Brachiaria spp. is a superior grass that has the potential to be developed in Indonesia as a feed plant. Brachiaria has high productivity and nutritive value. Apart from being a " cut and carry" feed grass, research on Brachiaria in grazing areas also shows that Brachiaria has positive value as pasture grass1. Types of Brachiaria grass that are widely developed in Indonesia include Brachiaria decumbens cv. Basilisk, Brachiaria ruziziensis cv. Kennedy and Brachiaria brizantha cv. MG 5.
Brachiaria decumbens cv. Basilisk is a tropical grass species originating from northern Africa and has been broadly introduced in grazing regions due to its tolerance of dry conditions. Brachiaria decumbens cv. Basilisk is typically planted in South Africa in areas with low rainfall of 750 mm year1. This cultivar can tolerate dry and acidic soils and displays medium palatability, rapid growth and greater biomass in low-rainfall areas than in acidic soil conditions with rainfall of 1800 mm year1 2. The in vitro dry matter digestibility of Brachiaria decumbens cv. Basilisk in the winter was approximately 49.7% at 12 weeks of regrowth after cut-off, whereas in the summer season, this digestibility was 44.8% at eight weeks after cut-off3.
Brachiaria ruziziensis cv. Kennedy is the result of diploid sexual crosses that are widely cultivated in the tropics and subtropics as feed plants. Brachiaria ruziziensis has good nutrient content and seed production and requires good soil fertility and drainage4. Brachiaria ruziziensis cv. Kennedy contains 18-20% dry matter, 80-82% moisture content, 89-90% organic matter, 9-10% ash, 8-14% crude protein, 50-61% Neutral Detergent Fiber (NDF) and up to 40% Acid Detergent Fiber (ADF)5.
Brachiaria brizantha originated in Africa. This grass has an upright growth pattern, the base of the stems is extensively branched, the height can reach approximately one meter and the base is covered with hairy leaves1. Brachiaria brizantha grass is drought-resistant, with production of 40 t ha1 year1 with a content of 13.5% crude protein, 3.4% fat, 64.2% NDF, 15.8% ash, 0.31% calcium and 0.37% phosphorus6.
The use of different planting materials affects the growth and productivity of plants because plants have different growth rates7. The use of pols as planting material facilitates rapid growth and the risk of death in the field is smaller; the limitation of this planting material is the need to obtain healthy pols with many roots8. Seed planting material requires less time to plant and can be applied to a very large area because it can be spread but newly harvested grain seeds are difficult to germinate, so the seeds must be stored for approximately 6-8 months or soaked with sulfuric acid. Preparation of the planting material should be tailored to the surrounding environment and easy to manage9.
The amount of material required for each hole also needs to be considered to avoid competition for nutrients in the soil that affect the quality of forage. Increasing populations of 10,000, 20,000 and 30,000 plants/hectare will have elevated levels of dry matter and a decrease in crude protein content. Strong light competition will result in plants growing more erect with fewer leaves and smaller stems, increasing the amount of dry matter stacked on the stem, such that the dry matter content is greater in plants grown at high population density10.
Forage quality is evaluated based on the nutrient content, production and digestibility value. The chemical analyses performed for this evaluation are proximate and in vitro digestibility analysis. In vitro digestibility analysis has many advantages. In vitro methods are inexpensive, rapid and provide results close to in vivo results that are usually performed on ruminants that mimic the processes occurring within the rumen11. Digestibility can be measured by in vitro fermentation techniques according to the Tilley and Terry method12. This research aimed to identify the nutrient quality, production and digestibility of Brachiaria spp. grown from different planting material.
MATERIALS AND METHODS
This study was conducted for 4 months from April-August 2017 in the Greenhouse and Laboratory of Forage and Pastures, Faculty of Animal Science of Universitas Gadjah Mada, Yogyakarta, Indonesia. The soil was taken from the field of the Forage and Pasture Laboratory, Faculty of Animal Science, UGM. The soil (regosol) used in this study was the topsoil approximately 15 cm from the ground surface. Soil analysis was conducted to determine the nutrient content. The soil composition was C-organic (5.46%), N-Total (0.57%), N-NH4 (257 ppm), P2O5 (180 ppm), K (600 ppm) and pH (6.87). The soil was first separated by hoeing and sieving. The sieved soil was then placed into a polybag (5 kg capacity). The treatments were arranged in a split-plot design in which the main plot was the variety of Brachiaria (B. brizantha cv. MG5, B. ruziziensis cv. Kennedy and B. decumbens cv. Basilisk) and the subplot was planting material. A total of 54 polybags were divided randomly into 6 treatments and 9 repetitions. All the polybags were placed in a greenhouse with a spacing of 50× 50 cm. Seedlings aged 10 days old and pols were planted into the polybags. The plants were fertilized once, 30 days after planting, using 3.75 g of NPK 25-5-7. The fertilizer was provided at four points around the plant. Harvesting was conducted on the 45th day after planting, with the plants cut at 10 cm from the soil. The plants from each polybag were weighed immediately to obtain a fresh weight of crown biomass. The whole sample was then chopped and weighed. Samples were inserted into a paper bag and dried in an oven at 55° C for approximately 5 days until a constant weight was achieved. The samples were milled using a Wiley mill with a screen diameter of 1 mm and then, the milled samples were analyzed considering the levels of dry matter, organic matter, crude fiber and crude protein following AOAC methods13. The dry matter content was obtained by drying the material at 105° C; the water in the feed evaporated completely and left behind the dry material. The organic matter content was obtained by burning the sample at 550° C, at which point all organic materials will oxidize to CO2, H2O and other gases, while those remaining were ash. The crude fiber content was obtained by boiling a fat-free sample with 1.25% H2SO4 and 1.25% NaOH and burning the remaining ingredients at 550° C. The material lost at the time is the crude fiber. The crude protein content was obtained by breaking the organic N bond using 20% H2SO4 and a catalyst into NH4HSO4, which in an alkaline atmosphere can release NH2 which is then captured by borax acid and titrated with 0.1 N HCl.
