Fecal sample preparation methods for gas chromatography analysis of fatty acids of ruminants fed different amounts of rumen protected conjugated linoleic acids (CLA)

Evaluation of autochthonous lactic acid bacteria as starter and non-starter cultures for the production of Traditional Mountain cheese

Lactococcus lactis subsp. lactis 68, Streptococcus thermophilus 93 and Lactobacillus rhamnosus BT68, previously isolated from Traditional Mountain (TM) cheese, were tested for the production of four experimental mountain cheeses, with the aim to assess their effectiveness in leading the TM-cheese-making process. Lactococcus lactis subsp. lactis 68 and Streptococcus thermophilus 93 were used as starter cultures, whereas Lactobacillus rhamnosus BT68 was used as non-starter culture. Three control (CTRL) cheeses were manufactured without adding any starter, according to the traditional cheese-making process; nine, cheeses were produced inoculating the vat milk with the starters (ST), starter and low concentration of non-starter culture (STLC), starter and high concentration of non-starter culture (STHC). Samples of vat milk, cheese after 24 h and 7 months ripening were processed for microbiological counts. Mesophilic cocci were dominant in all 24 h-cheese samples, while a dominance of both cocci and lactobacilli was observed after 7 months ripening. The total genomic DNA was extracted, and a fragment of V1-V3 region was amplified and pyrosequenced. Lactococci and streptococci were the most abundant species, and Lc. lactis ssp. lactis 68 affected the proliferation of milk-resident Lc. lactis ssp. cremoris, during the early fermentation. Lb. rhamnosus BT68 showed to be responsible in reducing the abundance of other Lactobacillus species. Moreover, it likely competed against Sc. thermophilus 93 for the same energetic sources, when added in concentration higher than 5 × 10³ CFU/mL milk. The sensorial and fatty acid (FA) composition analysis were performed on cheese samples at the end of ripening, demonstrating that the inoculated cheeses had better sensorial characteristics (aspect, smell, taste, texture) than CTRL cheeses, and that Lb. rhamnosus BT68 at high concentration is related to the increase of short chain fatty acids and conjugated linoleic acid in cheese after 7 months ripening.

Characterization of fecal fat composition and gut derived fecal microbiota in high-fat diet fed rats following intervention with chito-oligosaccharide and resistant starch complexes

The current study analyzed the different effects of intervention in high-fat diet fed rats using chito-oligosaccharides (CO group), resistant starch (RS group) and their complexes (CO–RS group), respectively.

The use of 2-dimensional gas chromatography to investigate the effect of rumen-protected conjugated linoleic acid, breed, and lactation stage on the fatty acid profile of sheep milk

In this study, 2-dimensional gas chromatography (GC × GC) was used to obtain a detailed fatty acid (FA) profile of sheep milk and to evaluate the effects of a rumen-protected conjugated linoleic acid (rpCLA) supply, breed, days in milk (DIM), sampling period, and number of lambs suckling on the FA profile. Twenty-four ewes, from 3 autochthonous breeds of the Veneto Alps (Brogna, Foza, and Lamon), were housed in 6 pens (2 pens/breed), according to DIM (38 ± 23 d) and body weight (61 ± 13 kg). The ewes and their offspring of 3 pens (1 pen/breed) were fed ad libitum a total mixed ration (control), and the other animals received the same diet supplemented with 12 g/d per ewe, plus 4 g/d for each lamb older than 30 d, of an rpCLA mixture. The study lasted 63 d. Two composite milk samples for each ewe were prepared during the first and second months of the trial. The pooled milk samples were analyzed in duplicate for FA profile by 2-dimensional gas chromatography, which allowed us to obtain a detailed FA profile of sheep milk, with 170 different FA detected, including many that were present in small concentrations. The milk relative proportions of individual FA, groups of FA, or FA indices were analyzed by PROC MIXED of SAS (SAS Institute Inc., Cary, NC), considering diet, breed, DIM, and sampling period as sources of variation. The random effect of animal was used to test diet, breed, and DIM, whereas the effects of period were tested on the residual. Breed had a small influence on milk FA profile, mainly on branched- and odd-chain FA. Within breed, animal repeatability for the relative proportions of milk FA was notable for almost all monounsaturated FA and for saturated FA with 14 to 19 carbon atoms, except C16:0, and less so for polyunsaturated FA. The inclusion of rpCLA (CLA cis-9,trans-11 and CLA trans-10,cis-12) increased the presence of the same CLA isomers in the milk as well as that of CLA trans-9,trans-11, and decreased the proportions of de novo-synthesized short-chain FA. From a cluster analysis based on the matrix of correlation coefficients among all FA relative proportions, 3 main FA groups were observed: the first included mainly odd- or branched-chain saturated FA, C18:0, C16:0 and CLA trans-10,cis-12; the second included monounsaturated FA or polyunsaturated FA with 16 to 20 carbons, CLA cis-9,trans-11, and CLA trans-9,trans-11; and the third included short- to medium-chain saturated FA, polyunsaturated FA with 2 to 5 double bonds, and 3 CLA isomers not affected by rpCLA addition (CLA trans-11,cis-13, CLA cis-9,cis-11, and CLA cis-10,cis-12).

Determination by GC×GC of fatty acid and conjugated linoleic acid (CLA) isomer profiles in six selected tissues of lambs fed on pasture or on indoor diets with and without rumen-protected CLA

In this study GC×GC was used to study the effects of pasture, hay, concentrate (indoor), and indoor plus 8 g/day of a rumen-protected conjugated linoleic acid (indoor-CLA) diets on the detailed fatty acid (FA) profiles of six tissues (muscles, fatty tissues, and liver) collected from 36 lambs. This powerful technique allowed the quantification of 128 FAs, of which 21 SFAs, 16 MUFAs, 19 PUFAs were identified by reference standards. The diets had similar, but not identical, effects on FA profiles (g/100 g FA) in the various tissues, as both indoor diets reduced total PUFAs (from 8.91 ± 6.27 to 8.06 ± 5.97; p < 0.05) and n-3 PUFAs (from 2.70 ± 2.37 to 1.50 ± 1.69; p < 0.01) and increased n-6 PUFA (from 3.76 ± 2.46 to 4.58 ± 3.42; p < 0.01), branched (from 2.37 ± 2.05 to 3.23 ± 0.54; p < 0.01), odd-chain FAs (from 5.88 ± 5.33 to 7.07 ± 1.51; p < 0.01) compared to pasture. Indoor-CLA increased CLAc9,t11 (from 0.42 ± 0.13 to 0.53 ± 0.19; p < 0.01), CLAt10,c12 (from 0.07 ± 0.06 to 0.12 ± 0.22; p < 0.05), and CLAc11,t13 (from 0.02 ± 0.04 to 0.05 ± 0.04; p < 0.05) compared to indoor.