Influence of moisture content of forage diets on intake and digestion by sheep.
To determine the effect of forage moisture content on intake and digestion kinetics in sheep, a metabolism trial was conducted using 16 mature wethers (44 kg BW) in a completely randomized design. Forage was harvested at two maturities in early spring from a naturalized pasture composed of temperate grass and legume species. Herbage was harvested at either 8 (early) or 16 cm (late) in height and fed after freezing (high-moisture) or as a dried hay. Intakes of DM (grams/[kilogram BW.75.day]), NDF, ADF, and CP (grams/day) (P < .05) and coefficients for DM, NDF, and ADF digestibilities were greater (P < .01) for hay than for high-moisture forage. Mean particulate retention times (MRT) were shorter (P < .05) for high-moisture forage (23.3 h) than for hay (30.7 h) diets. Early-harvested forages had shorter (P < .05) MRT values (23.9 h) than late-cut forages (30.1 h). Fractional passage rates of 1-mm nylon particles of specific gravity (SG) .90, 1.14, and 1.32 through the alimentary tract were influenced by moisture content of the forage (P < .10) and were faster for frozen forages and increased (P < .01) with an increase in SG. Nitrogen retention was greater (P < .01) for the hay than for the high-moisture forage. In situ DM digestion rates, determined using four ruminally fistulated wethers, showed no differences (P = .67) among forages. The results of this study indicate that differences in digestibilities between hays and high-moisture forages are most likely due to differences in digesta passage rates.
Pasha
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Division of Animal and Veterinary Science, West Virginia University, Morgantown 26505-6108.
Prigge
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Russell
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Bryan
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D000821:Animal Feed; D000818:Animals; D004043:Dietary Fiber / Q000008:administration & dosage; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D004435:Eating; D005772:Gastrointestinal Transit; D008297:Male; D009584:Nitrogen / Q000378:metabolism; D006109:Poaceae / Q000737:chemistry*; D011897:Random Allocation; D012756:Sheep / Q000502:physiology*; D014867:Water / Q000032:analysis
D004043:Dietary Fiber; D004044:Dietary Proteins; D014867:Water; D009584:Nitrogen