Dry matter and organic matter digestibility were measured using the Tilley and Terry method12. The determination of in vitro digestibility according to Tilley and Terry consists of 2 stages. Stage 1 is a carbohydrate digestion by microbial rumen for 48 h. Stage 2 is a digestion with pepsin and HCl to remove protein from the bacteria and feed that remain after the 48 h of incubation.
All data were subjected to analysis of variance using SPSS 18® , according to the split-plot design. The differences among mean values were compared by Duncans Multiple Range Test (DMRT) at the p = 0.05 probability level.
RESULTS AND DISCUSSION
Chemical composition: The chemical composition of Brachiaria spp. grown from different planting materials in Table 1. The planting material had a significant effect (p<0.05) on the dry matter content of three varieties of Brachiaria. The dry matter content of Brachiaria grown using pols was higher (23.10%) than that grown using seed (19.68%). The use of pols produces more dry matter because the nutrient absorption rate of pols is better than that of seeds. This difference occurs because the formation of grass tillers in plants grown using pols is less than that of seed (ten days after germination), so the level of competition for plants to absorb nutrients and sunlight is lower for plants grown from pols than from seeds.
||Chemical composition of Brachiaria spp. with different planting materials (%) in Yogyakarta, Indonesia
|a,bdifferent superscripts in the same row indicate significant differences (p<0.05)
x,y,zdifferent superscripts in the same column indicate significant differences (p<0.05)
Pols have faster root development than seeds. This change causes the plant to absorb nutrients more quickly and result in increased nutrient value of the plant14. An excessive number of plants would decrease crop production due to competition for nutrients, water, sunlight and plant growing space15.
Varieties of Brachiaria showed a significant difference (p<0.05) in dry matter content. Brachiaria decumbens cv. Basilisk produced the most dry matter (24.67%) compared to Brachiaria ruziziensis cv. Kennedy (19.15%) and Brachiaria brizantha cv. MG5 (20.36%). The amount of dry matter shows the efficiency of the plant in utilizing the available nutrients and converting them to dry matter.
Organic matter from grass grown using pols and seeds showed no significant difference (p>0.05), with organic matter contents of 87.23% for grass grown from pols and 86.54% for grass from seed. Varieties of Brachiaria showed a significant difference in organic matter content (p<0.05). Brachiaria decumbens cv. Basilisk produced the most organic matter (87.82%) compared to Brachiaria ruziziensis cv. Kennedy (87.34%) and Brachiaria brizantha cv. MG5 (85.48%). The content of organic matter is one of the main parameters determining the quality of the plant: feed with more organic materials has more components that can be utilized by livestock. Factors affecting grass nutrient values include plant maturity, plant species, plant spacing and nutrient content16.
The use of different planting materials produced a significant difference (p<0.05) in the crude fiber content of the grass. The crude fiber content of grass with pols planting material was higher (30.15%) than that of the grass grown from seed (27.70%). Brachiaria varieties showed no significant differences (p>0.05) in grass fiber content. The three varieties of grass have similar morphology and were also cut at the same age, with no real difference to the crude fiber content.
The planting material had no significant effect (p>0.05) on the crude protein content. Grasses grown using pols contained a crude protein content of 10.94%, while those grown using seeds had a crude protein content of 10.85%. Brachiaria varieties showed a significant difference (p<0.05) in protein content. Brachiaria ruziziensis cv. Kennedy had the highest crude protein content (11.86%), Table 1, compared to Brachiaria decumbens cv. Basilisk (10.86%) and Brachiaria brizantha cv. MG5 (9.97%). Protein content is strongly influenced by the ability of plants to assimilate nitrogen from the planting medium to internal nitrogen networks. Plants that are more effective and efficient in utilizing nitrogen will have higher protein contents. The crude protein contents of B. decumbens, B. ruziziensis and B. brizantha that were harvested at six weeks were 10.6, 11.6 and 10.8%9.
