The Influence of Ambient Temperature and the Energy and Protein Content of Food on Nitrogenous Excretion in the Egyptian Fruit Bat (<i>Rousettus aegyptiacus</i>)

Korine, Carmi; Vatnick, Itzick; Tets, Ian G. van; Pinshow, Berry

doi:10.1086/506004

Cited by 6 publications

(10 citation statements)

References 49 publications

(58 reference statements)

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“…Previous studies have shown a modest increase in ammonia excretion in urine when energy demands of bats were increased by lowering ambient temperature (Korine et al, 2006) or at low N intake (Herrera M. et al, 2006). Our study showed a large increase in ammonia excretion and a switch to ammonotely in some of the bats when energy ingestion was constrained and N intake was high.…”

Section: Discussionsupporting

confidence: 55%

“…We used the x-intercept of the linear regression equation for bats on sugar-rich diets to estimate apparent maintenance N requirements. Korine et al (Korine et al, 2006) assumed that the cost of synthesizing 1molof urea was 5mol of ATP, and estimated that R. aegyptiacus saved 2% of its daily water; closed symbols). Regression lines are shown only when there were significant correlations after multiple regression analysis followed by partial correlation estimates (r p ).…”

Section: Forms Of N Excretionmentioning

confidence: 99%

“…metabolic rate by increasing ammonia production when exposed to low ambient temperatures (Korine et al, 2006). When we used the same criteria as Korine et al (Korine et al, 2006), our estimate increased slightly to 1% of basal energy requirements.…”

Section: Forms Of N Excretionmentioning

confidence: 99%

“…Among mammals, ammonotely has only been reported in the nectar-feeding Pallas's long-tongued bat (Glossophaga soricina) (Herrera M. et al, 2006) and in the Egyptian fruit bat (Rousettus aegyptiacus) (Korine et al, 2006). Glossophaga soricina showed an increase of ammonia excretion with decreased N intake at moderate ambient temperatures (25-27°C) and two individuals became ammonotelic (Herrera M. et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

“…Ammonia production increased with food intake in R. aegyptiacus when the energy content of food was manipulated at low temperatures (12°C), and two individuals became ammonotelic at low N intake. Increased ammonia excretion was interpreted as a potential N-saving mechanism in G. soricina (Herrera M. et al, 2006), and it was proposed as a response to increased energy demands in R. aegyptiacus (Korine et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Ammonotely in a neotropical frugivorous bat as energy intake decreases

Osorio

2011

Journal of Experimental Biology

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SUMMARYWe tested the role of increased ammonia in urine as an energy-and/or nitrogen (N)-saving mechanism in the great fruit-eating bat Artibeus lituratus (Phyllostomidae). We compared N excretion in two groups of bats fed energy-rich (2.75kJg wet mass). Within each diet, bats were assigned to different N contents. In order to function as an energy-saving mechanism, ammonia production should increase with decreasing energy intake. To function as an N-saving mechanism, ammonia production should increase with decreasing N intake. Because we varied both diet energy density and N content, our study design allowed us to test these two possibilities simultaneously. Bats had higher food intake rate and, consequently, higher N intake rate on the energy-poor diet, but energy intake rate was lower. Most bats on the energy-rich diet were ureotelic whereas on the energy-poor diet bats were ureotelic, ammonotelic or ureo-ammonotelic. Bats fed the energy-poor diet had a higher excretion rate of ammonia and a higher percent of N excreted as ammonia. Percent N ammonia and ammonia excretion rate were inversely related to energy intake, but they were not related to N intake. By favoring ammonia production over urea, bats on the energy-poor diet may save up to 1% of their basal metabolic rate. Consumption of energy-dilute fruits by fruit bats might affect the way in which N wastes are excreted, favoring the excretion of ammonia N when food intake is accompanied by the ingestion of large volumes of water.

