Assessing rumen biohydrogenation and its manipulationin vivo,in vitro andin situ

INVITED REVIEW: Research on ruminal biohydrogenation: Achievements, gaps in knowledge, and future approaches from the perspective of dairy science

Scientific knowledge about ruminal biohydrogenation (BH) has improved greatly since this metabolic process was empirically confirmed in 1951. For years, BH had mostly been perceived as a process to be avoided to increase the post-ruminal flow of UFA from the diet. Two milestones changed this perception and stimulated great interest in BH intermediates themselves: In 1987, the in vitro anticarcinogenic properties of CLA were described, and in 2000, the inhibition of milk fat synthesis by trans-10 cis-12 CLA was confirmed. Since then, numerous BH metabolites have been described in small and large ruminants, and the major deviation from the common BH pathway (i.e., the trans-10 shift) has been reasonably well established. However, there are some less well-characterized alterations, and the comprehensive description of new BH intermediates (e.g., using isotopic tracers) has not been coupled with research on their biological effects. In this regard, the low quality of some published fatty acid profiles may also be limiting the advance of knowledge in BH. Furthermore, although BH seems to no longer be considered a metabolic niche inhabited by a few bacterial species with a highly specific metabolic capability, researchers have failed to elucidate which specific microbial groups are involved in the process and the basis for alterations in BH pathways (i.e., changes in microbial populations or their activity). Unraveling both issues may be beneficial for the description of new microbial enzymes involved in ruminal lipid metabolism that have industrial interest. From the perspective of diary science, other knowledge gaps that require additional research in the coming years are evaluation of the relationship between BH and feed efficiency and enteric methane emissions, as well as improving our understanding of how alterations in BH are involved in milk fat depression. Addressing these issues will have relevant practical implications in dairy science.

Enhanced Goat Milk MUFA Quality via Date Pit Supplementation: A Time-Based Pattern Recognition Analysis Utilizing Agricultural Waste Byproduct

Date pits are agricultural waste byproducts and are available in tons yearly. Milk MUFAs are lipids beneficial for health and sorted out for food product development. This work is aimed at researching the effect of supplementing dairy goats with date pit powder (DPP) as a source of fatty acids (FA), an alternative to enhancing the unsaturated FA in milk and analysed via chemometrics in a 3-month supplementation-based study. Saanen-Boer crossed dairy goats were divided into six groups comprising of control, 10 g and 20 g both for Ajwa DPP (high-quality dates) and Mariami DPP (agricultural waste byproduct), and another 30 g for Mariami DPP only. The supplementation exercise was done daily on each dairy goat. The DPP and milk samples were analysed for its FA profile applying GC-FID and followed by chemometric techniques, namely, PCA and PLS. Results indicated that the n-6/n-3 ratio was the highest for the unsupplemented group compared to the DPP-treated goats with lower n-6/n-3 ratios. The M30 group showcased the most promising health-related class of FAs viewed by 3D PCA and PLS model clustering patterns, in particular monounsaturated FA (MUFA) (C18:1n9c or oleic acid). These results suggest that Mariami DPP supplementation at higher doses and time to lactating Saanen-Boer cross goats can be a means to milk FA quantity and quality enhancement and that chemometrics via pattern recognition can be useful statistical tools when dealing with overwhelming data.

Effects of maternal dietary fatty acids during mid-gestation on growth, glucose metabolism, carcass characteristics, and meat quality of lamb progeny that were fed differing levels of dry matter of intake

This experiment evaluated growth, glucose metabolism, carcass characteristics, and meat quality of market lambs that were offered ad libitum or restricted (85% of ad libitum) feed intake following two different maternal fatty acid (FA) supplementations while in-utero. Ewes received either a diet supplemented with polyunsaturated FA or saturated/monounsaturated FA during mid- to late-gestation. Following weaning, progeny wethers were fed either ad libitum or a restricted level of feed intake. Ewe FA supplementation did not affect (P ≥ 0.11) growth, meat quality, nor plasma glucose or insulin concentrations of the progeny. Carcass body fat and yield grade of the progeny were affected (P = 0.01) by maternal FA supplementation and restricted feed intake. In summary, maternal FA supplementation did not affect progeny growth, while feed restriction during finishing did not affect meat quality. The interaction between maternal FA supplementation and finishing strategy for body fat accretion indicates that metabolism and the supply of FA during gestation may warrant further investigation.

