Local silage additive supplementation on fermentation efficiency and chemical components of leucaena silage

Chakrapong Chaikong, Nattanan Saenthaweesuk, Dennapa Sadtagid, Arunrung Intapim and Oanchalita Khotakham

Division of Animal Science, Department of Agricultural Technology, Faculty of Technology, Mahasarakham University,
Maha Sarakham 44150, Thailand
chakrapong_chaikong@hotmail.com

Abstract

Ensiling forage legumes has always been difficult due to low soluble sugar and high buffering capacity. Therefore local additive materials including brown sugar and bio-extract (homemade microbial inoculants) were used instead of sugarcane molasses and effective microorganism (EM) to improve fermentation efficiency and chemical contents of leucaena silage by using the 3 x 3 factorial in CRD with 4 replications.

The results found that each additive (1% fresh basis w/w) decreased the final pH although all silage had pH higher than 5.0, and produced an acceptable leucaena silage. Moreover the mixture of brown sugar and bio-extract reduced pH to the lowest at 4.82, remained protein content and declined fiber content (NDF and ADF) of the legume silage. The mixture of the local materials is able to be effectively applied as alternative silage additives for ensiling legumes.

Keywords: bio-extract, brown sugar, effective microorganism, molasses

Introduction

Leucaena leucocephala is a legume plant, commonly found in Thailand and other tropical countries. It has become important in the tropics to provide fuel wood, green manure and high protein animal feed. Its nutritive value is compared to alfalfa and considered to be a prospective protein source for tropical animals (Angthong et al 2007). Tropical farmers have used leucaena as “cut and carry” fodder for their animal and preserved in term of ensilage. However, ensiling forage legumes has always been difficult because of low water soluble carbohydrate and high buffering capacity. These conditions result in low lactic acid as well as high pH and acetic acid production. These notwithstanding, the fermentation characteristics of the tropical forage silage should be understood before the ensiling process can be manipulated to achieve a desirable product (Fleischer et al 1996). In Thailand, farmers practically use sugarcane molasses and effective microorganism (EM) for silage making. Nevertheless the benefit of EM cannot be expected due to unspecified-microbial source and the price of sugarcane molasses has been gradually higher nowadays. Brown sugar produced mostly from sugar cane can be easily found in any kitchen. Its nutrient consists of 97 % of sugar with 380 kcal per 100 g compared with 55 % and 290 kcal in molasses (Self nutrition data 2016). Bio-extract or bio-fermented or bio-decomposed matter is biological extracts from fresh organic matter which is fermented and digested with sugar or molasses, which contains many organic compounds and microorganisms, especially lactic acid bacteria from fruit fermentation (Department of Agriculture 2004). Therefore, the objective of this study was to improve the fermentation efficiency and chemical composition of leucaena silage by applying the local alternative sources of carbohydrate and microbial inoculants.

Materials and methods

Leaves and stems (<1.5 cm of diameter) of leucaena were harvested at early bloom state of growth during dry cool season (November to December), lead to low nutritive value of the silage material (Table 3), and then chopped into 2 to 3 cm of the length and ensiled without wilting. The 3x3 factorial in completely randomized design with 4 replications was applied: carbohydrate sources including none, sugarcane molasses and sugarcane brown sugar as well as microbial inoculants including none, effective microorganism (EM) and homemade bio-extract. Bio-extract was prepared easily at home by mixing water, brown sugar and pineapple peels at the ratio of 10 : 1 : 3 (w/w) according to Kromratanaporn (nd). The bio-extract was applied as microbial source at the fourth day of fermentation period which had the highest of lactic acid bacteria (LAB) at 2.9x10⁸ cfu/ml and the lowest pH at 3.15 showed in Table 1. The commercial EM applied in this study had an average of LAB at 3.1x10 ⁴ cfu/ml.

All silage additives were added at 1 % fresh basis (w/w) according to the practical process of local farmers at the time of ensiling in the laboratory silo (polyethylene and nylon bag containing 10 kg of ensilage). Three samples in each silo were taken from top to bottom parts of the silo before being blended and used as representative sample for laboratory analyses. The pH was measured using pH/Temperature meter consort C860 as well as LAB, yeast and mold were counted with spread plate technique at 7, 14, 21 and 30 days after ensiling. The chemical compositions of post-ensiled leucaena including DM, CP, ash, NDF and ADF were analyzed at 21 days of fermentation time according to AOAC (1990) and Goering and Van Soest (1970). All data were statistically analyzed by using the General Linear Model procedure and the difference among the treatments were performed by Least Square Means with significance of 5% (SAS 1998).

Results

Fermentation characteristics of ensiled leucaena

The pH was lower in almost treatment groups after 7 days compared with control group (P<0.05). However the supplementation of EM had no effect on pH in day 7 and 14 shown in Table 2. There was an interaction between carbohydrate and microbial source in pH at day 30 (P<0.05) as shown in Table 4. The mixture of carbohydrate source and microbial inoculants resulted lower pH silage when compare to microbial inoculants silage. Moreover bio-extract showed the most efficiency to decrease pH into the lowest when mixed with brown sugar or molasses (4.82 and 4.93 respectively) compared with EM (P<0.05).

There was a statistically significant difference in effect of the silage additives on the number of LAB in the legume silage. The LAB quantity was low in bio-extract group compared to control and EM silage at 7 days after ensiling (P<0.05). Yeast and mold in EM silage was high at 30 days of ensiling compared to none and bio-extract groups (P<0.05) (Table 2).

