Higher Feeding Activity Research Articles

Feeding efficiency and behaviour of growing bulls from the main Italian dual-purpose breeds

To characterise the main Italian dual-purpose breeds in terms of feed efficiency and behaviour, the dry matter intakes (DMI) of 890 young bulls were collected using automatic feeding systems in two Italian genetic centres. In Experiment 1, Italian Simmental (IS), Rendena (RE) and Alpine Grey (AG) young bulls were fed total mixed ration for 46 days. In Experiment 2, Valdostana Red Pied (VR) and Black Pied and Chestnut (VB) young bulls were fed hay and concentrate for 60 days. The IS and RE bulls grew faster than AG (1.6 vs. 1.3 kg/d, p < .01). The DMI was highest for IS and lowest for AG while all breeds had similar values for DMI expressed as relative to body weight. Overall, RE and AG bulls were more efficient than IS. Regarding feeding behaviour, the number of feeding events for IS and AG was higher than for RE, while the feeding time was not different between breeds. The IS bulls showed a higher value of feeding rate (FR) than RE and AG (98.2 vs. 83.1–86.5 g DM/min, p < .01). Overall AG breed, despite its high feeding activity, was particularly efficient. In addition, efficient animals showed a low FR compared to inefficient ones. In Experiment 2, VR and VB strains were quite similar in terms of growth capacity but VR was more efficient despite its higher daily activity. In conclusion, dual-purpose breeds can reach notable growths and feed efficiencies and FR is well related to feed efficiency. Highlights Rendena and Alpine Grey bulls are slightly more efficient than Italian Simmental bulls Valdostana strains differ for feed efficiency but not for growth capacity Feeding rate is a useful behaviour trait to consider in the study of feed efficiency

Aktivitas Makan Orangutan Kalimantan (Pongo pygmaeus wurmbii) di Taman Nasional Tanjung Puting Wilayah Camp Leakey Kab. Kotawaringin Barat Sebagai Penunjang Materi Konservasi

Conservation activities for the Bornean orangutan (Pongo pygmaeus wurmbii) are strongly influenced by several factors in environmental and habitat conditions so that the sustainability of the orangutan population is maintained, including playing an important role in terms of feeding activities and the ability to adapt to eating orangutans in reintroduction areas through monitoring activities in the daily lives of orangutans, emphasizing knowledge of eating activities in the Leakey camp area as an orangutan release conservation institution needs to be done. Observation of the eating activity of orangutans was carried out using the Focal Animal Sampling method. All activities carried out by individuals are observed and recorded. Observations were made starting from leaving the nest at around 06.30 WIB and finished observing at 17.30 WIB. Observations include diet (length of time), type of feed, portion of feed consumed. The data obtained will be tabulated and the percentage determined by displaying the data in the form of tables and charts. The length of time for eating activities of the Gara orangutans occupies the second highest percentage for eating activities, namely 33.0%, resting activity is 55.2% as the most activity and making nests 11.8%, Casper orangutans have the highest feeding activity, which is 91.4% and the second highest play activity 4.6% and the third to make a nest 4.1%. The types of feed consumed by Gara orangutans were 8 species consisting of Gluta renghas L 9%, Mangifera odorata 18%, Pandanus helicopus 14%, Symlecos celastrifolia 4%, Osbornia octodonta 4%, Musa acuminate 23%, Coptotermes curvignathus 14%, Coptotermes sp5% and Casper orangutan 4 species consisting of Diaphania indica s 46%, Mangifera odorata 23%, Musa acuminate 27%, Pimenta officinalis 4%. The portion of feed consumed by the orangutans Gara and Casper is dominated by the fruit portion.

