scholarly journals Novel energy-saving strategies to multiple stressors in birds: the ultradian regulation of body temperature

2016 ◽  
Vol 283 (1839) ◽  
pp. 20161551 ◽  
Author(s):  
Glenn J. Tattersall ◽  
Damien Roussel ◽  
Yann Voituron ◽  
Loïc Teulier
Keyword(s):  
Body Temperature ◽  
Multiple Stressors ◽  
Energetic Cost ◽  
Short Term ◽  
Ad Libitum ◽  
Key Sites ◽  
Ad Libitum Feeding ◽  
Reduced Surface ◽  
Internal Body

This study aimed to examine thermoregulatory responses in birds facing two commonly experienced stressors, cold and fasting. Logging devices allowing long-term and precise access to internal body temperature were placed within the gizzards of ducklings acclimated to cold (CA) (5°C) or thermoneutrality (TN) (25°C). The animals were then examined under three equal 4-day periods: ad libitum feeding, fasting and re-feeding. Through the analysis of daily as well as short-term, or ultradian, variations of body temperature, we showed that while ducklings at TN show only a modest decline in daily thermoregulatory parameters when fasted, they exhibit reduced surface temperatures from key sites of vascular heat exchange during fasting. The CA birds, on the other hand, significantly reduced their short-term variations of body temperature while increasing long-term variability when fasting. This phenomenon would allow the CA birds to reduce the energetic cost of body temperature maintenance under fasting. By analysing ultradian regulation of body temperature, we describe a means by which an endotherm appears to lower thermoregulatory costs in response to the combined stressors of cold and fasting.

scholarly journals Changes in blood glucose as a function of body temperature in laboratory mice: implications for daily torpor

2018 ◽  
Vol 315 (4) ◽  
pp. E662-E670 ◽  
Author(s):  
Viviana Lo Martire ◽  
Alice Valli ◽  
Mark J. Bingaman ◽  
Giovanna Zoccoli ◽  
Alessandro Silvani ◽  
...  
Keyword(s):  
Body Temperature ◽  
Core Body Temperature ◽  
Laboratory Mouse ◽  
Glucose Production ◽  
Endogenous Glucose Production ◽  
Limited Food ◽  
Hypometabolic State ◽  
Ad Libitum ◽  
Core Body ◽  
Ad Libitum Feeding

Many small mammals, such as the laboratory mouse, utilize the hypometabolic state of torpor in response to caloric restriction. The signals that relay the lack of fuel to initiate a bout of torpor are not known. Because the mouse will only enter a torpid state when calorically challenged, it may be that one of the inputs for initiation into a bout of torpor is the lack of the primary fuel (glucose) used to power brain metabolism in the mouse. Using glucose telemetry in mice, we tested the hypotheses that 1) circulating glucose (GLC), core body temperature (Tb), and activity are significantly interrelated; and 2) that the level of GLC at the onset of torpor differs from both GLC during arousal from torpor and during feeding when there is no torpor. To test these hypotheses, six C57Bl/6J mice were implanted with glucose telemeters and exposed to different feeding conditions (ad libitum, fasting, limited food intake, and refeeding) to create different levels of GLC and Tb. We found a strong positive and linear correlation between GLC and Tb during ad libitum feeding. Furthermore, mice that were calorically restricted entered torpor bouts readily. GLC was low during torpor entry but did not drop precipitously as Tb did at the onset of a torpor bout. GLC significantly increased during arousal from torpor, indicating the presence of endogenous glucose production. While low GLC itself was not predictive of a bout of torpor, hyperactivity and low GLC preceded the onset of torpor, suggesting that this may be involved in triggering torpor.

Long- and short-term effects on intake of pelleting a roughage for sheep

1974 ◽  
Vol 19 (1) ◽  
pp. 77-86 ◽  
Author(s):  
J. F. D. Greenhalgh ◽  
G. W. Reid
Keyword(s):  
Body Weight ◽  
Dry Matter ◽  
Dry Matter Intake ◽  
Short Term ◽  
05 C ◽  
Digestive Organs ◽  
Dry Matter Digestibility ◽  
Ad Libitum ◽  
Chopped Grass

SUMMARY1. Four groups of eight castrated male lambs, weighing initially about 37 kg, were fed ad libitum for 18 weeks on: C, chopped dried grass throughout; P, pelleted grass throughout; C/P (or P/C), the two forms alternated every 3 weeks; or C + P, both forms on offer.2. Daily dry-matter intake (g/kg W0·75) was 58·2 for treatment C and 814 for treatment P; thus the long-term difference in intake was 40%. However, in the alternated sheep, dry-matter intake was 53·6 g/kg W0·75 for chopped grass and 86·5 g for pelleted; this short-term difference (61%) was significantly greater than the long-term difference. Dry-matter intake for treatment C+P was 84·9 g/kg W0·75; after the first week, chopped grass comprised only 10% of this. Dry-matter digestibility coefficients (%) were: C, 740; P, 61·4 and C+P, 62·0.3. The sheep were killed in week 19 and the dimensions of digestive organs and their contents were adjusted to an animal of 50 kg empty body weight. The weight of the reticulo-rumen was greater for C (1·30 kg) than for P (0·94) or C+ P (1·05), C/P and P/C being inter-mediate (1·15). The water-filled volume of the rumen was proportional to weight, except that C/P (alternated sheep finishing on pelleted grass) had low volumes. Reticulo-rumen fill was greater for C (7·28 kg) than for P (3·97) or C+ P (4·53), P/C (5·90) and C/P (4·34) being intermediate. There were no other significant differences in organs or contents.4. Gains in empty-body weight (g/day) were: C, 112; P, 181; C/P and P/C, 126; C + P, 195.

Skin folds and Merino breeding. 9. Efficiency of conversion of food to wool

1976 ◽  
Vol 16 (80) ◽  
pp. 361 ◽  
Author(s):  
GE Robards ◽  
CH Davis ◽  
DG Saville
Keyword(s):  
Surface Area ◽  
The Other ◽  
Or Efficiency ◽  
Wool Production ◽  
Skin Fold ◽  
Significant Difference ◽  
Ad Libitum ◽  
Ad Libitum Intake ◽  
Ad Libitum Feeding ◽  
Reduced Surface

This paper reports a study of the efficiency of wool production, liveweight change and ad libitum intake of 60 hogget ewes from flocks selected for 15 years for skin wrinkle (Folds Plus), against skin wrinkle (Folds Minus) and randomly selected as a control (Random). Initially, under restricted feeding ewes from each genetic flock consumed 594, 750, 951 or 1097 g DM day-1 of a lucerne pellet ration. The mean efficiency of clean wool production of Folds Minus ewes (8.47 g CW/kg D.M.I.) was less (P < 0.05) than that of either Random (9.38) or Folds Plus (10.18) ewes, which did not differ significantly. During the following ad libitum feeding period, the Folds Minus ewes again produced less wool than either of the other groups and their wool production was less efficient even though they consumed significantly less feed than either Random or Folds Plus ewes. The significant difference in intake between Random and Folds Minus ewes remained when the n takes were corrected for liveweight (kg), metabolic body size (kg0.73) or surface area based on liveweight alone (kg0.67). However, when fold score (FS) was included in the surface area estimate as LW0.67 + FS0.2 the intake difference between flocks became very small. The experimental results and components analyses of the pre- and post-shearing data showed that selection for skin fold had not changed wool growth rate or efficiency of wool production, but had reduced staple length. On the other hand, the lower wool production of Folds Minus ewes was due to both reduced surface area and lower wool production per unit area.

scholarly journals The Evolutionarily Conserved Gonadotropin-Releasing Hormone II Modifies Food Intake

Endocrinology ◽  
2004 ◽  
Vol 145 (2) ◽  
pp. 686-691 ◽  
Author(s):  
Alexander S. Kauffman ◽  
Emilie F. Rissman
Keyword(s):  
Food Intake ◽  
Food Restriction ◽  
Similar Function ◽  
Structural Variants ◽  
Short Term ◽  
Primate Brain ◽  
Evolutionarily Conserved ◽  
Ad Libitum ◽  
Ad Libitum Feeding ◽  
Permissive Role

