The nutrient content of the sword bean leaves at various harvest times are shown in Table 1 and Table 2 and the field conditions are shown in Fig 1 to Fig 4.
The ash content of sword bean leaves from Table 1 at harvest age of 75 DAP (11.44%) and 180 DAP (12.77%) were not significantly different to each other but were significantly higher than the ash content at 20 DAP (8.47%). Crude protein content (Table 1) at the harvest age of 180 DAP (31.54%) was significantly higher than the harvest age at 120 DAP (20.17%) and 75 DAP (25.15%). In the studies (Table 1), the crude fiber content of sword bean leaves was not affected by the age of the plant. The crude fiber content was not significantly different in the leaves of the sword beans which were harvested at the age of 75.120 and 180 DAP (17.11%, 16.46 and 15.52% respectively). The calcium content in the leaves of the sword bean (Table 1) was not significantly different for all harvest ages. At harvest age of 75 DAP, the calcium content was 2.71%. The phosphorus content of the leaves in the study (Table 1) was directly proportional to the crude protein content of the leaves in various ages of the sword bean plant. At the age of 180 days, the phosphorus content (0.25%) was significantly higher than that harvested at 75 and 120 DAP.
The tannin content in sword bean leaves (Table 2) at 75 DAP (0.33%) and 180 DAP (0.33 %) were the same and significantly lower than 120 DAP (0.76 %). The saponin content in sword bean leave between plants aged 75 DAP (4.82%) and 180 DAP (5.74%) were not significantly different, but they were significantly lower than 120 DAP (6.99%). The treatment of various plant ages for lignin content in sword bean leave of 75.120 and 180 DAP, was not significantly different.
Nodule is the most important thing in legume like sword bean. The nutrient content of leaves is affected by nodule development stages. In the previous study showed that there was a nodule weight of 10.70 grams for a single sword bean plant with SP36 fertilizer of 100 kg/ha
(Indriani et al., 2018). According to
Tansley 2005, despite being degenerative, nodule aging is an active process in development in which the reactive oxygen species (ROS), antioxidants, hormones and proteinases have the key rolesancehave the key roles.
The ash content of sword bean leaves was similar to the research by
Susilawati et al., 2019 at harvest age of 90 days show that the ash contents of
Calopogonium mucunoides,
Centrosema pubescens and
Pueraria phaseoloides were 10.57%, 7.78% and 10.20% respectively. According to
Okello et al., (2018), ash content is important because it helps to determine the amount and the type of minerals in food.
The harvest age of 180 DAP is the right time to harvest both the pods and the leaves. The results of research by
Baloyi et al., (2008) show that the high crude protein content up to the post-flowering stage in legumes indicate that the plant is still growing vegetatively. According to research by
Baloyi et al., (2013), the crude protein of the Lablab bean plant (
Lablab purpureus) harvested at 15 weeks (105 days) was 22.7%. In the study of
Susilawati et al., (2019) the crude protein content of 90 days harvested
Calopogonium mucunoides,
Centrosema pubescens and
Pueraria phaseoloides were 14.93, 24.86 and 19.76% respectively.
Patil et al., (2021) stated that high protein in sword bean is one of protein source and gives beneficial for sustainable livestock production at low cost.
Cell walls are mostly composed of crude fibers (cellulose, hemicellulose and lignin) which are abundant in stems. According to research by Daning and Foekh (2018), the crude fiber content of the gamal plant (
Gliricidia sepium) is similar to the sword bean leaves, which is 15.7%. According to
Sutaryono et al., (2019) Moringa legumes at various cutting ages produced no different crude fiber content, namely 18.57% (1 month cutting age), 18.76% (2 months cutting age) and 18.92%. (3 months cutting age). The results of the research by
Susilawati et al., (2019) stated that at 90 days of harvest, the crude fiber content of
Calopogonium mucunoides (34.92%),
Centrosema pubescens (32.04%) and
Pueraria phaseoloides (34.66%) were found.
Bulyaba and Lenssen, (2019), stated that the use of legume leaves as forage can increase ruminant nutrients.
Hidosa (2017) stated that forage legumes have an important role in improving ruminant nutrients because it can be rapidly degraded in the rumen which is useful for meeting the needs of rumen microorganisms for the efficiency of low quality fiber degradation.
At harvest age of 75 DAP, the calcium content was 2.71% and higher than the research of
Indriani et al., (2016) at harvest age of 90 DAP of
Centrosema pubescens yielded 1.16%. According to research by
Baloyi et al., (2013) that the average Ca content of five
Lablab purpureus varieties with a harvest age of 15 weeks (105 days) was 2.73%. According to
Stavarache et al., (2014) calcium is a key element that cannot be replaced in basic metabolic functions by other cations.
Similar results show that the average phosphorus content of 5
Lablab purpureus varieties was 0.27% at harvest age of 15 weeks or 105 days
(Baloyi et al., 2013). Phosphorus (P) is the limiting nutrient after nitrogen for plant growth, production and quality. The demand for phosphorus is high during root proliferation, pod formation and seed maturation stages (
Bagale, 2021). According to
Bargaz et al., (2012), a significant decrease in growth was found for shoots, roots and nodules under low P soil compared to sufficient P soil. According to
Stavarache et al., (2014) which states that along with nitrogen, phosphorus is a basic element of plant nutrients, which is involved in energy production (ATP, ADP, NAD) and different nucleic acid molecular architectures.
According to
Meier and Bowman (2008), that high phenolic including tannins, can have a negative impact on the growth of surrounding plants by limiting the supply of N.
Arnoldi et al., (2020) say that secondary plant metabolites such as tannins mediate ruminants food plant interactions and also has an influence on decomposition and nutrient cycling in plants.
Hakl et al., (2015) that total forage (combined stems and leaves), around 80% of the crude protein fraction is effected by plant age/harvest and cutting time.
Forage legumes (
Vigna unguiculata and Lablab purpureus) significantly reduce enteric methane production in ruminants. This is achieved by the presence of tannins in the forage and a lower fiber content
(Washaya et al., 2018). Forages or by-products that are naturally rich in tannins can still be useful for reducing the environmental impact of providing protein feed to ruminants
(Herremans et al., 2020). Providing tannin can increase N retention, reduce nitrogen excretion and increase N metabolism in sheep (
Sharifi and Chaji, 2019).
The main effect of saponins in the rumen appears to be inhibition of protozoa (defaunation), which may increase the efficiency of microbial protein synthesis and protein flow to the duodenum. Saponins can also selectively affect certain rumen bacteria and fungi, which can alter rumen metabolism beneficially or detrimentally (
Patra and Saxena, 2009). However, with the increasing development of science, it is known that saponins also have a positive impact on both livestock and humans
(Yanuartono et al., 2017).
Saponins and tannins have been considered as chemical compounds that can reduce enteric methane fermentation. The addition of tannins and saponins at optimal doses can reduce methane production, metanogan populations and protozoa populations, as well as increase total and partial VFA production (especially propionate), rumen bacterial populations and does not interfere with the digestibility of feed ingredients (
Hidayah, 2016).
Moore and Jung (2001) stated that lignin is a polymer formed from monolignols derived from the phenylpropanoid pathway in vascular plants. It is deposited in the cell walls of plants as part of the process of cell maturation.
Frei (2013) reported that in animal nutrition, lignin is considered an anti-nutritional component in forage because it is not easily fermented by rumen microbes. In terms of energy yield from biomass, the role of lignin depends on the conversion process (
Frei, 2013).
