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FACTORS AFFECTING FORAGE QUALITY pp. 232 - 246

FACTORS AFFECTING FORAGE QUALITY pp. 232 - 246. FORAGES OR ROUGHAGES. General characteristics Higher fiber concentration than energy and protein supplements Lower energy concentration than energy or protein supplements Lower protein concentration than protein supplements

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FACTORS AFFECTING FORAGE QUALITY pp. 232 - 246

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  1. FACTORS AFFECTING FORAGE QUALITYpp. 232 - 246

  2. FORAGES OR ROUGHAGES • General characteristics • Higher fiber concentration than energy and protein supplements • Lower energy concentration than energy or protein supplements • Lower protein concentration than protein supplements • May have higher or lower protein concentration than energy supplements • A high proportion of the protein in most forages is highly degraded in the rumen • Calcium concentration greater than energy and plant protein supplements • Concentrations of phosphorus and other minerals is highly variable • Concentrations of fat soluble vitamins high in fresh forages, but low after storage

  3. WHAT DEFINES FORAGE QUALITY?

  4. FACTORS DETERMINING FORAGE QUALITY • Forage species • Maturity • Soil fertility • Harvest method and quality of storage • Leaf-to-stem ratio • Nutrient preservation

  5. MAJOR CLASSES OF FORAGE SPECIES

  6. NUTRITIONAL VALUE OF LEGUMES, COOL SEASON GRASSES, AND WARM SEASON GRASSES AT COMPARABLE MATURITIES

  7. COOL SEASON GRASSES • Most common grasses in the Midwest • Kentucky bluegrass- Tall fescue -Smooth bromegrass • Orchardgrass - Reed canarygrass - Timothy • Perennial ryegrass • Growth • 66% of production occurs before early-June • Very low productivity in mid-summer • Some late season growth • Yields • Species effects Tall fescue Reed >Smooth bromegrass>Timothy>>Kentucky canarygrassOrchardgrass bluegrass • Very sensitive to soil fertility • N, P, and K • When is it needed???????

  8. USES OF COOL SEASON GRASSES

  9. NUTRITIONAL QUALITIES OF COOL SEASON GRASSES

  10. ANTI-QUALITY COMPONENTS IN COOL SEASON GRASSES • Endophyte fungus • Found in • Tall fescue • Perennial ryegrass • Produces toxic alkaloids • Classes • Lysergic acid amides • Ergopeptines • Ergovaline • Location • Primarily in the seed • Also in stem and leaf • Transfer to a pasture • Via the seed

  11. Effects of fescue toxicosis • Physiological effects • Vasoconstriction • High core body temperatures • Low heart rate • Low prolactin • Suppression of immune system • Results on animal • Hoof loss • Low forage intake and weight gains during summer • Retention of winter hair coat • Standing in water sources • Low milk production • Reproductive problems • Low pregnancy rate • Dystocia • Retained placenta

  12. Management to prevent fescue toxicosis • Prevent excessive maturity of forage • Limit application of N-fertilizer • Plant or interseed legume forages in tall fescue pastures • Rotate animals to non-fescue pastures • Plant endophyte-free varieties of tall fescue • Poor persistence • Plant tall fescue varieties containing beneficial endophyte • Treatment of cattle with Ivermectin??? • A dewormer • Treatment of pregnant mares with Domperidone • Blocks receptors for dopamine

  13. Tryptamine alkaloids • Common in native reed canarygrassvarieties • Physiology • Serotonin receptor agonists • Can cause staggers or sudden death • Common effects on animal • Reduced feed intake and growth • Management • Plant low alkaloid varieties of reed canarygrass • Rotate animals for paddocks that do not contain reed canarygrass • Cobalt supplementation

  14. LEGUMES • Species • Alfalfa Red clover White clover Birdsfoot trefoil Sweet clover Berseem clover Sweet clover • Growth • Greatest in spring, but more uniform over the season than grasses • Yields Alfalfa > Red clover > Birdsfoot trefoil >> White clover Sweet clover • Fertility needs • N fertilization is not required • May reduce legume persistence in grass-legume pasture • Sensitive to pH, P, and K • Persistence • Very sensitive to management • Most species require some type of rest period to allow nutrient storage in roots and crown and/or reseeding • Competition with cool season grasses • Sensitive to most herbicides

  15. USES OF LEGUMES

  16. NUTRITIONAL QUALITIES OF LEGUMES

  17. NUTRITIONAL CONCERNS WITH LEGUME FORAGES • Bloat • Inability of ruminants to release fermentation gases • Occurs in ruminants consuming fresh, immature legumes like alfalfa, white clover, red clover, and kura clover • Caused by a high concentration of soluble protein in these legumes • Results in the formation of foam in the rumen • Inhibits eructation • Can result in death

  18. Bloat prevention • Plant mixtures of grasses and legumes • Utilize non-bloating legumes • Allow legumes to mature before grazing • Feed animals some dry hay before placing animal on pastures • Avoid moving animals into a pasture or paddock containing a high concentrations of legumes early in the morning • Limit the daily forage allowance to the cattle • Have water available in each paddock of a rotationally grazed pasture • Make poloxaleneavailable to animals grazing legumes • Sold as ‘Bloatguard’ • Available in blocks or supplements • Intake can be variable

