Relative Forage Quality

Transcription

1 Relative Forage Quality Dr. Dan Undersander University of Wisconsin Why a Forage Quality Index? When to harvest Benchmark quality performance Match forage quality to animal needs Inventory feeds Buying/selling hay Contracting for harvest with quality incentive 1

2 Relative Forage Quality Index of energy intake based on fiber and digestible fiber Index of 100 is maintenance Index of 150 or 170 is dairy cow feed Relative Feed Value RFV = Intake potential * DDM 1.29 = 120/NDF * [ (0.779*ADF)]

3 Use of ADF to estimate energy NEM = x ADF NEG = [ (2.42/(NEM x 2.2))]/2.2 TDN = x NEL NEL = x ADF DDM = (0.779*ADF) Total digestible nutrients for warm and cool season grasses Summative Equation TDN = (NFC*.98) + (CP*.87) + (FA*.97*2.25) + (NDF*NDFD/100) 10 3

4 Relative Forage Quality RFQ = (DMI grass, % of BW) * (TDN grass, % of DM) / 1.23 S45 Regional Project, Contribution States Alabama Florida Georgia Kentucky Louisiana Mississippi North Carolina Oklahoma Puerto Rico Tennessee Texas USDA Individuals W. B. ANTHONY J.E. MOORE W.G. MONSON D.R. JACOBSON R.W. HEMKEN G.L. M. CHAPPELL B.D. NELSON J.W. LUSK J. C. BURNS H.L. LUCAS, Jr. J.E. McCROSKEY F.P. HORN J.A. ARROYO-AQUILU M.J. MONTGOMERY K.M. BARTH H. LIPPKE D. BURDICK H.K. GOERING C. H. GORDON J.C. DERBYSHIRE 4

5 ADF in vivo digestibility Species included in S45 Trials Alfalfa Bahiagrass,Pensacola Bermudagrass,Coastal & Midland Fescue,Kenwel I & KY-31 Orchardgrass,Boone & Potomac Digitgrass,Pangola Sorghum,Haygrazer & SX-16 ADF vs ADF digestibility (S45) y = x R² = ADF 5

6 In vivo OM digestibility NDF in vivo digestibility NDF vs NDF digestibility y = x R² = NDF ADF vs In vivo digestibility y = x R² = ADF 6

7 Digestible Fiber, % of NDF In Vitro Digestibility, % of DM Relationship of ADF to In vitro Digestibility (2011 Worlds Forage Superbowl) y = -0.49x R² = Acid Detergent Fiber, % of NDF Relationship of ADF to Digestible Fiber (2011 Worlds Forage Superbowl) y = -0.42x R² = Acid Detergent Fiber, % of DM 7

8 Summative TDN Relationship of ADF to Summative TDN (2011 Worlds Forage Superbowl) y = -0.50x R² = Acid Detergent Fiber, % of DM Relative Forage Quality (RFQ) RFV = Intake potential * DDM 1.29 = 120/NDF * [ (0.779*ADF)] 1.29 RFQ = dintake potential * dtdn 1.23 = [NDF+((dNDF-avg dndf)*.374)] * [dnfc+dcp+dfa*2.25+dndf 7]

9 Total digestible nutrients for warm and cool season grasses calculated as: TDN grass = (NFC*.98) + (CP*.87) + (FA*.97*2.25) + (NDFn*NDFDp/100) 10 Where NDFDp = *NDFD Maximum protein = 16% (Moore and Undersander, 2002) Dry matter intake for warm and cool season grasses calculated as: DMI Grass = *CP *CP *TDN *TDN *ADF *ADF *CP*ADF Where: DMI is expressed as % of BW CP, ADF, and TDN as % of DM and maximum CP is 16%. (Moore and Kunkle, 1999) 9

10 Range of digestibility of Common Forages 30 Legume Silage/Hay 20 Grass Silage/Hay 10 Corn Silage NDF digestibility (% of NDF) Relative Forage Quality Change RFQ changes as following change: NDF digestible fiber (dndf) Crude protein Nonfibrous carbohydrate 10

11 Effect of protein change on RFV and RFQ RFQ RFV Effect of NDF change on RFV and RFQ RFQ RFV

12 Percent of Maximum Yield or quality Effect of NDFD change on RFV and RFQ RFQ RFV Yield and Quality Curve of Alfalfa Forage Quality 35 % NDF 30% yield reduction % NDF 20% yield reduction Yield Days of Regrowth 12

13 Forage Quality Needs of Animals Dairy, 1st trimester Dairy Calf Dairy, last 200 days Heifer, 3-12 month Stocker cattle Heifer, mo Dry cow Heifer, mo Beef cow & calf Relative Forage Quality Forage Quality Needs of Animals 1 Stocker cattle Growing lambs & kids Beef cow & calf Ewe with lamb Doe with kid Nursing mare Hard working horse Ewe/doe, not lactating Idle horse Relative Forage Quality 13

14 Timely harvest The largest single effect on forage quality is date of harvest. Daily Rate of Forage Quality Change in Spring Component Crude Protein Acid Detergent Fiber 0.36 Neutral Detergent Fiber 0.43 NDFD RFV -2.9 RFQ -3.6 Minimize Ash Content Ash Content of 2010 Superbowl Forage Samples Average 12.7 Minimum 7.9 Maximum

15 Change, Percentage Units Change, Percentage Units Harvesting/storage moisture Heat damage to hay haylage Dig NDF Dig CP Dig NFC Heating Degree Days > 86F Source: Coblentz, 2008, USDA -ARS Hay Preservation Results of Malliard Reaction TDN = dnfc + dcp+ 2.25*FA + dndf Dig CP Dig NFC Dig NDF TDN Heating Degree Days > 86F Source: Coblentz, 2008, USDA -ARS 15

16 Factors affecting RFQ Maturity at harvest Ash content Select high quality variety Genetics Disease Resistance Cool Weather Harvest to avoid heating Harvest for high NFC Sunny day AM/PM 16