Producing natural functional and low-carbon milk by regulating the diet of the cattle-The fatty acid associated rumen fermentation, biohydrogenation, and microorganism response

Conjugated linoleic acid (CLA) has drawn significant attention in the last two decades for its various potent beneficial effects on human health, such as anticarcinogenic and antidiabetic properties. CLA could be generally found in ruminant products, such as milk. The amount of CLA in ruminant products mainly depends on the diet of the animals. In general, the fat content in the ruminant diet is low, and dietary fat supplementation can be provided to improve rumen activity and the fatty acid (FA) profile of meat and milk. Especially, dietary 18-carbon polyunsaturated FA (C18 PUFA), the dominant fat source for ruminants, can modify the milk FA profile and other components by regulating the ruminal microbial ecosystem. In particular, it can improve the CLA in milk, intensify the competition for metabolic hydrogen for propionate producing pathways and decrease methane formation in the rumen. Therefore, lipid supplementation appears to be a promising strategy to naturally increase the additional nutritional value of milk and contribute to lower methane emissions. Meanwhile, it is equally important to reveal the effects of dietary fat supplementation on rumen fermentation, biohydrogenation (BH) process, feed digestion, and microorganisms. Moreover, several bacterial species and strains have been considered to be affected by C18 PUFA or being involved in the process of lipolysis, BH, CLA, or methane emissions. However, no review so far has thoroughly summarized the effects of C18 PUFA supplementation on milk CLA concentration and methane emission from dairy cows and meanwhile taken into consideration the processes such as the microorganisms, digestibility, rumen fermentation, and BH of dairy cattle. Therefore, this review aims to provide an overview of existing knowledge of how dietary fat affects rumen microbiota and several metabolic processes, such as fermentation and BH, and therefore contributes to functional and low-carbon milk production.

In vivo kinetics of oleic, linoleic, and α-linolenic acid biohydrogenation in the rumen of dairy cows

Ruminal biohydrogenation (BH) of unsaturated fatty acids (FA) reduces absorption of essential FA and can result in formation of bioactive FA that cause milk fat depression. Rates of biohydrogenation of unsaturated FA are commonly observed using in vitro systems and are not well described in vivo. Seven ruminally cannulated cows were enrolled in a 3 × 3 Latin square design study to quantify biohydrogenation of 18:1n-9, 18:2n-6, and 18:3n-3 using a recently developed in vivo BH assay. All cows were fed a common high corn silage basal diet. Biohydrogenation was quantified using a perturbation model that consisted of a bolus dose of 200 g of an oil enriched in each unsaturated FA (oleic acid, OA = 87% 18:1n-9 sunflower oil; linoleic acid, LA = 70% 18:2n-6 safflower oil; and α-linolenic acid, ALA = 54% 18:3n-3 flaxseed oil) and 12 g of 17:0 as a marker of rumen outflow. Rumen contents were sampled before and after the bolus and enrichment of the bolused FA modeled. Using first-order kinetics to model FA disappearance, the fractional rates of disappearance of 18:1n-9 was 0.597 per hour, 18:2n-6 was 0.618 per hour, and 18:3n-3 was 0.834 per hour, similar to rates previously reported with this approach. Rumen turnover of 17:0 was 0.123 per hour, 0.065 per hour, and 0.106 per hour during the OA, LA, and ALA treatments, respectively. The extents of BH were calculated to be 82.8, 90.4, and 88.6% for 18:1n-9, 18:2n-6, and 18:3n-3, respectively. Finally, compartmental modeling was used to quantify the amount of each unsaturated FA metabolized through trans-10 and trans-11 BH pathways. The recently developed in vivo BH assay was able to predict rates of BH and provide insight into rumen metabolism of individual FA and may be useful to future investigations.

Modulatory effects of dietary tannins on polyunsaturated fatty acid biohydrogenation in the rumen: A meta-analysis

Background

Tannins are a group of phenolic compounds that can modify the rumen biohydrogenation (BH) of polyunsaturated fatty acids (PUFA), but to date results obtained have been inconsistent. This study therefore aims to conduct a meta-analysis of the scientific literature related to the effects of tannins on rumen BH and fermentation.

Methods

A total of 28 articles were collected from various scientific databases, such as Scopus, Science Direct and Google Scholar, and the data were analysed using a random effects model and meta-regression for rumen BH. The publication bias on the main variables of rumen fermentation was assessed using a funnel plot and Egger's test.

Results

An increase in tannin levels significantly reduced methane production (p < 0.001) and the population of Butyrivibrio fibrisolvens (p < 0.05). Dietary tannins also decreased the SFA proportion (p < 0.001) and increased (p < 0.001) the rumen monounsaturated fatty acid (MUFA) and polyunsaturated fatty acid (PUFA) proportions. In additions, there were negative relationships between dietary tannin levels and BH rates of C18:2 n-6 and C18:3 n-3 (p < 0.05).

