Solar energy conversion efficiencies in photosynthesis: Minimizing the chlorophyll antennae to maximize efficiency

The theoretical maxima of solar energy conversion efficiencies and productivities in oxygenic photosynthesis are evaluated. These are contrasted with actual measurements in a variety of photosynthetic organisms, including green microalgae, cyanobacteria, C4 and C3 plants. Minimizing, or truncating, the chlorophyll antenna size of the photosystems can improve photosynthetic solar energy conversion efficiency and productivity up to 3-fold. Generation of truncated light-harvesting chlorophyll antenna size (tla) strains, in all classes of photosynthetic organisms would help to alleviate excess absorption of sunlight and the ensuing wasteful dissipation of excitation energy, and to maximize solar-to-product energy conversion efficiency and photosynthetic productivity in high-density mass cultivations. The tla concept may find application in the commercial exploitation of microalgae and plants for the generation of biomass, biofuels, chemical feedstocks, as well as nutraceuticals and pharmaceuticals.     

Change in apparent and true absorption and retention of dietary zinc with age in rats

Two groups of 16 rats each were fed the same diet with 12.9 ppm Zn. Nine days after each animal was injected with⁶⁵Zn for assessing fecal zinc of endogenous origin, zinc intake and excretion were determined for a six-day period at the age of about five (group I) and nine (II) weeks. At mean growth rates of 5.1 and 5.2 g/day, food consumption per gram of gain was 2.01 g in group I vs 2.86 g in II. Overall, zinc retention amounted to 21 vs 25 μg Zn/g of gain. Apparent absorption averaged 92 vs 74% of Zn intake (132 vs 189 μg/day), while true absorption averaged 98 vs 92%. It was concluded that endogenous fecal zinc excretion was limited to the indispensable loss (F _em) in group I (7 μg/day), while it exceeded this minimum loss in group II (33 μg/day). True retention, which reflected total zinc utilization (true absorption times metabolic efficiency), was derived from apparent absorption plusF _em (11 μg/day for group II according to the greater metabolic body size of the rats). It averaged 98% of Zn intake in group I vs 80% in group II. The mean metabolic efficiency was 100% vs 87%. The conclusion was that these marked differences between age groups in utilizing the dietary zinc reflected the efficient homeostatic adjustments in absorption and endogenous excretion of zinc to the respective zinc supply status.     

The relationship between size,budding rate,and growth efficiency in three species of hydra

Three species of the fresh water carnivore hydra, H. littoralis, H. pseudoligactis, and C. viridissima present a graduation in size with the first species the largest and albino Chlorohydra the smallest. When presented with a daily overabundance of food (artemia), considerable variation in food intake and gross efficiency of growth (proportion of food energy consumed that is turned into new protoplasm or buds) existed among the species. The degree of association between size of species and food intake was highly significant. However, budding efficiency among the species was found to be independent of food intake (when the effects of species size were eliminated) and of species size (when the effects of food intake were removed). However, species with high (low) efficiencies have significantly higher (lower) reproductive rates. A lowering of the temperature from 25° to 15° C. increased the size of the species, increased food intake, but decreased reproductive rate. In all species except H. pseudoligactis a corresponding increase in the production of bud energy with no change in efficiency also occurred. On the other hand, lowering of the temperature for H. pseudoligactis significantly lowered reproductive efficiency but had no effect on the total calorific output of buds. This species, in constrast to the others, appears to have a compensatory ability to adjust its efficiency to maintain a high calorific output when temperature increases. It was also found that albino Chlorohydra have budding efficiencies of around 35 percent which are not influenced by changes in food intake or light. Normal green hydras, however, have efficiencies which range from 40 to 62 percent above their albino counterparts when fed once a day and once every two days in light respectively. It it concluded first, that the symbiotic algae in the gastrodermals cells of green hydra contribute quantitatively in the order of the above amounts to the growth process in this species, and second, that green hydras have the ablity to increase their growth efficiency when food intake is reduced thus reducing the drop in calorific but output that normally occurs in the albino (control) form.     

