Energetics of free-ranging large herbivores: when should costs affect foraging behaviour?

2000 ◽  
Vol 78 (9) ◽  
pp. 1604-1615 ◽  
Author(s):  
Helen M Armstrong ◽  
Antony Robertson
Keyword(s):  
Energy Balance ◽  
Foraging Behaviour ◽  
Ovis Aries ◽  
Energetic Cost ◽  
Domestic Sheep ◽  
Net Energy ◽  
Large Herbivores ◽  
Wind Speeds ◽  
Free Ranging ◽  
The Impact

Published relationships were used to build a mathematical model that predicts the daily net energy balance of free-ranging domestic sheep (Ovis aries L.) grazing in the U.K. hills. Net energy balance was predicted for a plausible range of environmental conditions. The behaviour of the model suggested the following predictions. Locomotion will be a relatively unimportant energetic cost. Ambient temperature and rainfall alone will rarely affect energy expenditure, whereas wind will greatly increase energetic costs in winter. These are further increased, but to a relatively small extent, by any concurrent rainfall. Predictions of foraging behaviour based on maximisation of energy intake alone are likely to significantly overestimate dry matter intake from climatically exposed vegetation in winter. Where shelter is available, such models will also overestimate total intake in winter by not taking account of sheltering behaviour. This effect will be most pronounced when forage is of low digestibility or availability, wind speeds are high, or the level of coat insulation is low. Foraging models based instead on maximisation of net energy balance are likely to greatly improve predictions of the impact of large herbivores on vegetation and the mechanisms driving their population dynamics.

Mortality of lambs in free-ranging domestic sheep (Ovis aries) in northern Norway

2001 ◽  
Vol 254 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Jerry T. Warren ◽  
Ivar Mysterud ◽  
Torun Lynnebakken
Keyword(s):  
Ovis Aries ◽  
Domestic Sheep ◽  
Northern Norway ◽  
Free Ranging

scholarly journals Microstructure and mechanical properties of different keratinous horns

2018 ◽  
Vol 15 (143) ◽  
pp. 20180093 ◽  
Author(s):  
Yuchen Zhang ◽  
Wei Huang ◽  
Cheryl Hayashi ◽  
John Gatesy ◽  
Joanna McKittrick
Keyword(s):  
Mechanical Properties ◽  
Longitudinal Direction ◽  
Bighorn Sheep ◽  
Growth Direction ◽  
Ovis Aries ◽  
Domestic Sheep ◽  
Microstructure And Mechanical Properties ◽  
Mountain Goat ◽  
The Impact ◽  
Horn Core

Animal horns play an important role during intraspecific combat. This work investigates the microstructure and mechanical properties of horns from four representative ruminant species: the bighorn sheep ( Ovis canadensis ), domestic sheep ( Ovis aries ), mountain goat ( Oreamnos americanus ) and pronghorn ( Antilocapra americana ), aiming to understand the relation between evolved microstructures and mechanical properties. Microstructural similarity is found where disc-shaped keratin cells attach edge-to-edge along the growth direction of the horn core (longitudinal direction) forming a lamella; multiple lamellae are layered face to face along the impact direction (radial direction, perpendicular to horn core growth direction), forming a wavy pattern surrounding a common feature, the tubules. Differences among species include the number and shape of the tubules, the orientation of aligned lamellae and the shape of keratin cells. Water absorption tests reveal that the pronghorn horn has the largest water-absorbing ability due to the presence of nanopores in the keratin cells. The loading direction (compressive and tensile) and level of hydration vary among the horns from different species. The differences in mechanical properties among species may relate to their different fighting behaviours: high stiffness and strength in mountain goat to support the forces during stabbing; high tensile strength in pronghorn for interlocked pulling; impact energy absorption properties in domestic and bighorn sheep to protect the skull during butting. These design rules based on evolutionary modifications among species can be applied in synthetic materials to meet different mechanical requirements.

