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Fermentation and protein evaluation of 12 binary legume-grass mixtures ensiled during multiple small-plot harvests using vacuum-bag mini-silos.

A. Wilder

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06-23-2020

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Abstract:

T54
Fermentation and protein evaluation of 12 binary legume-grass mixtures ensiled during multiple small-plot harvests using vacuum-bag mini-silos.
A. Wilder*, S. Bosworth. University of Vermont Burlington, VT.

Perennial legumes and grasses are commonly grown in association for forage production in temperate regions of the world. Although much of this forage is preserved as fermented feed, little is known about how legume and grass species influence the fermentation and protein quality of legume-grass silages. To address this, binary mixtures of legumes (alfalfa, red clover, and birdsfoot trefoil) and grasses (timothy, tall fescue, meadow fescue, and perennial ryegrass) from small plots were artificially wilted to 45% DM and ensiled across 6 cuttings over 2 years. The grass proportion was measured in the field and used as a covariate for analysis and additional measurements were taken on vacuum-bag mini-silos to determine volumetric fermentation expansion and silage pH. Near infrared reflectance spectroscopy (NIRS) was used to determine crude protein, soluble protein (fractions A and B1), insoluble degradable protein (fractions B2 and B3), and degradable protein (fractions A, B1, B2 and B3). A split-plot analysis of covariance (ANCOVA) was used to analyze each cut and significance (α = 0.05) varied by cut for each parameter. Across all cuttings, legume-grass mixtures containing birdsfoot trefoil or red clover generally proportioned significantly more crude protein as insoluble degradable protein (fractions B2 and B3) and less crude protein as rapidly degradable soluble protein (fractions A and B1) compared with alfalfa mixtures. While grass species generally had little effect on silage protein fractions, tall fescue inclusion resulted in elevated soluble protein and reduced insoluble degradable protein in some cuttings. Mini-silos containing alfalfa-grass mixtures sometimes showed considerable expansion (up to nearly 200% of their original size), resulting in significant legume effects for 1st cut (P = 0.0143) and 3rd cut (P = 0.0003) ensilings. Significantly lower expansion was observed in red clover and birdsfoot trefoil mixtures in these cases.

Keywords: legume-grass mixtures, protein fractions, silage fermentation.

Biography: As a native of Northern Vermont, Allen has a passion for the dairy industry and the working and rural landscape. He holds degrees from Vermont Technical College (VTC) and the University of Vermont (UVM) and also studied at the W.H. Miner Institute in Chazy, NY. Allen has studied extensively under the guidance of UVM agronomist Sid Bosworth and has focused his research on perennial legume-grass mixtures that are commonly grown in the Northcountry.