Developing legume-grass mixtures to improve the environmental sustainability of northeastern organic dairies

View the project final report

Commodities

• Agronomic: clovers, medics/alfalfa, Birdsfoot trefoil
• Animals: bovine
• Animal Products: dairy

Practices

• Animal Production: animal protection and health, feed/forage, feed formulation, feed management, feed rations
• Education and Training: on-farm/ranch research, workshop
• Production Systems: organic agriculture
• Soil Management: green manures, soil quality/health

The goal of this project is to provide sorely needed, scientific-based information about the tradeoffs between milk production, nutrient utilization, and output of nitrogen and methane to the environment in forage-based dairy systems. Our goal will be accomplished by shedding light on the rumen microbiota and amino acids nutrition factors that modulate the relationship between efficiency of nutrient utilization and milk production in cows fed baleage harvested from 3 different legume-grass mixtures (alfalfa-, red clover-, or birdsfoot trefoil-meadow fescue-timothy) designed to yield a high energy to nitrogen ratio. This proposal is part of our recently funded USDA-NIFA-Organic Transitions project entitled “Developing advanced perennial legume-grass mixtures harvested as stored feeds to improve herd productivity and mitigate greenhouse gas emissions in organic dairies in the Northeast”. The scope of this larger project includes integrated research and educational approaches to mitigate greenhouse gas emissions through dairy cattle nutrition and agronomic trials in synchrony with outreach activities such as workshops and eOrganic webinars. We are proposing 2 complementary research objectives and we will capitalize on the established outreach platform to deliver our Legume-Grass Mixture Feeding Guide, which is the direct educational product of the current submission to Northeast SARE. Twenty-four organically-certified Jersey cows will be used in a 14-week experiment (n = 8/treatment) with rumen fluid and blood samples collected at weeks 4, 8, and 12. DNA will be extracted from isolated microbiota and submitted to quantitative real-time polymerase chain reaction, amplification, and sequencing analysis, while blood plasma will be analyzed for amino acids.

This proposal is part of a recently funded USDA-NIFA-ORG project (award #2016-51106-25713) entitled “Developing advanced perennial legume-grass mixtures harvested as stored feeds to improve herd productivity and mitigate greenhouse gas emissions in organic dairies in the Northeast”. The scope of this larger USDA-NIFA-ORG project includes integrated research and educational approaches to mitigate greenhouse gas emissions through dairy cattle nutrition and agronomic trials in synchrony with outreach activities such as workshops and eOrganic webinars. In the current project, we are proposing 2 complementary research objectives and we will capitalize on the established outreach platform to deliver our Legume-Grass Mixture Feeding Guide, which is the direct educational product of the present submission to Northeast SARE. Our proposal addresses the Northeast SARE priorities: “reduction of environmental and health risks in agriculture” and “improved productivity, the reduction of costs, and the increase of net farm income”.

Specific objectives of this proposal include:

Objective 1: IDENTIFY AND QUANTIFY RUMEN MICROOBIOTA
Identify and quantify ruminal microorganisms (i.e., bacteria, protozoa, and methanogens) in cows fed baleage harvested from different legume-grass mixtures designed to yield high energy:N ratio.

Objective 2: MEASURE BLOOD AMINO ACIDS
Measure the concentration of amino acids in blood plasma in cows fed baleage harvested from different legume-grass mixtures designed to yield high energy:N ratio.

We hypothesize that: (1) baleage harvested from the birdsfoot trefoil-grass mixture would decrease methanogens and proteolytic bacteria due to the toxic effects of condensed tannins on rumen microorganisms, which could ultimately reduce N and methane output to the environment; (2) the anti-proteolytic activity of birdsfoot condensed tannins would shift dietary protein degradation from the rumen to the small intestine so more amino acids could be available for milk production and milk protein synthesis; (3) cows fed the red clover-grass baleage would rank intermediate in milk N efficiency as the enzyme polyphenol oxidase appears to have less anti-proteolytic activity than condensed tannins; and (4) cows fed alfalfa-grass baleage would have more proteolysis in the rumen resulting in less amino acids available for milk production and milk protein synthesis as alfalfa lacks both condensed tannins and polyphenol oxidase. However, all 3 legume-grass mixtures were carefully designed to increase the energy:N ratio so we are expecting increased milk production compared with traditional mixtures used in the Northeast.