Feasibility of ensiling elephant grass varieties and comparison with maize for feeding livestock during periods of scarcity

Sharmila Islam, Khan Md. Shaiful Islam and Rakhi Chowdhury

Department of Animal Nutrition, Bangladesh Agricultural University. Mymensingh-2202, Bangladesh
sharmila.21130319@bau.edu.bd

Abstract

Livestock production faces challenges as green grass supplies become limited in winter. This has led to the practice of generating silage from maize. However, maize is a seasonal fodder and is increasingly not an efficient means for small-scale farmers to use their land. Elephant grass has recently become popular for ruminant animal feeding in many countries, but not compared with maize. Thus, the goal of the present study was to know the feasibility of elephant grass (napier pakchong, and napier hybrids) production and ensiling in poly bags in comparison to maize. Napier pakchong (NP) and napier hybrid (NH) generated more biomass (114.96±1.57 and 110.88±1.23 tons/acre/year) than maize (109.98±1.11 ton/acre/year) while maize produced a higher dry matter (DM) yield (24.73±1.24 ton/acre/year). After 30 days of fermentation, lactic acid and pH of silage from NP (3.58g/100g DM; 3.8±0.25) was lower than maize silage (3.43g/100g DM; 4.04±0.05), NH also found good as silage (4.40g/100g DM 4.2±0.17). NP and maize had experienced roughly same levels of organic matter losses after ensiling. Crude protein content of silage from NP increased after 30 days of ensiling as compared to silage from NH and maize whereas the crude fiber concentration of all experimental silages dramatically (P<0.01) decreased. Therefore, the findings indicate that silage quality of NP, NH, and maize was comparable and that elephant grass production and ensiling could potentially be advantageous than maize.

Keywords: fermentation, napier pakchong, napier hybrid, pH

Introduction

Maize is a common fodder for livestock, having a high biomass yield and energy density compared to other forages. It is also used for the production of quality silage, as it enables the uniform feeding of animals throughout the year due to the presence of readily available nutrients (Cueva et al 2023; Szulc et al 2023). However, maize is a seasonal fodder and is considered inefficient for the utilization of land by farmers with small land sizes. On the other hand, the season has an impact on plant growth, which makes green fodder more or less scarce at certain times (da Silva et al 2017). Hence, some perennial fodder, such as elephant grass, is becoming more and more popular because of its quick growth, high biomass yield and amazing adaptation to a variety of soil types, fertility, and suitability for ruminant feeding (Phitsuwan et al 2015; Tudsri et al 2002). Some high-yielding varieties of this grass have been developed, named napier packchong (Pennisetum purpureum× Pennisetum glaucum) and napier hybrid (Pennisetum purpureum× Pennisetum typhoidium), which are mostly adapted to tropical countries (Sarker et al 2019). Protein concentration of elephant grass can reach 21% of dry matter after 30 days of growth, but after that, it can sometimes drop to 4% of DM (Butterworth 1965). The dry matter yields of elephant grass cultivars ranged from 20 tons/ha to 80 tons/ha under high fertilizer inputs (Hidosa et al 2022).

Maximum utilization of existing green fodder by preparing silage is one of the most effective techniques for animal feed supply in the dry season in the tropics. The principle of ensiling is based on spontaneous lactic acid fermentation under anaerobic conditions that lowers the pH to a level (3.7 to 4.5) at which clostridia and most mold growth get stunned (Tangni et al 2013). It is mainly due to the oxidative reaction of soluble sugars. Elephant grass contains a high WSC concentration at 6–7 weeks of growth, but the high moisture percentage of elephant grass when its nutritive value is highest is an obstacle for ensiling since it results in undesirable fermentation with considerable nutrient losses (Manyawu et al 2003). Previous studies have been conducted with the inclusion of additives like molasses and cell wall-degrading enzymes for the ensiling of elephant grass. Nevertheless, the inclusion of additives increases the cost for farmers and makes it difficult for them to incorporate in the proper proportion.

The recent study by Wagali et al (2023) reported that despite having a low WSC, tropical grass can be ensiled with desirable dry matter content of fodder. Kim et al (2021) reported that the quality and nutritional value of silage depend on many microbiological and agricultural factors like cultivar, dry matter content, soluble sugars, nitrogen compounds, pH drop, and temperature, as well as microbial quantity and species composition that determine the course of the ensilage process. The napier packchong (NP) and napier hybrid (NH) varieties of elephant grass have 12% more sugar than typically grown elephant grass as they have been crossed with bajra and pear millet to produce the NP and NH varieties(Triveni et al 2022). In light of this, the current study considered ensiling NP and NH in a carry-on bag after 70 days of growth since a longer growing period raises the dry matter content of fodder. Therefore, the objectives of the current research were to assess the viability of ensiling fresh elephant grass varieties, NP and NH, in two-layered 50kg bags and their efficient utilization in the dairy diet as an alternative to maize silage in terms of biomass production, nutrient yield, and silage quality.

