The effect of temperature on the consumption,absorption and conversion of food in Ophiocephalus punctatus bloch

1. The overall feeding rate is maximum at 28°C and decreases at 20°C and 33°C for all sizes.
2. The smaller fish are cold-sensitive. At 28°C and at 33°C the time course rate shows the same decline, whereas at 20°C the response was anomalous.
3. Absorption efficiency is independent of size and temperature.
4. Rate of absorption and hence rate of conversion is primarily conditioned by rate of feeding.
5. At 20°C the conversion efficiency is directly related to size whereas at 28°C and 33°C it is inversely related to size.

     

The effect of starvation on energy turnover and protein metabolism in Ophiocephalus punctatus bloch

1. At 20°C, fish starved for various durations took less food than unstarved fish. At 28°C, 20-day starved fish alone consumed more food.
2. The maximum feeding was during the second ten days at 28°C but in the first ten days at 20°C.
3. Absorption efficiency was unaffected by temperature and starvation.
4. Absorption rate reflected feeding rate.
5. At 28°C the conversion efficiency was high for the ten-day starved fish but at 20°C the 30-day starved fish showe high conversion efficiency.
6. Conversion rate is governed not only by feeding rate but also by conversion efficiency.
7. At 28°C the 20-day starved fish alone compensated for loss of energy, total and protein nitrogen. At 20°C the loss was compensated for by all fish.

     

Histochemical studies on iron absorption in Ophiocephalus punctatus and Heteropneustes fossilis.

Iron absorption in both the teleost fishes Ophiocephalus punctatus and Heteropneustes fossilis, initially starts after 2h of feeding the iron diet. However, at this stage, there is no absorption of iron in the posterior intestine of both the fishes. Absorption initially starts along the brush border of enterocytes of the villi. Later, it gets accumulated in the supranuclear region of the epithelial cells and then through these cells, it is transported into the cores of the villi. The absorbed amount ultimately reaches along the bases of the villi. Through the blood capillaries, which are situated in the submucosa, absorbed iron is passed on to the blood stream. Although, the entire intestine of both the fishes is able to absorb iron but the regional variations have been noted. In contrast to the posterior intestine, the anterior and middle intestine of both the fishes show better iron absorption. The pyloric caeca of Ophiocephalus have comparatively less affinity for iron absorption. However, the intestine of Heteropneustes shows more affinity for iron absorption than the intestine of Ophiocephalus.     

The effects of food consumption rate, body size and temperature on net food conversion efficiency in saithe and whiting

Net food conversion efficiency κ was estimated from growth experiments on saithe Pollachius virens and whiting Merlangius merlangus that were fed natural prey at a range of ration levels including satiation rations. The conversion efficiency, which specifies the net energy fraction of ingested energy C , was described appropriately by a simple power function of food consumption rate as κ  = 0·272 C ^0·18 and κ  = 0·426 C ^0·11 for saithe and whiting. This functional relationship was supported by the patterns of accretion of lipids and proteins in saithe. No significant effects of temperature and body size on κ was, however, demonstrated in this study except for the indirect influence using feeding levels (rations expressed relatively to satiation rations) in bioenergetics models.     

Intestinal transport of fructose and glycine in Ophiocephalus punctatus.

The regional variations in the absorption of fructose and glycine have been studied in the intestine and pyloric caeca of the fish, Ophiocephalus punctatus in vivo, by preparing intestinal sacs. Diffusion of amino acids out of the intracellular compartment of the intestine was observed in all the portions of the intestine. The pyloric caeca showed maximum transport of fructose. Absorption of fructose was slightly more in the posterior intestine than in the anterior intestinal sac. Maximum transport of glycine took place in the anterior intestinal sac. Pyloric caeca adsorbed more glycine than did the posterior sac. For both nutrients, the rate of uptake did not differ significantly in the upper and the lower portion of the intestine. In all the portions, the transport of fructose was more rapid than that of glycine. The experiments revealed that though the nutrients are absorbed in the entire length of the intestine, the quantity absorbed varies from one portion to another and is dependent on the nature of the compound absorbed.     