Conclusion

Dietary tannins modulate the rumen fermentation profile, mitigate methane emissions, and inhibit rumen BH of PUFA.

Effects of Dietary Babassu Oil or Buriti Oil on Nutrient Intake and Total Tract Digestibility, and Abomasal Digesta Fatty Acid Profile of Lambs

Simple Summary

This research tested the effects of adding babassu oil (450 g/kg C12:0 of total fatty acids—FA) or buriti oil (750 g/kg C18:f total FA) to the diet of lambs on intake, nutrient digestibility, FA profile of abomasal digesta content and biohydrogenation patterns in digestive content. Both are widely available in the Northeast of Brazil and Amazon region. Our results provide evidence that the babassu supplemented diet promotes greater stress to the ruminal bacteria (due to the high concentration of C12:0), changing the normal biohydrogenation of polyunsaturated FA (PUFA) in the rumen, and the FA concentration that flows to the abomasum, compared to the buriti oil supplemented diet, which provided similar results to the non-supplemented diet.

Abstract

Our current understanding of the effect of medium-chain FA (MCFA) rich vegetable oils on ruminant nutrition is limited. We assessed the effects of babassu or buriti oil addition to the diet of lambs on intake, nutrient digestibility, FA profile of abomasal digesta content and biohydrogenation (BH) patterns in digestion. The experimental diets were defined by the addition of babassu oil or buriti oil to the diet, as follows: (1) non-supplemented diet (CON); (2) 40 g/kg of babassu oil (BAO, rich in C12:0); and (3) 40 g/kg of buriti oil (BUO, rich in c9 18:1), on a dry matter (DM) basis. During the last five days of the feedlot, samples of orts and feces were individually collected to determine the nutrient and FA digestibility. At the end of the experiment, animals were slaughtered, and the abomasal digesta was collected, freeze-dried and used for FA determinations conducted by gas chromatography. The BAO diet decreased the DM (p = 0.014) and nutrient intake. The lambs fed BUO had the greatest FA intake, followed by the BAO and CON diets. However, BAO increased total FA digestibility, compared with CON, but did not differ from BUO. The BAO diet extensively changed the FA composition of abomasal digesta when compared with both the CON and BUO diets. The BAO diet also increased C12:0 and C14:0, the sum of PUFA and the BH intermediates FA, including the t-10-18:1 but decreased the C18:0 in abomasal digesta. The BUO addition had the greatest total-FA and C18:0 and the lowest biohydrogenation intermediate content in abomasal digesta. The BH was less complete with the BAO diet and a large increase in t10-18:1 and of t10-/t11-18:1 ratio was observed, which indicates the occurrence of t10 possibly shifted rumen BH pathways, probably as a response to bacterial membrane stress induced by the greater C12:0 concentration in the rumen.

Dietary Omega-3 Source Effect on the Fatty Acid Profile of Intramuscular and Perimuscular Fat-Preliminary Study on a Rat Model

Fatty acids from the omega-3 family are an important element of both human and animal diets. Their activity involves a range of functions for the functioning of a whole organism, and their presence in animal diets can be considered as a means for animal origin product enrichment for human benefit or as compounds profitable for an animal's health status. The aim of this preliminary study was to compare the effect of supplements rich in omega-3 fatty acids (linseed oil, linseed oil ethyl esters, and fish oil) in rat feed on the fatty acid profile of their intramuscular and perimuscular fat. The results demonstrated beneficial changes in fatty acid profiles (a decrease in saturated acids, an increase in unsaturated ones, i.e., omega-3 acids share) of examined tissues in the case of all supplements however, particular attention should be paid to linseed oil ethyl esters, which significantly increased the content of all omega-3 acids. Supplementation of animal diet with linseed oil ethyl esters may be beneficial for both animals, as omega-3 fatty acids exhibit profitable properties related to an animal's health status and productivity, and humans who consume such enriched products.

Dietary supplemental plant oils reduce methanogenesis from anaerobic microbial fermentation in the rumen

