35 research outputs found

    Effects of peripartum biotin supplementation of dairy cows on milk production and milk composition with emphasis on fatty acids profile

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    Forty Holstein dairy cows receiving a 38% concentrate diet based on maize silage were assigned to either a control group, either a biotin group, receiving 20 mg of biotin per day from 15 days before expected calving date and for 120 days after calving. Milk production was measured daily, milk fat content, protein content, urea and somatic cell counts were determined weekly from week 2 to week 17 of lactation. The profile of milk fatty acids was determined at weeks 3 and 10. Plasma glucose and blood betahydroxybutyrate were determined before calving and at weeks 1, 2, 3, 5, 7 and 10 of lactation. Biotin supplementation resulted in an increased milk production in multiparous cows during weeks 2 to 6, but the effect was no more significant between 7 and 17 weeks of lactation. Milk protein percent was decreased by 0.1% in multiparous cows. Milk fat content was not affected by biotin, and milk fat daily production tended to increase during early lactation. In milk fat, biotin supplementation tended to decrease the proportion of fatty acids with less than 16 carbons at week 3, but the daily amount was not affected. Biotin tended to decrease biohydrogenation intermediates, increased C16:1 at week 3, and tended to increase cis-9 C18:1 at weeks 3 and 10. After 7 weeks of lactation, biotin tended to increase blood beta-hydroxybutyrate in multiparous cows with values remaining in a normal range, and decreased plasma glucose in primiparous cows. These modifications of plasma parameters, milk protein content and profile of milk fatty acids could be due to a higher lipid mobilisation from adipose tissue driven by the increased milk production

    Effects of heating process of soybeans on ruminal production of conjugated linoleic acids and trans-octadecenoic acids in situ

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    The effects of two thermal treatments of soybeans, i.e. roasting (150˚C dry heat) and extrusion (140-150˚C), on conjugated linoleic acids (CLA) and trans-octadecenoic acids (trans-C18:1) productions obtained throughout ruminal C18:2 biohydrogenation in cows were examined. Nylon bags containing raw, roasted or extruded soybeans were incubated in the rumen of dry fistulated cows, during 2, 4, 8, 16 or 24 hours. After incubation of 2-4 h, significantly greater amounts of linoleic acid (C18:2) remained in bags containing extruded and roasted soybeans than in those with raw soybeans, reflecting a lower biohydrogenation of C18:2 in both case. Furthermore, significant and marked accumulations of CLA and trans-C18:1 at a lesser extend were noticed in bags containing extruded soybeans compared to those with raw or roasted soybeans. By calculations of the efficiencies of the three reactions, an inhibition of the C18:2 isomerisation was evidenced with extruded and roasted soybeans, as well as an inhibition of the two reduction steps in presence of extruded soybeans. Consequently, the thermal treatment and the nature of heating process of fat are efficient ways to modulate the CLA and trans-C18:1 ruminal productions

    Effects of fat source and dietary sodium bicarbonate plus straw on the conjugated linoleic acid content of milk of dairy cows

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    The effects of fat source (0.7 kg of fatty acids from extruded soybeans or palmitic acid), of sodium bicarbonate (0.3 kg) plus straw (1 kg) and the interaction of these treatments on the content of conjugated linoleic acid (CLA) in the milk of dairy cows were examined. During nine weeks a group of 10 cows received a ration with palmitic acid and bicarbonate plus straw (ration PAB). During three periods of three weeks a second group of 10 cows received successively a ration with extruded soybeans and bicarbonate plus straw (ration ESB), a ration with palmitic acid without bicarbonate or straw (ration PA), and a ration with extruded soybeans without bicarbonate or straw (ration ES). Rations ES and ESB increased the content of polyunsaturated fatty acids in milk, but decreased milk fat content, compared to rations PAB and PA. Ration ESB led to the greatest milk CLA content, by a synergy between the high amount of dietary fat, and the action of bicarbonate plus straw, favouring trans11 isomers of CLA and C18:1, presumably via a ruminal pH near neutrality. Ration ES favoured trans10 isomers, not desaturated in the mammary gland, so that the milk CLA content was lower than with ration ESB, and resulted in the lowest milk fat content. In conclusion, a ration supplemented with both extruded soybeans and bicarbonate plus straw, was an efficient way to increase the CLA content in the milk of dairy cows