The effect of feeding frequency on consumption of food,absorption efficiency,and gonad production in the sea urchin Lytechinus variegatus

The frequency of feeding in the field is variable in sea urchins, ranging from nearly continuous to diel or intermittent. It is essential to know the effect of feeding interval on physiological and metabolic processes to understand the basis for production. Lytechinus variegatus (50 mm horizontal diameter) were collected in January 1999 and held in closed-circuit aquaria at 25 degrees C and 35 per thousand salinity. After 9 days without food, individuals were fed one of three treatments: food available ad libitum, food available for 1 day every 2 days or food available for 1 day every 4 days for 28 days. The rate of food consumption per day of all individuals was high the first week of feeding. It then decreased to a lower, constant rate in those fed ad libitum but remained high in those fed one day every 2 or 4 days. The total amount eaten was directly related to frequency of feeding. The apparent dry matter digestibility (absorption efficiency) did not vary with frequency of feeding. As the total amount of energy absorbed was directly related to the frequency of feeding, the increase in the rate of food consumption does not compensate for a decrease in frequency of feeding. Gonad production efficiency was directly related to frequency of feeding. Gonad gross production (assimilation) efficiencies were 8.4, 3.9 and 3.4% for individuals fed every day, or fed one day every 2 and 4 days, respectively. The corresponding gonad net assimilation efficiencies were 12.5, 5.5, and 4.8%. A decrease in frequency of food availability results in use of a greater proportion of the food consumed for maintenance and less for gonad production.     

The effect of the size of honeybee colonies on food consumption, brood rearing and the longevity of the bees during winter

Near Harpenden, Hertfordshire, brood rearing continues later into the autumn in small than in large colonies, and in colonies headed by queens of the current year than by queens of the previous year. In spring the amount of brood present increases with colony size, but there is more brood per bee in small than in large colonies. Food consumption per bee during winter decreased with increase in colony size, especially in colonies with fewer than 18,000 bees. The size of a colony in spring was related directly to its size in the previous autumn, and the proportion of bees that survived the winter was similar in large and small colonies.

---

Zusammenfassung In der Umgebung von Harpenden, Hertfordshire, erstreckt sich die Bruttätigkeit bei kleinen Völkern und bei Völkern mit diesjährigen Königinnen weiter, in den Herbst hinein als bei großen und bei Völkern mit vorjährigen Königinnen. Im Frühjahr steigt der Brutanteil mit der Größe des Volkes an, jedoch haben kleine Völker mehr Brut pro Biene als große. Der Nahrungsverbrauch pro Biene nimmt im Winter mit zunehmender Größe des Volkes ab, besonders bei Völkern mit weniger als 18000 Bienen. Bezieht man die Größe des Volkes im Frühjahr direkt auf seine Größe im vergangenen Herbst, dann erweist sich das Verhältnis der überwinternden Bienen bei großen und kleinen Völkern als ähnlich.

     

Colony size and food consumption of three species of Formica

Food consumption of ants was measured in artificial nests with colonies of different sizes and with different numbers of queens to determine which of three species of ants might prove the better predator for the control of harmful insects and to determine the queen: worker ratio and colony size best suited to establish colonies of these ants. A 50% honey solution and laboratory reared house fly larvae were the only food sources.In one experiment colonies of Formica exsectoides consumed approximately three times as many prey larvae as did comparable colonies of F. fusca. The consumption by F. exsectoides probably would have been greater had the number of larvae fed not been limited.In a second experiment large colonies of F. exsectoides consumed proportionately more prey than the small colonies; the reverse was true for F. polyctena. There were no differences in the prey consumption by all nests of F. exsectoides as compared with all nests of F. polyctena. Neither the number of queens nor the initial number of workers per colony of F. polyctena or F. exsectoides influenced the growth of the colonies.Individuals of both species consumed proportionately less honey solution in large colonies than in small ones.

