Independent Variables for Predicting Intake Rate of Mammalian Herbivores: Biomass Density, Plant Density, or Bite Size?

Oikos ◽  
1993 ◽  
Vol 68 (1) ◽  
pp. 75 ◽  
Author(s):  
John E. Gross ◽  
N. Thompson Hobbs ◽  
Bruce A. Wunder
Keyword(s):  
Plant Density ◽  
Intake Rate ◽  
Biomass Density ◽  
Bite Size ◽  
Mammalian Herbivores ◽  
Independent Variables

Effect of species composition and sward structure on the ingestive behaviour of cattle and sheep grazing South African sourveld

1996 ◽  
Vol 127 (2) ◽  
pp. 271-280 ◽  
Author(s):  
P. J. O'Reagain ◽  
B. C. Goetsch ◽  
R. N. Owen-Smith
Keyword(s):  
Species Composition ◽  
Plant Height ◽  
Functional Response ◽  
Major Effect ◽  
Intake Rate ◽  
Sheep Grazing ◽  
Bite Size ◽  
Ingestive Behaviour ◽  
Cattle And Sheep ◽  
Sward Structure

SUMMARYThe effects of species composition and sward structure on the ingestive behaviour of cattle and sheep grazing a mesic, low quality grassland in South Africa were investigated over the 1990–93 grazing seasons. Species composition had a significant (P < 0·05) effect on sheep bite size and on cattle and sheep bite rates but had no effect on dry matter intake rate (IR). Species composition could, however, affect IR over longer grazing periods than those used in the experiment.Sward structure had a major effect on ingestive behaviour. Cattle and sheep bite rates and cattle grazing time, were negatively correlated (P < 0·05) with plant height but positively correlated (P < 0·05) with sward greenness. Bite size and hence IR in cattle and sheep were strongly correlated (P < 0·001) with plant height. Cattle IR increased from 6 to 20g/min over the range of heights encountered and appeared to reach an asymptote at a plant height of 20–25 cm. Sheep IR, expressed per unit of body mass, increased from 0·01 to an asymptote or maximum of 0·13 g/min/kg at plant heights of 10–15 cm. For sheep there was evidence of a non-asymptotic functional response at some sites with IR being maximized at certain sward heights but declining thereafter. This suggests the possible existence of a third, quality dimension to the functional response on these low-quality grasslands.

Further development of the Spalinger-Hobbs mechanistic foraging model for free-ranging moose

1999 ◽  
Vol 77 (10) ◽  
pp. 1505-1512 ◽  
Author(s):  
John Pastor ◽  
Katie Standke ◽  
Keith Farnsworth ◽  
Ron Moen ◽  
Yosef Cohen
Keyword(s):  
Mechanistic Model ◽  
Sequence Length ◽  
Intake Rate ◽  
Frequency Distributions ◽  
Bite Size ◽  
Bite Rate ◽  
Independent Events ◽  
Epilobium Angustifolium ◽  
Free Ranging ◽  
Further Development

