Afduha Nurus Syamsi et al. Volatile Fatty Acids and Methane Profile of Dairy Cattle 283 Doi: 10.21059/buletinpeternak.v42i4.33074 Volatile Fatty Acids and Methane Profile of Dairy Cattle Ruminal Fluid was Gived Legumes in Ration Based on Synchronization Protein-Energy Index Afduha Nurus Syamsi*, Triana Yuni Astuti, and Pramono Soediarto Faculty of Animal Science, Universitas Jenderal Soedirman, Purwokerto, 53123, Indonesia Article history Submitted: 5 February 2018 Accepted: 8 November 2018 * Corresponding author: Telp: +62 85279129225 E-mail: nurussyamsiafduha@gmail.com ABSTRACT An experiment was aimed to assess the use of the legumes as a source of protein feedstuff and levels of protein-energy synchronization (PES) index in the diet of dairy cattles on volatile fatty acids (VFA) and methane (CH4) profile. The research was applied in In vitro techniques used a completely randomized design (CRD), with factorially pattern (2x3), the first factor was the two species of legumes (Sesbania and Leucaena) and the second factor was the three level of the PES index (0.4, 0.5, and 0.6), there were 6 treatment combinations and each was 4 replicates. The results showed that interaction between legumes with PES index was not significantly affected (P>0.05) on all variable. Legumes was not significantly affected (P>0.05) on all variables and PES index was significantly affected (P<0.05) on propionate, A:P ratio, and methane. The study concluded that the use of turi and lamtoro leaves combined with the protein- energy synchronization index (PES) at medium level (0.5) could increasing the production of VFA, especially propionate, suppressing A:P ratio and decreasing methane production. Key words: Legumes, Methane, Protein-energy synchronization index, Volatile fatty acids Introduction Dairy cattle ration consists of forages and concentrates, with a proportion of forage higher than concentrate. Common forages are from grass, such as elephant grass and king grass. The general characteristics of forages are containing high moisture and fiber content, but with low protein levels. Forage is an alternative fiber, namely leaves from the legumes group. Legumes is a proteinceus roughages which is a high protein fiber feed ingredient. Legumes protein levels reached 22% (Kushartono and Iriani, 2004), it can be used as a basis for growth that is only given in the dry season. Fulfillment of protein requirements in ruminants is not only focused on the quantity in the ration, but must have degradability that is in accordance with the energy source used. Protein and energy must be available simultaneously (synchronously) for the development of optimum rumen microorganisms, thus kinetic degradation of proteins must be in accordance with carbohydrate degradation. The balance of degradation can be achieved through the preparation of rations based on protein and energy synchronization (PES) index. The ration based on the PES index is determined as a ration that has a level of harmoniously degradation of protein and carbohydrates, expressed quantitatively with an optimum index, namely 1 (Ginting, 2005). The synchronization ratio of protein and carbohydrate degradation for local feed ingredients in the rumen is 20 g N / kg OM, meaning that to achieve the optimum PES index (1) it takes 20 g N in each kg of OM feed. This ratio is the standard used in determining the PES index in the rumen, thus the percent use of a feed ingredient in the ration must be adjusted to its index value to achieve a standard ratio or reach the optimum synchronization index (Hermon et al., 2008). Legumes is a feed ingredient with a low synchronization index, because of the protein matrix bond with the tannin. Legumes commonly used as animal feed are Leucaena glauca and Sesbania grandiflora, each of which has an PES index of 0.31 and 0.34 (Syamsi et al., 2015). The ration with a good synchronization index will increase the efficiency of microbial protein synthesis (MPS) and will maximize feed utilization in the rumen fermentation process. The simultaneous use of protein and energy will increase volatile fatty acids (VFA) production and reduce methane production. The aim of the study was to examine the use of legumes as feed ingredients for protein sources and PES index Buletin Peternakan 42 (4): 283-289, November 2018 Bulletin of Animal Science ISSN-0126-4400/E-ISSN-2407-876X Accredited: 36a/E/KPT/2016 http://buletinpeternakan.fapet.ugm.ac.id/