Differences In Mass Gain Research Articles

Preliminary Studies on Rare Elements Addition and Effect on Oxidation Behaviour of Pack Cementation Coatings Deposited on Variety of Steels at High Temperature

The aim of the paper was to investigate the air oxidation behaviour of pack aluminised steels exposed at 650 °C for 1000 h in static natural air atmosphere. The pack coatings were doped by rare elements such as gadolinium (Gd), cerium oxide (CeO2), and lanthanum (La) in order to enhance the corrosion resistance and plasticity of the deposited layers. In this work, the following steels were used: 16M, T91, VM12, Super 304H, and finally SANICRO25. The results indicated a much higher corrosion resistance in the coated 16M, T91, and VM12 steels; the steels with a higher Cr content than 16 wt % Cr indicated a better behaviour in the uncoated state than in the coated state. However, the observed difference in mass gain between the uncoated and the coated austenitic steels was not enormous. Furthermore, the addition of RE elements to the coating showed some effect in terms of coating thicknesses and differences in the layer structures. The materials prior to testing and after the exposure were investigated using XRD, the SEM X-ray maps with an EDS instrument were used for particular samples to evaluate the phase identifications, element concentrations, microstructure, and chemical composition.

Growing stock of nectar- and honeydew-producing tree species determines the beekeepers’ profit

Forests and woodlands are considered as the most important sources of honey bee forage in many European countries with several tree species providing nectar and/or honeydew flow. Slovenia boasts with high number of beekeepers and high colony count per square kilometer. We have investigated the impact of availability of natural resources and colony density on honey yield.Data presented here were collected on 57 locations with monitor hives, equipped with scales, over years 2011–2016. Locations were selected according to site vegetation, ensuring identified source of nectar or honeydew flow. The source of the flow was recorded and verified by contract beekeeper. We investigated (1) the relationship between abundance of the flow source expressed as the quantity of growing stock and net mass gain of the monitor colony during the flow and (2) the relationship between colony density expressed as the number of colonies against growing stock volume and net mass gain of the monitor colonies.We found an asymptotic exponential relationship between colony mass gain and growing stock of the species, providing flow. The exception was the spruce where the relationship was determined as linear (k = 0.023 ± 0.009). The τ of the exponential approach in the case of acacia flow was 9.8 ± 5.6 and in case of linden flow 6.6 ± 3.9 (mean ± SE). Colony density then determined the colony mass gain due to the flow. In cases of acacia, linden and spruce flow we have determined the relationship between colony density and mass gain as decaying exponential (τ = 283.9 ± 60.6, τ = 1.6 ± 0.4 and 3.0 ± 1.3, respectively, all mean ± SE). Combined linden/chestnut flow was fitted best with linear equation (k = −0.08 ± 0.019). Most likely, another variable should be used in the case of spruce flow: population of dew-producing insects. Periodical monitoring of eight acacia locations show differences in mass gain between years, thus allowing prediction of colony densities which guarantee profit: these locations are determined as those with colony density less than 50 hives/103 m3 growing stock gained more than 10 kg/hive in 83% of cases, regardless of the year.Our results indicate that a cap on the total number of colonies at one location should be considered to maximize beekeepers’ profit.

Comparison of Migrant Songbird Stopover Ecology on Two Islands in the Gulf of Maine

