ABI PhD candidate wins Dairy prize

10 February 2015

 

PhD candidate Stephen Waite was awarded the $1000 prize for “Best Talk” at the inaugural Auckland Dairy School Seminar Day with his presentation “A Computational Model of Rumen Structure and Motility”. In his the first year of doctoral study at the ABI, Stephen was one of 9 postgraduate students presenting for a period of 15 minutes each, followed by 5 minutes of questions per presentation.

Stephen’s supervisors are Dr Vinod Suresh, John Cater, and Dr Garry Waghorn of DairyNZ. For more information on Stephen and/or his supervisors, see the related links below.

The Auckland Dairy School Seminar Day was mounted by the Joint Graduate School in Dairy Research and Innovation, which is hosted by the University of Auckland's Faculty of Science, AgResearch, DairyNZ, and LIC. The aim of the school is to “educate future leaders of the dairy industry” through facilitating post graduate study in relevant areas.

 

A Computational Model of Rumen Structure and Motility

Abstract:
A major challenge for the New Zealand dairy and sheep farming sector is the need to improve animal productivity while maintaining and enhancing sustainability. Improvements in feed conversion efficiency, mitigation of disorders such as bloat and reduction of methane emissions (which represent a loss of bioavailable energy) will have significant economic and environmental payoffs.  Previous work focusing towards these goals has looked at issues such as animal intakes, diet chemical composition and digestibility, inhibiting methanogenesis and understanding variation between animals. Little attention has been given to the physical aspects of digestion in the ruminant forestomach (rumen) – breakdown of feed, mixing of rumen contents and outflow rates of digesta – and how they are influenced by rumen size and structure. Yet there is evidence that differences in rumen size and outflow rates are correlated with methane production and feed conversion efficiency.

The aim of this research is to develop a computational model that incorporates anatomical structure and muscular contractions to describe the physical processing of feed in the rumen. This model will then be combined with existing simulation models of rumen microbial chemistry and nutrient utilisation to produce a fully process driven model of rumen digestion.

In this talk I will describe the progress towards the development of the model. To model the geometry, excised sheep rumens were plaster cast while submerged within a buoyancy fluid and the surfaces were laser scanned. Data clouds from the scans were used to create a three dimensional surface mesh of the rumen. This mesh can then be used within a computational fluid dynamics (CFD) environment to simulate rumen contractions that drive mixing and outflow of digesta. To determine the mechanical properties of rumen tissue for simulating contractions uniaxial tension tests were performed on samples of rumen tissue at different locations and orientations. Histological studies were also performed to visualise the distribution of muscle and collagen within the rumen wall.

 

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