Spalinger and Hobbs proposed a mechanistic model of forage intake based on the mutually exclusive actions of biting and chewing. A necessary consequence of this model is that an animal postpones the intake of more food by biting when it is processing food by chewing. In previous work, the Spalinger-Hobbs model successfully predicted short-term intake in controlled experiments. Application of the model to an entire foraging bout requires the following assumptions: (i) biting and chewing are independent events; (ii) there are no periodicities in the length of consecutive bite or chew sequences; (iii) the average bite size is constant; and (iv) the bite rate does not change with the number of bites in the sequence. To test these assumptions, we videotaped entire foraging bouts of two free-ranging moose (Alces alces) feeding on dense swards of Epilobium angustifolium in midsummer. From these videotapes, we measured the time spent biting and chewing, the rates of biting and chewing, the frequency distributions of consecutive bite and chew sequences, and lengths of E. angustifolium shoots above the point of cropping. Plant samples were collected in order to determine bite mass. A total of 1050 bites and chews were analyzed for moose 1 and 1925 bites and chews for moose 2. For both moose, three chewing events occurred, on average, for each bite event. Given this 1:3 bite:chew ratio, the frequency distributions of consecutive bite and chew sequences were as expected from a geometric distribution of independent events. There were no time-series correlations or dominating frequencies in the lengths of bite and chew sequences. These findings fulfill the first three assumptions required to extend the Spalinger-Hobbs model to entire foraging bouts. However, the fourth assumption was not fulfilled, in that time spent per bite increased asymptotically with bite-sequence length. We therefore incorporated the effect of bite-sequence length on bite rate into the Spalinger-Hobbs model. The new model predicts that to simultaneously maximize the marginal intake rate with respect to both bite rate and bite mass, a moose should take single bites most often and bite mass should be approximately 3.6 g. Eighty-two percent of bite sequences were composed of single bites for both moose, and we and others independently observed a bite size of 3.24-3.75 g for free-ranging moose. These observations lend credibility to our modified model.

Mechanics of browsing in dense food patches: effects of plant and animal morphology on intake rate

1992 ◽  
Vol 70 (9) ◽  
pp. 1743-1752 ◽  
Author(s):  
Lisa A. Shipley ◽  
Donald E. Spalinger
Keyword(s):  
Functional Response ◽  
Rangifer Tarandus ◽  
Asymptotic Relation ◽  
Acer Rubrum ◽  
Neutral Detergent Fiber ◽  
Intake Rate ◽  
Red Maple ◽  
Bite Size ◽  
Snowshoe Hares ◽  
Asymptotic Function

There appear to be two dominant forms of the functional response of vertebrate herbivores, corresponding to animals foraging in spatially concentrated or spatially dispersed food patches. We examine the factors contributing to the functional response of herbivores feeding on spatially concentrated browses. Specifically, we tested the hypothesis that the instantaneous intake rate of four boreal browsers (moose, Alces alces, woodland caribou, Rangifer tarandus caribou, white-tailed deer, Odocoileus virginianus, and snowshoe hares, Lepus americanus) feeding on red maple (Acer rubrum) browse is an asymptotic function of the size of bite obtainable by the herbivore. Based on this functional response model, we also hypothesized that (i) cropping rate of the herbivores would decline curvilinearly with bite size, (ii) intake rate would decline with increasing fibrousness (measured, as the neutral detergent fiber of the foods consumed), and (iii) maximum intake rate would scale as the 2/3 power of herbivore body mass (BM). Intake rates of all animals increased 2- to 10-fold with increasing bite size of stems and leaves, and conformed to the hypothesized asymptotic relation. Similarly, cropping rate declined curvilinearly with increasing bite size, and intake rate declined with increasing fibrousness of foods consumed. Maximum intake rate scaled with BM0.76, not significantly different from the hypothesized exponent of 0.67. These data support the hypothesis that bite size affects intake rate by controlling the ratio of cropping and chewing, and that the asymptotic intake rate of herbivores is related to the food processing capability of the mouth.

scholarly journals Effect of nitrogen on intake and digestibility of a tropical grass grazed by Creole heifers

2002 ◽  
Vol 138 (1) ◽  
pp. 73-84 ◽  
Author(s):  
M. BOVAL ◽  
P. CRUZ ◽  
J. E. LEDET ◽  
O. COPPRY ◽  
H. ARCHIMEDE
Keyword(s):  
Nitrogen Fertilizer ◽  
Crude Protein ◽  
Live Weight ◽  
Leaf Number ◽  
Intake Rate ◽  
Bite Size ◽  
Nitrogen Levels ◽  
Sward Height ◽  
Biting Rate

