Results 1 - 10 of 2024
Results 1 - 10 of 2024. Search took: 0.026 seconds
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[en] Fledgling production has often been used as an estimator of avian reproductive success, and it is conditioned by factors affecting offspring development and/or survival during the nesting period. We aimed to determine which predictors influenced fledgling output among a set of basic breeding parameters and local temperature data collected over 25 years in a Mediterranean great tit, Parus major, population, using an information–theoretic approach for model selection. Of the studied variables, the number of hatchlings per nest was the single–most important predictor influencing fledgling production, with larger broods eventually yielding more fledglings, although mass prior to fledging may have been compromised. This result suggests an overall good adjustment between brood size and resource availability in the studied population. (Author)
[en] Dietary cholesterol should be limited to less than 200 mg/ day. A single large egg yolk contains approximately 275 mg of cholesterol. Thus, consumption of a single egg yolk exceeds the recommended daily intake of cholesterol. This study was focused on determination of the effect of addition of increasing amount of β-cyclodextrin (β-CD) to encapsulate cholesterol in egg yolk. The quality of cholesterol-reduced egg yolk powder was evaluated by determining its nutritional composition and colour analysis. Increasing amount of β-CD (0-15 mM) was added in liquid egg yolk and the encapsulated cholesterol in the form of precipitate was removed. The supernatant was dried and the end product; cholesterol-reduced egg yolk powder (CREYP) was analyzed for moisture content, total lipid, fatty acids content, protein and colour. There were no significant difference (p>0.05) in term of total solid content. However, protein content of CREYP was significantly (p<0.05) reduced up to 7 mM β-CD and no further significant reduction was noticed with further addition of β-cyclodextrin. The appearance of the powder became lighter in colour as validated using chromameter; L*, a*, b*, C* and ho values. The results obtained from this study indicate that cholesterol can be successfully removed from egg yolk. However, slight reduction in protein content was observed. Nutritional composition of CREYP was minimally affected with the removal of encapsulated cholesterol. Therefore, cholesterol-reduced egg yolk powder can be utilized as an essential ingredient in any egg yolk based products. (author)
[en] The diamondback moths, Plutella xylostella L. were reared with cabbage leaves under field condition at Khao Khor Highland Agricultural Research Station (16-47 degree celsius, 22-96% R.H.). The average duration of the egg, larval (1st and 2nd instar, 3rd instar and 4th instar), pupal and male and female adult stages were 3.21± 0.30, 5.57 ± 0.60, 3.16 ± 1.07, 3.43+0.97, 3.88 ± 1.59, 17.72 ± 2.74 and 16.16 ± 3.93 days respectively. Female laid eggs at 1 day old and the highest number of eggs were counted in the 2nd day of the oviposition period. The number of eggs laid per female averaged 109+77.60 eggs, ranging from 17 to 248 eggs. The life cycle from egg to adult stage was 13-31 days. The population parameters were the cohort generation time (Tc)=23.45 days, the net reproductive rate (Ro)=25 and the finite rate of increase (λ)=1.15 time per day respectively. Studies on reproductive system of this insect showed that the developed testes were found in the 4th instar larva while developed ovaries were found after emergence. Male mated many times (average 3.33 times) while almost female mated only once (92%). The ecological life table of this insect was studied in the cabbage field at the Khao Khor Highland Agricultural Research Station. The eggs hatch was 55.89% and the highest mortality occurred in the 1st and 2nd instar larval period (64.37%). The disease and parasites caused the high mortality in the 4th larval and pupal period (49.64 and 46.38%)
[en] Quantifying polychlorinated biphenyl (PCB) residues in nestlings of avian species is a common method for assessing trophic transfer and risk at PCB-contaminated sites. The proportion of nestling PCB mass due to maternal transfer is often accounted for by subtracting total PCB mass in eggs from nestlings. However, variation in physicochemical properties and metabolism among congeners may lead to differences between egg contribution based on total PCBs and dioxin-like congeners. We examined congener-specific variation in contribution of PCBs from eggs to nestlings in tree swallows and European starlings. Egg contribution of total PCB mass was 14.3 and 16.2%, respectively, whereas contribution based on dioxin-like congeners was 14.8 and 13.6%, respectively. These data suggest that using total PCB mass in eggs to adjust estimates of PCB accumulation in nestlings may not reflect patterns for dioxin-like congeners, potentially over or under-estimating the risk of toxicity of PCBs. - Congener-specific contribution of PCBs from egg to nestlings was examined.