Detailed Dimethylacetal and Fatty Acid Composition of Rumen Content from Lambs Fed Lucerne or Concentrate Supplemented with Soybean Oil

Abstract

Lipid metabolism in the rumen is responsible for the complex fatty acid profile of rumen outflow compared with the dietary fatty acid composition, contributing to the lipid profile of ruminant products. A method for the detailed dimethylacetal and fatty acid analysis of rumen contents was developed and applied to rumen content collected from lambs fed lucerne or concentrate based diets supplemented with soybean oil. The methodological approach developed consisted on a basic/acid direct transesterification followed by thin-layer chromatography to isolate fatty acid methyl esters from dimethylacetal, oxo- fatty acid and fatty acid dimethylesters. The dimethylacetal composition was quite similar to the fatty acid composition, presenting even-, odd- and branched-chain structures. Total and individual odd- and branched-chain dimethylacetals were mostly affected by basal diet. The presence of 18∶1 dimethylacetals indicates that biohydrogenation intermediates might be incorporated in structural microbial lipids. Moreover, medium-chain fatty acid dimethylesters were identified for the first time in the rumen content despite their concentration being relatively low. The fatty acids containing 18 carbon-chain lengths comprise the majority of the fatty acids present in the rumen content, most of them being biohydrogenation intermediates of 18∶2n−6 and 18∶3n−3. Additionally, three oxo- fatty acids were identified in rumen samples, and 16-O-18∶0 might be produced during biohydrogenation of the 18∶3n−3.

Age castration of Nellore males on the profile of fatty acids of meat

“…Bacterial lipids have a high proportion of branchedchain fatty acids, synthesized from propionate and/ or volatile branched-chain fatty acid derivatives of branched-chain amino acids and plasmogenic lipids, which have DMA (MIYAGAWA, 1982;VLAEMINCK et al, 2006). The presence of DMA indicates a pattern of rumen fermentation, in which the diet is the main determinant of ruminant meat quality (ALVES et al, 2013). These results are consistent since the animals were fed the same diet.…”

Effects of diet supplementation with herbal blend and sunflower seeds on fermentation parameters, microbial population, and fatty acid profile in rumen of sheep

“…Although the concentrations of some saturated fatty acids (palmitic, myristic, lauric acid) were decreased in the SS and HBSS diets, the content of stearic acid was significantly increased in the present experiment. According to Alves et al (2013), the common findings that a concentrate with PUFA overload inhibits the growth of bacteria able to hydrogenate 18:1 isomers to stearic acid, were not confirmed. In the present experiment, the fatty acid composition is probably due to sunflower seeds effect and this was not modified by herbs supplementation because the level of polyphenols in the ration was low if compared to the study of Vasta et al (2010).…”

“…The concentrations of iso-butyrate and iso-valerate were enhanced by SS and HBSS supplementation; these branched-chain volatile fatty acids are formed in the rumen by deamination of branched-chain amino acids, and their concentration is related to ruminal degradation of dietary protein. It is known that rumen fluid is very rich in branched-chain fatty acids, mainly of microbial origin produced from branched-chain SCFA and they are mostly affected by basal diet (Alves et al 2013). It seems that a higher content of branched-chain SCFA is due to the higher content of protein in SS diet with respect to the control diet.…”

Modulation ofin vitrorumen biohydrogenation byCistus ladanifertannins compared with other tannin sources

“…VFA were directly analysed by gas chromatography with flame ionization detection (GC‐FID) in a Shimadzu GC‐2010 Plus chromatograph (Kyoto, Japan) equipped with a Nukol capillary column (30 m, 0.25 mm i.d., 0.25 µm film thickness; Supelco Inc., Bellefonte, PA, USA) as described in the literature . Freeze‐dried rumen samples were transesterified into FA methyl esters by using a combined basic followed by acid catalysis . The internal standard was 19:0 (1 mg mL −1 ).…”

“…FA methyl esters were separated by GC‐FID using a Shimadzu GC‐2010 Plus chromatograph equipped with a TR‐CN100 silica capillary column (100 m, 0.25 mm i.d., 0.20 µm film thickness; Tecknokroma, Barcelona, Spain) according to procedures described in the literature . Identification of FA methyl esters and dimethylacetals (DMA) was achieved by comparison of retention times with those of authentic standards (37 Component FAME Mix, Supelco Inc.; Bacterial FAME Mix, Matreya LLC, Pleasant Gap, PA, USA) and by confirmation with gas chromatography/mass spectrometry (GC/MS) in a Shimadzu GC/MS QP 2010 Plus chromatograph …”