So far, little has been done on the effect of nitrogen fertilizer on intake and digestibility in tropical grazing conditions. The effect of two nitrogen levels, 0 (NF) and 50 kg/ha (F) for three successive grazing cycles, on organic matter intake (OMi) and digestibility (OMd) for Creole heifers (208 kg live weight) was determined. Two groups of four tethered heifers, allowed 18 kg of dry matter daily, grazed individual NF or F circular areas at 28 re-growth days. The heifers were moved and watered daily. Sward characteristics (height, herbage mass, morphological and chemical composition and in situ tiller measurements), OMi, OMd and feeding behaviour (biting rate, bite size, intake rate, grazing and ruminating times) were evaluated simultaneously per circular area.Under nitrogen fertilizer, the stems elongated rapidly (by 133%) as did the leaves, but to a lesser extent (by 40%). Consequently, canopy height, leaf and stem masses and crude protein content increased (respectively by 100%, 66%, 186% and 40%), while total bulk density decreased (by 10·5%). Throughout the successive grazing cycles, there was a particular effect on leaf number, both in the F and NF swards, whereas this parameter was not affected by the fertilizer level. Under fertilizer, OMi and OMd were both 9% greater than for the NF sward. The increase in herbage CP content partly explains the rise in OMi, and there is evidence that rumen load has a determining effect on OMi. Leaf mass is the major factor accounting for the 9% increase in OMd under fertilizer regime. On the other hand, whatever the fertilizer regime, OMd was positively influenced by the greater leaf number throughout the grazing cycles. Biting rate, bite size and intake rate were determined respectively by sward height, CP content and stem fraction, whereas grazing and ruminating times were partially influenced by sward characteristics.

Predicting Bite Size Selection of Mammalian Herbivores: A Test of a General Model of Diet Optimization

Oikos ◽  
1999 ◽  
Vol 84 (1) ◽  
pp. 55 ◽  
Author(s):  
Lisa A. Shipley ◽  
Andrew W. Illius ◽  
Kjell Danell ◽  
N. Thompson Hobbs ◽  
Donald E. Spalinger
Keyword(s):  
General Model ◽  
Bite Size ◽  
Mammalian Herbivores ◽  
Size Selection ◽  
Selection Of ◽  
Diet Optimization

scholarly journals Mechanisms and implications of a type IV functional response for short-term intake rate of dry matter in large mammalian herbivores

2017 ◽  
Vol 86 (5) ◽  
pp. 1159-1168 ◽  
Author(s):  
Jean C. Mezzalira ◽  
Olivier J. F. Bonnet ◽  
Paulo C. de F. Carvalho ◽  
Lidiane Fonseca ◽  
Carolina Bremm ◽  
...  
Keyword(s):  
Functional Response ◽  
Dry Matter ◽  
Intake Rate ◽  
Short Term ◽  
Mammalian Herbivores ◽  
Type Iv

The Scaling of Intake Rate in Mammalian Herbivores

1994 ◽  
Vol 143 (6) ◽  
pp. 1055-1082 ◽  
Author(s):  
Lisa A. Shipley ◽  
John E. Gross ◽  
Donald E. Spalinger ◽  
N. Thompson Hobbs ◽  
Bruce A. Wunder
Keyword(s):  
Intake Rate ◽  
Mammalian Herbivores

scholarly journals Winter foraging dynamics of woodland caribou in an artificial landscape

Rangifer ◽  
1996 ◽  
Vol 16 (4) ◽  
pp. 235
Author(s):  
Eric M. Rominger ◽  
Charles T. Robbins
Keyword(s):  
Forest Management ◽  
Intake Rate ◽  
Woodland Caribou ◽  
Bite Size ◽  
Bite Rate ◽  
Factors Influencing ◽  
Winter Foraging

The data suggest that arboreal lichen biomass and/or bite size are primary factors influencing intake rate. Caribou did not increase bite rate to compensate for smaller bite sizes or decreased biomass. Forest management should enhance lichen production to maximize intake rates for woodland caribou.

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