Animal and Forage Interactions in Beef Systems

Transcription

1 Planning and Managing for Dry Conditions in Range and Pasture Production Systems Don Adams Animal and Forage Interactions in Beef Systems 1

2 Diets of Grazing Cattle The Primary Factor Affecting Nutrient Content of Grazed Diets is Plant Maturity 2

3 14 Crude Protein in Cattle Diets on Sandhills Range APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB Month 8 In vitro Organic Matter Digestibility (IVOMD, % OM) of Cattle Diets on Sandhills Range IVOMD, % APR MAY JUN JUL AUG SEP OCT NOV DEC JAN FEB Month 3

4 Nutrient Requirements of the Cow Net Energy (NE) Requirements for a 12 lb March Calving Cow with 23 lbs/day Peak Milk Production 2 NE (Mcal/day) Calve 3 5 Wean 9 11 Months After Calving NRC (1996) 4

5 Forage Intake Needed to Provide Protein Required for Pregnancy and Milk (12 Pound Cow) 8 12% 8% 4% Forage lb/day Mid 1/3 pregnancy Last 1/3 pregnancy 1 lb milk/day 2 lb milk/day Physiological Status of the Cow 5

6 g/kg BW Rumen Volume and Dry Matter Fill of Steers Grazing Sandhills Meadow and Range Rumen Volume Dry Matter Fill Jun Jul Aug Sep Oct Dec Nebraska Ranch Practicum Forage Organic Matter Intake and Particulate Passage Observed Using Steers Grazing Sandhills Meadow or Range Organic Matter Intake g/kg BW Particulate Passage %/hr Meadow Range Jun Jul Aug Sep Oct Dec Nebraska Ranch Practicum 6

7 Lactation and Nutrient Content of Forages Forage Intake Needed To Provide Protein Required for Pregnancy And Milk (12 Pound Cow) 8 12% 8% 4% Forage lb/day Mid 1/3 pregnancy Last 1/3 pregnancy 1 lb milk/day 2 lb milk/day Physiological Status of the Cow g/kg BW Rumen Volume and Dry Matter Fill of Steers Grazing Sandhills Meadow and Range Rumen Volume Dry Matter Fill Jun Jul Aug Sep Oct Dec Forage Organic Matter Intake and Particulate Passage Observed Using Steers Grazing Sandhills Meadow or Range Organic Matter Intake g/kg BW Particulate Passage %/hr Meadow Range Jun Jul Aug Sep Oct Dec Effect of Precipitation Level on Forage and Cattle at the Gudmundsen Sandhills Laboratory (24-214) Source: Nebraska Ranch Practicum 7

8 3 Year Average ( ) Monthly Precipitation Levels At GSL January.32 February.43 March.66 April 2.5 May 3.9 June 3.66 July 2.95 August 2.17 September 1.72 October 1.18 November.52 December.18 Annual April, May, June Precipitation in Dry, Average and Wet Years Dry Years Average Years Wet Years

9 Precipitation Level on Crude Protein (CP) CP, % June July Sept Nov Dec Month DRY AVG WET Precipitation Level on TDN TDN, % June July Sept Nov Dec Month DRY AVG WET 9

10 Precipitation Level on Cow BW Cow BW, kg June July Sept Nov Jan Month DRY AVG.5 < P.1 P <.1 Precipitation Level on Cow BCS Cow BCS P <.1 June July Sept Nov Jan Month 1

11 Precipitation Level on Milk Production Milk production, kg June July Sept Nov Month P <.5 DRY AVG WET Precipitation Level on Pregnancy Rate Pregnancy rate, % DRY AVG WET Precipitation Level P =.95 11

12 Precipitation Level on Calf BW Calf BW, kg June July Sept Nov Month P.1 DRY AVG WET Weaning Date on Cow BW Cow BW, kg June July Sept Nov Jan Month P.1 Sept Nov 12