Abstract GnRH is an evolutionarily conserved peptide of which there are multiple structural variants. One form, GnRH II, is the most widespread in vertebrates, but its primary function remains unclear. In female musk shrews, administration of GnRH II, but not GnRH I, reinstates mating behavior previously inhibited by food restriction. Because this finding suggests that the function of GnRH II may be linked to energetic status, we tested whether GnRH II directly affects food intake. Adult female musk shrews were maintained on ad libitum feeding or food restricted for 48 h, after which they were infused centrally with GnRH I (1 μg), GnRH II (1 μg), or saline. Food intake was recorded 90 min, and 3, 6, 24, and 48 h after infusion. GnRH II administration, but not saline or GnRH I, reduced 24-h food intake in ad libitum animals. Short-term food intake (90 min and 3 h) of both ad libitum and underfed shrews receiving GnRH II was also reduced by as much as 33%, relative to the food intake of saline-infused controls. GnRH I infusion did not affect short-term food intake differently than saline infusion in shrews fed ad libitum. In underfed females, GnRH I had an effect on short-term food intake that was intermediate to saline and GnRH II. We conclude that, in addition to its permissive role in regulating reproduction, GnRH II may also modulate food intake in mammals. Because GnRH II is present in primate brain, it may also serve a similar function in humans.

Late Inhalation Toxicology and Pathology Produced by Exposure to a Single Dose of 2-Chlorobenzylidene Malononitrile (CS) in Rats and Hamsters

1983 ◽  
Vol 23 (4) ◽  
pp. 257-265 ◽  
Author(s):  
T. C. Marrs ◽  
E. Clifford ◽  
H. F. Colgrave
Keyword(s):  
Single Dose ◽  
Female Rats ◽  
Neoplastic Disease ◽  
Histological Changes ◽  
High Incidence ◽  
Ad Libitum ◽  
And Control ◽  
Ad Libitum Feeding ◽  
Long Term Adverse Effects

Hamsters and rats exposed to single doses of CS were retained for up to 32 months, together with appropriate controls. Survival was unaffected and in no case was the incidence of histological changes significantly higher in the test animals than corresponding control animals. The overall incidence of neoplastic disease was similar in test and control animals. A high incidence of pituitary acidophil adenomas was detected in the female rats: these tumours were present both in control and test rats and it was concluded that they were probably the result of ad libitum feeding. It was concluded that single doses of CS of 28 800 mg min m−3 administered during 1 hour or 18 000 mg min m−3 administered over 2 hours produced no long-term adverse effects in the two species studied.

scholarly journals Effects of long-term ad libitum feeding on plasma lipid components and blood glucose, β-hydroxybutyrate and insulin concentrations in lean adult sheep

1983 ◽  
Vol 23 (1) ◽  
pp. 51-63 ◽  
Author(s):  
Françoise VANDERMEERSCHEN-DOIZÉ ◽  
J.-C. BOUCHAT ◽  
Marie-Antoinette BOUCKOMS-VANDERMEIR ◽  
R. PAQUAY
Keyword(s):  
Blood Glucose ◽  
Plasma Lipid ◽  
Adult Sheep ◽  
Ad Libitum ◽  
Ad Libitum Feeding ◽  
Lipid Components

Short-term decoupling of otolith and somatic growth induced by food level changes in postlarval Baltic sprat, Sprattus sprattus

2005 ◽  
Vol 56 (5) ◽  
pp. 539 ◽  
Author(s):  
Hannes Baumann ◽  
Myron A. Peck ◽  
Jens-Peter Herrmann
Keyword(s):  
Somatic Growth ◽  
Field Studies ◽  
Food Level ◽  
Short Term ◽  
Weight Growth ◽  
Linear Relationships ◽  
Feeding Regimes ◽  
Ad Libitum ◽  
Second Period ◽  
Ad Libitum Feeding