Effect of L-Carnitine Supplementation on Utilisation of Energy and Protein in Broiler Chicken Fed Different Dietary Fat Levels

Effects of a supplementation of 80mg L-carnitine perkg diet were studied in broiler chicken at two dietary levels of fat (4 and 8 %) and different feeding levels (ad libitum in a growth trial, 95 and 85 % of ad libitum in a balance trial). A low-carnitine basal diet adequate in amino acid concentration was used. In the growth trial, each diet was fed to 9 groups of 10 birds each for 16 days from day 5 of live onwards. Growth and feed intake were determined. At the end of the trial, birds were killed and homogenised for subsequent empty body analysis. Accretion of protein and energy was determined using a representative blank group killed at the beginning of the trial. In the balance trial, 8 individual birds were used per treatment. Birds were offered the feed at approximately 85 and 95% of ad libitum intake, which was determined with separate birds for both fat levels. Excreta were quantitatively collected three times daily for 8 consecutive days beginning on day 17 individually for each bird. Supplemented L-carnitine did not significantly affect any response criterion. However, growth and feed conversion tended to be improved by about 5% in the carnitine supplemented diets when fed ad libitum. An interaction between carnitine and fat level occurred with regard to feed conversion, indicating that carnitine had a positive effect at the high fat level, but not at the low fat level. L-carnitine did not positively affect the metabolisability of energy (ME/GE) and the efficiency of energy utilisation (RE/GE or RE/ME). Similarly, no significant carnitine effect was determined with regard to N accretion and the efficiency of utilisation of dietary protein in both trials. It is concluded that endogenous carnitine synthesis is not the limiting factor for energy utilisation in broiler chicken, even at high dietary fat concentration. Occasionally reported positive effects of supplemental carnitine were likewise caused by reasons other than improved energy or protein utilisation. Further studies on amino acid utilisation and catabolism should consider marginal amino acid supply.     

Growth energetics in relation to temperature of the larvae of Rhopaea verreauxi (Coleoptera: Scarabaeidae)

Summary Instantaneous energy budgets were constructed at a range of constant temperatures (7.5°–27.5°C) for the larval stages of the scarabaeid Rhopaea verreauxi. It was found that as larvae increased in size the temperature optima/maxima for the components of the energy budget shifted to lower temperatures. Also, as larvae increased in size the instantaneous assimilation efficiency (A/C) decreased and the temperature range over which energy could be assimilated narrowed. Within this narrowing range, temperature was found to have an increasingly greater influence upon A/C. This was attributed to its influence upon the post-consumption energetics processes rather than upon consumption itself. The instantaneous net production efficiency (P/A) also decreased with increasing body size. Also, the temperature range over which assimilated energy could be partitioned to growth production became narrower as body size increased. These findings are discussed in relation to those of other energy budget studies. Some comment is made on the importance of temperature acclimation in studies such as this, and on the relation of energetics conversion efficiencies to ectothermy and endothermy and to trophic status. It was concluded that in terms of instantaneous conversion efficiences R. verreauxi could be described as a typical ectothermic herbivore, a moderately efficient converter.     

Effects of Ration on Growth and Reproductive Investment from Larva to Sexual Maturity in the Female Cyprinid Minnow,Tanichthys albonubes

Somatic growth and reproductive investment in female Tanichthys albonubes (Cyprinidae) individually cultured at the laboratory from larva to sexual maturity were examined under low, medium, and satiation food rations. All the 72‐day post‐hatch fish reached sexual maturity under all rations. The standard length, wet body mass, dry ovarian mass, dry liver mass, condition factor, energy content, and number of vitellogenic oocytes were all increased with ration levels. However, food conversion efficiency decreased with ration. There were no significant differences in total number of oocytes per female between rations. The species is a continuous batch‐spawner. The size‐frequency distributions of oocyte diameters showed a continuous pattern, ranging from 0.03 to 0.70 mm, at different rations. The proportion of energy intake allocated to growth decreased with ration levels. Only 3.29–4.60% of energy intake was stored in the ovary. These biological and energetic characteristics allow this fish to reach first maturity with low food intake, although it produced fewer vitellogenic oocytes at lower rations. This property enables T. albonubes survive in its native habitats where food is not only scarce, but also variable temporally and spatially. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Coping strategies in farmed African catfish Clarias gariepinus. Does it affect their welfare?

The objective of this study was to assess whether and how coping strategies affect the welfare of African catfish Clarias gariepinus housed at low and high densities. Group composition influenced feed intake; re‐active groups (comprised of 100% re‐active fish) had a lower specific growth rate (G) and feed intake and a higher feed conversion ratio (R_FC) than pro‐active groups. Furthermore, re‐active groups had a lower energy retention than pro‐active groups. The latter was fully due to differences in feed intake, since energy partitioning (on % total gross energy intake basis) was similar among the group composition treatments. Fish held at high stocking density showed a higher R_FC and feeding speed and a lower energy retention and agonistic behaviour. None of the measured variables was influenced by the interaction effect. In mixed groups, G and number of skin lesions seemed to be affected by different behavioural phenotypes at low stocking density, but not at high density. These results indicate that both stocking density and group composition affect physical and behavioural responses of C. gariepinus. Furthermore, physical and behavioural data of individual fish housed in mixed groups suggest that coping strategy affects the fitness of different behavioural phenotypes at low, but not at high, stocking density.     

