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Title: Overview of forage nutritive quality and availability in relations to cattle needs during the fall transition period in the Southeastern US

item BECK, PAUL - University Of Arkansas
item GADBERRY, MICHAEL SHANE - University Of Arkansas
item Gunter, Stacey

Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 9/14/2016
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: The forages in the Southeastern region are affected by both east-to-west and north-to-south climate gradients. Predominant forages in the western reaches (western Oklahoma and Texas) of the region are native warm-season (NWSG) and introduced bunch grasses with transitions to tall fescue dominated pastures in the northeastern areas of the Southeast (Kentucky, Tennessee, Virginia, North Carolina, and northern areas of eastern Oklahoma, Arkansas, Mississippi, Alabama, Georgia, and South Carolina) and sod-forming introduced warm-season grasses in the southern part of the Southeast (Louisiana, Florida, eastern Oklahoma, and Texas as well as southern portions of Arkansas, Mississippi, Alabama, Georgia, and South Carolina). The forage base in these diverse areas contribute to gaps in forage availability or nutrient deficiencies during different portions of the year for growing calves and brood cows. Managed introduced warm-season grasses normally have greater crude protein (CP) concentrations than NWSG, yet seasonal changes in nutritive quality and relative growth of forages rates follow similar patterns throughout the year. During the late spring and early summer, CP is usually greatest and detergent fiber concentrations the least with increases in detergent fiber and decreases in CP as the summer progresses to autumn. Tall grass species of NWSG have a more pronounced decline in nutritive quality than introduced grasses, decreasing from 15% CP (dry matter basis) in the late spring to = 4% CP (dry matter basis) during the late summer. Bahiagrass (Paspalum notatum) grown in southern Arkansas was analyzed to contain 13% CP (dry matter basis) in June only declining to 11% CP (DM basis) by August, likewise bermudagrass (Cynodon dactylon) grown in southern Arkansas did not have appreciable reductions in CP from the early summer (13% CP dry matter basis) to late summer (12% CP dry matter basis). Accumulation of bermudagrass DM during the late fall (September and October) are frequently < 25% of accumulations measured during the peak growth rate in July. Tall fescue (Festuca arundinacea [Schreb.] Darbysh.) has a much greater CP and lesser detergent fiber concentration during the fall and early spring then during the late spring and summer following stem elongation and seed head emergence, but forage accumulation rates are much greater during the spring growing period than during the fall. Gaps in forage availability for beef production is a result of slowing forage growth rates and decreasing forage quality in warm-season forages and slow growth rates of cool-season grasses. Forage management and complementary forages are necessary to sustainably fill these gaps to create year round grazing systems.