• Asian-Australasian Journal of Animal Sciences
• /
• 제13권2호
• /
• pp.176-181
• /
• 2000

In order to clarify the inhibitory effects of orchardgrass (Dactylis glomerata L.) lipids on ruminal fermentation and digestion, two experiments were carried out in vitro. Experiment 1 was carried out using residues of grass hay from which the lipid fraction was removed by ether extraction. To ground grass samples were added 0, 1.5, 3.0, 4.5 and 6.0% lipids and incubated anaerobically at $39^{\circ}C$ for 24 h, with the mixtures of artificial saliva and rumen fluid. Increasing grass lipid levels remarkably reduced DM and NDF disappearances. Volatile fatty acid concentration was significantly reduced at 3.0, 4.5 and 6.0% lipid levels. Microbial nitrogen proportion to total nitrogen tended to decrease by the addition of the lipids. These results indicated that grass lipids have a marked inhibitory effect on ruminal fermentation and digestion, especially when to the substrate was added 3% or more grass lipids as ether extracts. Experiment 2 was conducted to study the relationship between changes in the free fatty acids and changes in the fermentation traits. Samples were incubated for 3, 6, 9, 12, 15, 18, 21 and 24 h as a sole substrate. The polyunsaturated fatty acids steadily decreased during incubation, whereas the saturated fatty acid ($C_{18:0}$) increased. It was suggested that the hydrogenation was extended during the initial stage of incubation. The unsaturated fatty acids ($C_{18:2}$, $C_{18:3}$) produced at the initial stage of incubation were negatively correlated with the amount of microbial N and DM disappearance, indicating that polyunsaturated fatty acids had the possibility to show an inhibiting effect on ruminal fermentation and digestion.

• Asian-Australasian Journal of Animal Sciences
• /
• 제13권1호
• /
• pp.23-30
• /
• 2000

The effects of grass lipids and long chain fatty acids (LCFA; palmitic, stearic and oleic acids), at low concentrations (0.001~0.02%), on the growth and enzyme activity of two strains of anaerobic fungi, monocentric strain Piromyces rhizinflata B157 and polycentric strain Orpinomyces joyonii SG4, were investigated. The addition of grass lipids to the medium significantly (p<0.05) decreased filter paper (FP) cellulose digestion, cellulase activity and fungal growth compared to control treatment. However, LCFA did not have any significant inhibitory effects on fungal growth and enzyme activity, which, however, were significantly (p<0.05) stimulated by the addition of oleic acid as have been observed in rumen bacteria and protozoa. This is the first report to our knowledge on the effects of LCFA on the rumen anaerobic fungi. Continued work is needed to identify the mode of action of LCFA in different fungal strains and to verify whether these microorganisms have ability to hydrogenate unsaturated fatty acids to saturated fatty acids.

• 한국축산식품학회지
• /
• 제41권6호
• /
• pp.923-935
• /
• 2021

Fresh grass carp was used to produce surimi samples that were supplemented with 50 g/kg, 100 g/kg, or 150 g/kg pork back fat. The lipid composition, lipase activity, lipid oxidation index, and lipoxygenase activity of samples subjected to repeated freezethaw process were determined to assess the effects of the added fat on lipolysis and lipid oxidation of grass carp surimi. Freeze-thaw treatment increased free fatty acid content, mainly due to the decomposition of phospholipids and some neutral lipids by lipase. With repeated freeze-thaw treatment, the levels of free fatty acids and phospholipids were correlated with the lipid oxidation indexes and lipoxygenase activity, indicating that lipid degradation can promote lipid oxidation. In the same freeze-thaw cycle, surimi products with high fat content are more vulnerable to oxidative damage, neutral lipids are the main source of free fatty acids in the early stage of freeze-thaw, and phospholipids are the main source of free fatty acids in the late stage.

• 한국축산식품학회지
• /
• 제40권6호
• /
• pp.969-979
• /
• 2020

Fresh grass carp was used to produce surimi and 50 g/kg, 100 g/kg, or 150 g/kg pork back fat was added. The water distribution, thiobarbituric acid reactive substances (TBARS), myoglobin oxidation, color parameter (L*, a*, and b*), heme and non-heme iron content of samples were determined to analyze the effects of different fat content on the oxidation of myoglobin and lipids during multiple freeze-thaw cycles of grass carp surimi. Both multiple freeze-thaw cycles and increased fat content lead to an increase in TBARS, a blue shift in the absorption peak of myoglobin porphyrin, a decrease in heme iron content, and an increase of non-heme iron content. Repeated freeze-thaw caused a decrease in immobilised water content and L*, and caused an increase in a* and b*. Increased fat content caused an increase in immobilised water content, L* and a*, and caused a decrease in b*.

