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John R. Speakman - One of the best experts on this subject based on the ideXlab platform.

  • Energy expenditure and body temperature variations in llamas living in the High Andes of Peru
    Scientific Reports, 2019
    Co-Authors: Alexander Riek, Anna Stölzl, Rodolfo Marquina Bernedo, Walter Arnold, Catherine Hambly, Thomas Ruf, John R. Speakman, Martina Gerken
    Abstract:

    Some large herbivores exhibit seasonal adjustments in their energy metabolism. Therefore, our aim was to determine if the llama (one of the most extensively kept livestock breeds) exhibits seasonal adjustment of their energy expenditure, body temperature and locomotion, under its natural high altitude Andean habitat. For this purpose, energy expenditure, body temperature and locomotion were measured in seven non-pregnant llama dams for ten months on the Andean High Plateau (4400 m above sea level). Daily energy expenditure was measured as Field Metabolic Rate using the doubly labelled water method at four different measurement times. Additionally, a telemetry system was used to continuously record activity, body temperature (3 min intervals) as well as the position (hourly) of each animal. The results show that llamas adjusted their body temperature and daily energy expenditure according to environmental conditions. Furthermore, llamas under high altitude Andean climatic conditions exhibited a pronounced daily rhythm in body temperature and activity, with low values at sunrise and increasing values towards sunset. Llamas also had remarkably low energy expenditure compared to other herbivores. Thus, despite the domestication process, llamas have not lost the ability to adjust their body temperature and daily energy expenditure under adverse environmental conditions, similar to some wild herbivores.

  • seasonal changes in energy expenditure body temperature and activity patterns in llamas lama glama
    Scientific Reports, 2017
    Co-Authors: Alexander Riek, Walter Arnold, Catherine Hambly, John R. Speakman, Lea Brinkmann, Matthias Gauly, Jurcevic Perica, Martina Gerken
    Abstract:

    Mammals typically keep their body temperature (Tb) within a narrow limit with changing environmental conditions. There are indications that some wild ungulates can exhibit certain forms of energy saving mechanisms when ambient temperatures are low and/or food is scarce. Therefore, the aim of the study was to determine if the llama, one of the most extensively kept domestic livestock species, exhibits seasonal adjustment mechanisms in terms of energy expenditure, Tb and locomotion. For that purpose llamas (N = 7) were kept in a tempeRate habitat on pasture. Locomotor activity, Tb (measured in the rumen) and the location of each animal were recorded continuously for one year using a telemetry system. Daily energy expenditure was measured as Field Metabolic Rate (FMR). FMR fluctuated considerably between seasons with the lowest values found in winter (17.48 ± 3.98 MJ d−1, 402 kJ kg−0.75 d−1) and the highest in summer (25.87 ± 3.88 MJ d−1, 586 kJ kg−0.75 d−1). Llamas adjusted their energy expenditure, Tb and locomotor activity according to season and also time of day. Thus, llamas seem to have maintained the ability to reduce their energy expenditure and adjust their Tb under adverse environmental conditions as has been reported for some wild ungulates.

  • thyroid hormones correlate with Field Metabolic Rate in ponies equus ferus caballus
    The Journal of Experimental Biology, 2016
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    During winter, free-living herbivores are often exposed to reduced energy supply at the same time that energy needs for thermoregulation increase. Several wild herbivores as well as robust horse breeds reduce their metabolism during times of low ambient temperature and food shortage. Thyroid hormones (THs) affect Metabolic intensity and a positive effect of THs on basal Metabolic Rate (BMR) has been demonstRated in mammals and birds. As BMR and Field Metabolic Rate (FMR) are often assumed to be intrinsically linked, THs may represent a reliable indicator for FMR. To test this hypothesis, 10 Shetland pony mares were kept under semi-extensive central European conditions. During the winter season, one group was fed 60% and one group 100% of their maintenance energy requirements. We measured FMR, locomotor activity, resting heart Rate and TH levels in summer and winter. FMR, locomotor activity, resting heart Rate and total T3 concentrations decreased substantially in winter compared with summer, whereas total T4 increased. Food restriction led to a reduced FMR and resting heart Rate, while THs and locomotor activity were not affected. Across both seasons, FMR, resting heart Rate and locomotor activity were positively correlated with total T3 but negatively and more weakly correlated with total T4.

