Assessing on-farm pasture availability and forage quality for dairy feed planning

Assessing on-farm pasture availability and forage quality for dairy feed planning

Summary

Four grazing paddocks from each of the two partnership farms were monitored throughout the season in order to assess pasture growth rates, pre and post pasture mass, net harvested mass, percent utilization, percent grass and legume, and pasture quality. Although only twenty miles apart, the two farms vary in soil type, pasture composition and mass, stocking rate and utilization.

Although both farms utilize managed intensive grazing as a method of pasturing their dairy animals (usually moving their milk cows to new paddocks between each milking), Shelburne Farm utilizes the least amount of pasture (an average of 39%) whereas, Moultrup Farm utilized an average of 50% of their pasture each grazing. The main reasons for this difference are stocking rate and soil type. Shelburne Farms has a larger land base to work with and, in order to optimize milk production, applies less grazing pressure. The other factor that affected utilization was the unusually high rainfall during the summer of 2006. Many of the soils at Shelburne Farm are moderate to poorly drained and the farm decided to lightly graze in order to avoid serious pugging of the fields. During the heaviest rainfall period in late May/early June, the farm actually pulled cows off pasture for a couple weeks.

Moultrup farm has a more limited land base and well drained soils; therefore, they need to fully utilize their pasture without sacrificing milk production. If anything, the excessive rainfall was helpful on these soils producing pasture growth rates exceeding 90 lbs. of dry matter per acre per day.

Legume content varied across paddocks but most varied with season. Generally, legume content increased as the season progressed with highest levels in July and August. The recently overseeded paddocks did not show any higher levels of legume content as compared to the non-overseeded ones.

Objectives/Performance Targets

1. To collect quantitative information on pasture production and quality for a variety of soil types and species mixtures,

   To compare a method of on-farm record-based assessments as a way to estimated pasture yield and availability as compared to more intensive hand sampling,

   To demonstrate how farmers can collect their own data using daily record keeping and turn that data into feed planning information,

   To evaluate and demonstrate the impact of legume content on forage availability and quality through the grazing season by comparing frost-seeded clovers to the existing pasture.

Accomplishments/Milestones

• Eight paddocks varying in soil type, pasture species composition and stocking rate were monitored through the 2006 grazing season for pre and post pasture mass, net yield and utilization, legume content and quality.

  Using on-farm records to estimate pasture yield at one farm showed a very similar result to intensive hand sampling utilizing an acrylic pasture plate method taking the mean and standard deviation of 25 measurements per paddock. On farm records of the other partner farm was still being evaluated at the time of this report and will be discussed in the final report. However, the results of the one partner does demonstrate that on-farm records, if carefully collected, can be an important tool for feed budgeting purposes.

  Frost seeding on the partner farms did not appear to make a significant difference in legume content in the first year after overseeding. This may be due to the excessive rain in May and June leading to a higher mortality of legume seedlings. Legume content was most influenced by time of year. Generally, legume content was lowest in the May and June and highest in August and September.

  Pasture quality appeared to be affected by legume content. When legume content exceeding 30% of the botanical mixture, crude protein, total digestible nutrients and net energy of lactation increased while acid detergent fiber and neutral detergent fiber decreased. Neither soluble protein nor mineral concentration was affected by legume content.

  Results of the project will be posted on the Vermont Crops and Soils Homepage website.

  A presentation of the project will be made at the 2007 Vermont Grazing Conference and a pasture workshop to demonstrate feed budgeting is planned for spring of 2007.

  Additional pasture data will be collected on the same paddocks in 2007 to determine pasture growth rates for a second year.

  A future outcome of this project will be to coordinate with NRCS as they collect on-farm records from pasture-based farms enrolled in the Grassland Reserve Program and use that data to develop a pasture productivity database based on soil type and species composition.

Collaborators: