Master of Science / Department of Agronomy / Clenton E. Owensby / Currently there are no model inputs for eastern gamagrass [Tripsacum dactyloides
(L.) L] for use in the National Research Council's (NRC) beef cattle model. This study
was conducted to determine model inputs for two eastern gamagrass varieties for use
with the forage database of the NRC model. Cattle producers in the Midwestern US will
be able to evaluate eastern gamagrass in a forage system and estimate net energy for
maintenance (NEm), metabolizable protein (MP), and degradable intake protein (DIP)
balance for various production scenarios. Eastern gamagrass varieties 'Iuka' and 'Pete'
were arranged in a split-plot randomized complete block experiment with four
replications. Varieties were whole plots with harvest maturities as split plots. Plant
tissue was harvested from both varieties at four maturities: vegetative/early elongation,
anthesis, seed shattering and dormancy. Various compositional attributes were
determined on forage samples to enable the determination of model inputs for predicting
energy and protein balances. A slight difference between varieties was found for crude
protein concentration (p<0.05). Differences (p<0.05) due to maturity were found for all
analyses used in the model, corroborating the decline in nutritive value of eastern
gamagrass with advancing maturity. Neutral detergent fiber (NDF) ranged from 593 g
kg-1 at the vegetative/early elongation stage of maturity to 731 g kg-1 at dormancy.
Assumed animal and environmental inputs were used for beef cattle at two stages: nonlactating
160 d prepartum and 60 d peak lactation. Energy and protein balance were
estimated using level I of the model. The vegetative/early elongation stage of
development supplied the greatest amount of MP. Digestible intake protein declined as
plant tissue matured. All but the vegetative/early elongation stage of maturity were
limited in DIP for cows in both stages of production. Soybean meal was used as a protein
supplement in amounts ranging from 0.8 kg to 1.4 kg to meet nutritional demands of
cattle grazing eastern gamagrass at anthesis, seed shattering and dormancy. In the
simulations conducted, eastern gamagrass would be an acceptable forage source for beef
cattle provided that appropriate protein supplementation was given when the forage was
at more advanced stages of maturity.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/997 |
| Date | January 1900 |
| Creators | Meredith, Alisa Kaye |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
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