We studied the effects of food level changes on otolith and somatic growth in postlarval Baltic sprat reared initially for a period of 11 days under zero, low, and ad libitum feeding conditions. During a subsequent 11 day period, feeding regimes were reversed in half of the low and ad libitum feeding treatments, and starved fish were re-fed ad libitum rations. Somatic growth rates under low and ad libitum food rations ranged between 0.15–0.22 mm day−1 and 0.48–0.63 mm day−1, respectively, and led to significant differences in length and weight between feeding regimes. Previously starved fish, however, grew only 0.25–0.28 mm day−1 under ad libitum conditions. During the first period, significant linear relationships were found for otolith v. length and v. weight growth across all treatments. After changing feeding regimes, increment widths failed to significantly predict somatic growth for 9 days, after which a significant relationship between otolith and somatic growth became re-established. Recent otolith growth was a good predictor of fish condition after the first, but not after the second period. The results suggest that perturbations in environmental conditions can temporarily decouple otolith from somatic growth in postlarval sprat, which needs to be considered in field studies.

scholarly journals Effects of multiple stressors on river biofilms depend on the time scale

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ferran Romero ◽  
Vicenç Acuña ◽  
Carme Font ◽  
Anna Freixa ◽  
Sergi Sabater
Keyword(s):  
Exposure Time ◽  
Pesticide Exposure ◽  
Multiple Stressors ◽  
Freshwater Ecosystems ◽  
Additive Effects ◽  
Short Term ◽  
Multiple Stressor ◽  
Hydrological Stress ◽  
Additive Interactions

Abstract Global change exposes ecosystems to a myriad of stressors differing in their spatial (i.e. surface of stressed area) and temporal (i.e. exposure time) components. Among freshwater ecosystems, rivers and streams are subject to physical, chemical and biological stressors, which interact with each other and might produce diverging effects depending on exposure time. We conducted a manipulative experiment using 24 artificial streams to examine the individual and combined effects of warming (1.6 °C increase in water temperature), hydrological stress (simulated low-flow situation) and chemical stress caused by pesticide exposure (15.1–156.7 ng L−1) on river biofilms. We examined whether co-occurring stressors could lead to non-additive effects, and if these differed at two different exposure times. Specifically, structural and functional biofilm responses were assessed after 48 hours (short-term effects) and after 30 days (long-term effects) of exposure. Hydrological stress caused strong negative impacts on river biofilms, whereas effects of warming and pesticide exposure were less intense, although increasing on the long term. Most stressor combinations (71%) resulted in non-significant interactions, suggesting overall additive effects, but some non-additive interactions also occurred. Among non-additive interactions, 59% were classified as antagonisms after short-term exposure to the different stressor combinations, rising to 86% at long term. Our results indicate that a 30-day exposure period to multiple stressors increases the frequency of antagonistic interactions compared to a 48-hour exposure to the same conditions. Overall, the impacts of multiple-stressor occurrences appear to be hardly predictable from individual effects, highlighting the need to consider temporal components such as duration when predicting the effects of multiple stressors.

scholarly journals Perceptions on climate change and its impact on livelihoods in Hwange district, Zimbabwe

2014 ◽  
Vol 6 (1) ◽  
Author(s):  
Charles Nhemachena ◽  
Reneth Mano ◽  
Shakespear Mudombi ◽  
Virginia Muwanigwa
Keyword(s):  
Climate Change ◽  
Rural Communities ◽  
Rural Community ◽  
Multiple Stressors ◽  
Climatic Factors ◽  
Climate Change Impacts ◽  
Short Term ◽  
Local Livelihood ◽  
Impacts Of Climate Change

This study investigated perceptions of rural communities on climate change and its impacts on livelihoods. The research was conducted in the semi-arid Hwange district in Matebelel and North province of Zimbabwe. The perceptions were compared with empirical evidence from climatic studies on trends on temperature and rainfall, and impacts on livelihoods in the country and region. The findings from the current study are generally in agreement with those of other studies that indicate changes in the climate, especially in terms of rainfall. This largely applies to short-term periods; however, for long-term periods it is difficult to accurately relate rural community perceptions to changes in rainfall over time. Despite perceived changes and impacts of climate change on local livelihood activities, mainly agriculture, there are multiple stressors that the communities face which also affect their livelihoods. Further evidence-based research is required to disentangle climate change impacts on livelihoods, including livelihood impacts arising from interactions of climate and non-climatic factors.

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