Effects of ensilability traits of forage legumes and additives on silage quality assessed by fermentation pattern and qPCR quantification of clostridia
Year: 2020
Type: dissertation
Abstract: The objectives of this research were to investigate the ensilability of legume bi-crops and the effect of additives on silage fermentation quality. Silages were made in laboratory scale-silos, and their quality was assessed by qPCR quantification of clostridia DNA and fermentation pattern. Mixtures of white lupin (Lupinus albus) and spring wheat (Triticum aestivum) were ensiled unwilted at early and late maturity stages (publication I) and at late maturity stage both unwilted and wilted (publication II). A mixture of red clover (Trifolium pratense), timothy (Phleum pratense) and meadow fescue (Festuca pratensis) was wilted 21 and 45 hours before ensiling (publication III). The additive treatments were untreated control (CON), formic acid (FA, 4 L t-1 fresh matter), mixtures of sodium nitrite and hexamethylenetetramine (NaHe), and sodium nitrite alone (SN). Lactic acid bacteria (LAB, homofermentative) treatment was only used in I. Dry matter (DM) concentration of forage crops ranged from 199 to 314 g kg-1 DM. The ensiled bi-crops in I were low in nitrate (0.2 g kg-1 DM), while nitrate concentrations in II and III were 3.8 and 4.0 g kg-1 DM, respectively Control and FA treatments produced high butyric acid concentrations of silages in I, and lower or zero concentrations in II and III, whereas NaHe and SN exposed no or only traces of butyric acid. Lactic acid bacteria treatment was successful only with lupin-wheat mixtures having high WSC concentrations at early maturity stage (I). Control treatment exposed high ammonia-N values between 129 and 241 g kg-1 N in all investigated lupin-wheat mixtures (I and II). The number of clostridial DNA copies (spores, vegetative cells and dead cells/spores) was highest in the CON and FA treatments. All silages were aerobically stable (I-III). The effect of hexamine (hexamethylenetetramine) on silage quality was investigated at two DM concentrations of a lupine-wheat mixture (II). Hexamine addition did not improve silage quality. Increasing hexamine concentration in a sodium nitrite solution showed no effect on clostridial activity compared to sodium nitrite alone. Clostridia was detected only in a few FA replicate silos (II). The use of SN as a sole solution (900 g-1 t) or as a mixture with hexamine (NaHe) produced silages of better quality than the treatments with FA (4 L t-1). In conclusion, legume bi-crops are difficult to ensile due to low DM, high buffering capacity, low nitrate concentration and being prone to clostridial activity and butyric acid fermentation. Nitrite-based additives were more suitable than formic acid when ensiling legume bi-crops that are prone to clostridial contamination.
Source: Työväentutkimus Vuosikirja
Author: Walter König
Language: English
Subfield: Animal Science and Zoology
Domain: Life Sciences
SDG: Zero hunger
Open Access status: green
OpenAlex ID: W3021553002