercholesterolaemic diets. Animals (6 groups) fed with different diets for 6 wks were inoculated twice with antigen (IgY). Plasma samples were collected after each inoculation and anti-IgY antibody (IgM, IgG1 and IgG2a) levels were evaluated by ELISA. Animals receiving 1% cholesterol presented an increase in anti-IgY IgG1 and a reduction in anti-IgY IgM and IgG2a relative to control animals. These effects were abrogated in animals fed 1% cholesterol and oat bran or oat bran+soy protein, but not in animals fed 1% cholesterol and soy protein. Diets containing 1% cholesterol resulted in hepatic lesions and higher liver and spleen relative weights, but did not affect lipid profile, weight gain, food intake, or food conversion efficiency. In conclusion, a high-cholesterol diet influences classes of antibodies produced in response to an antigen in a way that can be reversed by oat bran.

SUBLETHAL EFFECTS OF THE ESSENTIAL OILS OF GARLIC (ALLIUM SATIVUM) AND LEMON (CITRUS LIMON) ON NUTRITIONAL INDICES AND MIDGUT HISTOLOGICAL AND ULTRASTRUCTURAL CHANGES IN THE EGYPTIAN COTTON LEAFWORM (SPODOPTERA LITTORALIS)

The present study was carried out to evaluate the nutritional indices, histological (light microscopy) and ultrastructural (transmission electron microscopy) changes in the midgut of the 4th larval instar of Spodoptera littoralis treated with the LC30 of the essential oil of garlic (Allium sativum) (16.60×104 mg/l) and lemon (Citrus limon) (20.09×104 mg/l) based on leaf–dip method compared to untreated larvae (control). The results of the nutritional metabolism revealed a significant reduction in food consumption index (CI), relative growth rate (RGR), and approximate digestibility (AD) of treated larvae. On the contrary, the efficiency of conversion of ingested food to body mass (ECI) and the efficiency of conversion of digested food to body mass (ECD) increased significantly in treated larvae. The most prominent symptoms revealed by light microscopy on the midgut of the treated larvae were vacuolization of the epithelial layer, clumping of the nuclear chromatin material and degeneration of the peritrophic membrane and microvilli. On the other hand, transmission electron microscopy showed vacuolization and degeneration of the columnar cells, clumping of the nuclear chromatin, breaking of microvilli, loss of the cytoplasmic projections of the goblet cells, appearance of residual bodies, and disintegration of mitochondria. In particular, treatment with lemon oil resulted in the appearance of numerous lysosomes and electron-dense mitochondrial matrices. In conclusion, the reduction of the RGR would result in undersized females in the next generations; in turn this would lead to a reduction of the reproductive potential. Also, the present investigation indicates that the microvilli and/or mitochondria are the probable target site(s) of action of garlic and lemon essential oils.