Impact of Long-Term Storage on Alfalfa Leaf and Stem Silage Characteristics

Miranda C Sikora,Kenneth F Kalscheur,Ronald D Hatfield

doi:10.3390/agronomy11122505

Miranda C Sikora, Kenneth F Kalscheur + Show 1 more

Open Access

https://doi.org/10.3390/agronomy11122505

Copy DOI

Abstract

Fractionation of alfalfa (Medicago sativa L.) into leaves and stems can reduce cutting frequency while producing a high-value feedstuff. A difficulty with fractionation is the higher moisture content at ensiling due to the inability to wilt leaves without substantial dry matter loss or financial cost. To evaluate whether the silage quality of fractionated alfalfa is competitive with conventional methods under long-term storage conditions, high-moisture leaves (250–280 g·kg−1 dry matter, DM) and stems (190–240 g·kg−1 DM) were ensiled for 21 and 350 days and compared to wilted whole-plant silage for two alfalfa developmental stages. At 21 days, leaf and whole-plant silage fermentation characteristics indicated suitable lactic acid bacterial fermentation through decreased pH, high lactic acid–to-acetic acid ratio, and a lack of clostridial fermentation. At 350 days, leaf silage fermentation and nutritional quality decreased due to sustained proteolysis, but true protein still exceeded that of whole-plant silage. High-moisture stem fractions fermented poorly; at 21 days, stage 3 stems had significant amounts of butyric acid, while stage 5 stems became clostridial at 350 days. Long-term storage of high-moisture leaf silages can produce good-quality silage despite exceeding moisture contents typically recommended for alfalfa, while wilting is required for stem silages.

Highlights

Alfalfa (Medicago sativa L.) has desirable characteristics as a feed source for highproducing ruminants such as dairy cows
The average pre-ensiling dry matter (DM) concentration of each plant fraction was determined from three subsamples using the microwave method [14] and subsequently used to determine the amount of fresh material required for producing a packing density of approximately 160 kg DM·m−3 for a 500 mL Weck canning jar
This study was undertaken to determine whether a satisfactory fermentation was achievable to preserve the nutritional quality of the feedstuffs for longer durations of storage (>140 days)

Summary

Introduction

Alfalfa (Medicago sativa L.) has desirable characteristics as a feed source for highproducing ruminants such as dairy cows On average, this leguminous forage’s crude protein (CP) content exceeds 200 g·kg−1 DM when harvested prior to late flowering [1,2]. This leguminous forage’s crude protein (CP) content exceeds 200 g·kg−1 DM when harvested prior to late flowering [1,2] This characteristic is primarily due to its high leaf-to-stem ratio during early developmental stages (vegetative to early bud) and its lack of structural components in its leaves [3]. Yield per cut and seasonal yield are higher when fewer cuttings occur within a growing season [5,6] To optimize both yield and nutritional quality of alfalfa, fractionation of the plant into leaves and stems at more mature developmental stages is a promising solution. Alfalfa leaves do not change substantially in their nutritional quality until the green pod developmental stage is reached, but stem quality decreases rapidly even during the early stages of development [4]

Methods

Results

Conclusion