Judul: Rumen Microbial Population in the In vitro Fermentation of Different Ratios of Forage and Concentrate in the Presence of Whole Lerak (Sapindus rarak) Fruit Extract
Abstrak: This experiment was designed to investigate the effect of lerak extract on the dynamic of rumen microbes in the in vitro fermentation of diet with different ratios of forage and concentrate. In vitro fermentation was conducted according to the method of Tilley and Terry (1963). The design of experiment was a factorial block design with 2 factors. The first factor was the ratio of forage and concentrate (90:10, 80:20, and 70:30 w/w) and the second factor was the level of lerak extract (0, 0.6, and 0.8 mg/ml). Total volatile fatty acid (VFA) concentration, proportional VFA and NH3 concentration were measured at 4 h incubation. Protozoal numbers in the buffered rumen fluid after 4 and 24 h of incubation were counted under a microscope. Bacterial DNAs of buffered rumen fluid were isolated from incubated samples after 24 h of incubation using a QiaAmp kit. Total bacteria, Fibrobacter succinogenes, Ruminococcus albus, and Prevotella ruminicola were quantified using real time polymerase chain reaction (PCR). Lerak extract markedly reduced protozoal numbers in buffered rumen fluid of all diets after 24 h of incubation. Total bacteria did not change with lerak extract addition. While no difference in F. succinogenes was found, there was a slight increase in R. albus number and a significant enhancement in P. ruminicola number by increasing the level of lerak extract in all diets. Propionate concentration significantly increased in the presence of lerak extract at level 0.8 mg/ml. It was concluded that the addition of lerak extract could modify rumen fermentation and had positive effects on rumen microbes. (Key Words : Sapindus rarak, Rumen Microbial, Fermentation, Forage to Concentrate Ratio).
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Judul: Model of beef cattle production system based on local resources in Sumedang West Java
Abstrak: The aim of this research was to investigate the utilization of whole lerak extract to improve the in vitro fermentation, microbe diversity and performance of beef cattle fed with high forage based ration. There were four experiments i.e. 2 in vitro and 2 in vivo experiment. The first in vitro experiment evaluated the effect of whole fruit lerak extract with different levels (0;0.001; 0.01; 0.1 and 1 mg/ml) on ruminal fermentation and microbial diversity using native grass and concentrate (50:50, w/w) as a substrate. The second in vitro was aimed to investigate the effect of different level of lerak extract (0, 0.6, 0.8 mg/ml) on fermentation, population of rumen microbes and enzyme activity in the in vitro fermentation of diets composed of different ratios of forage and concentrate (90:10, 80:20, 70:30, w/w). The first in vivo study was conducted using 12 local beef cattle which received 3 different treatments of 0, 500 and 1000 mg lerak meal/kg body weight (BW). Daily gain, nutrient digestibility and blood profile were measured. Thus, the second in vivo study was conducted using 12 local beef cattle with three diets containing lerak extract of 0, 100 and 200 mg/kg body weight. Parameters measured were nutrient digestibility, fermentation products, feed intake and daily gain of beef cattle during 90 days treatment. In vitro experiment showed that 1 mg/ml of lerak extract reduced (P<0.01) protozoa population. The gas production tended to increase while methane production/ml gas was reduced but total methane production was same among treatments. Although lerak extract did not affect concentration of total VFA, it decreased molar proportion of acetic and butyric acid but increased that of propionic acid significantly (P<0.01) and improved the ratio of acetate: propionate. The population of some bacteria spesies most closely related to Prevotella ruminicola increased. The second in vitro experiment showed that there was no interaction between ratio of forage and level of lerak extract for all parameters. The addition of lerak extract did not affect dry matter digestibility, but reduced organic matter digestibility. In contrast, total VFA and propionate production increased (P<0.05) with 0.8 mg/ml lerak extract addition. Total numbers of Ruminococcus albus and Prevotella ruminicola were enhanced by increasing level of lerak extract in all diets, but numbers of Fibrobacter succinogenes tended to decrease. In vivo experiment showed that the addition of lerak meal 500 mg/kg BW in the beef cattle ration did not affect nutrient intake and digestibility. In contrast, lerak meal at higher level (1000 mg/kg BW) increased fibre intake and decreased nutrient digestibility (P<0.05) and white blood cells (P<0.01). There was no difference on average daily gain among treatments. The addition of lerak extract up to 200 mg/kg BW did not affect on nutrients digestibility. Total VFA and propionate proportion increased (P<0.05) and ratio of acetate:propionate decreased (P<0.05) with lerak extract addition. The used of lerak extract decreased NH3 concentration while nitrogen balanced and microbial crude protein synthesis similar among treatments
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Judul: Closed Knight’s Tour pada Papan Catur Berbentuk Persegi Panjang dengan Ukuran Maksimal 8 × 8
Abstrak: Closed Knight’s Tour merupakan langkah kuda yang mengunjungi setiap kotak pada papan catur tepat satu kali dengan langkah kuda berawal dan berakhir pada kotak yang sama. Graf yang terbentuk dari closed knight’s tour dinotasikan sebagai graf G(m,n), dengan m adalah banyaknya baris dan n adalah banyaknya kolom. Graf tersebut memuat Hamiltonian cycle. Sebuah graf terhubung G adalah graf bipartite jika dan hanya jika graf tersebut tidak memiliki cycle dengan panjang ganjil. Papan catur yang memenuhi syarat cukup untuk memiliki closed knight’s tour adalah papan catur berukuran 5 × 6, 5 × 8, 6 × 6, 6 × 7, 6 × 8, 7 × 8, dan 8 × 8.
Keyword: bipartite, closed knight’s tour, hamiltonian cycle, knight’s tour, teori graf