We compared migrant bird recapture rate, stopover time, mass gain, and fat class between Star Island, New Hampshire and Appledore Island, Maine during spring and fall migration in relation to differences in relative species abundance between the islands; and examined potential movement of migrants between the islands. The average recapture rate in spring was 5.7% on Star Island and 3.6% on Appledore Island. Five species were recaptured more frequently on Star Island and one species more frequently on Appledore Island. There was no difference in mean minimum stopover time during spring (2.4 days on Star Island; 2.5 days on Appledore Island) and fall (2.9 days on Star Island; 3.2 days on Appledore Island). Three species had a longer mean stopover time on Appledore Island than Star Island. The island with the greater percentage of recaptures and longer stopover had more captures for a given species. Mass gains were significant for six species during spring (27.3%) and 10 during fall (38.5%) on Star Island, and five (22.7%) during spring and 13 (50.0%) during fall on Appledore Island. Five species had a difference in rate of mass gain between the islands. The between-island difference in species abundance was not reflected in between-island differences in mass gain, except for Red-eyed Vireo (Vireo olivaceus) during fall. There was no clear pattern in species differences in fat levels and differences in captures, stopover length, or mass gain between the islands. The fat-class and mass-gain results suggest habitat use, as measured by relative abundance, is not based on the ability to gain mass at the time of stopover. The notable fall mass gains for Red-eyed Vireo illustrate the availability of food resources for some species on both islands. Only 42 of 10,437 migrant birds banded moved from one island to the other. There was little evidence of movement between islands in a seasonally-appropriate direction for continued migration, or evidence indicating a shift between islands after initial capture.

The Effect of Different Levels of Organic and Inorganic Chromium Supplementation on Production Performance, Carcass Traits and Some Blood Parameters of Broiler Chicken Under Heat Stress Condition

A total of 250 broilers in a completely randomized design selected to evaluate the effect of different levels of chromium (Cr) supplementation on performance, carcass traits and some blood parameters of heat-stressed broiler chicks. All birds were kept under heat stress temperature (33 ± 3°C) and divided into five treatments groups. Each treatment consisted of five pens with 10 birds in each pen. The basal diets were supplemented with 0ppb (control), 800ppb Cr-L-Met (T(1)), 1,200ppb Cr-L-Met (T(2)) or 800ppb CrCl(3) (T(3)), and 1,200ppb CrCl(3) (T(4)). The feed intake and body mass were measured at 10, 21, and 42days of age. Blood samples were collected from two birds in each replicates to determine biological and hematological values at 28 and 42days of age. There were no significant difference in mass gain and feed conversion of broilers that received Cr supplementations compared with controls. The serum glucose concentration decreased in broilers received organic chromium methionine supplements compared with other treatments groups. Slight but not significant increases were observed in serum high-density lipoprotein (HDL) concentration of treated groups than controls while the mean serum HDL concentration was significantly higher in T(2) group compared with control group. Serum low-density lipoprotein level decreased in broiler received organic Cr supplements (p < 0.05).

Mouth coloration in nestling birds: increasing detection or signalling quality?

The bright colours of nestlings' mouths are conspicuous when they beg. Three main hypotheses suggest that nestling mouth colour (1) increases detectability in dim ambient light, (2) signals health or quality, or (3) provides a means of offspring recognition. To distinguish these hypotheses, we manipulated both the flange colour (visual and UV spectrum) and the ambient light in the nest of three cavity-nesting species: a woodpecker and two passerines. Parents avoided nestlings with black-painted flanges to a greater extent in dim than in bright ambient light conditions, and the effect was most pronounced in the woodpecker, which had the deepest and darkest nest cavity of the three species studied. There was no difference in mass gain of nestlings with flanges painted white or yellow or with UV-block cream relative to controls, suggesting that neither UV reflectance nor carotenoid colour was a cue of nestling quality. These results support the detectability hypothesis and not the health-signalling or recognition function for bright flanges. Black-painted flycatcher nestlings were more disadvantaged in short trials ( 3 h), and we developed a model to explain how nonvisual components of begging, such as vocalizations or movements, may become more important than visual cues as nestlings become hungrier and beg more intensively over time. Our results suggest that bright flanges in cavity-nesting birds evolved primarily so that parents can locate offspring in dim light, but competition among nestlings may lead to exaggerated brightness. Furthermore, other components of begging such as movements or vocalizations may temporarily override a disadvantage of dull mouth colour.

Sibling Growth Patterns in Great tits: Does Increased Selection on Last-hatched Chicks Favour an Asynchronous Hatching Strategy?

