In vitro study of dietary factors affecting the biohydrogenation shift from trans-11 to trans-10 fatty acids in the rumen of dairy cows

Productive Performance, Milk Composition and Milk Fatty Acids of Goats Supplemented with Sunflower and Linseed Whole Seeds in Grass Silage-Based Diets

The objective of this study was to determine productive performance, milk composition and milk fatty acids (FA) of goats supplemented with sunflower and linseed whole seeds in grass silage-based diets. Nine Alpine goats were grouped in a replicated 3 × 3 Latin square design (n = 3), that included three 21-d periods. Treatments were based on grass silage offered ad libitum and a concentrate mixture supplemented with either 40 g/d of Megalac-R^® (control), 80 g/d of sunflower seed (SF), or 80 g/d of linseed (LS). Dry matter intake (1292 ± 14.0 g/d) and digestibility (g/kg) of dry matter (640 ± 32.1), organic matter (668 ± 32.4), neutral detergent fiber (628 ± 41.4) and acid detergent fiber (567 ± 60.9) was not affected by treatments (p > 0.05). Treatment did not affect milk fat yield (39.9 ± 1.24 g/d), protein content (4.5 ± 0.03 %) and protein yield (34.7 ± 1.22 g/d). Compared to control, SF and LS, decreased C16:0 (28.2 vs. 23.1 and 22.4 g/100 g), and increased total C18:1 (24.1 vs. 27.6 and 28.4 g/100 g) respectively. Overall, SF and LS resulted an effective strategy for altering the FA composition of goat´s milk towards a healthier profile for humans without deleterious effects on animal performance.

Liquid molasses interacts with buffers to affect ruminal fermentation, milk fatty acid profile, and milk fat synthesis in dairy cows fed high-concentrate diets

We aimed to evaluate the effects of feeding sugarcane liquid molasses (LM) with or without a commercial buffer mix (BFM) on ruminal fermentation parameters, milk fatty acid (FA) profile, and milk yield and composition in dairy cows fed high-concentrate diets (35:65 forage-to-concentrate ratio). Eight multiparous Holstein cows (4 ruminally cannulated) averaging 165 ± 12 d in milk at the beginning of the study were randomly assigned to a replicated 4 × 4 Latin square design with a 2 × 2 factorial arrangement of treatments. Each period lasted 21 d with 14 d for diet adaptation and 7 d for data and sample collection. Cows were fed the following diets: (1) no LM or BFM supplementation (CTRL), (2) LM without BFM supplementation (MOL), (3) BFM without LM supplementation (BUF), and (4) LM plus BFM supplementation (COMBO). These 4 isonitrogenous and isoenergetic diets were formulated by replacing (dry matter basis) 5% ground corn with LM, whereas BFM replaced wheat bran at 0.8% of the diet. Significant LM × BFM interactions were observed for the duration of ruminal pH below 5.8, molar proportion of propionate, acetate-to-propionate ratio, milk proportions of trans-10 18:1 and total trans FA, and concentration and yield of milk fat. Feeding MOL and BUF alone were effective on reducing the time that ruminal pH remained below 5.8 compared with the CTRL treatment, and the COMBO diet decreased it further. A similar pattern was observed for the ruminal molar proportion of propionate. The milk proportions of trans-10 18:1 and total trans FA dropped significantly with BFM or LM supplementation versus cows fed CTRL, and the COMBO diet decreased these variables further. Note, however, that these changes elicited by the COMBO diet were not in the same magnitude as those caused by MOL or BUF fed alone. The ruminal molar proportion of acetate increased with the BUF diet and that of butyrate increased in cows fed MOL, but mean ruminal pH was not affected by treatments. Diets with LM resulted in increased concentrations of short- and medium-chain FA in milk fat. The yield of 3.5% fat-corrected milk increased significantly in cows fed MOL or BUF due to the improved concentration of milk fat. A trend and a significant increase for energy-corrected milk were observed with feeding MOL or BUF, respectively. Overall, inclusion of LM and BFM appears to reduce milk trans-10 18:1 FA and total trans FA by modulating ruminal pH and volatile FA profile in cows fed high-concentrate diets.