Effects of water temperature and initial weight on growth,digestion and energy budget of yellow catfish Pelteobagrus fulvidraco (Richardson, 1846)

The effects of water temperature and body weight on feeding, growth, and energy budget were inevitable in the yellow catfish Pelteobagrus fulvidraco (Richardson, 1846), an important fish cultivated in China. This study explores the interaction of water temperature and body weight on both energy utilization strategy and energy conversion efficiency to promote further healthy culture of yellow catfish. Fish with body weights of 6 g (Group S), 16 g (Group M) and 35 g (Group B) were reared in 15 circular glass steel cylinders 80 cm in diameter × 70 cm in height (180 L) at water temperatures of 21, 24, 27, 30 and 33°C (3 replicates for each temperature) for 42 days to investigate effects of water temperature and body weight on the feeding, growth, digestion and energy budget in yellow catfish. Results showed that the levels of dry matter, protein and energy in the body were significantly affected by water temperature (p < .05). Feeding, growth, feed conversion efficiency, digestion and energy allocation parameters were significantly related to both water temperature and body weight (p < .05). Yellow catfish had higher maximal food consumption (C_max), food intake rate, specific growth rate, food conversion efficiency, appear digestibility coefficient, and growth energy allocation (G) at 24–30°C, and optimal growth at a water temperature of 27°C. Two‐factor analysis of variance revealed that there was reciprocation of both water temperature and body weight on the above parameters. At the optimal temperature of 27°C, the value of energy for growth (G) was the highest, and the value of energy for feces (F) produced was the lowest. Yellow catfish with various body weights had energy budget equations of 100 A = 63.70 R + 36.30 G in Group S, 100 A = 62.54 R + 37.46 G in Group M, and 100 A = 67.47 R + 32.53 G in Group B if the equations were described as percentage of the proportion of the assimilation energy. Therefore, the optimal temperature was 27°C according to its feeding, growth and digestion.     

Package Unit Size and Amount of Food: Do Both Influence Intake?

Objective: Large portions increase intake and are hypothesized to contribute to the obesity epidemic. However, it is unclear if portion size affects intake through changes in the unit size of available food or the overall amount of food available for consumption. Thus, this study examined the independent effects of package unit size and amount of food on intake. It was hypothesized that both variables would influence intake. Research Methods and Procedures: Non‐obese (BMI <30 kg/m²), non‐smoking, unrestrained, college‐aged men (n = 12) and women (n = 16) who regularly consumed (≥3 times/wk) snack foods were randomly assigned to one of four groups crossing package unit size (small vs. large) and amount of food (small vs. large). Participants were given a box with 4 snack foods (potato chips, cheese crackers, cookies, and candy) packaged according to their assigned group to take home and eat over 3 days. Dependent variables were energy and gram intake of provided snack foods. Results: An effect of amount of food was found (p < 0.01). A 100% increase in the amount of food provided produced an 81% increase in energy consumed from the snack foods [small amount, 21,037.6 ± 10,852 kJ (5028 ± 2596 kcal) vs. large amount, 11,640.7 ± 4914.1 kJ (2782 ± 1174 kcal)]. No effect of package unit size was found. Discussion: These results suggest that the amount of food available to eat strongly influences intake.     

Physiological energetics of the green abalone, Haliotis fulgens, fed on a balanced diet

A regression of different physiological responses against body size enables populations or stock cultures of various size ranges to be compared. Thus, the aim of the present work was to evaluate the physiological responses from juvenile green abalone (Haliotis fulgens), grouped according to size, in a standard controlled culture condition within their optimal range to create the balanced growth equation within an allometric relation, providing a basic framework for physiological research into H. fulgens. Feed intake, absorption efficiency, respiration and excretion were measured as functions of dry tissue weight (DTW) in juvenile abalone acclimated on a balanced diet. The daily feed intake (I) was related to body mass by the relationship I (mg day⁻¹)=24.25W^0.59. Absorption efficiency averaged 87% and was independent of body size. The equation relating daily respiration rate (R) to body mass was R (ml O₂ day⁻¹)=12.013W^0.704, including night correction. The rate of ammonia excretion (U) was related to dry tissue weight by the equation U (μmol N-NH₄ day⁻¹)=43.57W^0.85. The energetic value of food was 18.8 J mg⁻¹. The low feeding activity (<1% of abalone live weight per day) was compensated for by a relatively high absorption efficiency and a depression of 23% in the metabolic rate during diurnal activity. Gross and net growth efficiencies were constant throughout the size range, with average values of 36.4% and 41.5%, respectively. Values of the O/N ratio, with an average of 31.5, showed a higher use of proteins from the diet as an energy source for the size range studied.     