• Asian-Australasian Journal of Animal Sciences
• /
• 제22권9호
• /
• pp.1341-1350
• /
• 2009

Dietary lipids are rapidly hydrolysed and biohydrogenated in the rumen resulting in meat and milk characterised by a high content of saturated fatty acids and low polyunsaturated fatty acids (PUFA), which contributes to increases in the risk of diseases including cardiovascular disease and cancer. There has been considerable interest in altering the fatty acid composition of ruminant products with the overall aim of improving the long-term health of consumers. Metabolism of dietary lipids in the rumen (lipolysis and biohydrogenation) is a major critical control point in determining the fatty acid composition of ruminant lipids. Our understanding of the pathways involved and metabolically important intermediates has advanced considerably in recent years. Advances in molecular microbial technology based on 16S rRNA genes have helped to further advance our knowledge of the key organisms responsible for ruminal lipid transformation. Attention has focused on ruminal biohydrogenation of lipids in forages, plant oils and oilseeds, fish oil, marine algae and fat supplements as important dietary strategies which impact on fatty acid composition of ruminant lipids. Forages, such as grass and legumes, are rich in omega-3 PUFA and are a useful natural strategy in improving nutritional value of ruminant products. Specifically this review targets two key areas in relation to forages: i) what is the fate of the lipid-rich plant chloroplast in the rumen and ii) the role of the enzyme polyphenol oxidase in red clover as a natural plant-based protection mechanism of dietary lipids in the rumen. The review also addresses major pathways and micro-organisms involved in lipolysis and biohydrogenation.

• Journal of Microbiology and Biotechnology
• /
• 제29권2호
• /
• pp.256-267
• /
• 2019

The use of low-cost substrates represents one key issue to make single cell oil production sustainable. Among low-input crops, Arundo donax L. is a perennial herbaceous rhizomatous grass containing both C5 and C6 carbohydrates. The scope of the present work was to investigate and optimize the production of lipids by the oleaginous yeast Cutaneotrichosporon curvatus from undetoxified lignocellulosic hydrolysates of steam-pretreated A. donax. The growth of C. curvatus was first optimized in synthetic media, similar in terms of sugar concentration to hydrolysates, by applying the response surface methodology (RSM) analysis. Then the bioconversion of undetoxified hydrolysates was investigated. A fed-batch process for the fermentation of A. donax hydrolysates was finally implemented in a 2-L bioreactor. Under optimized conditions, the total lipid content was 64% of the dry cell weight and the lipid yield was 63% of the theoretical. The fatty acid profile of C. curvatus triglycerides contained 27% palmitic acid, 33% oleic acid and 32% linoleic acid. These results proved the potential of lipid production from A. donax, which is particularly important for their consideration as substitutes for vegetable oils in many applications such as biodiesel or bioplastics.

• 생명과학회지
• /
• 제26권5호
• /
• pp.592-602
• /
• 2016

풀사료를 주식으로 하며 자유롭게 방목되는 호주산 소와 곡물사료를 주식으로 하며 상대적으로 제한된 면적의 축사에서 사육되는 한국산 소의 두 가지 근육에서 디스트로핀 단백질 발현 수준을 비교하였다. 총 244 두의 식용소 도체로부터 양국에서 같은 부위의 골격근 조직을 채취하고 10% 중성 포르말린을 이용해 고정하였다. 본 연구에서 지방 침착률이 골격근 막 관련 단백질들의 소실과 밀접한 연관이 있다는 점을 발견하였는데, 특히 디스트로핀이 지방이 침착된 골격근에서 가장 유의적으로 감소하는 것을 확인하였다. 이와 동시에 CD36이 지방이 침착된 골격근에서 가장 풍부하게 발현하는 것도 확인하였다. 이렇게 정상 골격근의 구조를 유지하는 데 필요한 세포골격 단백질들의 소실에는 산화적 스트레스에서부터 사료의 종류에 따른 산화 지질 및 운동, 기후, 성장 기간 등의 환경에 이르기까지 다양한 사육 조건들이 영향을 미쳤을 것으로 여겨졌다. 디스트로핀은 근형질막 관련 단백질들 중에 근이영양증이나 근육 변성과 관계된 가장 민감한 막 단백질이다. 그러므로 본 연구는 사람의 근이영양증 관련 연구를 비롯해 동물모델을 이용하여 근육질환의 기전을 찾는 연구에도 중요한 초석이 될 것으로 보이며, 나아가 근이영양증 기전 규명을 위한 기초연구뿐만이 아니라 치료를 위한 실용화 연구에도 응용될 수 있을 것으로 사료된다.