Foraging mechanics and their outcomes for cattle grazing reproductive tropical swards

Benvenutti, Marcelo A., Gordon, Iain J., Poppi, Dennis P., Crowther, Robert and Spinks, Warwick (2008) Foraging mechanics and their outcomes for cattle grazing reproductive tropical swards. Applied Animal Behaviour Science, 113 1-3: 15-31. doi:10.1016/j.applanim.2007.10.005

Author Benvenutti, Marcelo A.
Gordon, Iain J.
Poppi, Dennis P.
Crowther, Robert
Spinks, Warwick
Title Foraging mechanics and their outcomes for cattle grazing reproductive tropical swards
Journal name Applied Animal Behaviour Science   Check publisher's open access policy
ISSN 0168-1591
Publication date 2008-09-01
Year available 2007
Sub-type Article (original research)
DOI 10.1016/j.applanim.2007.10.005
Open Access Status DOI
Volume 113
Issue 1-3
Start page 15
End page 31
Total pages 17
Editor C. Petherick
P. Jensen
Place of publication Netherlands
Publisher Elsevier BV
Language eng
Subject C1
070202 Animal Growth and Development
8303 Livestock Raising
Abstract For grazing animals an important determinant of animal performance is the rate of nutrient intake (RNI) which depends on diet quality and instantaneous intake rate (IIR). In turn, diet quality and IIR are the outcome of the interaction between the morphology and behaviour of the animal and the structure of the sward. Using artificial microswards of Panicum maximum we evaluated the effect of four levels of the tensile resistance of stems in tropical swards on the grazing behaviour of cattle of two age classes (1- and 3-year-old steers) faced with a stem barrier either in a vertical (experiment 1, E1) or horizontal plane (experiment 2, E2). The animals did not select against low tensile resistance stems (LTRS) but did avoid high tensile resistance stems (HTRS) which resulted in a significant difference (P < 0.001) between diet DM (dry matter) digestibility and forage DM digestibility in swards with HTRS. IIR decreased (P < 0.001) on average 62% in E1 and 67% in E2 as stem tensile resistance increased, 144% and 177% in E1 and E2, respectively. This led to a reduction (P < 0.001) in digestible DM IIR in both young and mature cattle respectively of 56% and 68% in E1, and 45% and 79% in E2, as stem tensile resistance increased. The decline in IIR was due to an increase in time per bite and a reduction in bite dimensions that were the result of different mechanisms in the two experiments: when leaves were taller than the stems (E1) the decrease in bite area was associated with an asymptotic increase (P < 0.001) in bite force in mature animals, and a maintenance (P = 0.456) of bite force in young animals, suggesting that maximum bite force regulated bite area in E1. This was not the case in E2 because both bite area and bite force decreased (P < 0.05) with the increase in stem tensile resistance suggesting that the animals were not able to gather enough plant material with the tongue in order for bite force to regulate bite area. We conclude that bite force and tongue force regulate selectivity and bite dimensions, which are the ultimate determinants of the RNI; IIR is the primary determinant of the RNI with diet quality being of lesser importance; and HTRS act as deterrents to achieving maximum IIR in tropical swards, particularly in mature cattle.
Keyword Foraging behaviour
Tropical pastures
Diet quality
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ
Additional Notes Epublication 28 November 2007

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Agriculture and Food Sciences
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Citation counts: TR Web of Science Citation Count  Cited 18 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 18 times in Scopus Article | Citations
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Created: Fri, 17 Apr 2009, 00:01:22 EST by Mrs Kathy Bachmann on behalf of School of Animal Studies