Improvements in feed efficiency, milk yield, and components by delineating the rumen microbiome

Project Overview

Project Type: Graduate Student
Funds awarded in 2015: $15,000.00
Projected End Date: 12/31/2016
Grant Recipient: University of Vermont
Region: Northeast
State: Vermont
Graduate Student:
Faculty Advisor:
Dr. Andre Brito
University of New Hampshire
Faculty Advisor:
Dr. Jana Kraft
University of Vermont

Annual Reports


  • Animal Products: dairy


  • Animal Production: animal protection and health

    Proposal abstract:

    Each grazing season, Northeast U.S. dairy farmers are challenged by three main periods of low herbage. These periods include early spring, mid-late summer, and late-fall. To overcome this obstacle, farmers are interested in using alternative forage crops (AFC) such as cool and warm season annuals. During periods of low herbage, our study will measure feed efficiencies and identify the rumen microbes of lactating dairy cattle on a 50% legume-based pasture versus a 25% mixed AFC pasture. Specific rumen microbes and their fermentation products, volatile fatty acids, have been linked to feed efficiency and milk production and components. Furthermore, increased methane emissions from dairy cattle decrease feed efficiency and contribute to climate change. No study has investigated a mixture of AFC to alter the rumen microbiome. Therefore, our research will focus on three key rumen microbes: bacteria, methanogens, and protozoa. The bacteria and protozoa ferment feed into volatile fatty acids while the methanogens produce methane. The four main objectives of this study are to: 1) quantify the feed efficiency of each animal, 2) identify and quantify the rumen bacteria, methanogens, and protozoa 3) measure rumen fermentation products, and 4) determine if the incorporation of AFC will benefit dairy farmers. Presenting at Northeast organic farming conferences and publishing in Hoard’s Dairyman magazine will provide outreach to farmers, researchers, and extension members. This study will enable future research to develop strategies resulting in a more feed efficient and low -methane producing dairy cow that will increase farm profitability and benefit the environment.

    Project objectives from proposal:

    1. Quantify feed efficiencies of each animal
    The specific aim of this objective will be to compare the feed efficiencies of the experimental group (25% AFC, 25% legume-pasture, 50% TMR) to a control group (50% legume-pasture, 50% TMR) during early spring, mid-summer, and late fall.


    2. Identify and quantify the rumen bacteria, methanogens, and protozoa
    We will collect whole rumen digesta samples to delineate what microbes (diversity) and how many are present (density).

    The specific aims of this objective are to:
    a. Determine the species of each type of rumen microbe with DNA sequencing
    b. Estimate the microbial densities via real-time polymerase chain reaction (PCR)
    c. Determine if certain microbial taxa relate to feed efficiency

    3. Measure the rumen fermentation products
    We will study the rumen fermentation products because they contribute to the environment of the microbes and are key to their growth. For example, some microbes prefer a higher pH optimum than other microbes or produce different volatile fatty acids. Therefore, if we know what environment the rumen microbes are living in, we can better understand why they thrive over other microbes.

    The specific aims of this objective will be to:
    a. Measure the nutrient composition of the experimental diets
    b. Quantify the volatile fatty acids (rumen microbial fermentation by-products) via gas-liquid chromatography (GLC)
    c. Measure rumen pH with a portable pH meter

    4. Determine if the incorporation of AFC will benefit dairy farmers
    The specific aims of this objective are to:
    a. Compare feed costs, dry matter intake (DMI), and cow performance (milk yield, butterfat and protein) between the legume-based pasture and AFC-based feeding groups; and
    b. Determine if the milk check is affected by the different diets and time periods.

    Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.