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Associate Professor
51C McCord Hall
2640 Morgan Circle Drive
Knoxville, TN 37996-4574
(865) 974-3150
Fax: (865)974-7297
Email: jwaller@utk.edu
Research Appointment: 70%
Teaching Appointment: 30%
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EDUCATION and TRAINING
B.S. University of Florida
M.S. University of Nebraska
Ph.D. University of Nebraska
RESEARCH INTERESTS
Southern Extension and Research
Activity Information Exchange Group 8 - Fescue Endophyte Reseach
and Extension
IMPROVING EFFICIENCY OF BEEF PRODUCTION ON TALL FESCUE PASTURE
SYSTEMS: Tall fescue is the predominant cool-season grass in
Tennessee because of its persistence and its productivity in spring
and fall. More than 95% of existing tall fescue pastures are infested
with the endophytic fungus Neotyphodium coenophialum which
causes tall fescue toxicosis and costs the Tennessee beef industry
about 100 million dollars annually. My research focuses on quantifying
performance and physiological characteristics of beef cattle grazing
endophyte-infested tall fescue. Specifically, these studies involve
the use of pasture systems located at branch experiment stations
across the state and the metabolic and analytical laboratories located
in Knoxville. This research is a vital component of the University
of Tennessee Tall Fescue Toxicosis Team which is a collaborative
effort involving investigators representing many disciplines from
several departments.
EVALUATION OF NONTOXIC ENDOPHYTE/TALL FESCUE CULTIVAR COMBINATIONS:
Tall fescue benefits from association with the endophytic fungus
N. coenophialum because of alkaloids produced by the fungus/host
plant combination. The alkaloids are biologically active compounds
that suppress consumption of endophyte-infected tall fescue by both
mammals and insects, while enhancing stress and drought tolerance
of the host plant. Removal of the fungus from tall fescue results
in a plant that does not persist under normal grazing conditions.
Researchers in New Zealand have identified strains of endophytic
fungus that do not produce the alkaloids associated with fescue
toxicosis in cattle. These new nontoxic endophyte have been placed
in elite cultivars of tall fescue to create a potentially new approach
to reducing the toxicosis problem. Evaluation of these new nontoxic
endophyte/tall fescue cultivar combinations under grazing conditions
and measuring the responses in animals is essential.
IMPROVING REPRODUCTIVE PERFORMANCE OF BEEF CATTLE GRAZING ENDOPHYTE-INFECTED
TALL FESCUE: Research conducted at The University of Tennessee
and other locations where endophytic-infected tall fescue is the
major forage base for beef cattle operations have reported calf
crop percentages of 50 to 55% compared to 85 to 95% in non-fescue
systems. Understanding when these losses in fertility occur is very
important to developing management systems to alleviate this problem.
Currently, studies are underway to identify the most critical periods
in the reproductive cycle affected by the alkaloids produced by
the endophytic fungus. This knowledge will enable us to design strategies
to reduce the reproduction inefficiency, thus improving profitability
for beef producers.
QUANTIFYING THE CONTRIBUTION RUMINANTS MAKE TO THE ENVIRONMENT:
Methane produced by enteric fermentation in domesticated ruminants
is an important research area because methane represents an energetic
inefficiency of microbial fermentation. Methane also is suspected
of playing an important role in global warming. Tall fescue pastures
managed in different ways provide an economically important experimental
situation in which to study whether methane emissions from cattle
can be mitigated with improved management strategies. The sulfur
hexafluoride tracer technique is used to determine the effects of
tall fescue pasture management on consequential methane production.
Tall fescue comprises 37 million acres of pasture in the U.S. By
determining methane emissions from beef steers and cows grazing
tall fescue, benchmarks for future decisions involving grazing ruminants
and methane emissions can be established.
CHANGING THE NUTRIENT COMPOSITION OF MEAT AND MILK FROM RUMINANT
ANIMALS: Nutrient composition of ruminant products is influenced
greatly by the microbial fermentation of feedstuffs within the rumen.
This is one of the most unique aspects of how ruminant animals contribute
to our food supply by converting high fiber, low quality feedstuffs
to highly nutritional products such as meat and milk. However, the
fatty acid profile of ruminant products contains more saturated
fat than desired by today's consumer. Shifting to less saturated
fat in these products is difficult because the rumen microbes change
unsaturated fat fed to the animal to saturated fat before it is
deposited in meat and milk. Protecting unsaturated fat from attack
by rumen microbes would result in products of less saturated fat.
Collaborative research with a food chemist and a biosystems engineer
has resulted in a new method to protect selected compounds, including
fat, from degradation by rumen microbes. Both meat and milk have
been produced with significantly more unsaturated fat as a result
of feeding supplements produced using this new method. Future applications
of this method are promising.
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