  19. Phytoestrogens • Present in alfalfa, red clover, and ladino clover • Have affected reproduction and mammary development in sheep • Coumarin • Present in sweet clover • Converted to dicoumarol in moldy sweet clover • Results in hemorrhaging in animals consuming the hay • Tannins • Present in birdsfoot trefoil • Reduce protein degradation in the rumen and feed intake

  20. WARM SEASON GRASSES • Warm season grasses • Perennial • SwitchgrassBig bluestem Eastern gamagrass • Annual • Sudangrass Sorghum x SudangrassCorn • Growth • 70% of production occurs in June and July • Yields • Very productive • Very sensitive to soil fertility • N, P, and K • Persistence • Require rest • Competition with cool season grasses • Very sensitive to early harvest or grazing

  21. USES OF WARM SEASON GRASSES

  22. NUTRITIONAL QUALITIES OF WARM SEASON GRASSES

  23. NUTRITIONAL CONCERNS WITH WARM SEASON GRASSES • Nutritional quality of perennial WSG • Nitrates • Most common in drought-stricken corn and sorghum • Highest concentrations in stalks • Also present in some weeds • Converted to nitrite in the rumen • Inhibits oxygen transport by hemoglobin • Levels (DM basis) • < 3000 ppm Safe • 3000 - 6000 ppm Limit to 50% of diet for stress animals • 6000 – 9000 ppm Potentially toxic to cattle; Do not feed as only component of diet • >9000 ppm Dangerous to cattle • Management • Ensile crops • Take measures to avoid exposure to nitrogen dioxide • Dilute high nitrate feeds with other feeds • Particularly grains

  24. Cyanogenic glycosides • Present in new growth of sorghum x sudangrass and sudangrass forages • May be in spring growth or regrowth after harvest, drought or frost • Converted hydrocyanic acid (prussic acid) • Inhibits oxygen uptake by the hemoglobin • Management • Avoid grazing until forage is a minimum of 18 inches tall

  25. Excessive corn intake • May occur in cattle grazing standing corn or grazing corn stalks fields with a large amount of fallen ears • May result in lactic acidosis or founder of the grazing animals • Management: • Limit grain intake by controlling access

  26. AnnualPasture Options

  27. ANNUAL FORAGESSpecies • Useful as cover crops following row crop harvest

  28. LIMITATIONS OF ANNUAL FORAGES • May have limited production • Drought • Length of growing season before frost • Shading in standing row crop • Weather losses of nutrients • Problem with brassicas and berseem clover • Winter varieties must be killed before planting in the subsequent year • Unless reseeding is desired (Annual rye) • Limited spring use • Soil compaction • Late growth • Health problems • Bloat with brassicas and wheat • Goitrogens in brassicas

  29. Chicory • A perennial broadleaf from sunflower family • Drought resistant • Persistent for three to four years • Uses • Good for grazing • Poor for harvest • Good nutritional value: • 60 – 70% TDN • 13 – 16% CP

  30. MATURITY EFFECTS ON FORAGE QUALITY • Increasing forage maturity • Increases NDF • Reduces feed intake • Increases ADF and lignin • Reduces digestibility • Reduces CP and soluble carbohydrates • Reduces digestiblity

  31. EFFECTS OF MATURITY ON THE COMPOSITION OF FORAGES SB NDF, % DM 35 40 45 50 55 60 65 Alf ADL, % DM 5 10 15 Alf SB I M Maturity I M Maturity Alf Alf Digestible DM, %DM 45 50 55 60 65 70 CP, %DM 5 10 15 20 SB SB I M Maturity I M Maturity

  32. CHANGES IN PLANT STRUCTURE WITH MATURITY Immature Mature Secondary cell wall (Cellulose) Cell Contents L L L L CC L LLLLL Primary cell wall (Hemicellulose) Middle lamella (Lignin)

  33. LIGNIN • A complex polymer of phenylpropane units • Binds to hemicellulose in cell wall • Needed to provide strength to plant • Increases with maturity • Reduces the digestibility of plant cell walls • Bonds to carbohydrates differ between forage species • Legumes • Ether linkages • Tough • Grasses • Ester linkages • Degraded by alkali treatment

  34. STRATEGIES TO MANAGE LIGNIN BEYOND CONTROLLING MATURITY • Alkali treatments • Mature grass, straw, corn stalks • Treatments • 3% anhydrous ammonia • 4% sodium hydroxide • 5% calcium oxide • Calcium hydroxide ??? • Effects • Increase digestibility 10% • Increase intake 20% • Only effective on grass lignins • Economics • Profitable at high feed prices • A potential replacement for corn in ruminant diets?

  35. Brown mid-rib varieties • Corn and Sorghum • Genetically engineered to have lower lignin content • Increases digestibility and intake of forage • Reduce stem strength

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