Production: Production metrics of Brachiaria spp. grown from different planting material in Table 2. The use of different planting materials did not have a significant effect (p> 0.05) on fresh biomass production. The grass grown using pols produced fresh biomass of 5.43 t ha1, while the grass grown from seed produced fresh biomass of 5.46 t ha1. The Brachiaria variety showed a significant relationship (p<0.05) with fresh production. Brachiaria decumbens cv. Basilisk produced the greatest fresh biomass production of 6.83 t ha1 while Brachiaria ruziziensis cv. Kennedy produced 5.56 t ha1 and Brachiaria brizantha cv. MG5 produced 3.94 t ha1.
|Table 2:|| Production of Brachiaria spp. with different planting materials (t ha1)
|x,y,zdifferent superscripts in the same column indicate significant differences (p<0.05)
The number of shoots present in each clump will affect the production of the plant. The formation of buds is closely related to the formation of productive shoots, with more buds relating to more productive shoots17.
The planting material did not show any significant correlation (p>0.05) with the dry matter production. The grass planted using pols produced 1.25 t ha1 of dry matter while the grass planted using seed produced 1.12 t ha1 of dry matter. The production of this dry matter is based on the production of fresh grass, which does not show any real difference between the grass grown using pols and using seeds. Brachiaria varieties showed a significant difference (p<0.05) in dry matter production. Brachiaria decumbens cv. Basilisk produced the greatest dry matter production of 1.69 t ha1, while Brachiaria ruziziensis cv. Kennedy produced 1.07 t ha1 and Brachiaria brizantha cv. MG5 produced 0.79 t ha1. The shape and morphology of the plants are very influential on the production. The height of the grass plant Brachiaria decumbens influences the resulting dry weight of the plant18.
The planting material did not show any significant relationship (p>0.05) with the production of grass organic material. The grasses grown using pols produced 1.03 t ha1 of organic matter and the grasses grown from seed produced 1.03 t ha1 dry matter. Brachiaria varieties significantly differed (p<0.05) in the production of organic matter. Brachiaria decumbens cv. Basilisk had the highest organic matter production of 1.48 t ha1 while Brachiaria ruziziensis cv. Kennedy produced 0.94 t ha1 and Brachiaria brizantha cv. MG5 produced 0.67 t ha1. The ability of a plant to absorb nutrients affects the organic matter content of a plant19. The results for Brachiaria decumbens cv. Basilisk indicated that this variety can optimize the use of nutrients available in the soil better than the other varieties of Brachiaria.
Digestibility: In vitro levels of dry matter and organic matter digestibility of Brachiaria spp. grown from different plant materials in Table 3. The different planting materials showed no significant effect (p>0.05) on the resulting dry matter digestibility.
|Table 3:|| Digestibility of Brachiaria spp. with different planting materials (%)
|x,y,zdifferent superscripts in the same column indicate significant differences (p<0.05)
The dry matter digestibility with pols as planting material was 72.81%, while this digestibility for the grass grown from seed was 74.95%. The Brachiaria varieties significantly differed (p<0.05) in dry matter digestibility. Brachiaria ruziziensis cv. Kennedy showed the highest dry matter digestibility of 78.40% while Brachiaria decumbens cv. Basilisk had 78.25% and Brachiaria brizantha cv. MG5 had the lowest dry matter digestibility of 64.99%. In general, Brachiaria has a high dry matter digestibility and can improve average daily gain as well9. One of the factors that affect dry matter digestibility is the nutrient content of the feed. Higher nutrient content in feed ingredients will also increase digestibility20.
Planting material did not show any significant relationship (p>0.05) with the digestibility of organic matter. The grasses planted with pols as the planting material showed 76.11% digestibility, while those planted from seeds showed 78.82% digestibility. The Brachiaria varieties showed significant differences (p<0.05) in the digestibility of organic matter. Brachiaria decumbens cv. Basilisk showed the highest dry matter digestibility (82.56%), followed by Brachiaria ruziziensis cv. Kennedy (81.84%) and Brachiaria brizantha cv. The MG5 had the lowest digestibility (68.00%). The digestibility of organic matter is related to dry matter digestibility; a higher level of dry matter indicates greater digestibility of organic matter. A high percentage of crude fiber in the diet will lower the digestion of food substances because crude fiber contains components that are difficult to digest, such as lignin and silica21.
It can be concluded that the use of pols as planting material can increase the dry matter of plants but also increase the content of crude fiber. Brachiaria decumbens cv. Basilisk showed the best chemical composition. The use of different planting materials had no significant effect on grass production. Brachiaria decumbens cv. Basilisk showed the best production. The difference in planting material did not produce any significant difference in the dry matter and organic matter digestibility. Brachiaria ruziziensis cv. Kennedy showed the best dry matter digestibility and Brachiaria decumbens cv. Basilisk showed the best organic matter digestibility.
This study found that the use of different planting materials can affect the nutrient content of the mature plant. Pols is the best planting material because it can increase the dry matter content of grass. The use of different planting materials did not affect the production or digestibility of Brachiaria. Brachiaria ruziziensis cv. Kennedy was the best variety based on nutrient content, production and digestibility. Direct field tests are needed to identify the real effects of the selection of planting material in Brachiaria spp.
This study was funded by the Ministry of Research, Technology and Higher Education with the PTUPT project and the seeds used in this study were provided by Prof. Ryo Akashi, University of Miyazaki, Japan.