Enzymatic Study of Linoleic and Alpha-Linolenic Acids Biohydrogenation by Chloramphenicol-Treated Mixed Rumen Bacterial Species

In the rumen, dietary polyunsaturated fatty acids (PUFA) are reduced by a multistage reaction called biohydrogenation (BH). BH leads to a high proportion of saturated fat in ruminant products, but also products some potential bioactive intermediates like conjugated linoleic and linolenic acids. BH is composed of two kinds of reactions: first an isomerization of PUFA followed by reductions (two for linoleic acid, C18:2n-6; three for α-linolenic acid, C18:3n-3). There is little knowledge about BH enzymes as BH bacterial species are the subject of a lot of studies. Nevertheless, both aspects must be explored to control BH and enhance the fatty acids profile of ruminant products. In the present study, an alternative approach was developed to study the enzymes produced in vivo by mixed ruminal bacteria, using inactivation of bacteria by chloramphenicol, an inhibitor of protein synthesis in prokaryotes, before in vitro incubation. To study C18:2n-6 and C18:3n-3 BH several experiments were used: (1) with different incubation durations (0 to 3) to estimate average rates and efficiencies of all BH reactions, and intermediates production; and (2) with different initial quantities of PUFA (0.25 to 2 mg) to estimate Michaelis–Menten enzymatic parameters, K_m and V_max. A last experiment explored the effect of pH buffer and donor cow diet on C18:2n-6 isomerization pathways. Concerning C18:2n-6 BH, this study confirmed the high saturability of its isomerization, the inhibition of both trans11 and trans10 pathways by a low pH, and the last reduction to stearic acid as the limiting-step. Concerning C18:3n-3, its BH was faster than C18:2n-6, in particular its isomerization (V_max = 3.4 vs. 0.6 mM/h, respectively), and the limiting-step was the second reduction to t11-C18:1. Besides, our mixed isomerases had a higher affinity for C18:2n-6 than for C18:3n-3 (K_m = 2.0 × 10^-3 vs. 4.3 × 10^-3 M, respectively), but due to their high saturability by C18:2n-6, they had a lower efficiency to isomerize C18:2n-6 than C18:3n-3. Chloramphenicol-treated ruminal fluid would be a meaningful method to study the BH enzymes activities.

The reduction of starch in finishing diets supplemented with oil does not prevent the accumulation of trans-10 18:1 in lamb meat

The experiment was conducted to test the hypothesis that the replacement of cereal with low-starch feed ingredients in lambs' finishing diets supplemented with oils could prevent the accumulation of -10-18:1 in meat. Forty lambs were fed 1 of 4 diets supplemented with soybean oil (5.9%) and fish oil (1%) for 6 wk before slaughter. The control (CON) diet contained 43% barley, and in the other diets, barley was completely replaced by dehydrated citrus pulp (DCP), dehydrated sugar beet pulp (DBP), or soybean hulls (SH). Growth performance, feed intake, and carcass and meat quality traits were analyzed. At slaughter, LM samples were collected for gene expression evaluation, and 3 d after slaughter, LM and subcutaneous (s.c.) fat samples were collected for fatty acid analysis. None of the diets affected meat quality, but the DCP diet reduced ADG ( < 0.05) and the DCP and SH diets decreased the feed-to-gain ratio ( < 0.01). The DCP diet increased ( < 0.05) the risk of parakeratosis and the severity of the lesions. Moreover, the DBP treatment led to increased a* (redness) and b* (yellowness) in s.c. fat compared with the CON treatment ( < 0.05). The lipid content of LM did not differ ( > 0.05) with treatment and averaged 34.4 g/kg of meat. Diets had no effect ( > 0.05) on SFA, PUFA, and -MUFA sums and on the -6:-3 ratio in both LM and s.c. fat. A lower expression of fatty acid synthase (FASN) was found with the DCP treatment than with the other treatments ( < 0.001). All treatments showed a high accumulation of -10-18:1, averaging 91 mg/g fatty acid in LM and 147 mg/g fatty acid in s.c. fat. The concentration of -11-18:1 in the tissues was considerably lower than that of -10-18:1, and thus the -10-18:1:-11-18:1 ratio was above 3 with all treatments. Despite this, the SH diet clearly promoted a larger deposition of -11-18:1 and -9,-11-18:2 in tissues compared with the other treatments. () gene expression and SCD activity index in LM were reduced with the SH diet compared with the CON and DCP diets. Overall, these results clearly showed, for the first time, that low-starch/high-NDF diets are not able to prevent the establishment of -10 shifted rumen biohydrogenation pathways, evaluated by the deposition of biohydrogenation intermediates in lamb meat and fat.