---

Zusammenfassung In künstlichen Nestern mit Kolonien verschiedener Größe und mit unterschiedlichen Anzahlen von Königinnen wurde der Nahrungsverbrauch der Ameisen bestimmt, um festzustellen, welche der drei Ameisenarten sich als besserer Prädator zur Bekämpfung schädlicher Insekten erwiese, und um das geeignete Königin-Arbeiterinnen-Verhältnis und die Koloniegröße zu ermitteln, die zur Koloniegründung dieser Ameisen am besten geeignet sind. Eine 50% ige Honiglösung und im Labor gezüchtete Stubenfliegenmaden waren die alleinigen Nahrungsquellen.In einem Versuch verzehrten Kolonien von Formica exsectoides Forel annähernd dreimal so viel Beutelarven wie vergleichbare Kolonien von F. fusca (L.). Dabei wäre der Nahrungsverbrauch von F. exsectoides wahrscheinlich noch größer gewesen, wenn nicht die Anzahl der gefütterten Maden begrenzt gewesen wäre.In einem zweiten Experiment verbrauchten große Kolonien von F. exsectoides verhältnismäßig mehr Beute als kleine Kolonien, während für F. polyctena Foerst. das Umgekehrte galt. Es bestanden keine Unterschiede im Beuteverzehr bei allen Nestern von F. exsectoides verglichen mit allen Nestern von F. polyctena. Weder die Anzahl der Königinnen noch die Anfangszahl der Arbeiterinnen je Kolonie beeinflußten das Wachstum der Kolonien von F. polyctena und F. exsectoides.Individuen beider Arten verzehrten in großen Kolonien verhältnismäßig weniger Honiglösung als in kleinen.

     

The effect of body size on food consumption, absorption efficiency, respiration, and ammonia excretion by the inland silverside, Menidia beryllina (Cope) (Osteichthyes: Atherinidae)

The inland silverside, Menidia beryllina (Cope), is an annual zooplanktivore that occurs in estuarine and freshwater habitats along the Atlantic and Gulf of Mexico coasts and drainages of the United States. Experiments were conducted at 25 ± 1°C to quantify the relationship between mean dry weight (W_D) and rates of energy gain from food consumption (C), and energy losses as a result of respiration (R) and ammonia excretion (E) during routine activity and feeding by groups of fish. The absorption efficiency of ingested food energy (A) was also quantified. Rates of C, E, and R increased with W_D by factors (b in the equation y = aW_D^b) equal to 0.462, 0.667, and 0.784, respectively. Mean (±SE) rates of energy loss during feeding were 1.6 ± 0.1 (R) and 3.4 ± 0.6 (E) times greater than those for unfed fish. Absorption efficiency was independent of W_D and estimated to be 89% of C. From these measurements, the surplus energy available for growth and activity (G) and growth efficiency (K₁) were estimated. Over the range in sizes of juveniles and adults (5–500 mg W_D), predicted G and K₁ values decreased from 7.42 to 0.20 J mg fish^?1 day^?1 and 63 to 21%, respectively. Measured and predicted bioenergetic parameters are discussed within an ecological context for a northern population of this species.     

Histochemical localization of glucose-6-phosphatase and 5-nucleotidase in the digestive system of Ophiocephalus Channa punctatus.

The histochemical localization of G6Pase and 5-Nase in the digestive system of Ophiocephalus (Channa) punctatus was studied. The highest activities of these enzymes were found in the liver. Appreciable activity was also found in the anterior intestine (duodenum) and pyloric caeca. The activity faded toward the middle and posterior intestine and rectum. In the stomach the activity was moderate. The activity of 5-Nase was weaker than that of G6Pase. In the stomach the enzymes were localized in the mucosa and gastric glands. The absorptive columnar epithelial cells were the major sites of localization in the intestine. The goblet cells were negative. The G6Pase activity was associated with the cytoplasm, while the 5-Nase activity was found in the cell membranes and the nuclei.     