A human tissue-based assay identifies a novel carrion blowfly strain for maggot debridement therapy

Maggot debridement therapy (MDT) is a form of therapeutic wound treatment in which live fly larvae are used intentionally to debride necrotic tissues. MDT has been widely used to treat chronic wounds in humans or animals, such as diabetic foot ulcers. Larvae of a carrion blowfly, Lucilia sericata (green bottle fly), debride wounds by consuming necrotic tissue and removing pathogenic bacteria, promoting effective wound healing. Most medical L. sericata strains were initially collected from natural environments using animal meat as bait and reared on artificial protein-rich media or ground meat. It remains to be examined which strain would be more appropriate for MDT, whereas any method for evaluating the fly’s therapeutic potential in humans has not been available. A feeding assay was developed using minced human tissues obtained from surgical waste. To establish L. sericata strains highly eligible for MDT, carrion fly larvae were collected from 45 corpses subjected to forensic autopsy (such as decomposed bodies). Four corpse-derived L. sericata strains were obtained and evaluated using the feeding assay. One strain showed that its feeding activity was 1.4 times higher than the control strain used in conventional MDT. The body length of the adult fly of the corpse-derived strain was longer than the control, which was consistent with the observation that its cell size was enlarged. The human tissue-based assay developed in this study accurately evaluated the ability of fly larvae to debride necrotic wounds. The L. sericata strain newly established from human corpses harboring high feeding activity may offer a clinically significant improvement in MDT.

Linking vgll3 genotype and aggressive behaviour in juvenile Atlantic salmon (Salmo salar).

We tested the possibility that vgll3, a gene linked with maturation age in Atlantic salmon (Salmo salar), may be associated with behaviour by measuring aggressiveness and feeding activity in 380 juveniles with different vgll3 genotypes. Contrary to our prediction, individuals with the genotype associated with later maturation (vgll3*LL) were significantly more aggressive than individuals with the genotype associated with earlier maturation (vgll3*EE). Individuals with higher aggression were also significantly lighter in colour and had higher feeding activity. Although higher aggression was associated with higher feeding activity, there was no association between feeding activity and vgll3 genotype. Increased aggression of vgll3*LL individuals was independent of their sex and size, and genotypes did not differ in their condition factor. These results imply that aggressive behaviour may have an energetic cost impairing growth and condition, especially when food cannot be monopolized. This may have implications for individual fitness and aquaculture practices.

Accumulation of PBDEs and MeO-PBDEs in notothenioid fish from the South Shetland Islands, Antarctica: An interspecies comparative study

Concentrations of polybrominated diphenyl ethers (PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs); are reported in specimens of fish notothenioids Chaenocephalus aceratus (SSI), Trematomus bernacchii (ERN), and Nototheniops nudifrons (NOD) from the South Shetland Islands, Antarctica. Significant differences in the accumulation of 2′-MeO-BDE-68 and 6-MeO-BDE-47 were detected among the analysed species. MeO-BDEs were significantly higher in SSI (11.7, 8.6, and 14.1 ng g−1 lw) than in NOD (1.63, 1.63, and 3.0 ng g−1 lw) in muscle, liver, and gill, respectively. Feeding ecology traits explain the accumulation patterns of MeO-PBDEs. SSI has a higher feeding activity with a broader diet, followed by ERN, whereas NOD is a benthic/sedentary fish with a narrower diet. The accumulation of PBDEs was neither species-, nor tissue-specific. The current study expands the knowledge concerning the accumulation of PBDEs and MeO-PBDEs in Antarctic marine fish and supports the importance of species-specificity in the accumulation of MeO-PBDEs.

Effective Defense of Aleppo Pine Against the Giant Scale Marchalina hellenica Through Ecophysiological and Metabolic Changes.