Effects of diet, body size, age and temperature on growth rates in the amphipod Gammarus pulex

SUMMARY. Increase in body wet weight of Gammarus pulex fed on decaying elm leaves was followed to senescence and death. Growth in juveniles was approximately exponential; from birth to death it conformed to a logistic growth curve, with maximum absolute increments in weight about half-way through a life span of 350–450 days at 15°C. Some individuals lived longer, for up to 640–700 days. The instantaneous or specific growth rate was maximal near birth, at c. 5–6% wet wt day^?1, and declined exponentially with increasing size and age. Over the range 4.7–14.8°C there was a log-log relationship between temperature and specific growth rate. Growth was maximal at 20°C in newborn animals and at 15°C in 6–9-mg animals. The specific growth rate of young individuals was fastest on decaying leaves of elm with a well developed flora of fungi and other microorganisms. Leached elm leaves without this flora supported growth at a lower rate. The latter diet was sufficient for survival and growth of newborn individuals; detritus, faeces or other food items were not needed. Isolated specimens grew as fast as those kept in groups. Growth was generally slower on leached leaves of oak and sycamore. In newborn animals fed on the fine roots of aquatic plants (Veronica, Rorippa and Glyceria), growth was as fast as on decaying elm leaves; growth on the green living leaves of the plants was slower, as on detritus from two streams and on a pure culture of an aquatic fungus. Consumption of leached elm leaves was related to leaf thickness. In a full gut the wet weight (1.34–1.37 mg) and volume (3.8–4.1 mm³) (for 20-mg animals) was independent of leaf thickness but dependent on animal size, increasing 4-fold over the range 2–50 mg body wt. Daily consumption (dry wt) was approximately equivalent to 50% body dry wt at 5 mg and 20% at 50 mg body wet wt. Individuals fed on thick leaves ingested 50% more dry weight per day and absorbed more in the gut than when fed on thin leaves, but the relative efficiency of absorption was the same at 36–59% for 10–20-mg animals. Weight-specific absorption in the gut was highest in juveniles and decreased with increasing body weight; relative efficiency of absorption was generally lower in the larger individuals. Assuming an energy value of 5 cal mg^?1 dry wt for elm leaves, daily mean energy intake by absorption in thegutof G. pu/ex was2.2 cal mg^?1 animaldry wt (9.2 J mg^?1) in individuals of 0.4 mgdry wt (2 mg wet wt), decreasing to 0.3 cal mg^?1 (1.3 J mg^?1) at 10 mg dry wt (50 mg wet wt). Growth in Gammarus is briefly reviewed in the hght of work on other animals and it is emphasized that all aspects of feeding, growth and metabol-ism should be specifically related to size and age of the individuals, using well defined diets.     

Expression of candidate genes for residual feed intake in Angus cattle

Residual feed intake (RFI) has been adopted in Australia for the purpose of genetic improvement in feed efficiency in beef cattle. RFI is the difference between the observed feed intake of an animal and the predicted feed intake based on its size and growth rate over a test period. Gene expression of eight candidate genes (AHSG, GHR, GSTM1, INHBA, PCDH19, S100A10, SERPINI2 and SOD3), previously identified as differentially expressed between divergent lines of high‐ and low‐RFI animals, was measured in an unselected population of 60 steers from the Angus Society Elite Progeny Test Program using quantitative real‐time PCR. Results showed that the levels of gene expression were significantly correlated with RFI. The genes explain around 33.2% of the phenotypic variance in RFI, and prediction equations using the expression data are reasonably accurate estimators of RFI. The association of these genes with economically important traits, such as other feed efficiency‐related traits and fat, growth and carcass traits, was investigated as well. The expression of these candidate genes was significantly correlated with feed conversion ratio and daily feed intake, which are highly associated with RFI, suggesting a functional role for these genes in modulating feed utilisation. The expression of these genes did not show any association with average daily gain, eye muscle area and carcass composition.     