In birds, competitive abilities of siblings in relation to their sex and the magnitude of hatching delay are still poorly understood. We compared the sex-specific growth of the last-hatched, competitively disadvantaged chicks with that of synchronously hatched chicks in two successive years. Sons exhibited higher growth rates than daughters in a year with delayed onset of breeding, and this sex-related difference was more pronounced among the asynchronously hatched chicks. Females apparently do not selectively allocate more resources to the last-laid eggs because neonatal body mass and the growth rate of asynchronously hatched chicks did not differ between years, despite the fact that in one of the years, asynchronous chicks hatched from replaced eggs taken randomly from other nests and not from eggs laid last by the incubating female. Among chicks that survived, moderately asynchronous siblings grew at a lower rate than synchronous ones, whereas no difference in mass gain was revealed between synchronous and strongly asynchronous siblings irrespective of their contrasting competitive abilities. We suggest that selection of the fittest asynchronous chicks may improve the overall quality of asynchronous broods, thus favouring the maintenance of asynchronous hatching strategies in variable environments.

Transgenic UDP‐glucuronosyltransferase 1 mice are protected from obesity‐induced type 2 diabetes

Obesity-induced type 2 diabetes is a growing human health issue in Western societies. Fibrates are PPARα agonists used to treat dyslipidemia and diabetes and are targeted by glucuronidation for elimination. Initially, to examine the effects of PPARα agonists on human UDP-glucuronosyltransferase 1 (UGT1) regulation, transgenic human UGT1 mice (Tg-UGT1) were treated with the fibrate WY-14643. Oral administration of WY-14643 to Tg-UGT1 mice induced UGT1A1 and 1A4 in the liver. To examine the contribution of human glucuronidation towards obesity-induced type 2 diabetes, wild type (WT) and Tg-UGT1 male mice were fed a normal diet or a 35% fat diet (HFD) for 16 weeks. Mass gain was monitored and diabetic status established by insulin and glucose tolerance tests and serum insulin levels. There was no difference in mass gain between male WT or Tg-UGT1 mice on HFD. Obese WT mice were insensitive to insulin, retained elevated blood glucose levels, and displayed hyperinsulinemia, indicating the onset of type 2 diabetes. Interestingly, obese Tg-UGT1 mice were insulin sensitive and displayed normal blood glucose clearance. Blood insulin levels for obese Tg-UGT1 mice were similar to WT and Tg-UGT1 males on normal diets. To determine if human UGT1A expression correlated with protection from type 2 diabetes, human UGT1A protein levels were measured by Western blot analysis. UGT1A1 and UGT1A4 in the small intestine were down-regulated in obese Tg-UGT1 mice. While it is not clear why down-regulation of the human UGT1A proteins might protect against obesity-induced type 2 diabetes, the reduction may lead to reduced clearance and increase the potential for toxicity of drugs in diabetic patients. (Supported by USPHS grants GM49135 and ES10337)

Nutrition interacts with parasitism to influence growth and physiology of the insectManduca sextaL.

The influence and interaction of dietary protein:carbohydrate balance and parasitism by Cotesia congregata on nutrient intake and growth were examined over the last two larval stadia of Manduca sexta. Effects of nutritional status on host blood metabolite concentrations were also determined. Six fat-free chemically defined diets were tested, each having the same total level of casein and sucrose, but with casein to sucrose ratios varying from low protein/high carbohydrate to equal levels of both nutrients through to high protein/no carbohydrate. Nutrient ratio and parasitism each affected nutrient consumption and growth. Feeding responses differed between normal and parasitized larvae, as illustrated by nutrient arrays, two-dimensional plots of protein and carbohydrate consumption on diets having different nutrient ratios. Normal larvae consumed more nutrients and took longer to develop as dietary nutrient ratio was displaced from equal levels of both nutrients. Except on the diet having the same amount of protein and carbohydrate, parasitized larvae consumed less nutrients than normal larvae, although on all diets parasitized larvae took longer to develop. When the contribution of parasite biomass was excluded, parasitized larvae showed lower mass gain than normal larvae on all diets. Total mass gain by normal and parasitized larvae with parasite biomass included, however, was similar on diets having intermediate nutrient ratios. Differences in mass gain between diets relative to nutrient consumption were evident from multi-dimensional representations of mass gain with protein and carbohydrate consumption. Three-dimensional plots and contour maps of normal and parasitized larvae were different. When differences in nutrient consumption between diets were taken into account, protein consumption had a greater effect on growth than carbohydrate consumption and normal larvae generally displayed greater mass gain than parasitized larvae on the same diets. Utilization efficiency, the efficiency of conversion of ingested food to body mass, was, therefore, generally reduced in parasitized insects. Concentrations of blood protein, total free amino acids and trehalose were each influenced by dietary nutrient ratio and parasitism. Concentrations of protein and free amino acids generally increased and trehalose concentration decreased as dietary protein increased and carbohydrate decreased. The opposite was the case as dietary carbohydrate increased and protein decreased. Dietary nutrient ratio, however, affected normal and parasitized larvae differently. Parasitized larvae had higher overall trehalose concentrations while normal larvae had higher protein and total free amino acid concentrations. When differences in nutrient consumption between diets were accounted for, protein consumption had a greater effect on blood protein and free amino acid concentrations than did dietary nutrient ratio or parasitism. Protein consumption, however, did not affect trehalose concentration. Carbohydrate consumption had no effect on the concentration of any of the metabolites after differences in nutrient consumption were taken into account. Effects of nutrient consumption on trehalose concentration, therefore, were due to dietary nutrient ratio and parasitism. The potential relevance of the above findings to the biology of parasitized M. sexta larvae is discussed.