Effect of reproductive state and body size on food consumption in captive Galago senegalensis braccatus

Measurements of food consumption for different types of foods were made for seven Galago senegalensis braccatus. Differences because of reproductive state in females and body size were found. Lactating females consumed more food in total and had greater energy and protein intake than they did during other reproductive states. Near-term pregnant females consumed less food, energy, and protein than they did during other reproductive states. Body size affected food intake, with smaller animals ingesting more per unit metabolic weight than larger subjects.     

The effect of meal size and meal duration on food anticipatory activity in greenback flounder

Latency of food anticipatory activity (FAA) in greenback flounder Rhombosolea tapirina was about 21 days. Fish fed at meal sizes of 0·25 and 0·5% W day⁻¹ exhibited FAA under meal durations of 1, 3 and 7 h. Fish fed at 1·5% W day⁻¹ showed FAA only at a meal duration of 1 h. At each meal size, FAA was shorter and lower the longer the duration of the meal. The mean durations of FAA and post-feeding activity were correlated positively ( r =0·87; P <0·01; n =7). FAA persisted for <3 days during food deprivation. It is suggested that greenback flounder was capable of evaluating the energetic and temporal impacts of a single daily meal.     

The effect of food consumption on sodium and water balance in the predaceous diving beetle,Dytiscus verticalis

Summary Sodium and water balance ofDytiscus verticalis in fresh water were investigated under three feeding regimes: unfed, and fed a diet either low or high in sodium chloride. Unfed sodium influx was 0.13 and sodium efflux was 0.74 moles/100 gwm·h. These values are low in comparison with most freshwater animals. The electrical potential difference across the integument in artificial soft water (ASW) was about 150 mV smaller than the potential necessary to maintain sodium balance in the absence of active transport. However, sodium influx did not show saturation kinetics over an external concentration range of 91 to 1725 M. Unfed beetles failed to arrest net sodium loss to baths that were initially distilled water or ASW, even when bath sodium concentrations reached 75–298 M. The long-term rate of net sodium loss ranged from 0.61 to 4.4 moles/100 gwm·h for four sets of animals. Beetles decreased sodium efflux during a period of fasting. During subsequent feeding, beetles fed a high sodium diet (HSD) increased sodium efflux while beetles fed a low sodium diet (LSD) maintained low rates of sodium efflux. HSD fed beetles increased body sodium and hemolymph sodium concentration, and expanded extracellular fluid, relative to LSD fed beetles. Thus beetles cannot achieve sodium balance in fresh water without dietary sodium input, although they are able to regulate sodium loss.Abbreviations gwm grams wet mass - ASW artificial soft water - DW distilled water - HSD high sodium diet - LSD low sodium diet - ECF extracellular fluid volume     

Evidence for the effect of tryptophan on the pattern of food consumption in free feeding and food deprived rats.

The effects of injections of 50 mg/kg L-tryptophan upon meal size, meal frequency, rate of eating and satiety ratios were measured in rats whose feeding behaviour was monitored continuously over 24-h periods. A number of precautions were taken to minimize the effects of novel or stressful experimental procedures, to prevent the contamination of behaviour during periods of data collection and to maximise the detection of subtle effects on behaviour. In freely-feeding rats tryptophan brought about a significant diminution in the 24-h food intake and significantly reduced meal size. When food deprived rats were tested under similar circumstances tryptophan significantly reduced the size of the first large meal taken after the deprivation period and markedly extended the duration of the post-meal interval. The conditions adopted in this study to improve the sensitivity of the behavioural assay for feeding have made possible the detection of certain small but clear effects of tryptophan on food consumption in rats.