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Manure nutrient excretion by Jersey and Holstein cows.

K F Knowlton¹, V A Wilkerson, D P Casper

¹Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA. knowlton@vt.edu

Journal of Dairy Science

|January 12, 2010

Summary

Jersey cows excrete less feces and urine than Holstein cows, impacting nutrient management. Breed differences in manure excretion are significant and affect prediction equations.

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Area of Science:

Animal Science
Nutrient Management
Agricultural Engineering

Background:

Dairy cow manure and nitrogen excretion are critical for environmental management.
Existing prediction equations for nutrient excretion may not account for breed-specific differences.

Purpose of the Study:

To evaluate and compare feces, urine, and nitrogen excretion between Jersey and Holstein dairy cows.
To assess the accuracy of American Society of Agricultural and Biological Engineers (ASABE) equations for predicting manure excretion in different breeds.

Main Methods:

Sixteen multiparous cows (8 Jersey, 8 Holstein) were used in a switchback design with two diets (corn or whole cottonseed).
Cows were housed in open-circuit respiration chambers for 7-day collection periods at different lactation stages.
Total collection of feed, milk, feces, and urine was performed to measure excretion.

Main Results:

No significant interaction between diet and breed was found for nutrient digestibility or manure excretion.
Jersey cows consumed less feed and excreted significantly less wet feces, urine, and nitrogen compared to Holstein cows.
ASABE equations underpredicted observed values and showed breed bias for urine, nitrogen, and wet manure excretion, but not for manure solids.

Conclusions:

Breed significantly impacts manure and nitrogen excretion levels in dairy cows.
Current ASABE prediction equations require refinement to account for breed-specific variations, particularly for urine, nitrogen, and wet manure.
Accurate nutrient excretion data is essential for effective on-farm nutrient management strategies.