Are High Potassium Forage Increasing the Occurrence of Metabolic Diseases in Dairy Cows?
Roberta L. Crill, Diane J. Carroll, and Mike Gangwer, Department of Animal Sciences, and John Hart, Department of Crop and Soil Science, Oregon State University, Corvallis, February, 1998 - Research in progress.
RESEARCH QUESTION
Some producers have discontinued feeding forages high in potassium because of increasing occurrences of early postpartum metabolic diseases, whereas others continue to feed this type of forage to their dry cows without problems. What variables are different between dairies that feed high potassium forages to their dry cows and have problems and those whose cows don't experience difficulties?
SUMMARY
Producers in the dairy industry have used manure recycling practices for years without repercussion. Cycling of nutrients from the soil to plants, and ultimately to animals, decreases the need for commercial fertilizer. However, potassium concentrations have been building up in manure fertilized soils. Grasses grown in these fields mirror the soils' increase in available potassium. Elevated potassium concentrations in forages may be a contributing factor to increased metabolic diseases in early lactating cows on Oregon dairy farms.
STUDY DESCRIPTION
From September, 1996, until September, 1997, monthly on-site interviews were conducted on ten dairy farms that fed high potassium forages to their dry cows.
-- Oral and written records concerning the cows in the periparturient phase (the interval 60 days before calving to 60 days after calving) were gathered.
-- Records were collected on ration formulation, dry date, calving date, metabolic problem occurrences, and milk production.
-- Blood samples were obtained from the fresh cows within 48 hr after calving.
-- Urine samples were collected from dry cows that were within two weeks of calving.
-- Plant samples were collected from fields where the dry cows' forage was grown.
-- Soil samples were gathered from two fields per dairy at the beginning of the trial (October 1996) and again at the end of the trial (September 1997).
APPLIED QUESTIONS
How will the knowledge of potassium and its effect on the dairy help producers?
The association between high potassium concentrations in forages and metabolic problems will be documented. In addition, management practices associated with low and high occurrence of metabolic disorders when feeding high potassium forages will be reported.
What is the potassium usage of the soils over a growing season on the dairies?
| Potassium | Top 2" (1996) | Top 2" (1997) |
| Average, ppm | 1202 | 898 |
| High Observation, ppm | 1716 | 1092 |
| Low Observation, ppm | 675 | 523 |
The average decrease in soil K was 304 mg/kg. This is evidence that one growing season can mine a significant amount of K from the top 2" of soil (P< 0.05).
Progress report:
As of February, 1998, all of the data has been collected and blood, soil, urine and feed samples have been analyzed. Statistical analysis is in progress. Results will be reported at the American Dairy Science Association Meetings in Denver this July.
Funds provided by:
Agricultural Research Foundation Center for Applied Research (CAAR), ODA Oregon Dairy Farmers Association USDA Animal Health and Disease Grant