The diet of brown bears Ursus arctos in central Scandinavia: effect of access to free-ranging domestic sheep Ovis aries

1998 ◽  
Vol 4 (1) ◽  
pp. 147-158 ◽  
Author(s):  
Bjørn Dahle ◽  
Ole J. Sørensen ◽  
Egil H. Wedul ◽  
Jon E. Swenson ◽  
Finn Sandegren
Keyword(s):  
Ursus Arctos ◽  
Ovis Aries ◽  
Domestic Sheep ◽  
Brown Bears ◽  
Free Ranging

scholarly journals Exercise reduces appetite and traffics excess nutrients away from energetically efficient pathways of lipid deposition during the early stages of weight regain

2011 ◽  
Vol 301 (3) ◽  
pp. R656-R667 ◽  
Author(s):  
Amy J. Steig ◽  
Matthew R. Jackman ◽  
Erin D. Giles ◽  
Janine A. Higgins ◽  
Ginger C. Johnson ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Energy Balance ◽  
Weight Regain ◽  
De Novo Lipogenesis ◽  
Energetic Cost ◽  
Positive Energy ◽  
Regular Exercise ◽  
Fuel Utilization ◽  
Energy Imbalance ◽  
The Impact

The impact of regular exercise on energy balance, fuel utilization, and nutrient availability, during weight regain was studied in obese rats, which had lost 17% of their weight by a calorie-restricted, low-fat diet. Weight reduced rats were maintained for 6 wk with and without regular treadmill exercise (1 h/day, 6 days/wk, 15 m/min). In vivo tracers and indirect calorimetry were then used in combination to examine nutrient metabolism during weight maintenance (in energy balance) and during the first day of relapse when allowed to eat ad libitum (relapse). An additional group of relapsing, sedentary rats were provided just enough calories to create the same positive energy imbalance as the relapsing, exercised rats. Exercise attenuated the energy imbalance by 50%, reducing appetite and increasing energy requirements. Expenditure increased beyond the energetic cost of the exercise bout, as exercised rats expended more energy to store the same nutrient excess in sedentary rats with the matched energy imbalance. Compared with sedentary rats with the same energy imbalance, exercised rats exhibited the trafficking of dietary fat toward oxidation and away from storage in adipose tissue, as well as a higher net retention of fuel via de novo lipogenesis in adipose tissue. These metabolic changes in relapse were preceded by an increase in the skeletal muscle expression of genes involved in lipid uptake, mobilization, and oxidation. Our observations reveal a favorable shift in fuel utilization with regular exercise that increases the energetic cost of storing excess nutrients during relapse and alterations in circulating nutrients that may affect appetite. The attenuation of the biological drive to regain weight, involving both central and peripheral aspects of energy homeostasis, may explain, in part, the utility of regular exercise in preventing weight regain after weight loss.

Energetics of hummingbird foraging at low ambient temperature

1999 ◽  
Vol 77 (2) ◽  
pp. 314-320 ◽  
Author(s):  
C L Gass ◽  
M T Romich ◽  
R K Suarez
Keyword(s):  
Energy Balance ◽  
Ambient Temperature ◽  
Energy Intake ◽  
Energy Gain ◽  
Energetic Cost ◽  
Net Energy ◽  
Metabolic Rates ◽  
Energetic Costs ◽  
Net Energy Gain ◽  
Low Ambient Temperature

Because of their small size and the high energetic costs of hovering and forward flight, hummingbirds achieve the highest mass-specific metabolic rates known among vertebrates. Rufous hummingbirds (Selasphorus rufus) stop to refuel on floral nectar in subalpine meadows as they migrate south from British Columbia to Mexico. In such habitats they face the challenge of achieving daily net energy gain despite the high energetic costs of flight and thermoregulation at near-freezing morning temperatures. Hummingbirds provided with 15 or 20% sucrose while subjected to these conditions for 4 h in the laboratory did not remain in energy balance and lost mass. However, they achieved energy balance or net energy gain on 30% sucrose. Because these sucrose concentrations are within the range observed in the nectar of hummingbird-visited flowers, the results suggest that the energetic cost of thermoregulation may influence the coevolution of hummingbirds and flowers. Hummingbirds maintaining energy balance at low ambient temperature via high foraging frequencies and high rates of energy intake can sustain average metabolic rates of about 250 W/kg over a 4-h period. These are the highest metabolic rates known among vertebrates at which rates of dietary energy intake equal rates of energy expenditure.

