The Effects of Altering the Protein Efficiency of Lactating Dairy Cows on the Whole-farm Nitrogen Efficiency of Dairy Farms: Subcontract 1

2000 Annual Report for SW99-024

Project Type: Research and Education
Funds awarded in 1999: $19,184.00
Projected End Date: 12/31/2001
Region: Western
State: Utah
Principal Investigator:
Allen Young
Utah State University

The Effects of Altering the Protein Efficiency of Lactating Dairy Cows on the Whole-farm Nitrogen Efficiency of Dairy Farms: Subcontract 1


Software had been previously developed to quantify nitrogen and phosphorus balances on livestock farms in Maryland, and was beta tested in the western region. This software was distributed via the internet to users in 25 states and 27 countries. Our lab assisted with development of two papers on use of the software to characterize nutrient balances in the western region of the US. Our lab also tested the use of MUN on dairy farms in Maryland. We updated comprehensive web pages that disseminate information on reducing nutrient losses from agriculture, especially dairy farms.

Objectives/Performance Targets

Our contribution to the overall project is based on the following specific objectives:

1) to improve computer worksheets for calculating whole farm balances by adapting them to the western region and by implementing changes identified by using the worksheets in this region,

2) to assist with evaluation and improvement in MUN analysis based on research conducted at Utah State University, and

3) to disseminate information from this project to farmers via extension publications and the World Wide Web.


Specific Results

Prior to this grant, our lab developed a software application to calculate phosphorus and nitrogen flows on livestock farms. In the first year, the software was tested in the western region of the US and refined. In the past year, the software was implemented to assist farmers with calculating nutrient balances, and to collect data from farms. The software was distributed via the internet. It has been registered by 65 users in the US among 25 states. It has also been distributed to users in 76 in 27 other countries. In the current and final phase, we are using collected data to improve our understanding of current practices affecting nutrient flows so as to improve incentive, regulatory or technology transfer programs.

Experiments were conducted at Utah State University to verify a model we developed that uses milk urea nitrogen (MUN) and other variables to predict aspects of nitrogen utilization efficiency by dairy cows. While most of the equations were shown to be accurate under different conditions, the prediction of urinary nitrogen excretion as a function of MUN differed from the original model. We conducted a series of investigations at the University of Maryland to better understand the differences. A refereed journal article on these differences was accepted by the Journal of Dairy Science.

Dissemination of Findings

Several extension publications were developed to disseminate this information to dairy farmers. Our World Wide Web site ( receives 2000 to 5000 visits per month. The software refined by the project is available for download from our web site and it has been downloaded by more than 141 sites in 27 countries and 25 states. Extensive information on using MUN and improving herd N utilization efficiency is available on the site. This information was updated this year to reflect changes in measurements made by DHIA laboratories.

Impacts and Contributions/Outcomes

Potential Benefits or Impacts on Agriculture

Dairy farmers can use MUN to fine tune diets and prevent overfeeding or underfeeding of protein to their cows. The work we conducted will make it possible for farmers to use this technology more effectively. If they reduce overfeeding of cows, it will reduce their cost of feed because protein is an expensive ingredient. In addition, cows use energy to excrete the excess nitrogen. Thus, by not overfeeding, energy costs or lost production can be reduced. In addition, with less protein being fed, less N will be excreted in manure. This effect will make it easier to comply with field-by-field nutrient management plans. Many farmers in the west export their manure to the nearest available land. By reducing N in manure, the distance the manure must be shipped is reduced. Finally, reducing N excreted to manure will reduce ammonia-N volatilization, N runoff, and N leaching proportionally. The software for calculating nutrient balances can be used to help farmers and consultants understand the balance of nutrients on their farm and to quantify the unaccounted for N and P. These unaccounted for nutrients may accumulate in soils or be lost to the environment.

Farmer Adoption and Direct Impact

We have introduced the use of MUN to over 450 farmers in Maryland, Pennsylvania, Virginia, West Virginia and Delaware through a project in which we paid for sampling and sent interpretive results. Participants in the project decreased MUN by 0.5 mg/dl compared to non-participants. Participants with high MUN decreased MUN by 1 mg/dl compared to non-participants, and participants with low MUN increased it by 3 mg/dl compared to non-participants. Thus, it appears that participants in the program increased or decreased protein feeding when recommended. The typical farm would have saved $595 per annum in feed costs by reducing protein feeding.

Producer Involvement

Of 454 participants in the MUN study, 190 returned surveys about their participation, and 70% of these respondents reported using results from the program. Thirty percent indicated that they planned to use MUN analysis again. While most farmers were unsure of the economic impact the program had, several reported positive returns up to $1,500 from the program due to reduced feeding costs.


Richard Kohn

[email protected]
Associate Professor
University of Maryland
Department of Animal & Avian Sciences
College Park, MD 20742
Office Phone: 3014054583