Chemical compositions of leucaena silage

Supplementing only carbohydrate or microbial source had no effect on the chemical compositions of leucaena silage (Table 3). However there was an interaction effect (P<0.05) between the both additives on CP, NDF and ADF as shown in Table 4. EM silage had low protein content compared with the mixture of EM and carbohydrate sources (P<0.05) while homemade bio-extract supplement had no negative effect on protein degradation. Brown sugar applied with microbial inoculate was able to reduce protein degradation (P<0.05). The mixture of brown sugar and EM or bio-extract showed the lowest in NDF and ADF content compared to other groups (P<0.05).

Discussion

The quality of leucaena silage with and without silage additive in this study can be accepted in terms of fermentation efficacy and nutrient contents. All additives can reduce the legume pH compared with untreated silage. However an average final pH of leucaena in this study was relatively high (5.19) compared with usual grass silage and compared with legume ensiling with higher level of additive supplying reported in other studies. This high pH of ensiled legume agrees with Fleischer et al (1996) who found that pH of leucaena silage without any additive at 30 days of fermentation was 5.27 compared to 4.0 and 3.94 for guinea grass and sorghum respectively. However the lower pH of legume silage can be achieved by supplementing higher level of carbohydrate source. Angthong et al (2007) ensiled leucaena leaf with 20% rice bran and 20% water (fresh basis). They found that all silage had pH of 4.4 to 4.5. Siangjong et al (2011) found that fermentation of leucaena with molasses 4, 6 and 8 % had pH lower than 5.0 but the higher pH (>5.0) found in supplementing vinasses. Moreover legumes are easily fermented when respectively substituted by grass with microbial inoculants supplementation. Jatkauskas and Vrotniakiene (211) applied homo- and heterofermentative lactic acid bacteria from commercial inoculants in legume-grass silage (red cover and ryegrass, 1:1). All microbial inoculants had a positive effect on silage pH and characteristics. Fleischer et al (1996) reported that the fermentability rate of leucaena was slow compared to grasses. This may be due to the lower content of water soluble carbohydrates and the higher buffering capacity of the legume. Consequently the pH of the legume silage remained relatively high. Unlike most tropical forages which on ensiling have high pH (Miller 1969). The lowest final pH (4.82) of the ensiling leucaena can be obtained from supplementing microbial inoculants and carbohydrate. Yitbarek and Tamir (2014) reported that forages with insufficient carbohydrate substrate could be successfully fermented if the sugar content of the material was increased by adding sugars directly in order to permit the lactic acid bacteria to complete with other components of the silage microflora and thus ensure preservation.

Yeast and mold eventually grew in ensiled material through fermentation time in this study that cause by high pH of ensiled legume. As yeast species that can utilize lactic acid aerobically develop, pH increases in the silage. This opens the way for the growth of other spoilage (aerobic) microorganisms, particularly once pH is above 4.5. Grasses including corn have a higher water activity at a given DM content compared with legumes like alfalfa so that fermentation to a lower pH is required in grasses to prevent clostridial growth. Because it is easy to obtain a silage pH below 4.0 in corn, clostridial silage is uncommon in corn silage. In alfalfa and grass silages, it is more difficult to achieve a sufficiently low pH to inhibit clostridia (Muck 2010).

The number of LAB, yeast and mold in ensiling leucaena was not much difference among the silages. However the bio-extract group had smaller counts of LAB than other groups at the first week of fermentation period that is due to the fact that the rapid reducing pH in the bio-extract silage (Table 2) can control microorganism growth even lactic acid bacteria in the silo. That is contrary to Harrison et al (1989) reported that forages treated with lactic acid bacteria contained greater quantities of lactobacili throughout the 57-d fermentation period and Amanullah et al (2014) found that lactic acid bacteria was higher in Lactobacillus plantarum and EM silages than in the control silage for 100 days. Yeast and mold at 30 days had high in EM group compared to others. It is due to the fact that high diversity of microbial species of EM consisting of predominant populations of LAB and yeasts as well as smaller numbers of photosynthetic bacteria, actinomycetes and other types of organisms (Higa 1991). However this result is contrary to Amanullah et al (2014) found that EM silage had a decreased yeast and mold count compared with no inoculants and Lactobacillus plantarum silages.

High efficiency of fermentation by mixing microbial inoculants and carbohydrate sources resulted in protecting protein degradation and reducing NDF and ADF contents of leucaena silage. The most efficacy of nutrient improvement was the additive mixture of sugarcane brown sugar and homemade bio-extract. Yitbarek and Tamir (2014) reviewed that in the present study, silages treated with lactic acid bacteria resulted in highest amount of organic acids and lowering final pH value improved the qualitative parameters of the silage compared with untreated silage. The silage treated with biological additives had also lower cell wall components (NDF and ADF) than control silage due to partial acid hydrolysis of hemicellulose. Some data suggests that certain microbial inoculants can decrease fiber content, increase fiber digestion and limit the formation of NH₃N from protein content in grass-legume silage (Harrison et al 1989). However, according to Woolford (1984) cited by Yitbarek and Tamir (2014) the provision of extraneous sugar alone is not sufficient to permit the lactic acid bacteria to compete with other components of the silage microflora and thus ensure preservation.

Conclusion

• Sugar cane molasses and brown sugar as well as EM and homemade bio-extract are able to be used locally as silage additives in order to decrease pH and produce an acceptable quality of leucaena silage.
  
  
• However homemade bio-extract and brown sugar is the best mixture additive to enhance the fermentation efficiency of ensiled leucaena as a result in reducing final pH to lower than 5.00, maintaining protein content and reducing structural carbohydrate by improving the fermentation efficiency.
  
  
• More efficacy of the leucaena fermentation from more supplement level of the silage additives could be possible.

Acknowledgments

This research was financially supported by Mahasarakham University, Thailand.

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Received 9 December 2016; Accepted 11 March 2017; Published 1 June 2017

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