ARS | Publication request: Dry Matter Intake and Digestion of Perennial and Annual Cool-Season Grasses by Sheep

Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 10, 2009
Publication Date: October 13, 2009
Citation: Phillips, W.A., Northup, B.K., Venuto, B.C. 2009. Dry matter intake and digestion of perennial and annual cool-season grasses by sheep. Professional Animal Scientist. 25:610-618.

Interpretive Summary: Excess spring perennial cool-season grass forage production can be harvested as hay and stored for feeding later. The objectives of these experiments were to estimate dry matter intake and digestibility of perennial cool-season grasses relative to an annual cool-season grass harvested as either high moisture hay, requiring only 24 h of field drying, but wrapped in plastic, or as field dried hay, requiring several days before drying and increasing the risk of rain damage. The drying process to produce field dried hay was accomplished without a rain event occurring. As a result, little differences were noted in nutrient density between field dried and high moisture hays. Lambs consumed more field dried wheat hay than field dried perennial cool-season grass hay. Lambs compensated for lower digestibility of field dried wheat hay by increasing hay intake in comparison to field dried perennial cool-season grass hay and could be an explanation for greater animal performance observed for calves grazing wheat pasture as compared to calves grazing perennial cool season grasses.

Technical Abstract: Excess perennial cool-season grass production can be harvested as hay for feeding later. Thus a series of experiments were conducted to estimate DMI and digestibility of perennial cool-season grasses relative to an annual cool-season grass harvested as either high moisture (HM) hay or field dried (FD) hay. In experiment 1, wheat (Triticulm aestivum Var. Pioneer 2174), tall wheatgrass (Elytrigia ponticum Var. Jose), smooth brome (Bromus inermis Var. Lincoln), and intermediate wheatgrass (Thinopyrum intermedium Var. Manska) were harvested in the spring as HM hay and fed to lambs. At feeding, all four hays contained more (P < 0.05) ADF and less N than as standing forage. Apparent digestibility of the DM, NDF and ADF fractions and DMI were not different (P > 0.10) among the hays used in this experiment. In experiment 2, FD (DM > 65%) hays were harvested from established stands of Jesup Max Q (Festuca arundianaceace) and Nanyro (Festuca arundianaceace) tall fescues, Harusakae meadow fescue (Festuca pratensis), and wheat (Var.. Pioneer 2174). Lambs fed wheat hay had greater (P < 0.05) DMI (69.3 g/kg BW0.75, respectively) compared to lambs fed Jessup or Nanyro (35.0 and 33.8 g/BW 0.75), while lambs fed Harusakae hay had intermediate DMI (50.2 g/BW 0.75). Digestibility of Jesup hay was greater (P < 0.05) than the other three hays. Excess cool-season grasses can be harvested as HM or FD hay, but harvested hays had greater concentrations of ADF and NDF and a lesser concentration of N.