Aleppo pine (Pinus halepensis) is widely distributed in the Mediterranean region and in other areas of the world, where it has been introduced due to its adaptive capacity to xerothermic conditions. The giant pine scale Marchalina hellenica often infests Aleppo pine, as well as other pines, in several southeastern European countries, causing pine declines. When combined with the expected intensified heat and drought events in eastern Mediterranean, the impact of this biotic parameter on the host pines may be exacerbated. The importance of understanding the defense mechanisms of Aleppo pine is emphasized by the recent invasion of the pine scale in new regions, like Australia, lacking the insect’s natural enemies, where more intense negative effects on pine species may occur. To date, Aleppo pine’s physiological responses to the infestation by M. hellenica are largely unknown. This study aimed at assessing the responses of Aleppo pine to the giant pine scale attack, both on an ecophysiological and a metabolic level. For this purpose, gas exchange, needle water status, and carbon and nitrogen content were measured during 1 year on healthy and infested adult trees. M etabolic profiling of Aleppo pine needles was also performed before, during, and after the high feeding activity of the insect. The maintenance of stable relative water content, δ13C signatures, and chlorophyll fluorescence in the needles of infested pines indicated that infestation did not induce drought stress to the host pines. At the peak of infestation, stomatal closure and a pronounced reduction in assimilation were observed and were associated with the accumulation of sugars in the needles, probably due to impaired phloem loading. At the end of the infestation period, tricarboxylic acids were induced and phenolic compounds were enhanced in the needles of infested pines. These metabolic responses, together with the recovery of photosynthesis after the end of M. hellenica intense feeding, indicate that in the studied region and under the current climate, Aleppo pine is resilient to the infestation by the giant pine scale. Future research should assess whether these promising defense mechanisms are also employed by other host pines, particularly in regions of the world recently invaded by the giant pine scale, as well as under more xerothermic regimes.

Insectivorous bats foraging in cotton crop interiors is driven by moon illumination and insect abundance, but diversity benefits from woody vegetation cover

Landscape and biophysical determinants of insectivorous bat activity and community composition in space and time are central to understanding how growers can maximise bat-mediated pest control services in crops. We measured community composition, abundance, richness and foraging attempts of insectivorous bats in the centre of dryland cotton crops using acoustic sampling. We examined how bat activity was related to woody vegetation in the surrounding landscape, prey insect abundance, distance to crop edge, size of field, proximity to waterbodies and moon illumination to better understand insectivorous bat diversity and foraging in crop interiors. We collected a total of 9467 acoustic files including 1198 foraging attempts (feeding buzzes) of at least 21 insectivorous bat species. The bat assemblage in cotton crop interiors (richness and diversity) was positively related to woody vegetation foliage cover within 5–10 km of the crop, as well as Lepidoptera and Hymenoptera abundance, but was negatively related to distance from the field edge into the crop and moon illumination. Increased feeding attempts were linked to increased Lepidoptera and Hemiptera on nights of high moon illumination (> 75 %). Bat activity and foraging was also higher during nights of increased insect abundance, particularly Lepidoptera, indicating that bats track food resources. Our results highlight the importance of managing bat roosting habitat at different landscape scales to enhance bat diversity and foraging in crop interiors and thus insect consumption. Given the high bat feeding activity on nights of high moon illumination and increased Hemiptera abundance, the timing of insecticide sprays to target pests, such as Hemipteran sucking bugs, could be scheduled on nights of low moon illumination. Such information is useful in identifying conservation priorities for the management of bats in intensively farmed agroecosystems and should facilitate habitat management by growers to maximise crop pest protection services in crop interiors.

Does a bigger mouth make you fatter? Linking intraspecific gape variability to body condition of a tropical predatory fish.

In gape-limited predators, gape size restricts the maximum prey size a predator is capable to ingest. However, studies investigating the energetic consequences of this relationship remain scarce. In this study, we tested the hypothesis that gape-size variability influences individual body condition (a common proxy for fitness) in one of the largest freshwater teleost predators, the barramundi. We found that individual barramundi with larger gapes relative to body size had higher body condition values compared to conspecifics with smaller gapes. Body condition was highest soon after the wet season, a period of high feeding activity on productive inundated floodplains, and body condition decreased as the dry season progressed when fish were restricted to dry season remnant habitats. The increased condition obtained during the wet season apparently offsets weight loss through the dry season, as individuals with large gapes were still in better condition than fish with small gapes in the late-dry season. Elucidation of the links between intraspecific variability in traits and performance is a critical challenge in functional ecology. This study emphasizes that even small intraspecific variability in morphological trait values can potentially affect individual fitness within a species' distribution.