Does dietary n−3 highly unsaturated fatty acids level influence the European sea bass ( Dicentrachus labrax) capacity to adapt to a high temperature?

Triplicate groups of European sea bass juveniles (60 g) were fed for 84 days two experimental diets containing either vegetable or marine oil (0.4 and 2.2% n−3 highly unsaturated fatty acid [ n−3 HUFA] dry matter in LD and HD, respectively) and held at 22 or 29 °C (LD-22, LD-29, HD-22 and HD-29 groups). Significant differences in mass gain between the two diets and temperatures were observed from day 28 onwards, and on day 84, weight was 18% higher in the HD-29 group than in the LD-22 group (the highest and lowest values, respectively). Over the 84-day period, SGR was significantly affected both by temperatures and diets ( P=6×10 −4 and 2×10 −4 respectively), averaging 1.01 and 1.07 in the HD-22 and HD-29 groups compared to 0.92 and 1.0 in the LD-22 and LD-29 groups. Differences in growth rate between the experimental conditions were mainly explained by differences in feed intake (FI). FI was more affected by temperature than by diets (in fish fed HD, it was 1.7% day −1 at 29 °C and 1.4% day −1 at 22 °C, and 1.7% day −1 and 1.3% day −1, respectively, with LD). Feed conversion ratio (FCR) was significantly affected by temperature and diets; days 0–84 FCR was on HD and LD 1.6 and 1.7 at 29 °C and 1.4–1.5 at 22 °C. Considering growth and feeding parameters, no interaction between dietary concentration in n−3 HUFA and temperatures were observed. In acclimated fish, MO 2 on routine metabolism was the highest at HD-29 (396 mg O 2 kg −1 h −1) as it was dependent on FI. There was no major difference in fish whole body composition, and protein retention was more affected by temperature than by diets. Diets and temperature affected polar lipid fatty acid content, without interaction; n−3 HUFAs were lower at 29 °C than at 22 °C. Fatty acids of total and neutral lipids (NL) were mainly affected by dietary fatty acids, while some low but significant influences of temperature were observed. Interactions between the two studied factors concerned particularly n−3 HUFAs content, lower at 29 than at 22 °C only in fish fed vegetable oil (LD). This study demonstrated that in high-quality sea bass juveniles, a 3-month deficiency in dietary n−3 HUFA did not drastically impair fish capacity to adapt to a high temperature, 29 °C.

Influence of nitriding on the oxidation behaviour of titanium alloys at 700 °C

The influence of nitridation treatments at 600 and 800 °C on the oxidation resistance of pure titanium, Ti-6Al-4V, and Ti-7Nb in air at 700 °C has been studied. Nitridation may increase the oxidation resistance, but the influence of the nitriding treatments depended on the composition of the material. For pure titanium and alloy Ti-6Al-4V, the nitride layer prevented oxygen dissolution into the alloy during the earliest stages of oxidation, thus reducing the contribution of this process to the total mass gain. For Ti-7Nb, a material that stabilises a nitride layer at the scale/alloy interface during air oxidation, small differences in mass gain between nitrided and nonnitrided samples were related to the different structures of the nitride layer.