Materials and methods

The research was carried out in the area of Melandaha which was located at 24.96670N 89.83330E of Bangladesh. Soil type of the area was loam, clay loam, sandy loam and loam in 0-15 cm, 15-30 cm, 45 -60 cm and 60-75 cm respectively. The temperature of that place was 27.50°C (81.50°F) and the area precipitation was 67.6 ml (2.66 inch) annually. Farmers of that area cultivated elephant grasses (NP, NH) and maize for trade to local livestock farmers and for their own livestock farms. The experiment was conducted as a completely randomized design (3×3). Three groups of fodder were selected with three replications for studying the biomass yield, nutrient yield, silage quality and their economic practicability.

Cultivation of fodders

Nine farmers were selected with nine acres of land, and every experimental group of fodder was cultivated on one acre of land with three replications. The land of elephant grass and maize was prepared using 90 kg of urea, 40 kg of TSP, and 20 kg of MOP fertilizer. Then cuttings of napier pakchong (NP) and napier hybrid (NH) were planted, maintaining a row-to-row distance of 91 cm and a plant-to-plant distance of 61 cm. Maize seed were planted in line sowing with (30x10) cm of 3-5 cm depth. Intercultural operations (irrigation, weeding and replacement of death plants) were conducted time to time. After 70 days of sawing, the perennial plant (NP and NH) height reached 70-75cm and the maize plant height reached 35-45 cm after 50 days of cultivation, and the milk line was visible in the maize plant. Fodders were harvested using a brush cutter-based forage harvester, and the green biomass yield was calculated by taking the weight of the fodder. The total harvest per plot of fresh forage was weighed, and sub-samples of 100g were taken from each experimental group of fodder and chopped into short lengths (2-5 cm) for determination of dry matter using the procedure of AOAC (2005). This involves drying in an oven at 60° C for 24 hours and 105°C for the subsequent 24 hours. After first cutting, 16-18 kg of urea was supplied to the plot of NP and NH. Maize was further cultivated using the previous methods taking 20 days for preparation of land. Harvesting of NP and NH was performed after 60 days of first harvesting, and maize was harvested after 50 days of planting. Then biomass and dry matter yield were determined following the same procedure as the first harvest.

Ensiling

Elephant grass (NP and NH) and maize were chopped into 2-3 cm using a chopper (Stationary Chopper Hege-44). Three different fodders were compacted in nine double layer bags considering three replicate for each type of fodder. In each two-layered silo bag, 50kg chopped grass was packed and vacuumed using vacuum pump. After proper compaction and removal of air, silo bags were sealed using sealer machine (pneumatic impulse heat sealer). Silo bags were preserved at room temperature (25-27°C) by covering them with a black sheet and opened after 30 days of fermentation.

Determination of silage quality

15g of silage and 100 ml of distilled water were taken. 50 ml of water was first mixed with the samples and blended (Philips HL7756/00) for 2-3 seconds. The remaining 50 ml of water was mixed, and the extract was prepared by removing silage particles. The electrode of the pH meter (PH 8-25 pH meter) was immersed in buffer solutions of 4.5 and 7.0 to check the accuracy of the reading. The reading was recorded by repeating it three times. Fleig’s point index was calculated using pH and the dry matter of silage by following the formula of Gao et al (2021) as a higher fleig's point index means the quality of silage is good for feeding animals. Lactic acid concentrations were analyzed using a spectrophotometer (UV/VIS Spectrometer) via the methods of Borshchevskaya et al (2016).

Proximate analysis of fodder and silage

100g of samples from perennial fodder (NP and NH) and maize were collected immediately for analyzing the chemical composition of fresh matter. 25 to 30 g fresh samples were dried in an oven at 105°C for subsequent 24 hours and dry matter was determined on a fresh basis by following the formula of DM%= (Weight of Sample after drying /Weight of Sample before drying) ×100.Samples from three types of fodder and silage were also sun-dried and ground using a DZJX universal grinder. Afterwards proximate components (Crude protein, Crude fiber, Ether Extract, Ash, and nitrogen-free extract) were determined according to AOAC (2005).

Statistical analysis

Biomass yield, nutrient yield, economics of fodder production, and ensiling quality were analyzed using the mean comparison test of SPSS (IBM SPSS Statistics Version 20). Changes in chemical composition were analyzed using independent t test of SPSS. The relationship between ensiling period and the chemical indexes of silage was determined by using pearson correlation analysis in SPSS software.

Results

Biomass and nutrient yield

The biomass yield from napier pakchong (NP) was higher compared to napier hybrid (NH) and maize in the first cutting, but the dry matter yield from maize was significantly greater than NH and NP during the 1st and 2nd harvestings and even after whole-year maize production (Table 1).

Although the dry matter yield of elephant grass was lower than maize, it slightly increased from their 1st cutting to their 2nd harvesting times. When it comes to the nutrient yield of three different fodders, NP had a significantly higher protein yield compared to NH and maize from their year-round production (Table 2). Up until the second harvesting, the crude fiber yields of the experimental NP and maize fodders were comparable, but NP had more tons than NH and M after end of year (Table 2).

Fermentation quality

Silage quality of NP was best, with a lower pH, higher fleigs point index compared to NH and maize (Table 3). Lactic acid concentration of maize silage was significantly greater than elephant grass silage but NP silage had higher amounts than NH silage.