scholarly journals Shared Bacterial and Viral Respiratory Agents in Bighorn Sheep (Ovis canadensis), Domestic Sheep (Ovis aries), and Goats (Capra hircus) in Montana

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
David S. Miller ◽  
Glen C. Weiser ◽  
Keith Aune ◽  
Brent Roeder ◽  
Mark Atkinson ◽  
...  
Keyword(s):  
Disease Outbreaks ◽  
Bighorn Sheep ◽  
Cross Sectional Study ◽  
Ovis Canadensis ◽  
Ovis Aries ◽  
Capra Hircus ◽  
Domestic Sheep ◽  
Infectious Agents ◽  
Cross Sectional ◽  
The Impact

Transmission of infectious agents from livestock reservoirs has been hypothesized to cause respiratory disease outbreaks in bighorn sheep (Ovis canadensis), and land management policies intended to limit this transmission have proven controversial. This cross-sectional study compares the infectious agents present in multiple populations of bighorn sheep near to and distant from their interface with domestic sheep (O. aries) and domestic goat (Capra hircus) and provides critical baseline information needed for interpretations of cross-species transmission risks. Bighorn sheep and livestock shared exposure to Pasteurellaceae, viral, and endoparasite agents. In contrast, although the impact is uncertain,Mycoplasmasp. was isolated from livestock but not bighorn sheep. These results may be the result of historic cross-species transmission of agents that has resulted in a mosaic of endemic and exotic agents. Future work using longitudinal and multiple population comparisons is needed to rigorously establish the risk of outbreaks from cross-species transmission of infectious agents.

Integrating anaerobic processes into wastewater treatment

2011 ◽  
Vol 63 (7) ◽  
pp. 1459-1466 ◽  
Author(s):  
E. J. McAdam ◽  
D. Lüffler ◽  
N. Martin-Garcia ◽  
A. L. Eusebi ◽  
J. N. Lester ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Energy Balance ◽  
Domestic Wastewater ◽  
Granular Sludge ◽  
Ammonia Removal ◽  
Net Energy ◽  
Methane Recovery ◽  
Anaerobic Processes ◽  
Unit Operations ◽  
The Impact

Over the past decade, the concept of anaerobic processes for the treatment of low temperature domestic wastewater has been introduced. This paper uses a developed wastewater flowsheet model and experimental data from several pilot scale studies to establish the impact of integrating anaerobic process into the wastewater flowsheet. The results demonstrate that, by integrating an expanded granular sludge blanket reactor to treat settled wastewater upstream of the activated sludge process, an immediate reduction in imported electricity of 62.5% may be achieved for a treated flow of c. 10,000 m3 d−1. This proposed modification to the flowsheet offers potential synergies with novel unit processes including physico-chemical ammonia removal and dissolved methane recovery. Incorporating either of these unit operations can potentially further improve the flowsheet net energy balance to between +0.037 and +0.078 kWh m−3 of produced water. The impact of these secondary unit operations is significant as it is this contribution to the net energy balance that facilitates the shift from energy negative to energy positive wastewater treatment.

Parasite-induced anorexia in a free-ranging mammalian herbivore: an experimental test using Soay sheep

2006 ◽  
Vol 84 (5) ◽  
pp. 685-692 ◽  
Author(s):  
O.R. Jones ◽  
R.M. Anderson ◽  
J.G. Pilkington
Keyword(s):  
Parasite Burden ◽  
Gastrointestinal Parasites ◽  
Ovis Aries ◽  
Domestic Sheep ◽  
Intake Rate ◽  
Soay Sheep ◽  
Day Range ◽  
Behavioural Effects ◽  
Host Mortality ◽  
Free Ranging