  • Saving energy during hard times: energetic adaptations of Shetland pony mares.
    The Journal of experimental biology, 2014
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher Field Metabolic Rate (FMR; 63.4±15.0 MJ day(-1)) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day(-1), respectively). During summer, locomotor activity, resting heart Rate and total water turnover were considerably elevated (P

  • Saving energy during hard times: energetic adaptations of Shetland pony mares
    Journal of Experimental Biology, 2014
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher Field Metabolic Rate (FMR; 63.4±15.0 MJ day –1 ) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day –1 , respectively). During summer, locomotor activity, resting heart Rate and total water turnover were considerably elevated ( P N =5) compensated for the decreased energy supply by reducing their FMR by 26% compared with control animals ( N =5). Furthermore, resting heart Rate, body mass and body condition score were lower (29.2±2.7 beats min –1 , 140±22 kg and 3.0±1.0 points, respectively) than in control animals (36.8±41 beats min –1 , 165±31 kg, 4.4±0.7 points; P

Alexander Riek - One of the best experts on this subject based on the ideXlab platform.

  • Energy expenditure and body temperature variations in llamas living in the High Andes of Peru
    Scientific Reports, 2019
    Co-Authors: Alexander Riek, Anna Stölzl, Rodolfo Marquina Bernedo, Walter Arnold, Catherine Hambly, Thomas Ruf, John R. Speakman, Martina Gerken
    Abstract:

    Some large herbivores exhibit seasonal adjustments in their energy metabolism. Therefore, our aim was to determine if the llama (one of the most extensively kept livestock breeds) exhibits seasonal adjustment of their energy expenditure, body temperature and locomotion, under its natural high altitude Andean habitat. For this purpose, energy expenditure, body temperature and locomotion were measured in seven non-pregnant llama dams for ten months on the Andean High Plateau (4400 m above sea level). Daily energy expenditure was measured as Field Metabolic Rate using the doubly labelled water method at four different measurement times. Additionally, a telemetry system was used to continuously record activity, body temperature (3 min intervals) as well as the position (hourly) of each animal. The results show that llamas adjusted their body temperature and daily energy expenditure according to environmental conditions. Furthermore, llamas under high altitude Andean climatic conditions exhibited a pronounced daily rhythm in body temperature and activity, with low values at sunrise and increasing values towards sunset. Llamas also had remarkably low energy expenditure compared to other herbivores. Thus, despite the domestication process, llamas have not lost the ability to adjust their body temperature and daily energy expenditure under adverse environmental conditions, similar to some wild herbivores.

  • seasonal changes in energy expenditure body temperature and activity patterns in llamas lama glama
    Scientific Reports, 2017
    Co-Authors: Alexander Riek, Walter Arnold, Catherine Hambly, John R. Speakman, Lea Brinkmann, Matthias Gauly, Jurcevic Perica, Martina Gerken
    Abstract:

    Mammals typically keep their body temperature (Tb) within a narrow limit with changing environmental conditions. There are indications that some wild ungulates can exhibit certain forms of energy saving mechanisms when ambient temperatures are low and/or food is scarce. Therefore, the aim of the study was to determine if the llama, one of the most extensively kept domestic livestock species, exhibits seasonal adjustment mechanisms in terms of energy expenditure, Tb and locomotion. For that purpose llamas (N = 7) were kept in a tempeRate habitat on pasture. Locomotor activity, Tb (measured in the rumen) and the location of each animal were recorded continuously for one year using a telemetry system. Daily energy expenditure was measured as Field Metabolic Rate (FMR). FMR fluctuated considerably between seasons with the lowest values found in winter (17.48 ± 3.98 MJ d−1, 402 kJ kg−0.75 d−1) and the highest in summer (25.87 ± 3.88 MJ d−1, 586 kJ kg−0.75 d−1). Llamas adjusted their energy expenditure, Tb and locomotor activity according to season and also time of day. Thus, llamas seem to have maintained the ability to reduce their energy expenditure and adjust their Tb under adverse environmental conditions as has been reported for some wild ungulates.

  • thyroid hormones correlate with Field Metabolic Rate in ponies equus ferus caballus
    The Journal of Experimental Biology, 2016
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    During winter, free-living herbivores are often exposed to reduced energy supply at the same time that energy needs for thermoregulation increase. Several wild herbivores as well as robust horse breeds reduce their metabolism during times of low ambient temperature and food shortage. Thyroid hormones (THs) affect Metabolic intensity and a positive effect of THs on basal Metabolic Rate (BMR) has been demonstRated in mammals and birds. As BMR and Field Metabolic Rate (FMR) are often assumed to be intrinsically linked, THs may represent a reliable indicator for FMR. To test this hypothesis, 10 Shetland pony mares were kept under semi-extensive central European conditions. During the winter season, one group was fed 60% and one group 100% of their maintenance energy requirements. We measured FMR, locomotor activity, resting heart Rate and TH levels in summer and winter. FMR, locomotor activity, resting heart Rate and total T3 concentrations decreased substantially in winter compared with summer, whereas total T4 increased. Food restriction led to a reduced FMR and resting heart Rate, while THs and locomotor activity were not affected. Across both seasons, FMR, resting heart Rate and locomotor activity were positively correlated with total T3 but negatively and more weakly correlated with total T4.

  • Saving energy during hard times: energetic adaptations of Shetland pony mares.
    The Journal of experimental biology, 2014
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher Field Metabolic Rate (FMR; 63.4±15.0 MJ day(-1)) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day(-1), respectively). During summer, locomotor activity, resting heart Rate and total water turnover were considerably elevated (P

  • Saving energy during hard times: energetic adaptations of Shetland pony mares
    Journal of Experimental Biology, 2014
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher Field Metabolic Rate (FMR; 63.4±15.0 MJ day –1 ) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day –1 , respectively). During summer, locomotor activity, resting heart Rate and total water turnover were considerably elevated ( P N =5) compensated for the decreased energy supply by reducing their FMR by 26% compared with control animals ( N =5). Furthermore, resting heart Rate, body mass and body condition score were lower (29.2±2.7 beats min –1 , 140±22 kg and 3.0±1.0 points, respectively) than in control animals (36.8±41 beats min –1 , 165±31 kg, 4.4±0.7 points; P

A. Allan Degen - One of the best experts on this subject based on the ideXlab platform.

  • Resting and Field Metabolic Rates of Awassi sheep and Baladi goats raised by Negev bedouin
    The Journal of Agricultural Science, 2020
    Co-Authors: Michael Kam, Shaher El-meccawi, Arieh Brosh, A. Allan Degen
    Abstract:

    AbstractSheep are grazers and goats are intermediate feeders. By employing O2 consumption and heart Rate measurements, resting Metabolic Rate (RMR) and Field Metabolic Rate (FMR) were determined in four male fat-tailed Awassi sheep (44.0 ± 3.94) and four male Baladi goats (35.5 ± 5.42 kg) that were co-grazing natural pasture in the Negev Desert. There were 67.7 ± 3.75 g DM/m2 of herbaceous vegetation biomass, which was rapidly becoming senescent and more fibrous. We hypothesized that FMR of these desert-adapted ruminants would be relatively low when compared to other sheep and goat breeds, as animals in arid areas tend to have low Metabolic Rates. Both sheep (n = 6) and goats (n = 6) foraged 71% of the allotted 11 h free-pasture period; however, sheep grazed more than goats (P < 0.001); whereas goats browsed more than sheep (P < 0.001). RMR was higher (P = 0.007) in sheep than in goats (529 ± 23.5 v. 474 ± 25.4 kJ/kg0.75 BW/d), but FMR did not differ between species (618 ± 55.7 v. 613 ± 115.2 kJ/kg0.75 BW/d). In addition, the cost of activities, as a proportion of FMR, did not differ between sheep and goats; FMR increased by 89 kJ/kg0.75 BW/d or 17% in sheep and by 138 kJ/kg0.75 BW/d or 29% in goats. In comparing FMRs of sheep and goats in this study with these species in other studies, differences were inconsistent and, therefore, our hypothesis was not supported.

  • Effect of Group Size on Field Metabolic Rate of Arabian Babblers Provisioning Nestlings
    The Condor, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps; adult body mass 65–75 g) are territorial, cooperatively breeding passerines that inhabit hot, dry deserts. Groups include breeding adults and helpers and generally consist of 3 to 5 individuals (range 2 to 22). All group members provision nestlings at similar Rates, and individual visitation Rates decline with increasing group size. Consequently, we predicted that the Field Metabolic Rate (FMR) of individuals provisioning nestlings would decrease with increasing group size. To test this prediction, we determined FMR of primary female, primary male, female helper and male helper babblers in different sized groups provisioning nestlings. Field Metabolic Rate of primary females, but not other classes, decreased linearly with group size. This energy savings could allow primary females in larger groups to start a new nest more quickly. FMR for all babblers was 61% to 66% of the value predicted for a passerine of its body mass provisioning nestlings and was 3.11 × BMR, similar to the mean value of 3.13 × BMR reported for a number of terrestrial species.

  • Does Group Size Affect Field Metabolic Rate of Arabian Babbler (Turdoides squamiceps) Nestlings?
    The Auk, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps) are territorial, cooperative breeding passerines in which groups consist of parents and helpers. All members of the group feed nestlings in a single nest and all group members provision at similar Rates. We hypothesized that the Field Metabolic Rate (FMR) of Arabian Babbler nestlings is related to group feeding; that is, FMR would be greater in nestlings of larger rather than smaller sized groups. To test that hypothesis, we measured FMR of 10 day old nestlings from small (2 and 3 individuals), medium (4 and 5 individuals), and large (6 or more individuals) groups. We also determined number of hatchlings and fledglings produced per group. There was an increase in body mass and FMR from small to medium-sized groups, but there was a levelling off or decrease in those parameters in large groups. That suggests that there is an optimum group number for provisioning nestlings, above which there may be a negative effect. The relationship between group size and annual number of eggs was not significant, but there was a positive and linear relationship between group size and annual fledglings production. Thus, more eggs reached the fledgling stage with an increase in group size, suggesting that larger groups are better able to defend the nest against predators.

  • Effect of Group Size on Field Metabolic Rate of Arabian Babblers Provisioning Nestlings
    The Condor, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps; adult body mass 65–75 g) are territorial, cooperatively breeding passerines that inhabit hot, dry deserts. Groups include breeding adults and helpers and generally consist of 3 to 5 individuals (range 2 to 22). All group members provision nestlings at similar Rates, and individual visitation Rates decline with increasing group size. Consequently, we predicted that the Field Metabolic Rate (FMR) of individuals provisioning nestlings would decrease with increasing group size. To test this prediction, we determined FMR of primary female, primary male, female helper and male helper babblers in different sized groups provisioning nestlings. Field Metabolic Rate of primary females, but not other classes, decreased linearly with group size. This energy savings could allow primary females in larger groups to start a new nest more quickly. FMR for all babblers was 61% to 66% of the value predicted for a passerine of its body mass provisioning nestlings and was 3.11 ...

  • Does Group Size Affect Field Metabolic Rate of Arabian Babbler (Turdoides squamiceps) Nestlings
    The Auk, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps) are territorial, cooperative breeding passerines in which groups consist of parents and helpers. All members of the group feed nestlings in a single nest and all group members provision at similar Rates. We hypothesized that the Field Metabolic Rate (FMR) of Arabian Babbler nestlings is related to group feeding; that is, FMR would be greater in nestlings of larger rather than smaller sized groups. To test that hypothesis, we measured FMR of 10 day old nestlings from small (2 and 3 individuals), medium (4 and 5 individuals), and large (6 or more individuals) groups. We also determined number of hatchlings and fledglings produced per group. There was an increase in body mass and FMR from small to medium-sized groups, but there was a levelling off or decrease in those parameters in large groups. That suggests that there is an optimum group number for provisioning nestlings, above which there may be a negative effect. The relationship between group size and ann...

