The Effect of Methanogenic Inhibitor Feed on Propionic Acid and Lamb Meat Chemical Quality

This study aimed to determine the effect of medium chain fatty acids (MCFA) on propionic acidsand lamb meat chemical quality. The treatment given was R1: feed without medium chain fatty acids(MCFA), while R2 dan R3 were the feed contained 1.0% and 1.5% of MCFA, respectively. The twelveheads of lambs yearling weight of 16-17 kg were used as materials. Biological trial was done for threemonths and then was slaughtered. Before being slaughtered, the animal was taken rumen fluid to beanalyzed for propionic acid. The carcass was sampled to be analyzed for chemical composition,cholesterol and fatty acids content. This study showed that methanogenic inhibitor feed with 1.0-1.5%MCFA could be used as sheep feed, and the results: the propionic acid content in rumen increased 29.59– 36.11%. The cholesterol content decreased 7.14-10.06%. For the meat fatty acids composition,unsaturated fatty acids increased 9.05 – 17.96%. while saturated fatty acid decreased 6.59 – 11.88%.


INTRODUCTION
Global warming is an issue that can interfere with the development of animal husbandry. Farms are considered as the cause of accumulation of these gases as environmental contaminants. The world's environment showed position the livestock sector as the largest contributor to green house gases (GHG). As most of the gas accumulating in the atmosphere that comes from the livestock sector is methane gas.
Inhibit the production of methane in the rumen was supposed to be done to respon global challenge of environment. Inhibition of methane production in the rumen resulting in changes in volatile fatty acids, especially propionic acid. Hydrogen (H 2 ) which is not formed into methane will be used for the formation of propionic acid. So, the inhibition of methane that will enhance the production of propionic acid.
In this study, the coconut cake was used as a source of medium chain fatty acid (MCFA) which can inhibit the production of methane, resulting in the increase of propionic acid production. In chemical process, propionic acid could minimize rumen biohydrogenation, making unsaturated fatty acid lead to small intestine without experiencing process of rumen hydrogenation (Marmer et al., 1985;Gilka et al., 1989). Meat quality is also influenced by the availability of sufficient propionic acid, the sufficient propionic acid content cause unsaturated fatty acid content in meat increases. The objectives of this study were to evaluate the effect of medium chain fatty acids (MCFA) on propionic acid and the lamb meat chemical quality.

MATERIALS AND METHODS
The animals used were twelve heads of male yearling lamb having body weight of 16-17 kg that were divided into the groups and reraed in individual cages equipped with place for feed and drink.
The treatment and nutrient composition are presented in Table 1. Biological trial was done in 3 months. After feeding treatment for three months, rumen fluid was taken for analysis of propionic acid content (Doreau et al., 1993), and then the animals were slaughtered. Muscle samples were taken from the Longissimus dorsi for moisture, crude protein, crude fat, cholesterol and fatty acids composition. Moisture was determined by air drying (AOAC, 2005). Crude protein content was calculated by converting the nitrogen content, determined by the Kjeldahl method (6.25 x N) (AOAC, 2005), crude fat by Soxhlet extraction using diethyl ether (AOAC, 2005), cholesterol -using Leibermann and Burchard Method Procedure (Plumer,1988) and meat fatty acids composition (AOAC, 2005).

Data Analysis
Data were analyzed using one-way ANOVA and differences between average of treatment were continued by Duncan's Multiple Range Test (Steel and Torrie, 1989).

Propionic acid
Rumen propionic levels in the study increased. Feed containing MCFA 1.0 to 1.5% could increase the propionic acid in rumen fluid. The raise of propionate causing methane amount in rumen declined (Christophersen et al., 2008). The linkage between propiogenic and methanogenic in competition is to get hydrogen (H 2 ). According to Martinko and Madigan (2005), propionic acid is formed from two pathways through the acrylate and succinate. Both of these two pathways in the form of propionic always need hydrogen.

