Location: Forage and Range Research
Project Number: 2080-21000-018-041-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Apr 1, 2021
End Date: Mar 31, 2024
In 2019, there were over 3.6 million dairy cows in the western U.S., making dairy a dominant sector of the western-region’s agriculture. Pasture-based and organic milk production is becoming more prevalent, with organic milk products increasing from 1.92% to 4.38%, of all milk products sold, between 2006 and 2013. Organic milk companies promote their product based upon the health and environmental benefits of pasture-raised milk, and require at least 120 grazing days per year for both lactating cows and replacement heifers. However, milk production was 32% lower in organic dairies using 75-100% of pasture-based forage compared to those using 25% or less pasture forage. Low dry matter intake (DMI) of pasture by dairy cows has been shown to be a major factor limiting milk production, and producers have observed that some dairy breeds are more finicky grazers than others [personal communication].
A multi-disciplinary team of animal and plant scientists will conduct this research at the Utah State University Lewiston Pasture Research Facility. Replicated pastures consisting of grass monoculture (MONO) (tall fescue, meadow bromegrass, and high-sugar orchardgrass and perennial ryegrass) or grass-legume mixtures (birdsfoot trefoil; legume) (MIXED) are established. Four breeds of dairy heifers (Holstein, Jersey, Holstein x Jersey crossbred, and ProCross crossbred [e.g., 3-way Holstein x Viking red x Montbeliard cross]) will rotationally graze pasture treatments (MONO vs MIXED) throughout the summer. Dry matter intake, growth performance, grazing efficiency (e.g., intake/gains), N utilization efficiency (e.g., N in leachate), and economic comparisons will be made between dairy breeds grazing the grass-legume mixed and grass monoculture pastures.