Michael Kam - One of the best experts on this subject based on the ideXlab platform.

  • Resting and Field Metabolic Rates of Awassi sheep and Baladi goats raised by Negev bedouin
    The Journal of Agricultural Science, 2020
    Co-Authors: Michael Kam, Shaher El-meccawi, Arieh Brosh, A. Allan Degen
    Abstract:

    AbstractSheep are grazers and goats are intermediate feeders. By employing O2 consumption and heart Rate measurements, resting Metabolic Rate (RMR) and Field Metabolic Rate (FMR) were determined in four male fat-tailed Awassi sheep (44.0 ± 3.94) and four male Baladi goats (35.5 ± 5.42 kg) that were co-grazing natural pasture in the Negev Desert. There were 67.7 ± 3.75 g DM/m2 of herbaceous vegetation biomass, which was rapidly becoming senescent and more fibrous. We hypothesized that FMR of these desert-adapted ruminants would be relatively low when compared to other sheep and goat breeds, as animals in arid areas tend to have low Metabolic Rates. Both sheep (n = 6) and goats (n = 6) foraged 71% of the allotted 11 h free-pasture period; however, sheep grazed more than goats (P < 0.001); whereas goats browsed more than sheep (P < 0.001). RMR was higher (P = 0.007) in sheep than in goats (529 ± 23.5 v. 474 ± 25.4 kJ/kg0.75 BW/d), but FMR did not differ between species (618 ± 55.7 v. 613 ± 115.2 kJ/kg0.75 BW/d). In addition, the cost of activities, as a proportion of FMR, did not differ between sheep and goats; FMR increased by 89 kJ/kg0.75 BW/d or 17% in sheep and by 138 kJ/kg0.75 BW/d or 29% in goats. In comparing FMRs of sheep and goats in this study with these species in other studies, differences were inconsistent and, therefore, our hypothesis was not supported.

  • Effect of Group Size on Field Metabolic Rate of Arabian Babblers Provisioning Nestlings
    The Condor, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps; adult body mass 65–75 g) are territorial, cooperatively breeding passerines that inhabit hot, dry deserts. Groups include breeding adults and helpers and generally consist of 3 to 5 individuals (range 2 to 22). All group members provision nestlings at similar Rates, and individual visitation Rates decline with increasing group size. Consequently, we predicted that the Field Metabolic Rate (FMR) of individuals provisioning nestlings would decrease with increasing group size. To test this prediction, we determined FMR of primary female, primary male, female helper and male helper babblers in different sized groups provisioning nestlings. Field Metabolic Rate of primary females, but not other classes, decreased linearly with group size. This energy savings could allow primary females in larger groups to start a new nest more quickly. FMR for all babblers was 61% to 66% of the value predicted for a passerine of its body mass provisioning nestlings and was 3.11 × BMR, similar to the mean value of 3.13 × BMR reported for a number of terrestrial species.

  • Does Group Size Affect Field Metabolic Rate of Arabian Babbler (Turdoides squamiceps) Nestlings?
    The Auk, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps) are territorial, cooperative breeding passerines in which groups consist of parents and helpers. All members of the group feed nestlings in a single nest and all group members provision at similar Rates. We hypothesized that the Field Metabolic Rate (FMR) of Arabian Babbler nestlings is related to group feeding; that is, FMR would be greater in nestlings of larger rather than smaller sized groups. To test that hypothesis, we measured FMR of 10 day old nestlings from small (2 and 3 individuals), medium (4 and 5 individuals), and large (6 or more individuals) groups. We also determined number of hatchlings and fledglings produced per group. There was an increase in body mass and FMR from small to medium-sized groups, but there was a levelling off or decrease in those parameters in large groups. That suggests that there is an optimum group number for provisioning nestlings, above which there may be a negative effect. The relationship between group size and annual number of eggs was not significant, but there was a positive and linear relationship between group size and annual fledglings production. Thus, more eggs reached the fledgling stage with an increase in group size, suggesting that larger groups are better able to defend the nest against predators.