    Enzymatic approach of linoleic acid ruminal biohydrogenation

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    Ruminal biohydrogenation (BH) corresponds to a microbial reduction of dietary unsaturated fatty acid. The linoleic acid (C18:2) BH is divided into three steps: first an isomerisation into conjugated linoleic acids (CLA), then a reduction producing mainly trans-octadecenoic acids (trans-C18:1), and a final reduction producing stearic acid (C18:0). Isomerisations of CLA and trans-C18:1 can lead to a number of positional and geometrical isomers. The control of BH reactions is of interest for researchers because BH directly affects the composition of fatty acids of milk and meat. In order to better understand C18:2 BH and its variations, the development of an enzymatic approach is necessary to ascertain if the action of modulators affects the bacterial enzyme activity or ruminal bacteria. The aim of this study was to investigate the C18:2 BH capacity of ruminal content after inactivation of bacteria by chloramphenicol (Cm), an inhibitor of protein synthesis in prokaryotes. The BH of C18:2 produced mainly cis9,trans11-CLA and trans10,cis12-CLA, and trans11-C18:1 and trans10-C18:1 isomers, as previously described (Jouany et al., 2007). The increase in cis12-C18:1 came from reduction of trans10,cis12-CLA, that of trans6+7+8-C18:1 from the reduction of minor CLA isomers not quantified in this study, like trans8,trans10-CLA (Shingfield et al., 2008). The trans11 pathway was rapid: the cis9,trans11-CLA production was maximal at about 1h of incubation while trans11-C18:1 accumulated throughout incubation. On the other hand, trans10 pathway was slow: trans10,cis12-CLA regularly increased during incubation, so that it was more abundant than cis9,trans11-CLA after 3h incubation, and trans10-C18:1 only began to increase after 2h of incubation. The amount of C18:0 began to increase in the media when trans11-C18:1 concentration was over 0.05 mg/mL. Such evolution of fatty acids involved in C18:2 BH was similar to that reported in vitro with living ruminal microorganisms by Harfoot et al. (1973) and Jouany et al. (2007). So, this enzymatic approach using Cm could be an interesting and valid method to study C18:2 BH, however 3h of incubation were not sufficient to study the final reduction

    Comparison of enzymatic activities of the reactions of linoleic and linolenic acids ruminal biohydrogenation

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    Introduction: Biohydrogenation (BH) is a microbial hydrogenation of dietary unsaturated fatty acids occurring in the rumen. BH is of interest because it directly affects the fatty acids composition of milk and meat. The linoleic acid (C18:2) BH is divided into three reactions: isomerisation into conjugated linoleic acids (CLA), reduction to trans-C18:1 and then to stearic acid (C18:0); that of alpha-linolenic acid (C18:3) into four reactions: isomerisation to conjugated linolenic acid (CLnA), reduction to trans11,cis15-C18:2, then to trans-C18:1 and finally to C18:0. The aim of this study was to compare enzymatic activities of the reactions of C18:2 BH to those of C18:3 BH. Materials and methods: Rumen fluid was collected from a dry dairy cow and strained on a metal sieve (1,6mm). Then, it was mixed with Chloramphenicol (Cm), an inhibitor of protein synthesis in prokaryotes, at a dose of 1mg/mL . Incubations were prepared by adding 1mL of rumen fluid + Cm, with 1mL of bicarbonate buffer and 1mg of C18:2 or C18:3 (purity ≥ 99%, Sigma), and were conducted in a waterbath at 39°C, with 3h agitation, in 3 replicates. Fatty acids were quantified by gas chromatography. Then rate (v, mg/L/h) and efficiency (E, %) of the reactions were calculated. Results and Discussion: The isomerisation of C18:3 was quicker and more efficient than that of C18:2, which was probably saturated2 (v = 129.6 vs. 94.4 mg/L/h; E = 80.2 vs. 52.7%, respectively. The reductions of conjugated isomers were rapid and efficient, mainly for CLnA (v = 123.7 mg/L/h; E= 95.5%) compared to CLA (v = 78.1 mg/L/h; E= 82.0%). However, for C18:2 BH, cis9,trans11-CLA disappeared quicker than trans10,cis12-CLA so that their respective production after 3h incubation was +0.016mg vs. +0.073mg. The last reduction of C18:2 BH was the slowest (v = 63.8 mg/L/h; E= 68.9%), and constituted the limiting step, resulting in trans-C18:1 accumulation. The second reduction of C18:3 BH was very slow and poorly efficient (v = 48.8 mg/L/h; E= 38.2%), so that trans11,cis15-C18:2 highly accumulated (+0.450mg produced). The last reduction of C18:3 BH was also a slow and poorly efficient reaction (v = 38.8 mg/L/h; E= 41.9%), so that trans-C18:1 would probably have accumulated with a longer incubation. Conclusion: The BH of C18:2 and C18:3 were not exactly similar. C18:2 BH was slower, its isomerisation seemed to be rapidly saturable and the limiting step was the final reduction inducing an accumulation of trans-C18:1. For C18:3 BH, first and second reactions were rapid, so that few CLnA was present in the media. Contrarily, the third and fourth reactions were slow so that trans11,cis15-C18:2 firstly accumulated. Such an evolution was previously reported in vitro with live mixed ruminal bacteria2, indicating that the evaluation of BH does not require live bacteria, and confirming the validity and interest of this enzymatic approach

