Ketahanan amida dalam sistem rumen dan efektivitasnya memodifikasi komposisi asam lemak pada tikus sebagai hewan model pascarumen

Abstract

Dietary n-3 polyunsaturated fatty acids (PUFA n-3), such as fish oil in ruminant potentially decrease cholesterol concentration in meat. Due to extensive lipolysis and hydrogenation of n-3 PUFA by rumen microorganism, n-3 PUFA was reacted with butylamine to produce fish oil amides that resist microbial breakdown in the rumen. Three in vitro trials were conducted to determine whether fish oil amides were degraded and hydrogenated by ruminal organism. The treatments consisted of ground corn hay supplemented with either no lipid, fish oil, combination of fish oil and amide, and amide alone. After 24 hours incubation, the degradation of amide was lower for 10% supplementation than for 5% supplementation (13% and 30% respectively). Fish oil amides had no effect on VFA, acetat:propionate, NH3, microbial protein, and gas production. Relative to control, fish oil amide significantly reduced the degradabilities of dry and organic matters, and protozoa population in cultures. In in vivo experiment, fish oil amide was added to rat diets as post ruminal model. This experiment was conducted to study the effectiveness of fish oil amide in decreasing plasma cholesterol and triglyceride concentrations, increasing PUFA in rat muscle and its effect on blood hematological status. Thirty five male Sprague Dawley rats of 7 weeks old were randomly divided into 5 (five) treatment groups. Control group (A) was fed with semi-purified diet containing of 8% corn oil. Treatment groups were supplemented with 4.5% fish oil (B), 3% fish oil+1.5% fish oil amide (C), 1,5% fish oil+3% fish oil amide (D), and 4.5% fish oil amide (E), respectively. The result showed that fish oil amide supplementation could maintain the number of erythrocytes and hemoglobin, while hematocrit value began to decrease with 3% amide supplementation compared to fish oil supplementation (B) and 1.5% amide supplementation (C). The number of leucocytes in group with 4.5% amide supplementation significantly increased (P<0,05) compared to the group supplementing fish oil (B). Fish oil amide supplementation had no effect on plasma cholesterol and HDL concentrations, but began markedly increased (P<0,05) plasma triglyceride, LDL concentrations, and muscle cholesterol at 3% amide supplementation. There was no enriched levels of n-3 PUFA in rat muscle with amide supplementation. It was concluded that 3% amide supplementation gave negative impact on hematological status, plasma lipid profile, mucle and adipose tissue.

Pemberian pakan tinggi asam α-linolenat dan khususnya asam lemak dengan rantai yang lebih panjang, yaitu EPA dan DHA, dapat memperbaiki kandungan asam lemak tak jenuh rantai ganda atau polyunsaturated fatty acids (PUFA) n-3 dalam jaringan daging domba untuk memenuhi standar kesehatan yang optimal bagi diet manusia. Pada ruminansia, diet asam lemak mengalami biohidrogenasi yang ekstensif oleh mikroorganisme rumen sehingga penyerapan didominasi oleh asam lemak jenuh yang mengarah pada pembentukan lipoprotein berdensitas sangat rendah atau very-low-density lipoprotein (VLDL). Biohidrogenasi asam lemak dalam rumen dapat diatasi dengan melindungi asam lemak, terutama PUFA n-3 dalam bentuk amida. Penelitian ini dimulai dari tahap pembuatan amida minyak ikan, uji ketahanan dalam sistem rumen, dan efektivitasnya dalam mengubah profil lemak pada hewan model. Identifikasi gugus amida yang terbentuk dilakukan dengan spektroskopi inframerah, sedangkan GC-MS digunakan untuk mengetahui kadar senyawa amida yang terbentuk. Pengujian dalam sistem rumen secara in vitro memperlihatkan bahwa senyawa amida tetap terdeteksi dalam kultur setelah inkubasi selama 24 jam, dengan tingkat degradasi masing-masing 30% untuk pemberian 5% dan 13% untuk pemberian amida sebesar 10%. Namun kondisi ini belum mampu memperbaiki kecernaan substrat dalam kultur. Kondisi lingkungan rumen, seperti pH, produksi gas, VFA, NH3 dan protein mikrob, masih dapat dipertahankan pada kisaran normal, dan tidak berbeda dari kontrol. Namun jumlah protozoa mulai menurun, kemungkinan karena mengalami lisis akibat pemberian amida. Pada pengujian ini, amida belum mampu mengatasi gangguan fermentasi akibat pemberian lemak, terutama asam-asam lemak tak jenuh. Hal ini ditandai dengan rendahnya degradasi bahan kering dan bahan organik dibandingkan dengan kontrol yang tidak mendapat sumber lemak.