The chemical composition of lamb
The results of research showed that the addition of coconut cake as methanogenic suppressing agent in the diet were not significantly different on moisture content of meat ( Table 2). The moisture in this research varied at 71.92-72.95%. Soeparno (2005) reported that the moisture in meat was 68-75%, meanwhile Lawrie (1979) also stated that meat moisture ranged 68-80%. Differences in moisture content could be influenced by environmental and genetic factors (Berg and Butterfield, 1976). Several authors had mentioned that moisture had an inverse relationship on the fat content of meat (Sheridan et al., 2003;Lee et al., 2008;Santos et al., 2008;Madrugan et al., 2005).
The results of research showed that the addition of coconut cake as methanogenic suppressing agent in the diet did not affect on crude protein of meat ( Table 2). The crude protein content in this research (R1, R2 and R3) was similar. The crude protein content of meat in this research varied at 20.84-21.33%. Crude protein levels were still within the range as reported by Soeparno (2005) that crude protein content of lamb varied at 16-22%. Meanwhile, Geay et al. (2001) stated that protein of meat ranged at 17-22%. No difference on crude protein of lamb given methanogenic inhibitor feed caused due to similar growth. According to Sherdian et al. (2003) the difference in energy level did not affect the protein content of meat.
The results of research indicated that feed treatment using coconut cake of MCFA source as methanogenic inhibitive agent did not affect meat fat content. In this study, fat level of meat varied at 5.12-5.22%. These results are still in range of meat fat content according to Forest et al. (1975) that was 1.5-13%. Differences in lipid levels could be caused by the variations in growth patterns of carcass that consisted of bone, muscle and fat, besides it was also influenced by other factors such as genotype and physiological status of livestock (Soeparno, 2005). In general, reduction in muscular activity would increase fat deposition in muscular tissue, whereas intramuscular fat was widely affected by heredity factors (Forest et al., 1975).
The meat cholesterol levels decreased when the feeding was supplemented by MCFA. Meat cholesterol content in treatment R1 was found sufficiently higher than treatment R2 and R3. There was reduction approximately 7.14% when feed was given with coconut cake with 1.0% of MCFA content than without coconut cake. It indicated that feed containing coconut cake as much as 14% could reduce cholesterol content of lamb. In rumen digestion, MCFA content of coconut cake played a vital role in reducing methane production (Machmuler et al., 2006), affecting increase of propionate acid production. According to Duckett et al. (1992), propionic acid did not affect total fat and crude fat, but it could reduce cholesterol level. Furthermore, Duckett et al. (1992) stated that about 27 carbon chains of cholesterol were derived from acetate acid. Propionic could reduce acetate availability making cholesterol synthesis inhibited. According to Odle (1997) stated that MCFA had high soluble force and lower digestion enzyme need, making it easy to enter liver through venous without passing through lymph circulation and quickly burnt to be energy. It caused increasing of metabolism in Mean with different superscript at the same row differ significantly (P <0.05). C-12 = lauric acid; C-14= miristic acid; C-16= palmitic acid; C-16(1)= palmitoleic acid; C 18 = stearic acid; C-18 (1)= oleic acid; C-18(2)= linoleic acid; C-18(3)= alpha-linolenic acid; C-22 = behenic acid.; C-24 = lignoceric acid; SAFA= saturated fatty acid; MUFA= mono unsaturated fatty acid; PUFA=polyunsaturated fatty acid; UFA=unsaturated fatty acid body so that fatty acids not deposited in body and not changed into cholesterol.

The Fatty Acid Content of Lamb Meat
Composition of the fatty acid content of meat is presented in Table 3. Differences in fatty acids occurred in stearic acid (C-18). There was reduction of stearic acid content when animal consumed medium chain fatty acid (MCFA). Stearic acid level reduced in giving 1% of MCFA in feed, then reduced again when feed increased MCFA content. Change in fatty acids also occured in C-18 unsaturated fatty acids for both MUFA and PUFA. Giving 1% of MCFA increased oleic, linoleic and linolenic acids, and after adding 1.5% of MCFA, more increase. The content of SAFA in lamb was reduction when the animals consumed 1%-1.5% of MCFA. Similarly, MUFA and PUFA were change in content after giving MCFA. Content of MUFA and PUFA was increasing. MCFA could increase composition of meat fatty acids especially MUFA and PUFA. Ratio between saturated fatty acids and unsaturated fatty acids showed significant difference. Feed containing 1-1.5% of MCFA produced more meats containing unsaturated fatty acids (MUFA/PUFA). Whereas treatment of feed which did not contain MCFA produced meats widely containing saturated fatty acids (SAFA).
The increase of meat unsaturated fatty acid content caused by feed treatment (R2 and R3) contains MCFA. Therefore, when MCFA is consumed, propionic acid increased (Tabel 2). The propionic acid played of role on the quality of meat produced. According to Marmer et al. (1985), propionic suppressed rumen biohydrogenase causing unsaturated fatty acids was not degradated in rumen and the unsaturated fatty acids went into the small intestine. The presence of propionic in the rumen not only inhibit the biohydrogenase process in rumen, but also increased the odd-chain fatty acids of intramuscular fat (Duckett et al., 1993).

CONCLUSION
Methanogenic inhibitor feed with 1.0-1.5% MCFAcan be used as feed for sheep, and the results showed that the propionic acid content in rumen increased at range of 29.59-36.11%. The cholesterol content decreased at range of 7.14-10.06%. For the meat fatty acids composition, unsaturated fatty acids increased at range of 9.05-17.96%, while saturated fatty acid decreased at range of 6.59-11.88%.