Uji Hemaglutinasi Assay pada Hemolimf Spodoptera exigua yang diberi Perlakuan Botani Pestisida

Abstract. The larval stage of the armyworm (Spodoptera exigua), has a high and polyphagous feeding activity so that these insects have the potential to be pests in agriculture. The use of botanical pesticides in this case Mirabilis jalapa, is expected to control agricultural pests so that research on the immune system of S. exigua larvae is carried out by observing lectins that play a role in analyzing foreign molecules that enter the insect's body. The results were obtained, the higher the M. jalapa concentration, at the concentration of M. jalapa 0.4% and 0.8%, the lower the hemolymf agglutination titers. This is thought to decrease the binding capacity of lectins to foreign molecules. So that M. jalapa has the potential to be used as an environmentally friendly botanical pesticide.Keywords: agricultural pests, botanical pesticides, lectin agglutination.

The influence of thermal extremes on coral reef fish behaviour in the Arabian/Persian Gulf

Despite increasing environmental variability within marine ecosystems, little is known about how coral reef fish species will cope with future climate scenarios. The Arabian/Persian Gulf is an extreme environment, providing an opportunity to study fish behaviour on reefs with seasonal temperature ranges which include both values above the mortality threshold of Indo-Pacific reef fish, and values below the optimum temperature for growth. Summer temperatures in the Gulf are comparable to those predicted for the tropical ocean by 2090–2099. Using field observations in winter, spring and summer, and laboratory experiments, we examined the foraging activity, distance from refugia and resting time of Pomacentrus trichrourus (pale-tail damselfish). Observations of fish behaviour in natural conditions showed that individuals substantially reduced distance from refugia and feeding rate and increased resting time at sub-optimal environmental temperatures in winter (average SST = 21 °C) and summer (average SST = 34 °C), while showing high movement and feeding activity in spring (average SST = 27 °C). Diet was dominated by plankton in winter and spring, while fish used both plankton and benthic trophic resources in summer. These findings were corroborated under laboratory conditions: in a replicated aquarium experiment, time away from refugia and activity were significantly higher at 28 °C (i.e. spring temperature conditions) compared to 21 °C (i.e. winter temperature conditions). Our findings suggest that P. trichrourus may have adapted to the Arabian/Persian Gulf environment by downregulating costly activity during winter and summer and upregulating activity and increasing energy stores in spring. Such adaptive behavioural plasticity may be an important factor in the persistence of populations within increasing environmentally variable coral reef ecosystems.

Modeling the functional link between movement, feeding activity, and condition in a marine predator

AbstractThe ability to quantify animals’ feeding activity and the resulting changes in their body condition as they move in the environment is fundamental to our understanding of a population’s ecology. We use satellite tracking data from northern elephant seals (Mirounga angustirostris), paired with simultaneous diving information, to develop a Bayesian state-space model that concurrently estimates an individual’s location, feeding activity, and changes in condition. The model identifies important foraging areas and times, the relative amount of feeding occurring therein, and thus the different behavioral strategies in which the seals engage. The fitness implications of these strategies can be assessed by looking at the resulting variation in individuals’ condition, which in turn affects the condition and survival of their offspring. Therefore, our results shed light on the processes affecting an individual’s decision-making as it moves and feeds in the environment. In addition, we demonstrate how the model can be used to simulate realistic patterns of disturbance at different stages of the trip, and how the predicted accumulation of lipid reserves varies as a consequence. Particularly, disturbing an animal in periods of high feeding activity or shortly after leaving the colony was predicted to have the potential to lead to starvation. In contrast, an individual could compensate even for very severe disturbance if such disturbance occurred outside the main foraging grounds. Our modeling approach is applicable to marine mammal species that perform drift dives and can be extended to other species where an individual’s buoyancy can be inferred from its diving behavior.