    Effects of preconditioning and extrusion of linseed on the ruminal biohydrogenation of fatty acids 1. In vivo studies

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    The extent and intermediates of ruminal biohydrogenation (BH) of fatty acids (FA) from a blend of linseed and wheat bran (70:30) were investigated in the rumen fluid, rumen particle phase and duodenal flow. The blend was ground through a 3 mm screen and used raw or extruded, or was ground through a 6 mm screen and preconditioned. Three dry Holstein cows fitted with ruminal and duodenal cannulas were used in a 3 × 3 Latin square design, with 18 days adaptation. The diet contained 20% (DM basis) of the linseed based blend. Twelve samples taken over 3 days were composited for analysis of rumen fluid, rumen particle phase and duodenal flow. The BH of FA from linseed resulted in the appearance of a great number of C18:1 intermediates, among which trans-10+11 to trans-16C18:1 were the most abundant. The proportion of cis-9,trans-11C18:2 was low. Preconditioning coarsely ground linseed resulted in a lower extent of C18:2 and C18:3 BH, and lower proportions of trans-12 to trans-16C18:1 intermediates than extrusion or a lack of processing of finely ground linseed. On the contrary, extrusion did not affect the extent of BH and had no significant effect on the proportions of trans-C18:1 intermediates, but increased the proportion of cis-9,trans-11C18:2 in both rumen phases. Different digesta types resulted in different estimates of BH. The extent of BH and the proportions of trans-C18:1 intermediates were lower in the rumen particle phase and higher in the rumen fluid than in the duodenum. Moreover, interactions between digesta type and treatment of linseed were observed

    Effects of preconditioning and extrusion of linseed on the ruminal biohydrogenation of fatty acids. 2. In vitro and in situ studies

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    The extent and/or intermediates of ruminal biohydrogenation (BH) of fatty acids (FA) were investigated in vitro and in situ using a raw, pre-conditioned or extruded blend of linseed and wheat bran (70:30). The duration of in vitro incubations were 2, 4, 8, 16 and 24 h, with 5 replicates. In situ studies used 3 dry ruminally fistulated Holstein cows in a 3 × 3 Latin square design, with 3 weeks adaptation to the linseed form. The diet contained 20% (DM basis) of the linseed based blend. The duration of in situ incubations were 2, 4, 8, 16, 24 and 48 h. BH was much slower in situ than in vitro, resulting in a much lower effective disappearance of C18:2 and C18:3. Moreover, the in situ technique suggested that the technological pre-treatment of linseed did not affect C18:2 and C18:3 rate of BH, whereas reduced rates were observed in vitro. After 8 h of in vitro incubation and onwards, proportions of cis-9,trans-11C18:2 were the highest with extruded linseed. The BH of FA from linseed resulted in the appearance of great proportions of trans-10+11 to trans-16C18:1 intermediates. Extrusion increased the proportions of trans-10+11C18:1 both in vitro and in situ and proportions or trans-C18:1 were higher in situ than in vitro. Compared to previous in vivo results with the same material, the in situ method provided poor estimates of BH rates and intermediates

    Conjugated linolenic acid (CLnA), conjugated linoleic acid (CLA) and other biohydrogenation intermediates in plasma and milk fat of cows fed raw or extruded linseed