Effect of photoperiod manipulation on the growth performance of juvenile lenok,Brachymystax lenok (Pallas, 1773)

The effect of four different light regimes on growth was studied in lenok, Brachymystax lenok. Fish with average weights of 5.5 g were subjected to four different photoperiods (0L:24D, 6L:18D, 12L:12D and 24L:0D) for 35 days. The specific growth rate (SGR) of lenok in 24‐h darkness had a significantly higher SGR than those in the continuous light regime (P < 0.05); however, there was no significant difference among fish exposed to 6L:18D, 12L:12D and 24L:0D photoperiods. There was a tendency for higher food intake over the light period extension from 0L to 24L, and feed intake was significantly higher in the continuous light group than in 24‐h darkness (P < 0.05). No significant difference in feed conversion efficiency (FCE) was observed between fish exposed to 0L:24D and 6L:18D photoperiods, however, the FCE in both photoperiods was significantly higher than that in the other two groups. The final survival rate of juveniles varied from 79.67 to 95.33%, with significant differences among experimental groups. Fish tested in continuous illumination spent much more energy on respiration and excretion while depositing less energy for growth than in the other photoperiods. In contrast, fish in 24‐h darkness deposited more energy for growth and spent less energy on respiration and excretion. Results show that photoperiod manipulation can affect growth, and that a continuous dark regime could improve growth in lenok at this stage of development.     

Non‐replication of genome‐wide‐based associations of efficient food conversion in dairy cows

Animal growth relative to food energy input is of key importance to agricultural production. Several recent studies highlighted genetic markers associated with food conversion efficiency in beef cattle, and there is now a requirement to validate these associations in additional populations and to assess their potential utility for selecting animals with enhanced food‐use efficiency. The current analysis tested a population of dairy cattle using 138 DNA markers previously associated with food intake and growth in a whole‐genome association analysis of beef animals. Although seven markers showed point‐wise significance at P < 0.05, none of the single‐nucleotide polymorphisms tested were significantly associated with food conversion efficiency after correction for multiple testing. These data do not support the involvement of this subset of previously implicated markers in the food conversion efficiency of the physiologically distinct New Zealand Holstein‐Friesian dairy breed.     

Adrenalectomy Reduces Adiposity by Decreasing Feed Efficiency,Not Direct Effects on White Adipose Tissue

EDENS, N. K., A. MOSHIRFAR, G. M. POTTER, S. K. FRIED, AND T. W. CASTONGUAY. Adrenalectomy reduces adiposity by decreasing feed efficiency, not direct effects on white adipose tissue. Obes Res. Objective: This study was conducted to establish the effects of adrenalectomy (ADX) on adipose tissue metabolism in male Sprague—Dawley rats fed a standard chow diet. Research Methods and Procedures: The effects of adrenalectomy on adipose cell size, lipoprotein lipase activity, and basal and insulin-stimulated glucose conversion to lipid and lipolysis were measured. Results: ADX decreased body weight gain during the postoperative period in the absence of changes in food intake; feed efficiency was decreased significantly. ADX decreased adipocyte size by 30%. ADX increased adipocyte response to the effect of submaximal concentrations of insulin on lipid synthesis and lipolysis. ADX decreased maximally insulin-stimulated lipid synthesis, but this effect was accounted for by decreased adipocyte size. In contrast, ADX had no effect on maximally insulin-inhibited lipolysis. ADX did not affect heparin-releasable LPL. The small effect of ADX on residual extractable adipose tissue LPL activity was accounted for by decreased fat cell size. Discussion: ADX decreased adiposity in the absence of changes in food intake, lipoprotein lipase activity, and adipocyte lipid metabolism. The effect is best attributed to decreased feed efficiency.     

Contribution of Different Mechanisms to Compensation for Energy Restriction in the Mouse

Objective: Restriction of energy intake produces weight loss, but the rate of loss is seldom sustained. This is presumed to be a consequence of compensatory reductions in energy expenditure, although the exact contributions of different components to the energy budget remain uncertain. We examined the compensatory responses of mice to a 20% dietary restriction. Research Methods and Procedures: We measured body mass, body fatness, body temperature, and the components of daily energy expenditure for 50 MF1 mice. Forty mice were then placed on a restricted diet at 80% of their ad libitum intake for 50 days. The remaining 10 mice continued to feed ad libitum. Ten days before the end of the restriction period, the same measurements were taken. Results: There were no significant differences between the control and restricted groups in any parameters before restriction. During the restriction period, body mass increased in both the control and restricted groups, but at a slower rate in the restricted mice. The control group increased in both fat and fat free mass; however, although the restricted group increased fat to the same extent as the controls, fat free mass increased to a lesser extent. The contributions of the different components of the expended energy to compensate for the reduced energy intake were energy deposition, 2.2%; resting metabolic rate, 22.3%; and activity, 75.5%. Discussion: Mice were able to compensate almost completely for the restricted energy intake that was achieved by altering the amount of energy required for each component of the energy budget except digestive efficiency.     