Intriguing compensation by adult female spiders for food limitation experienced as juveniles

We conducted a field experiment to test for food limitation in immature stages, and its consequences for mature females, in the territorial, cannibalistic spider Lycosa tarentula (L.). Randomly selected antepenultimate juveniles were provided supplemental prey until they matured, at which time supplemental feeding ceased. Immature stages of L. tarentula are food‐limited. Supplemented juvenile spiders decreased foraging activity, disappeared at a lower rate and grew faster than the control spiders, which had been exposed only to ambient prey levels. Fed juvenile females were less hungry at maturity, as judged by an index of body condition, and showed higher mating success as adults, as judged by cohabitation rates with mature males. Foraging theory predicts that in order to compensate for residual effects of food limitation, adult female spiders that had experienced a shortage of prey as juveniles – the controls – would have to exhibit a greater increase in foraging activity upon maturing than the prey‐supplemented group. Contrary to expectation, the control females did not increase their foraging activity, but the previously fed females did forage more actively as adults. Furthermore, the difference in mass gain during the mating period between the two groups was opposite from what the difference in change in foraging activity would predict. Control females, the spiders that had not changed their foraging activity, gained mass more rapidly than the previously fed females, with the result that the two groups were similar in mass by the end of the mating period. We hypothesize that an increased rate of sexual cannibalism may have been one mechanism by which control females compensated for the food limitation that they had experienced as immatures.

The effect of social dominance on fattening and food-caching behaviour in Carolina chickadees, Poecile carolinensis

Subordinates often have to wait for dominants to obtain food. As a result, their foraging success should be less predictable and they should therefore maintain a higher level of energy reserves compared with dominants. A corollary of this prediction is that subordinates should gain mass earlier in the day and maintain higher mass than dominants. We tested these predictions with captive Carolina chickadees. In two different experiments (one where birds were given ad libitum access to food and the other with food access limited to 60min/day), we formed social flocks of two previously unfamiliar birds and compared their energy management (body fat and food caches) while they were in the flock with energy management when housed alone. Results from both experiments failed to support the predictions. Of all the parameters of body mass and food caching we measured only the following results were significant: (1) On the ad libitum food schedule, both subordinates and dominants accumulated more mass over the day when in a flock compared with when they were solitary, and there were no differences in mass gain between dominants and subordinates. (2) When analysed separately, dominants showed a higher evening mass in the flock compared with the solitary condition, a trend that runs opposite to the prediction. Our results suggest that when in favourable foraging conditions, social interactions might cause dominant and subordinate birds to accumulate more energy reserves as a result of competition. On the other hand, if food supply is limited, both dominants and subordinates may be forced to maintain similar fat reserves as an insurance against increased risk of starvation.

Sexual size dimorphism and sex‐specific survival in adults of the damselfly Lestes disjunctus

1. A population of adult Lestes disjunctus (Odonata: Lestidae) was studied in eastern Ontario, Canada. Mass at sexual maturity and activity rates of individuals were measured. Population density was estimated on transects, while survival rates and population size were estimated using mark−recapture methods.2. There was no difference in mass of mated and unmated males. Females were more than 50% heavier than males, and were also more active than males.3. Males were almost eight times more abundant on transects than females, but Manly−Parr estimates of male population size were only a maximum of 2.5 times larger than estimates for females.4. Males were 2.5 times more likely to be resighted after marking than were females. This accounts for much of the discrepancy between transect estimates and mark−recapture estimates of relative population size.5. Daily survival rates of sexually mature females were not significantly less than those of males, and therefore cannot account for a change in sex‐ratio from 1 : 1 at emergence to more males than females in sexually mature adults.6. Differences in mortality must occur prior to sexual maturity, coincident with the time during which differences in mass gain are also taking place.