  • Effect of Group Size on Field Metabolic Rate of Arabian Babblers Provisioning Nestlings
    The Condor, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps; adult body mass 65–75 g) are territorial, cooperatively breeding passerines that inhabit hot, dry deserts. Groups include breeding adults and helpers and generally consist of 3 to 5 individuals (range 2 to 22). All group members provision nestlings at similar Rates, and individual visitation Rates decline with increasing group size. Consequently, we predicted that the Field Metabolic Rate (FMR) of individuals provisioning nestlings would decrease with increasing group size. To test this prediction, we determined FMR of primary female, primary male, female helper and male helper babblers in different sized groups provisioning nestlings. Field Metabolic Rate of primary females, but not other classes, decreased linearly with group size. This energy savings could allow primary females in larger groups to start a new nest more quickly. FMR for all babblers was 61% to 66% of the value predicted for a passerine of its body mass provisioning nestlings and was 3.11 ...

  • Does Group Size Affect Field Metabolic Rate of Arabian Babbler (Turdoides squamiceps) Nestlings
    The Auk, 2001
    Co-Authors: Avner Anava, Michael Kam, Amiram Shkolnik, A. Allan Degen
    Abstract:

    Abstract Arabian Babblers (Turdoides squamiceps) are territorial, cooperative breeding passerines in which groups consist of parents and helpers. All members of the group feed nestlings in a single nest and all group members provision at similar Rates. We hypothesized that the Field Metabolic Rate (FMR) of Arabian Babbler nestlings is related to group feeding; that is, FMR would be greater in nestlings of larger rather than smaller sized groups. To test that hypothesis, we measured FMR of 10 day old nestlings from small (2 and 3 individuals), medium (4 and 5 individuals), and large (6 or more individuals) groups. We also determined number of hatchlings and fledglings produced per group. There was an increase in body mass and FMR from small to medium-sized groups, but there was a levelling off or decrease in those parameters in large groups. That suggests that there is an optimum group number for provisioning nestlings, above which there may be a negative effect. The relationship between group size and ann...

Martina Gerken - One of the best experts on this subject based on the ideXlab platform.

  • Energy expenditure and body temperature variations in llamas living in the High Andes of Peru
    Scientific Reports, 2019
    Co-Authors: Alexander Riek, Anna Stölzl, Rodolfo Marquina Bernedo, Walter Arnold, Catherine Hambly, Thomas Ruf, John R. Speakman, Martina Gerken
    Abstract:

    Some large herbivores exhibit seasonal adjustments in their energy metabolism. Therefore, our aim was to determine if the llama (one of the most extensively kept livestock breeds) exhibits seasonal adjustment of their energy expenditure, body temperature and locomotion, under its natural high altitude Andean habitat. For this purpose, energy expenditure, body temperature and locomotion were measured in seven non-pregnant llama dams for ten months on the Andean High Plateau (4400 m above sea level). Daily energy expenditure was measured as Field Metabolic Rate using the doubly labelled water method at four different measurement times. Additionally, a telemetry system was used to continuously record activity, body temperature (3 min intervals) as well as the position (hourly) of each animal. The results show that llamas adjusted their body temperature and daily energy expenditure according to environmental conditions. Furthermore, llamas under high altitude Andean climatic conditions exhibited a pronounced daily rhythm in body temperature and activity, with low values at sunrise and increasing values towards sunset. Llamas also had remarkably low energy expenditure compared to other herbivores. Thus, despite the domestication process, llamas have not lost the ability to adjust their body temperature and daily energy expenditure under adverse environmental conditions, similar to some wild herbivores.