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    Thirty lactating dairy cows were used in a 333 Latin-square design to investigate the effects of a raw or extruded blend of linseed and wheat bran (70:30) on plasma and milk fatty-acids (FA). Linseed diets, containing 16.6% linseed blend on a dry-matter basis, decreased milk yield and protein percentage. They decreased the proportions of FA with less than 18 carbons in plasma and milk and resulted in cis-9, cis-12, cis-15 18:3 proportions that were more than three and four times higher in plasma and milk, respectively, whereas cis-9, cis-12 18:2 proportions were decreased by 10–15%. The cis-9, trans-11, cis-15 18:3 isomer of conjugated linolenic acid was not detected in the milk of control cows, but was over 0.15% of total FA in the milk fat of linseed-supplemented cows. Similarly, linseed increased plasma and milk proportions of all biohydrogenation (BH) intermediates in plasma and milk, including the main isomer of conjugated linoleic acid cis-9, trans-11 18:2, except trans-4 18:1 and cis-11, trans-15 18:2 in plasma lipids. In milk fat, compared with raw linseed, extruded linseed further reduced 6:0–16:0 even-chain FA, did not significantly affect the proportions of 18:0, cis-9 18:1 and cis-9, cis-12 18:2, tended to increase cis-9, cis-12, cis-15 18:3, and resulted in an additional increase in the proportions of most BH intermediates. It was concluded that linseed addition can improve the proportion of conjugated linoleic and linolenic acids, and that extrusion further increases the proportions of intermediates of ruminal BH in milk fat

    Effects of induced subacute ruminal acidosis on milk fat content and milk fatty acid profile

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    Two lactating dairy cows fitted with a rumen cannula received successively diets containing 0%, 20%, 34% and again 0% of wheat on a dry matter basis. After 5, 10 and 11 days, ruminal pH was measured between 8:00 and 16:00 hours, and milk was analysed for fat content and fatty acid profile. Diets with 20% and 34% wheat induced a marginal and a severe subacute ruminal acidosis respectively. After 11 days, diets with wheat strongly reduced the milk yield and milk fat content, increased the proportions of C8:0 to C13:0 even- or odd-chain fatty acids, C18:2 n-6 and C18:3 n-3 fatty acids but decreased the proportions of C18:0 and cis-9 C18:1 fatty acids. Wheat also increased the proportions of trans-5 to trans-10 C18:1, the latter exhibiting a 10-fold increase with 34% of wheat compared with value during the initial 0% wheat period. There was also an increase of trans-10, cis-12 C18:2 fatty acid and a decrease of trans-11 to trans-16 C18:1 fatty acids. The evolution during adaptation or after return to a 0% wheat diet was rapid for pH but much slower for the fatty acid profile. The mean ruminal pH was closely related to milk fat content, the proportion of odd-chain fatty acids (linear relationship) and the ratio of trans-10 C18:1/trans-11 C18:1 (nonlinear relationship). Such changes in fatty acid profile suggested a possible use for non-invasive diagnosis of subacute ruminal acidosis

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

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    On the basis of the isomer-specific effects of trans fatty acids (FA) on human health, and the detrimental effect of t10,c12-conjugated linoleic acid (CLA) on cows’ milk fat production, there is a need to identify factors that affect the shift from trans-11 to trans-10 pathway during ruminal biohydrogenation of FA. This experiment was conducted in vitro and aimed at separating the effects of the diet of the donor cows from those of the fermentative substrate, which is necessary to prevent this shift. A total of four dry Holstein dairy cows were used in a 434 Latin square design. They received 12 kg of dry matter per day of four diets based on maize silage during four successive periods: the control diet (22% starch, ,3% fat); the high-starch diet, supplemented with wheat plus barley (35% starch, ,3% crude fat); the sunflower oil diet, supplemented with 5% of sunflower oil (20% starch, 7.6% crude fat); and the high-starch plus oil diet (33% starch, 7.3% crude fat). Ruminal fluid of each donor cow was incubated for 5 h with four substrates having similar chemical composition to the diets, replacing sunflower oil by pure linoleic acid (LA). The efficiency of isomerisation of LA to CLA was the highest when rumen fluids from cows receiving dietary oil were incubated with added LA. The shift from trans-11 to trans-10 isomers was induced in vitro by high-starch diets and the addition of LA. Oil supplementation to the diet of the donor cows increased this shift. Conversely, the trans-10 isomer balance was always low when no LA was added to incubation cultures. These results showed that a large accumulation of trans-10 FA was only observed with an adapted microflora, as well as an addition of non-esterified LA to the incubation substrate
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