جستجوی مقالات مرتبط با کلیدواژه « feeding strategy » در نشریات گروه « علوم پایه »

This study was conducted with the aim of determining the effect of different probiotics administration on alterations in biochemical parameters of juvenile sea bass (Lates calcarifer). Four hundred and twenty sea bass with an average weight of 34 ± 4.5 g were prepared and randomly divided into seven groups with three replications (40 fish in each replication) and fed with experimental diets for 90 days. The experimental treatments included: group 1 (T1): different Lactobacillus plantarum sp.; group 2 (T2): L. plantarum sp., L. bulgaricus, L. acidophilus and L. rhamnosus in a combined form (combination of lactobacilli); group 3 (T3): the combination of diets 1 and 2 as well as Bacillus cereus and B. thuringiensis which was administered to fish every two weeks; group 4 was the control group without probiotics (C4). In addition, groups 5, 6 and 7 (T5, T6 and T7) were similar to groups 1, 2 and 3 which were continuously fed to fish. The results showed that there was a significant increase in blood serum cholesterol at the end of the experiment in T7 compared to the control group. The calcium level in T3 showed the highest amount compared to other treatments. All treatments showed a decreased amount of total protein at the end of the experiment compared to the control (C4). Moreover, the highest value was related to T6. T7 exhibited the highest amount of triglycerides and glucose at the end of the experiment. In case of liver enzymes, the lowest serum ALP level was found in T1 and the lowest AST in T6, while serum ALT level did not display any significant difference in any group. In cases of Cpk and HDL, the lowest values belonged to T1. In general, it can be concluded that the use of a mixture of probiotics in a pulse administration can cause positive effects on the blood biochemical parameters of L. calcarifer.

Morphogroup analysis, due to independence of species level taxonomy, as wel as permit to comparison of assemblages of differing ages, is a useful tool for ecological and palaeoecological interpretation. Foramniferal study of the Qom Formation in the Natanz (with Rupelin-Chattian?-Aquitanian in age and 330 m thickness) and Khorabad (southeastern Qom; with Rupelin-Burdigalian in age and 260 m thickness) sections resulted in identification of 8 morphogroups. The morphogroups were distinguished according to test/shell morphology and architecture (general shape, mode of coiling, and arrangement and number of chambers), inferred life habitat either living on the surface of the sediments or within the sediments (epifaunal and infaunal), and feeding strategy. Generaly, epifaunal morphogroups were dominated in both study sections. The lower 200 m of the Natanz section, are dominated by calcareous porcelaneous morphogroups; while the upper layers are dominated by hyaline morphogroups, which indicates the lower and upper parts were deposited in inner ramp (lagoonal environments) and open sea, respectively. This significant change through time reffers to gradual increasing of the basin depth, decreasing the light intensity, reducing the salinity and decreacing the nutrient level. The distribution of morphogroups in the Khorabad section follows a reverse pattern; so that, despite the minor fluctuations, the lower 200 m of the Khorabad section, are dominated by hyaline morphogroups; while the upper layers are dominated by porcelaneous morphogroups, which indicates the lower and upper parts were deposited in open sea and inner ramp (lagoonal environments), respectively.

The Qom Formation is the main reservoir and source rock of hydrocarbons in central Iran. Foraminifera are now central to our ability to date, correlate and analyse the sedimentary basins that are currently key to the economic wellbeing of the world. Morphogroup analysis, due to independence of species level taxonomy, as wel as permit to comparison of assemblages of differing ages, is a useful tool for ecological and palaeoecological interpretation. It is independent of species level taxonomy and is thus relatively elementary to translate from one worker to another. Foramniferal study of the Qom Formation in the Bujan (eastern Sirjan; with Rupelin-Chattian in age and 156 m thickness) and Varkan (southwestern Kashan; with Rupelin in age and 190 m thickness) sections resulted in identification of seven morphogroups. The morphogroups were distinguished according to test/shell morphology and architecture (general shape, mode of coiling, and arrangement and number of chambers), inferred life habitat either living on the surface of the sediments or within the sediments (epifaunal and infaunal), and feeding strategy (suspension-feeder, herbivore, etc.). Generaly, epifaunal morphogroups were dominated in both study sections. The morphogroup analyses showed variations in the percentage of the dominant morphotypes, suggesting fluctuations in the paleoecological conditions. In the Bujan section, the Rupelin deposits are dominated by calcareous porcelaneous morphogroups; while the Chattian deposits are dominated by hyaline morphogroups, which indicates the lower and upper parts were deposited in inner ramp (lagoonal environments) and middle ramps, respectively. This significant change through time reffers to gradual increasing of the basin depth, decreasing the light intensity, reducing the salinity and decreacing the nutrient level. De dominance of the hyaline morphogroups throughout of the Varkan section is indicative of the deposition in middle ramp environments with normal salinity under meso-photic to oligo-photic conditions.

In recent decades, coastal artificial structures have been increased in response to increment of storms, and coastal settlement. Round goby belong to family Gobiidae, one of the most important fish families in the Caspian Sea because of their abundance. In this study, we compared the feeding strategy and species diversity diet of the round goby, Neogobius melanostomus between artificial shores (Riprap structures) and natural shores including gravel and stony shores. According to the results, overall ten prey items consist of Xanthidae, Palaemonidae, Gammaridae, Amphibalanus improvisus, Ostracoda, Nereis diversicolor, Bivalvia, Foraminifera, fish remains and fish eggs were observed in the diet of round gobies. In artificial, gravel and stony shores, A.improvisus (%19.37), Ostracoda (%78.44) and N.diversicolor (%1.42) were most abundant food items. Analysis of the digestive tract contents revealed that round gobies consume wide spectrum of distinct food items in different shores. individuals of the fish have more specialized on distinct prey items at the artificial rocky shores in comparison with the other shores. At the artificial shores, round gobies are specialized on fish eggs, Ostracoda, Palaemonidae, Amphibalanus improvisus, Nereis diversicolor, Foraminifera and Xanthidae. 10, 8 and 6 prey items were observed in the diet of round gobies at the artificial rocky, gravel and sandy shores, respectively. Comparison of the species diversity in the gut contents of round goby showed higher value (1.94) at the artificial rocky shores than the gravel (1.62) and sandy (1.55) shores but, there was no significant difference in shannon index between artificial and natural shores.

The effects of feeding strategy of broiler breeder hens on reproductive performance and ovarian morphology from 42 to 54 week of age were studied with using 50 Ross 308 broiler breeder hens. Hens were randomly divided to 2 groups of restricted (160 g/d) and ad libitum (208 g/d) feeding. Ad libitum fed hens had 630 g heavier body weight than restricted hens. Egg production rate decreased 23. 3% during the first 2 weeks of experiment in ad libitum fed hens compared to restricted hens. Egg weight was increased quickly during first 5 week of experiment in ad libitum fed hens and then continued slowly. Percentage of fertility and hatchability significantly decreased in ad libitum fed hens compared to restricted hens (P≤0. 05). Ad libitum fed hens had more atretic and third follicles (P≤0. 05). However، there were no significant difference in ovary weight between the two feeding group، oviduct weight was lower in ad libitum fed hens (P≤0. 05). Abdominal fat pad weight، liver weight، percentage of liver lipids and cholesterol was higher in ad libitum fed hens compared to restricted hens (P≤0. 05). Microscopic examination of liver tissue revealed huge vacuoles of fat which was not detected in restricted hens. Results indicate that ad libitum feeding of broiler breeder hens by increasing of fat deposit in abdomen and liver، reduce reproductive performance.