Diet Composition and Seasonal Fluctuations in the Feeding Habit of Snow Barbel (Schizothorax plagiostomus) in River Indus, Pakistan

Background:Schizothorax plagiostomus is widely distributed in river Indus and is most important food fish in Pakistan. The feeding habit of fish is directly related to the size of fish, its metabolic rate and environmental temperature. The accurate description of fish diet and feeding habit is a very important aspect in fisheries management for the purpose of species conservation, breeding and culture. The present work was aimed to investigate the specie abundance, the diet composition and seasonal variations in the feeding habit of Snow barbell Schizothorax plagiostomus.Materials, Methods &amp; Results: A total of 1799 fish specimens were caught at the confluence of six tributaries along river Indus at Indus Kohistan, northeastern Pakistan. The fish were collected by 5-panels of gill net during first week of each month. The site specific Catch Per Unit Effort (CPUE) and season specific CPUE of fish fauna were assessed. For the gut content analysis 240 samples (99 male and 141 females) of S. plagiostomus were selected on monthly basis. Frequency of occurrence method and volumetric method were applied to record the different food items in the gut of S. plagiostomus. The physico-chemical parameters, NO3 concentration and dissolved Co2 of water from different localities of river Indus were recorded month wise by Hach sensION 156 meter, Horiba LAQUA Nitrate Meter and EA80 meter respectively. Significant difference was observed in water temperature during the four seasons. Except alkalinity no other water parameter showed significant variation across different localities. The results showed that highest Mean CPUE was observed for Darel Stream (0.55) and lowest for Jalkot stream (0.26). Peak abundance of fish was recorded in the month of November with a mean catch of 44.50, mean CPUE of 0.74 and mean Kruskal-Wallis rank value of 63.25. Spirogyra and Ulothrix occurred as maximum food items in the gut of S. plagiostomus during summer while their minimum amount occurred during autumn. According to the ranking index spirogyra and ulothrix ranked higher with significant difference in comparison to other food items. The results showed that S. plagiostomus is phytophagous in its feeding habit, which consumed mainly algae attached to stones and pebbles during the whole year. However, the presence of some secondary items such as animal matter, detritus, sand and mud might be due to the distinct availabilities of food along the seasons. The highest feeding activity of S. plagiostomus was recorded during summer while the lowest one occurred during autumn, spring and winter. Discussion: Catch per unit effort (CPUE) is an indirect measure of the abundance of a target species. It is used as an index of stock abundance in fisheries and conservation biology. During the study low fish fauna was found in River Indus as reported previously. Majority of the fish occurred in snow fed river tributaries in the study area as these tributaries are comparatively less turbulent. Previous studies have also recorded that Schizothoracine generally prefer clean waters. The present findings of gut contents analysis showed clearly that S. plagiostomus is a phytophagous fish which scrap and consumed spirogyra and ulothrix attached to stones and pebbles. Earlier it was reported that mouth of S. plagiostomusis is inferior, wide, with deep lower jaw having keratinized cutting edge and the lower lip is folded and expanded with numerous papillae making it best suited for scrapping algae attached to stones and pebbles. The highest feeding activity was observed during warmer months as compared to cold months. S. plagiostomus spawn twice in a year in autumn and in spring. The highest feeding activity of S. plagiostomus seems to be link with a reflex of recovery strategy due to physiological process of gonadal development.

Effects of intrapopulation phenotypic traits of invasive crayfish on leaf litter processing

The impact of invasive alien species (IAS) on an ecosystem is primarily studied at the species level, whereas the functional impacts of their genetic and phenotypic traits are poorly investigated. We used two laboratory based experiments to assess how intrapopulation phenotypic traits (size, sex, and number of claws) of the invasive red swamp crayfish Procambarus clarkii affect invertebrate shredders and leaf processing. Leaf consumption was significantly affected by the size and number of claws but not by the sex of the crayfish. Bigger animals presented a higher overall consumption but, in contrast, the mass of leaves consumed per unit crayfish body mass decreased with size. Indeed, the production of particulate organic matter followed the same trend, suggesting that the higher metabolic needs of smaller animals are responsible for their higher feeding activity on leaf litter. Claw loss in P. clarkii also led to increased leaf consumption and may be related to increased energy requirements for claw regeneration. Our results highlight the importance of also considering the phenotypic traits within populations for better understanding the impacts of IAS on ecosystem processes.

Eat Behavior Muara Goat (Capra aegagrushircus) in the village of Batubinumbun, Muara, North Tapanuli Regency

Goat eating behavior can support nutrition of goat feed. This information is important for farmers in an attempt for Muara condition the environment and design the appropriate management needs goats. This research was conducted in July and August 2016. Livestock were used as many as 30 individuals. Eating behavioral observations performed on four groups, namely: group I (adult males and adult females with a ratio of 1: 9), Group II (adult males and adult females with a ratio of 1: 4), Group III (young male 6 tails and females young or virgin 4 individuals) and group IV (tiller consists of 2 males and females tails 3 tails). Research method was One Zero with a 15 minute interval performed on at 08.00-12.00. The results showed higher feeding activity compared to activity of rumination, the group with the highest feeding activity in the goat group samplings, rumination activity while highest in the group of adult goat.

Comparative study of feeding behaviour of fiveMugilidaespecies juveniles from two estuarine systems in the North Aegean Sea

Food is an important factor for the survival of juvenile fish. Knowledge of the diet of co-existing species helps clarify their relationships with each other. A number of Mugilidae species are known to co-exist in estuarine systems, raising the question of whether they compete for food resources. The feeding behaviours of five juvenile Mugilidae species were studied in the estuaries of Strymonikos (North Aegean Sea) using stomach content analysis. It was found that the speciesChelon labrosus, Liza saliensandMugil cephaluspresented high feeding activity during summer and autumn andL. ramadaandL. aurataduring winter and spring. The diet overlap between the species was generally moderate to low and the pairL. saliens–M. cephalusexhibited the highest overlap in Richios estuarine system. The species do not appear to compete for common resources, probably because there is not always a spatiotemporal overlap, enough food is available or they exploit different resources. Four out of the five species exhibited similar patterns of feeding strategies with varying levels of specialization at an individual level and a rather generalized pattern at the population level. This more generalized feeding strategy may permit them to co-exist. OnlyM. cephalusshowed a more specialized feeding behaviour, with a strong preference for microalgae. The absence of a general pattern for the trophic levels according to seasons, sizes or locations, also imply the opportunistic character of the species. Both season and fish size influenced the variation in the diet composition.

Thermal acclimation in American alligators: Effects of temperature regime on growth rate, mitochondrial function, and membrane composition

We investigated the ability of juvenile American alligators (Alligator mississippiensis) to acclimate to temperature with respect to growth rate. We hypothesized that alligators would acclimate to cold temperature by increasing the metabolic capacity of skeletal muscles and the heart. Additionally, we hypothesized that lipid membranes in the thigh muscle and liver would respond to low temperature, either to maintain fluidity (via increased unsaturation) or to maintain enzyme reaction rates (via increased docosahexaenoic acid). Alligators were assigned to one of 3 temperature regimes beginning at 9 mo of age: constant warm (30°C), constant cold (20°C), and daily cycling for 12h at each temperature. Growth rate over the following 7 mo was highest in the cycling group, which we suggest occurred via high digestive function or feeding activity during warm periods and energy-saving during cold periods. The warm group also grew faster than the cold group. Heart and liver masses were proportional to body mass, while kidney was proportionately larger in the cold group compared to the warm animals. Whole-animal metabolic rate was higher in the warm and cycling groups compared to the cold group – even when controlling for body mass – when assayed at 30°C, but not at 20°C. Mitochondrial oxidative phosphorylation capacity in permeabilized fibers of thigh muscle and heart did not differ among treatments. Membrane fatty acid composition of the brain was largely unaffected by temperature treatment, but adjustments were made in the phospholipid headgroup composition that are consistent with homeoviscous adaptation. Thigh muscle cell membranes had elevated polyunsaturated fatty acids in the cold group relative to the cycling group, but this was not the case for thigh muscle mitochondrial membranes. Liver mitochondria from cold alligators had elevated docosahexaenoic acid, which might be important for maintenance of reaction rates of membrane-bound enzymes.

Soil Fauna Abundance, Feeding and Decomposition in Different Reclaimed and Natural Sites in the Sanjiang Plain Wetland, Northeast China

We investigated the effects of anthropogenic land change on soil fauna density, decomposition and feeding activity in five natural and reclaimed sites of the Sanjiang Plain, China. During the past 60 years, much of the land was converted from forests and wetlands to reclaimed agricultural land use areas. The highest feeding activity and mesofauna density, dominated by springtails, oribatid/gamasid mites and proturans, was found in the wetland site followed by a plantation forest and a secondary island forest. By contrast, two reclaimed soybean fields had significantly lower mesofauna densities and reduced feeding activities in the first six centimeters of the topsoil. The decomposition process after 60 days in these agricultural sites showed decreased values for mesofauna and microorganisms with increasing land use. The loss of functional guilds for the secondary decomposition process could explain the need for increasing fertilization to reach the same yield in the reclaimed soybean fields of this region. This investigation further underlines the outstanding role of the remaining fragmented wetland sites as a mesofauna biodiversity refugium and the importance of these communities in the feeding and decomposition processes in such ecosystems.

Ontogeny in Feeding Behaviour of Chocolate Mahseer, Neolissocheilus hexagonolepis in Captive Environment

The paper embodies to determine the sequential pattern of feeding behaviour of chocolate mahseer in pond condition. The diet composition of different developmental stages of Neolissochilus hexagonolepis during fry, fingerling and juvenile were determined based on the analysis of 98 specimens (17 fries, 43 fingerlings and 38 juveniles), collected from the pond environment of Mahseer Hatchery Complex of ICAR- DCFR, Bhimtal. Zooplanktons were the most dominant prey category (%F = 129.38, %N = 45.73) in fry, while phytoplankton's were the most dominant prey items in fingerling (%F = 139.59, %N = 63.67) and juvenile (%F = 233.88, %N = 70.84). The results of the study revealed that fry and juvenile seems to have a higher feeding activity in relation to fingerling and the diet of the fish varies with different stages of development. Hence, the fry are carni-omnivore while fingerlings and juveniles are herbi - omnivore.

Food and feeding habit of a freshwater catfish, Mystus tengara (Siluriformes: Bagridae)

Feeding is the dominant activity in entire life cycle of fish; thus detailed knowledge on food and feeding habit of any fish species is really essential to get success in culture of that particular fish species. Mystus tengara is a popular food fish due to its good taste; and recently it has also got its entry in ornamental fish markets. No such detail works till date has been performed on food and feeding habit of this fish species. So the present study has been performed to get information on the food and feeding habit of Mystus tengara. Gastro Somatic Index, Relative Length of Gut, Gut Fullness & Feeding Intensity and Gut Content Analysis have been performed as parts of the study. Results of the study have revealed that Mystus tengara is a carnivorous fish and zooplankton is the basic food group for this fish species; rotifera has also been observed as the most preferable food class. During the study, feeding activity of this fish species has never been observed to be discontinuous; though it has been observed to vary according to the breeding season; lowest feeding activity has been observed during intense breeding season while highest feeding activity has been observed during pre-spawning months.

Feeding and intoxication–detoxification dynamics in two populations of the mussel Mytilus chilensis (Hupé, 1854) with different histories of exposure to paralytic shellfish poisoning (PSP)

Individuals of Mytilus chilensis with different histories of exposure to paralytic shellfish poisoning (PSP) were exposed to a diet containing the dinoflagellate Alexandrium catenella. Feeding and intoxication–detoxification dynamics were evaluated over a period of 12–16 days. Feeding activity was reduced during the first days of exposure, followed by a period of recovery from day 5 to the end of the experiment. Mussels from Corral population (no history of PSP exposure) exceeded the concentration of 80 μg STX eq. 100 g−1 tissue, although filtration activity was significantly lower compared with individuals from Melinka (frequent PSP exposure). The higher feeding activity and the lower degree of toxin accumulation in the Melinka population appear be associated with frequent exposure to PSP in the natural environment. The use of A. catenella as food resource and the capacity of a rapid intoxication of both populations showed that M. chilensis is an adequate indicator for early detection of PSP.