Examining pasture-based dairy systems to optimize profitability environmental impact, animal health and milk quality

Examining pasture-based dairy systems to optimize profitability environmental impact, animal health and milk quality

Summary

This report covers the first few months of a 3-year study. Optimal grazing strategies require an appropriate balance between stocking rate and per cow performance in pasture-based dairy systems. This project was established to focus on questions that limit current grazing systems such as: forage species and quality, stocking rates, nutrient supplementation strategies, and use of crossbreeding. After being notified of the grant award, two planning meetings for principal investigators and others were held on June 19 and August 19 at the Center for Environmental Farming Systems in Goldsboro NC. Two 40-cow herds were established with cows calving from late September through December, 2003. Based on soil maps to ensure comparable percentages of similar soil types, paddock areas were carefully defined to allow one herd access to 40 acres (1 cow/acre) and the other herd access to 27 acres (1.5 cows/acre) of pasture. Cows in each group included Holsteins, Jerseys, and crosses of those breeds. Cows at the higher stocking rate are expected to have less pasture forage available and therefore are provided supplemental concentrates at a higher rate than the herd at the lower stocking rate. Pasture types for the grazing paddocks were set to include 50% summer and winter annuals, 30% fescue clover mix, and 20% Bermudagrass over-seeded with ryegrass. Paddock areas were arranged to allow multiple rotational subdivisions so that cows would have access to fresh pasture allowances after each milking. A 6-acre area for each group was designated as a winter sacrifice area for feeding supplemental forage when pastures were limiting. Shade paddock areas were also designated for summer.

Objectives/Performance Targets

1). Examine and quantify factors affecting economic and production efficiency of environmentally sound pasture-based dairy systems in the region;
2). Characterize potentially beneficial differences in the composition of milk produced under pasture-based production systems;
3). Characterize the antioxidant components of forages and their impact on cow immunocompetence and health;
4). Provide interactive educational programs for dairy producers and industry leaders to enable them to make informed production and management decisions.

Accomplishments/Milestones

Intensive soil sampling areas were chosen within each pasture system to monitor soil nutrients and preliminary soil samples were collected.

Equipment was upgraded to allow for monthly weights of cows and daily milk production by group for each of the two experimental groups.

A schedule was set for investigators from Virginia Tech for collecting blood samples from cows to examine various antioxidant concentrations based on various seasons and stages of the cow production cycle.

Plans were also made via investigators at Clemson to measure the impact of pasture systems on the conjugated linoleic acid (CLA) content of milk at the research site and in several cooperating herds in SC, NC, and VA.

The Clemson experiment to evaluate different starch sources for grazing cows is underway. That experiment is designed to evaluate if starch sources (barley, molasses, citrus pulp) that degrade at different rates from corn will promote microbial growth and fermentation by increasing the free ammonia capture from pasture.

Electronic grazing monitors have been ordered for conducting grazing behavior work with the grazing cows at CEFS in 2004 and beyond.

Impacts and Contributions/Outcomes

Preliminary discussion of some aspects of the project will be presented as part of the American Forage and Grassland Council/Mid-Atlantic Dairy Grazing Conference in Roanoke, VA in June 2004.

This SARE project is expected to be of interest to many dairy graziers throughout the United States. It will also serve as a training site for farmers, student interns, and graduate students with interests in sustainable agricultural systems.

Collaborators: