2013 Northeast Pasture Consortium Annual Meeting Northeast Pasture Research and Extension Consortium 2016 Annual Meeting, Manchester, NH, February 6-7, 2013
Sid Bosworth, University of Vermont
Assisting Organic Dairy Producers to Meet the Demands of New and Emerging Milk Markets: An update on using complex blends of perennial ryegrass varieties for pasture
Sid Bosworth than presented the forage agronomist portion of the project that Andre had just reported on from the livestock specialist side. Sid emphasized the collaborative nature of this research project noting that people from the University of New Hampshire, University of Maine, and USDA-ARS along with the University of Vermont were on the perennial ryegrass project team.
Sid pointed out the difference between forage blends and mixtures. Blends – combining cultivars of a species in a planting. Mixtures – combining species in a planting. Their recent needs assessment of organic dairy producers in the region revealed that extending the grazing season, complying with the new pasture rules, and implementing strategies to facilitate value-added marketing of milk are major challenges to the industry. From the forage side, producing and maintaining productive pastures as well as extending the grazing season (early spring and late fall) requires:
- Mixtures of adapted species and cultivars,
- Optimum soil fertility, pH and soil quality,
- Proper grazing management, and
- Minimal forage disease and pest pressures.
Their hypotheses for this perennial ryegrass forage trial on cultivar blends are:
- Cultivar-level variation in resource acquisition will lead to greater overall use of available resources resulting in greater yields and a more highly competitive environment.
- Mixing cultivars with different growth rates and patterns will result in a longer grazing season, greater stand stability, and a reduced chance of stand failure.
- Mixing cultivars with differing growth patterns will result in a more stable quality forage.
- The variation in levels of host resistance and susceptibility between the different cultivars will decrease overall disease and pest severity.
Why perennial ryegrass? It is touted as having these beneficial properties:
- Perennial ryegrass is more digestible and has a higher energy content than most other cool season grasses.
- High-TNC (total nonstructural carbohydrates) forage increases the supply of readily ferment-able energy, enhancing the capacity of ruminal microorganisms to capture ammonia from forage soluble proteins.
- Reported to have high levels of alpha-linolenic acid (an omega-3 fatty acid, also in flaxseed).
- Newer cultivars of perennial ryegrass are more winter hardy (older cultivars died overwinter).
- Perennial ryegrass germinates quickly and is relatively easy to establish.
The perennial ryegrass mixture (blend) trials are being conducted at 4 places scattered around the Northeast: Orono, ME; Durham, NH; Burlington, VT; and State College, PA. The main study has six mixture treatments (plus optional 7th) with 5 replications. The criteria for formulating mixtures are:
- Number of cultivars in the mixture
- Relative heading date
- Winter hardiness rating
- Ploidity level (2N verses 4N) (See note on next page.)
All the treatments include white clover as a companion species.
The chart below describes the six mixtures (blends) and the seventh optional blend. In an ancillary study all ryegrass cultivars are seeded with white clover in individual plots with 3 to 4 replications. The trials were planted in August of 2012. The team plans to measure:
- Simulated grazing
- Quadrat cuttings when sward reaches 10 inches
- Clip down to 3 to 4 inches
- Dry matter yield per “grazing”
- Seasonal distribution and total seasonal production
- Forage Nutrient Content and Digestibility
- Foliar Disease Ratings
- Botanical composition three times per year
Cultivar survival/composition using DNA analysis
Note: Tetraploid versus Diploid Tetraploid ryegrasses offer several benefits in terms of animal performance. These are all due to the higher ratio of cell contents to cell wall in the tetraploid plants. One benefit is that it is more palatable to animals. This improves intake, and therefore leads to an in-creased animal production. In addition, tetraploid cell contents consist of rapidly available nutrients, such as sugars and starches, necessary for more efficient rumen function. However, it is important to remember that tetraploids have a higher water content in the cells. Therefore, when livestock are full from grazing, the actual dry matter intake could be lower compared to that of diploid plants. A mix of tetraploid and diploid ryegrass could achieve a more balanced pasture retaining a good level of dry matter production, an improved balance of quality feed, and if used for silage or balage, will be more easily wilted than a pure tetraploid pasture. From Specialty Seeds, NZ with edits.
The hoped for outcome of the ryegrass study is to develop a rational basis for formulating perennial ryegrass blends that results in higher yield, a longer grazing season, and greater forage quality.