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Precision Feeding of Phosphorus for Dairy Farms- Katharine Knowlton


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Katharine Knowlton of Virginia Tech and Virginia dairy farmer Jimmy Huffard gave this presentation on February 7, 2011.

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  • This material was presented during DAIReXNET’s February 7, 2011 webinar entitled 'Precision Feeding of Phosphorus for Dairy Farms'. The recorded versions of all of our webinars are located at
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Precision Feeding of Phosphorus for Dairy Farms- Katharine Knowlton

  1. 1. Dietary nutrient management: What goes in, must come out.<br />Dr. Katharine Knowlton, Dep’t of Dairy Science, Virginia Tech<br />Jimmy Huffard, Huffard Dairy Farm, Crockett VA<br />
  2. 2. Nutrient concentration<br />Specialization<br />Nutrient Importation<br />Nutrient Concentration<br />Ground and Surface Water<br />
  3. 3. Sources of nutrients<br />Smith & Alexander, 2000<br />
  4. 4. Soil P accumulation<br />Phosphorus<br />Manure N and P in imbalance<br />Manure application to meet N needs = excess P<br />P accumulates<br />P can runoff from saturated soil, even without erosion<br />Contaminates surface water<br />Soil test P in Rockingham county, VA, ‘07-10<br />
  5. 5. Does diet matter?<br />
  6. 6. P intake and excretion<br />Relationship between P intake and excretion?<br />13 early-lactation cows<br />Fed diets containing one of 3 levels of dietary P<br />Days 7-75 of lactation<br />Total collection study (milk, urine, feces)<br />Direct, linear relationship between P intake and excretion<br />Knowlton et al., 2002<br />
  7. 7. Why overfeed?<br />Uncertainty about requirements - What’s the “bare minimum”?<br />Marketing<br />Link to reproduction?<br />Bad habits<br />Undetected variation in feed P, “problem feeds”<br />
  8. 8. Phosphorus<br />Dietary requirement<br />
  9. 9. Survey says???<br />Survey of dairy nutritionists across US<br />Independent & company affiliated<br />131 respondents<br />Range from 1 client to 150<br />From 200 cows to 95,000<br />
  10. 10. “Energy balance is more critical to reproductive success than "over-loading" P to replace heat detection management. “<br />53% say ‘yes, a priority’<br />“Clients are being regulated with nutrient management plans, so it is a priority, but ration cost dictates the use of higher levels of byproduct feed that contain more P.”<br />“I work close to the Bay, so I constantly monitor the P levels in my diets.”<br />“P requirements are met or exceeded by natural sources in almost all cases. We do not address excesses unless nutrient management plans dictate.”<br />
  11. 11. “Slightly high”<br />“Only a tad low”<br />“I feed at NRC recommendations and production, health and reproduction among the 25,000 cows I serve is excellent.”<br />“I am very confident that the 0,31% P requirement was well researched. Dr. Larry Satter's group at USDA Dairy Forage center did good work looking at bone strength with 0.31 P diets in lactating first calf heifers, the class of animal with the greatest P requirements.”<br />“Most of the problem is with availability data”<br />“Why is Germany's bioavailability correct at 80% when the 1989 NRC used a lower figure?”<br />
  12. 12. “(Our company) has recommended lower P levels for years and I always try to keep at the low end.”<br />“The mindset of vets and educators has changed allowing us to run lower P levels.”<br />“I reduced my recommendations because of manure management concerns and how feeding management can impact P levels in manure.”<br />“Public perceptions of animal agriculture & CAFO's may prevent future expansion of many dairy farms. If we’re not proactive , we’ll be seen as "hiding" poor practices.”<br />“I changed because of research showing we did not need to supplement as much.”<br />
  13. 13. Precision Phosphorus Feeding for Virginia Dairy Farms<br />
  14. 14. Components<br />Feed sampling, analysis, bimonthly 3 years<br />Calculate P requirements, P intake<br />Incentive payments based on ( intake / req’t )<br />$12 / $6 / $3 per cow per year<br />Payment capped at 400 cows<br />No penalty for overfeeding<br />
  15. 15. Did it work?<br />215 herds<br />Each year, more farms succeeded in reducing dietary P to receive incentive payment<br />P feeding down by ~5-15%<br />Next steps?<br />
  16. 16. Survey says???<br />Survey of dairy nutritionists across US<br />Independent & company affiliated<br />131 respondents<br />Range from 1 client to 150<br />From 200 cows to 95,000<br />
  17. 17. The most challenging aspect of reducing dietary P?<br />“I sample, so content is not a worry. The biggest problem is that low cost byproducts like DDG have too much P.”<br />“Price is easy - the problem is trusting the P value on Soy, DD, Wheat, Brew etc.”<br />“P availability????”<br />“Sometimes higher P feeds, like distillers dried grains, are cost effective feeds. Hence, overfeeding P may be more economical than keeping P at NRC 2001 levels.”<br />“We need new research considering the availability of organic P.”<br />
  18. 18. What new information do you need?<br />What about new and well designed research?<br />“Not all software programs are "current" and I question myself on how low is too low.”<br />“I think current NRC recommendations are adequate. The biggest thing is making sure our feedstuffs have the true amounts and that they are available to the animals.”<br />Need to work on true bioavailability of P in feedstuffs<br />Adequate data and field experience exist. Train people. Or do a P tax like Netherlands.<br />
  19. 19. The distillers grain challenge<br />
  20. 20. Organic P availability?<br />Endogenous phytase activity is affected by diet.<br />Phytate escape from rumen<br />Heat treated grains<br />High rate of passage<br />High organic P<br />Yanke et al., 1998<br />
  21. 21.
  22. 22. “If it was easy, everyone would do it.”<br />
  23. 23. Virginia regulations<br />Virginia Pollution Abatement permit<br />CAFO is > 300 animal units, liquid manure storage<br />P-based nutrient mgmt planning since 2007<br />Storage required, no discharge to surface water<br />120-150 days manure storage <br />Annual inspections of permitted facilities<br />
  24. 24.
  25. 25.
  26. 26. Farm in the family for >200 years<br />Jerseys arrived in 1929<br />350 milking cows, plus 360 heifers<br />Milk 2X<br />
  27. 27. Huffard dairy<br />General manure & crop management<br />Impact of dietary changes on manure P<br />Outlook for future, concerns and opportunities<br />
  28. 28. In the real world…<br />0.49%<br />0.40%<br />< 0.4%<br />Dietary P:<br />
  29. 29. This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S.D.A., Award No. 2009-55206-05267 . <br />