  • seasonal changes in energy expenditure body temperature and activity patterns in llamas lama glama
    Scientific Reports, 2017
    Co-Authors: Alexander Riek, Walter Arnold, Catherine Hambly, John R. Speakman, Lea Brinkmann, Matthias Gauly, Jurcevic Perica, Martina Gerken
    Abstract:

    Mammals typically keep their body temperature (Tb) within a narrow limit with changing environmental conditions. There are indications that some wild ungulates can exhibit certain forms of energy saving mechanisms when ambient temperatures are low and/or food is scarce. Therefore, the aim of the study was to determine if the llama, one of the most extensively kept domestic livestock species, exhibits seasonal adjustment mechanisms in terms of energy expenditure, Tb and locomotion. For that purpose llamas (N = 7) were kept in a tempeRate habitat on pasture. Locomotor activity, Tb (measured in the rumen) and the location of each animal were recorded continuously for one year using a telemetry system. Daily energy expenditure was measured as Field Metabolic Rate (FMR). FMR fluctuated considerably between seasons with the lowest values found in winter (17.48 ± 3.98 MJ d−1, 402 kJ kg−0.75 d−1) and the highest in summer (25.87 ± 3.88 MJ d−1, 586 kJ kg−0.75 d−1). Llamas adjusted their energy expenditure, Tb and locomotor activity according to season and also time of day. Thus, llamas seem to have maintained the ability to reduce their energy expenditure and adjust their Tb under adverse environmental conditions as has been reported for some wild ungulates.

  • thyroid hormones correlate with Field Metabolic Rate in ponies equus ferus caballus
    The Journal of Experimental Biology, 2016
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    During winter, free-living herbivores are often exposed to reduced energy supply at the same time that energy needs for thermoregulation increase. Several wild herbivores as well as robust horse breeds reduce their metabolism during times of low ambient temperature and food shortage. Thyroid hormones (THs) affect Metabolic intensity and a positive effect of THs on basal Metabolic Rate (BMR) has been demonstRated in mammals and birds. As BMR and Field Metabolic Rate (FMR) are often assumed to be intrinsically linked, THs may represent a reliable indicator for FMR. To test this hypothesis, 10 Shetland pony mares were kept under semi-extensive central European conditions. During the winter season, one group was fed 60% and one group 100% of their maintenance energy requirements. We measured FMR, locomotor activity, resting heart Rate and TH levels in summer and winter. FMR, locomotor activity, resting heart Rate and total T3 concentrations decreased substantially in winter compared with summer, whereas total T4 increased. Food restriction led to a reduced FMR and resting heart Rate, while THs and locomotor activity were not affected. Across both seasons, FMR, resting heart Rate and locomotor activity were positively correlated with total T3 but negatively and more weakly correlated with total T4.

  • Saving energy during hard times: energetic adaptations of Shetland pony mares.
    The Journal of experimental biology, 2014
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher Field Metabolic Rate (FMR; 63.4±15.0 MJ day(-1)) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day(-1), respectively). During summer, locomotor activity, resting heart Rate and total water turnover were considerably elevated (P

  • Saving energy during hard times: energetic adaptations of Shetland pony mares
    Journal of Experimental Biology, 2014
    Co-Authors: Lea Brinkmann, Catherine Hambly, Martina Gerken, John R. Speakman, Alexander Riek
    Abstract:

    Recent results suggest that wild Northern herbivores reduce their metabolism during times of low ambient temperature and food shortage in order to reduce their energetic needs. It is, however, not known whether domesticated animals are also able to reduce their energy expenditure. We exposed 10 Shetland pony mares to different environmental conditions (summer and winter) and to two food quantities (60% and 100% of maintenance energy requirement) during low winter temperatures to examine energetic and behavioural responses. In summer, ponies showed a considerably higher Field Metabolic Rate (FMR; 63.4±15.0 MJ day –1 ) compared with food-restricted and control animals in winter (24.6±7.8 and 15.0±1.1 MJ day –1 , respectively). During summer, locomotor activity, resting heart Rate and total water turnover were considerably elevated ( P N =5) compensated for the decreased energy supply by reducing their FMR by 26% compared with control animals ( N =5). Furthermore, resting heart Rate, body mass and body condition score were lower (29.2±2.7 beats min –1 , 140±22 kg and 3.0±1.0 points, respectively) than in control animals (36.8±41 beats min –1 , 165±31 kg, 4.4±0.7 points; P