Theory suggests that gastrointestinal parasites can influence herbivore population dynamics by increasing host mortality rates. In addition, parasites may have a non-lethal range of both physiological and behavioural effects on their hosts. Two potential behavioural effects are parasite-induced anorexia and the alteration of diet selection patterns — both of which may influence plant communities without necessarily causing herbivore mortality. We report here the results of an experiment carried out in August–September 2001 to examine herbivore response to parasitism using feral Soay sheep ( Ovis aries L., 1758) living on Hirta, St. Kilda (Scotland, UK), as a model system. The aim of the experiment was to determine whether the sheep exhibit significant parasite-induced anorexia and whether diet selectivity was also altered in response to parasitism. The n-alkane technique was used to estimate forage intake rates and diet composition. Overall, intake rate increased with body mass and the mean (±SE) over both sexes was 737 ± 40 g DM / day (range 458–1241 g DM / day). However, we found no effect of parasite burden upon intake rate or selection patterns. The results of a power analysis imply that any reduction in intake rate was less than 30%, which is less than the 30%–60% reduction in intake rate recorded for domestic sheep under moderate parasite burdens. This suggests that Soay sheep are more resilient to parasitism than domestic breeds. Despite evidence to the contrary from simple farm-based studies, the lack of any effect on selection patterns in this case suggests that parasites do not cause significant alterations to the selection patterns of herbivores in complex non-agricultural environments.

scholarly journals Effects of agronomic factors on yield and quality of whole corn plants and the impact of feeding high concentrations of corn silage in diets containing distillers grains to finishing cattle1

2017 ◽  
Vol 1 (3) ◽  
pp. 367-381 ◽  
Author(s):  
D. B. Burken ◽  
B. L. Nuttelman ◽  
J. L. Gramkow ◽  
A. L. McGee ◽  
K. M. Sudbeck ◽  
...  
Keyword(s):  
Corn Silage ◽  
Distillers Grains ◽  
Net Energy ◽  
Harvest Time ◽  
Marbling Score ◽  
Finishing Diets ◽  
Plant Yields ◽  
Corn Plants ◽  
The Impact ◽  
Corn Grain

Abstract Corn plants were sampled over 2 consecutive years to assess the effects of corn hybrid maturity class, plant population, and harvest time on whole corn plant quality and yield in Nebraska. A finishing experiment evaluated the substitution of corn with corn silage in diets with corn modified distillers grains with solubles (MDGS). The first 2 harvest dates were at the mid- and late-silage harvest times whereas the final harvest was at the grain harvest stage of plant maturity. Whole plant yields increased as harvest time progressed (yr 1 quadratic P < 0.01; yr 2 linear P < 0.01). However, differences in TDN concentration in both years were quite minimal across harvest time, because grain percentage increased but residue NDF in-situ disappearance decreased as harvest time was delayed. In the finishing experiment, as corn silage inclusion increased from 15 to 55% (DM basis) by replacing dry rolled and high moisture corn grain with corn silage in diets containing 40% MDGS, DMI, ADG, and G:F linearly decreased (P ≤ 0.01), with the steers on the 15% corn silage treatment being 1.5%, 5.0%, and 7.7% more efficient than steers on treatments containing 30, 45, and 55% corn silage, respectively. Calculated dietary NEm and NEg decreased linearly as corn silage inclusion increased indicating that net energy values were greater for corn grain than for corn silage. In addition, dressing percentage decreased linearly (P < 0.01) as silage inclusion increased suggesting more fill as silage inclusion increases in diets. Cattle fed greater than 15% corn silage in finishing diets based on corn grain will gain slower and be slightly less efficient and likely require increased days to market at similar carcass fatness and size. When 30% silage was fed with 65% MDGS, DMI, and ADG were decreased (P < 0.01) compared to feeding 30% silage with 40% MDGS suggesting some benefit to including a proportion of corn in the diet. Conversely, when 45% silage was fed with 40% MDGS, ADG, and G:F were greater (P < 0.04) than when 45% silage was fed with just grain implying a greater energy value for MDGS than for corn grain. Substituting corn silage for corn grain in finishing diets decreased ADG and G:F which would increase days to finish to an equal carcass weight; however, in this experiment, increasing corn silage levels with MDGS present reduced carcass fat thickness without significantly decreasing marbling score.

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