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Section: Discussionsupporting

confidence: 55%

Section: Forms Of N Excretionmentioning

confidence: 99%

Section: Forms Of N Excretionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ammonotely in a neotropical frugivorous bat as energy intake decreases

Osorio

2011

Journal of Experimental Biology

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The relationships between food and energy intakes, salt content and sugar types in Egyptian fruit bats

M.¹,

Cruz‐Neto²,

Wojciechowski³

et al. 2015

Mammalian Biology

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Frugivorous animals may face an osmoregulatory challenge due to the watery nature of their food and low concentration of electrolytes therein. We examined the effects of salt content (NaCl) and sugar type (sucrose vs. glucose) on the intake rate of dilute sugar solutions by the Egyptian fruit bat (Rousettus aegyptiacus). Increased salt content did not bring about an increase in energy intake by bats fed dilute sucrose diets and the bats did not compensate by hyperphagia to achieve the energy intake of bats fed concentrated sucrose solution without salt. Moreover, increasing salt content had a negative effect on the total energy intake of Egyptian fruit bats fed equicaloric sucrose solutions. There were no differences in hematocrit in bats fed the diets of different sucrose concentration, but plasma osmolality was higher in those bats fed more concentrated sugar solutions, and urine osmolality was higher in those fed on highsalt diets. Food and energy intake did not differ between bats that were fed dilute glucose and sucrose solutions. Our findings indicate that Egyptian fruit bats do not modulate food intake when salt content of dilute sugar solutions is increased, and that increasing salt content might constrain their food intake rate. Sugar type did not affect food intake by Egyptian fruit bats, indicating that sucrose hydrolysis alone does not limit the intake of dilute sugar nectar.

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Effects of Ethanol on Food Consumption and Skin Temperature in the Egyptian Fruit Bat (Rousettus aegyptiacus)

Korine

Sánchez²,

Pinshow³

2011

Integrative and Comparative Biology

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Since mammalian frugivores generally choose to eat ripe fruit in which ethanol concentration ([EtOH]) increases as the fruit ripens, we asked whether ethanol acts as an appetitive stimulant in the Egyptian fruit bat, Rousettus aegyptiacus, and also studied the effects of ethanol on their skin temperature (T(s)). We hypothesized that the responses of fruit bats to dietary ethanol are concentration dependent and tested the predictions that the bats' response is positive, i.e., they eat more when [EtOH] in the food is in the range found in naturally ripe fruit, while it negatively affects them at higher concentrations. We also tested the prediction that in winter, even when availability of fruit is low and thermoregulatory costs are high, ingestion of ethanol by fruit bats is low because assimilated ethanol reduces shivering thermogenesis and peripheral vasodilation; these, alone or together, are detrimental to the maintenance of body temperature (T(b)). In summer, captive bats offered food containing 0.1% ethanol significantly increased consumption over food with no ethanol; they did not change consumption when food contained 0.01, 0.3, or 0.5% ethanol; but significantly decreased consumption at higher levels of ethanol [EtOH], i.e., 1 and 2%. In winter, captive bats ate significantly less when their food contained 0.1% ethanol than when it contained 0, 0.3, or 0.5%. During summer, freshly caught bats ate significantly more ethanol-containing food than freshly caught bats in winter. Skin temperature (T(s)) in Egyptian fruit bats decreased significantly at an ambient temperature (T(a)) of 12 °C (winter conditions) after gavage with liquid food containing 1% ethanol. The effect was clearly temperature-dependent, since ethanol did not have the same effect on bats gavaged with food containing 1% or no ethanol at a T(a) of 25 °C (summer conditions). In conclusion, ethanol may act as an appetitive stimulant for Egyptian fruit bats at low concentrations, but only in summer. Bats are deterred by food containing [EtOH] corresponding to that in overripe, unpalatable fruit (1 and 2%). Furthermore, during winter, Egyptian fruit bats are deterred by ethanol-rich fruit, possibly due to the potential thermoregulatory consequences of ethanol consumption.

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The Influence of Ambient Temperature and the Energy and Protein Content of Food on Nitrogenous Excretion in the Egyptian Fruit Bat (Rousettus aegyptiacus)

Cited by 6 publications

References 49 publications

Ammonotely in a neotropical frugivorous bat as energy intake decreases

Ammonotely in a neotropical frugivorous bat as energy intake decreases

The relationships between food and energy intakes, salt content and sugar types in Egyptian fruit bats

Effects of Ethanol on Food Consumption and Skin Temperature in the Egyptian Fruit Bat (Rousettus aegyptiacus)

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