13 Weaning Date on Cow BCS Cow BCS June July Sept Nov Month Jan P <.1 Sept Nov Managing During Drought 13

14 Precipitation Level on CP CP, % June July Sept Nov Dec Month DRY AVG WET Crude Protein Content of Cattle Diets on Sandhills Range Date Average 22 June 7 th July 16 th July 3 th August 2 th September 5 th October 14 th

15 Precipitation Level on TDN TDN, % June July Sept Nov Dec Month DRY AVG WET TDN Content of Cattle Diets on Sandhills Range Date Average 22 June 7 th July 16 th July 3 th 6 5 August 2 th September October

16 Amount of Milk Produced by the. Cow Milk Production by Cows With High and Low Production During Summer Grazing Daily milk production, lbs Low High 5 May 28 June 18 Aug 1 Sept 14 Adams et al

17 Body Condition Score Change for Cows With High or Low Milk Production During Summer Grazing 1 Body condition score change.5 (.5) Low High (1) April 1 On grass June 19 Beginning breeding Aug 5 End breeding Sept 2 Weaning Weight Gain of Calves From Cows With High or Low Milk Production During Summer Grazing 4 High Calf gain, lbs 3 2 Low 1 April 1 June 19 Aug 5 Sept 2 Weaning 17

18 CRUDE PROTEIN IN THE DIETS OF SUCKLING CALVES AND MATURE STEERS ON MONTANA RANGE Date Suckling Calves Mature Steers June July September November Crude protein and digestibility of cow and calf diets on Sandhills Range Crude Protein 1 Organic Matter Digestibility Date Cow Calf Cow Calf June July August September Crude protein expressed on organic matter basis 18

19 Early Planning gives more Flexibility Conserving Grazed Forages 19

20 Plan Expected days of grazing vs. Needed days of grazing Adjustments to attain needed days of grazing: Weaning Culling Marketing Supplements Purchased Feed and/or Grazing Weaning 2

21 Weaning the calf early saves grazed forage when the calf is fed harvested feeds or is moved off of the ranch. Forage organic matter intake (lb/day) by cows and calves grazing Sandhills range Total Date Cow 1 Calf (Cow + Calf) July September July Average body weight of cows for 1991 = 197 lb; for 1992 = 1139 lb 21

22 About 1 pounds of forage is conserved for each day a calf is weaned (1 lbs forage =.4 day grazing for a dry cow) Weaning Primary Impacts of Drought 1. Lower forage production 2. Lower diet nutrients 22

23 Crop Residue Concerns 1)Nitrates 2)Poisonous Plants 23

24 22 Drought Actions taken by University at the Gudmundsen Sandhills Ranch 1. Kept inventory current culls sold as identified 15 cows for 1 month = 18 aums 2. Identified 15 cows in May as culls and sold them in June as pairs instead of at weaning. 15 cows off ranch for 5 months = 113 aums 3. Weaned March born in early Sept. 1 month early. 3 calves off ranch 1 mo = 12 aums 4. Steer calves shipped within 1 days of weaning (included in 3) 24

25 Actions (continued) 5. Surplus heifer calves sold 3 weeks after weaning (2 mo. Early) = 24 aums 6. Reduced March herd 5% (15 cows) and sold remaining open/culls in Sept. a) 3 fewer cows due to June sales and the 15 reduction for 9 mos (Sept. thru May) = 324 aums b) 2 open cows sold in Sept. (2 mos. Early) = 48 aums Actions (continued) cows to corn stalks in early November to late February = 475 aums pregnant June calving cows sold in January rather than April as normal = 75 aums saved 9. TOTAL AUMs SAVED FOR COWS = 1197 or 58 days for 52 cows 25

26 Actions (continued) 1. Projected savings in hay = 14 tons or about 18 days for the entire herd. 11. TOTAL COW DAYS OF FEED SAVED FOR 52 COW HERD = 58 (grazing) + 18 (hay) = 76 Days Implement Plan Early 26