Effect ofPropionibacterium freudenreichiion ruminal fermentation patterns, methane production and lipid biohydrogenation of beef finishing diets containing flaxseed oil in a rumen simulation technique

Meale, S. J., Ding, S., He, M. L., Dugan, M. E. R., Ribeiro Jr. G. O., Alazzeh, A. Y., Holo, H., Harstad, O. M., McAllister, T. A. and Chaves, A. V. 2014. Effect of Propionibacterium freudenreichii on ruminal fermentation patterns, methane production and lipid biohydrogenation of beef finishing diets containing flaxseed oil in a rumen simulation technique. Can. J. Anim. Sci. 94: 685–695. The objectives of this study were to examine the effects of Propionibacterium freudenreichii (strain T54; PB) and flaxseed oil (FO) in a total mixed ration on ruminal fermentation, CH4production and fatty acid biohydrogenation in two artificial rumens (RUSITEC). The experiment consisted of 8 d of adaptation and 12 d of sample collection with four replicate fermenters per treatment. Treatments were: (1) CON; (2) PB; (3) FO (60 g kg−1DM with autoclaved PB); (4) FOPB (60 g kg−1DM with PB). Disappearance of DM (g kg−1DM) and gas production (mL g−1DM) were not affected by treatment (P>0.05). Inclusion of FOPB increased (P=0.01) total volatile fatty acid (VFA) production (mmol d−1), compared with CON and PB. The acetate:propionate ratio was reduced (P<0.001) in all treatments, compared with CON. Methane production (mL g−1DM or mL g−1DMD) was lowest (P<0.001) with PB (27.1%); however, FO (14.3%) and FOPB (19.3%) also reduced CH4compared with CON. Fatty acid profiles for PB were similar (P>0.05) to CON for most fatty acids. Concentrations of 18:3n-3 were greater (P<0.001) in FO and FOPB in both digesta and effluent, compared with CON. Propionibacterium freudenreichii had very little effect on ruminal biohydrogenation, but reduced CH4production under the current conditions as a result of increasing propionate production.

Qualitative characteristics of meat from young bulls fed different levels of crude glycerin

The objective was to evaluate the fatty acid profile and qualitative characteristics of meat from young bulls fed crude glycerin. Forty-four animals with an initial live weight of 368 ± 4 kg were used in a completely randomized design, with four treatments: no glycerin or addition of 6, 12 or 18% glycerin. The animals were slaughtered with 519.5 ± 14.9 kg of live weight. The meat characteristics assessed were chemical composition, shear force, fatty acid concentration, color and lipid oxidation. The addition of glycerin increased the content of ether extract (P<0.05) in the muscle. A linear increase was observed (P<0.05) in the oleic acid contents (C18:1 cis 9). The saturated fatty acid (SFA) contents linearly decreased in the muscle as a function of glycerin addition. The lightness (L*) and yellowness (b*) indices increased with the use of crude glycerin (P<0.05). The crude glycerin increased the intramuscular fat and oleic acid content in the longissimus dorsi muscle.

Evaluation of FT-NIR and ATR-FTIR spectroscopy techniques for determination of minor odd- and branched-chain saturated and trans unsaturated milk fatty acids

Determination of nutritionally important trans MUFA, CLA, and OBCFA milk fatty acids (often present in amounts lower than 1.0 g/100 g of total fat) using fast and nondestructive analytical methods would enhance their use as diagnostic tools in dairy herd and human health management. Here, PLS regression using ATR/FTIR spectra indicated potential for determination of trans-11 C18:1 and trans-12 C18:1 (Rcv² ≥ 0.80), and trans-9 C18:1 in very minor concentration (Rcv² > 0.82), as well as anteiso C15:0 (Rcv² = 0.57) and iso C17:0 (Rcv² = 0.61). Furthermore, the main cis-9,trans-11 CLA isomer was predicted well despite the high trans MUFA concentration. Differentiation between the CLA and the trans MUFA signals was evident (based on specific cis/trans bands), and branched-chain saturated fatty acid methyl esters revealed specific iso and anteiso ATR/FTIR absorbance bands. None of the minor FA PLS results with FT-NIR showed interesting potential, except satisfactory predictions for trans-9 C18:1 and cis-9,trans-11 CLA. Overall, ATR/FTIR resulted in better calibrations and provided more specific information for determination of minor milk fatty acids.