Lower foraging efficiency of offspring constrains use of optimal habitat in birds with extended parental care

After reproducing successfully, birds with extended parental care form family groups. Despite being the dominant social unit, such family groups have been reported to switch to alternative habitat earlier than adults without offspring, with potential negative carry‐over effects for the next breeding season. Here we test a proposed mechanism for this earlier habitat switch, namely a low foraging efficiency in juveniles. Such a test is best performed under controlled conditions because in the field families may occupy food patches of a different quality than singles or pairs without young. We studied this mechanism in Bewick's Swans Cygnus columbianus bewickii, which trample (or ‘treadle’) for food buried in the sediment. The gross intake rate of juveniles was as low as 60% of that of adults, depending on the burial depth of the food. Trampling effort did not differ between age classes, but differences in intake rate were related to body size, suggesting that larger or heavier birds were trampling more efficiently. Corresponding giving‐up densities in the field were calculated to be c. 60% higher for juveniles than for adults. Our findings are consistent with the hypothesis that the lower foraging efficiency of juveniles may be responsible for the segregation of family groups from adults without offspring.     

Perylene Sensitization of Fullerenes for Improved Performance in Organic Photovoltaics

We present the addition of an energy relay dye to fullerenes resulting in increased light harvesting and significantly improved power conversion efficiency for organic photovoltaic (OPV) devices. Although exhibiting excellent properties as electron acceptors, visible light absorption of fullerenes is limited. Strongly light absorbing donor materials are needed for efficient light harvesting in the thin active layer of OPV devices. Therefore, photocurrent generation and thus power conversion efficiency of this type of solar cell is confined by the overlap of the relatively narrow absorption band of commonly used donor molecules with the solar spectrum. Herein the concept of fullerene dye sensitization is presented, which allows increased light harvesting on the electron acceptor side of the heterojunction. The concept is exemplarily shown for an UV absorbing small molecule and a near infrared absorbing polymer, namely hexa‐peri‐hexabenzocoronene (HBC) and Poly[2,1,3‐benzothiadiazole‐4,7‐diyl[4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b:3,4‐b']dithiophene‐2,6‐diyl]] (PCPDTBT), respectively. In both systems remarkably higher power conversion efficiency is achieved via perylene sensitization of the fullerene acceptor. Steady state photoluminescence, transient absorption and transient photocurrent decay studies reveal pathways of the additionally generated excited states at the sensitizer molecule. The findings suggest fluorescence resonance energy transfer from the photo‐excited dye to the fullerene enabling decoupling of light absorption and charge transport. The presented sensitization method is proposed as a viable new concept for performance enhancement in organic photovoltaic devices.     

Effects of age on children's intake of large and self-selected food portions

Objective: Whether developmental periods exist in which children become particularly sensitive to environmental influences on eating is unclear. This research evaluated the effects of age on intake of large and self‐selected portions among children 2 to 9 years of age. Research Methods and Procedures: Seventy‐five non‐Hispanic white children 2 to 3, 5 to 6, and 8 to 9 years of age were seen at a dinner meal in reference, large, and self‐selected portion size conditions in which the size of an entrée was age‐appropriate, doubled, and determined by the child, respectively. Weighed food intake data were collected. Entrée bite size and bite frequency were assessed. Height and weight measurements were obtained. Results: The effect of age on children's intake of the large portion was not significant. Entrée consumption was 29% greater (p < 0.001) and meal energy intake was 13% greater (p < 0.01) in the large portion condition than in the reference condition. Increases in entrée consumption were attributable to increases in average bite size (p < 0.001). Neither child weight nor maternal weight predicted children's intake of large portions. Self‐selection resulted in decreased entrée (p < 0.05) and meal energy (p < 0.01) only among those children who ate more when served the large portion. Discussion: The results of this research confirm that serving large entrée portions promotes increased intake at meals among 2‐ to 9‐year‐old children. These findings suggest that any age‐related differences in children's response to large portions are likely to be smaller than previously suspected.