Changes of chemical composition

The dry matter (DM), crude protein (CP), crude fiber (CF), ether extracts (EE), and ash content of all silages were changed after ensiling. NP silage showed an increased concentration of CP compared to maize and NH silage. The CF and NFE concentration of all experimental silages were reduced substantially than that of fresh fodder, whereas ash contents increased due to an anaerobic environment. The organic matter (OM) of all silages got reduced after 30 days of fermentation and the loss of OM was almost similar in the cases of NP and Maize (Table 4).

Correlation between ensiling days and chemical indexes

The three sets of silage's chemical indices and ensiling days followed nearly an identical pattern Dry matter, crude protein, ash, ether extract, and fleigs point index were positively correlated while pH, NFE, and CF were negatively connected with fermentation period (Table 5). The relationship between DM and CP was positive for every experimental silage. On the other hand, pH and fleigs point showed a negative relationship.

Discussion

The aforementioned experiment was conducted to assess the possibility of ensiling fresh elephant grass (NP and NH) varieties in two-layered bags and compare it with corn silage in terms of silage quality and chemical changes, as well as analyze the profitability of NP, NH, and maize production to find out the sustainability of fodder production and silage making from elephant grass in contrast to maize silage.

In the current research, biomass yield was higher from elephant grass because of multiple harvesting opportunities and outstanding fodder growth and quality, which were also observed in the studies of Rengsirikul et al (2013) and Sarkar et al (2016). However dry matter output was maximum from maize, as elephant grass contains a higher moisture percentage than maize, which results in a lower dry matter yield from elephant grass(Table 1).The nutrient yield of three experimental group was almost similar but napier pakchong showed higher protein yield compared to napier hybrid and maize. On the other hand fiber fraction of mazie was lower than NP and NH (Table 2).

The pH values of NP, NH, and maize were lower than 4.5, whereas the fleigs point index of maize and NP was above 80 which indicates the quality of silage was good (Table 3). The study of Bureenok et al.(2012) reported that silage pH and lactic acid levels are indicators of silage quality and McDonald et al(1991) reported that lactate levels should be >30 g/kg. In this study, silages of NP, NH, and maize clearly met these criteria.

The Dry matter (DM) content typically affects the silage's fermentation quality, and the ideal DM content considered for good silage is above 21 percent (McDonald et al 1991). In the present work, the DM content of harvested napier pakchong, napier hybrids and maize was higher than 21 percent. After the end of the fermentation period, the DM content of three groups of silage increased sharply as the activity of silage microorganisms slowed, which led to an increment in grass DM content (Table 4). This increased DM content indicates good fermentation and preservation of nutrients in silage (Amanullah et al 2014). Along with that, enhanced DM% led to an increment in fleig's point index and crude protein percentage as protein dimensions were hydrolyzed by lactic acid. As a consequence, dry matter and crude protein had a positive relationship (Table 5). The crude protein content of both silages climbed, but elephant grass types showed a higher escalation (Table 4). The study of Rahman et al (2021) also reported an increment of CP in grass silages after 30 days of fermentation but a reduction of CP after 60 and 90 days of ensiling. The presence of water-soluble carbohydrates (WSC) in the ensiling material is essential for proper fermentation because it provides the main energy source for the lactic acid bacteria that make lactic acid to thrive (Zhang et al 2016). Although NP and NH were cut at 70 days of growth, which was not the peak of high WSC concentration, it had no impact on the silage's quality. Due to the lactic acid's propensity to break down in ether, the amount of EE surged in grass silage and corn silage at the end of the fermentation period (Filachione and Fisher 2016). The corresponding rise in the EE value of corn silage was also observed in Yan and Agnew’s (2004) investigation. On the other hand, the percentage of CF in all three groups of silage got reduced after ensiling because of bacterial fermentation which indicates the possibility of digestibility improvement. Ensiling at high temperatures or in wet conditions is known to increase the rate of DM losses (Borreani et al 2016). The organic matter loss was similar in NP and maize silages as the moisture percentage of fresh fodder was not very low and the fermentation pattern was very rapid which contributes to the low percentages of organic matter loss (Table 4). Elephant grass variants had larger biomass yields, which can increase the economic benefit of farmers through low input even if maize's selling price become higher. Moreover, the yield of CP and EE from year-round production of elephant grass variants was also higher, which is a promising sign. The current study discovered that, in terms of fermentation quality and chemical contents, well-fermented corn and elephant grass silage followed the same pattern. Further study is necessary to evaluate the digestibility of fresh elephant grass silage and its effect on the milk production of dairy cattle. Animal feeding experiments will complete the assessment of elephant grass bag silage for inclusion in the ration of high-yielding dairy cows.

Conclusions

The similarities between the two varieties of elephant grass (NP and NH) and maize silage were demonstrated by the lower pH and lactic acid content, higher fleigs point index, and substantial chemical changes. Therefore, in addition to maize production, farmers can consider growing napier pakchong and napier hybrids for boosted fodder and nutrient yield and silage quality.

Acknowledgement

The study was made possible by the cooperation of farmers from Jamalpur district of Bangladesh.

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