Ruminants contribute to the emissions of greenhouse gases, in particular methane, due to the microbial anaerobic fermentation of feed in the rumen. The rumen simulation technique was used to investigate the effects of the addition of different supplemental plant oils to a high concentrate diet on ruminal fermentation and microbial community composition. The control (CTR) diet was a high-concentrate total mixed ration with no supplemental oil. The other experimental diets were supplemented with olive (OLV), sunflower (SFL) or linseed (LNS) oils at 6%. Rumen digesta was used to inoculate the fermenters, and four fermentation units were used per treatment. Fermentation end-products, extent of feed degradation and composition of the microbial community (qPCR) in digesta were determined. Compared with the CTR diet, the addition of plant oils had no significant (P > 0.05) effect on ruminal pH, substrate degradation, total volatile fatty acids or microbial protein synthesis. Gas production from the fermentation of starch or cellulose were decreased by oil supplementation. Methane production was reduced by 21-28% (P < 0.001), propionate production was increased (P < 0.01), and butyrate and ammonia outputs and the acetate to propionate ratio were decreased (P < 0.001) with oil-supplemented diets. Addition of 6% OLV and LNS reduced (P < 0.05) copy numbers of total bacteria relative to the control. In conclusion, the supplementation of ruminant diets with plant oils, in particular from sunflower or linseed, causes some favorable effects on the fermentation processes. The addition of vegetable oils to ruminant mixed rations will reduce methane production increasing the formation of propionic acid without affecting the digestion of feed in the rumen. Adding vegetable fats to ruminant diets seems to be a suitable approach to decrease methane emissions, a relevant cleaner effect that may contribute to alleviate the environmental impact of ruminant production.

Effects of supplemental plant oils on rumen bacterial community profile and digesta fatty acid composition in a continuous culture system (RUSITEC)

Lipid supplementation of ruminant diets may trigger changes in the ruminal microbiota and in anaerobic digestion. Changes in the bacterial community composition and in the fatty acid hydrogenation caused by the addition of different supplemental plant oils to a high concentrate diet were investigated in vitro using RUSITEC (rumen simulation technique) fermenters. The control (CTR) diet was a high-concentrate total mixed ration for dairy sheep, with no supplementary oil. The other experimental diets were supplemented with olive (OLV), sunflower (SFL) or linseed (LNS) oils at 6% (dry matter basis). Four RUSITEC fermenters were used for each experimental diet, all inoculated with rumen digesta of sheep. Extent of dry matter and fat degradation, composition of the bacterial community and long-chain fatty acids in digesta were determined. The addition of plant oils increased (P < 0.001) apparent degradation of fat in the fermenters, whereas fermentation kinetics (gas production and average fermentation rate) were lower (P < 0.05) with the LNS than with the CTR diet. Hydrogenation of C18 unsaturated fatty acids (P < 0.05), in particular that of oleic acid (P < 0.001), and stearic acid proportion (P < 0.001) were reduced, and oleic acid proportion was increased (P < 0.001) with all oil supplements. Addition of OLV decreased linoleic and LNS increased α-linolenic (P < 0.001), whereas conjugated linoleic was increased with SFL oil (P = 0.025) and vaccenic increased with both SFL and LNS oils (P = 0.008). Addition of 6% OLV and LNS reduced (P < 0.05) microbial community diversity and quantity of total bacteria relative to the control. Some specific microbial groups were affected (P < 0.001) by oil addition, with less relative abundance of Clostridiales and Actinobacteria and increased Bacteroidales, Aeromonadales and Lactobacillales species. In conclusion, the supplementation of high-concentrate ruminant diets with plant oils, in particular from sunflower or linseed, causes shifts in the rumen microbiota and fatty acid hydrogenation in the rumen increasing the formation of vaccenic and conjugated linoleic acids.

Effects of Supplementation of Rumen Protected Fats on Rumen Ecology and Digestibility of Nutrients in Sheep

Simple Summary

Rising populations and urbanization are transforming into increased demand for livestock products, particularly in developing countries. The world will need more meat and more milk and in order to meet these demands, huge quantities of feed resources will be required. However, there is a substantial deficit of energy feeds affecting the growth and production of animals. The common method to increase energy value of ruminant diets is to provide them with fats. However, higher level of fats in the diet could prove toxic to rumen microbes and affect fibre digestibility, which ultimately results in reducing the feed intake and lowering animal production. These negative effects of fat supplementation can easily be overcome by feeding ruminants with specifically designed fats called rumen protected fats. In order to evaluate the efficacy of rumen protected fats (RPF), three different types of protected fats were examined in sheep. The results suggested that different types of protected fats have no unfavourable influences on the ruminal fermentation and productive parameters. Therefore, prilled fat, prilled fat with lecithin and calcium soaps did not improve animal performance as compared to the diet without protected fats in Dorper sheep.

Abstract

Rumen protected fats (RPF) are known to improve animal performance without affecting rumen metabolism in sheep. However, comparative effects of prilled fat, prilled fat with lecithin and calcium soap have not been fully studied. Hence this experiment was planned using 36 male Dorper sheep in a completely randomized design in four treatment groups. The diets included: Basal diet (70:30 concentrate to rice straw) with no added RPF as a control (CON), basal diet plus prilled fat (PF), basal diet plus prilled fat with lecithin (PFL) and basal diet plus calcium soap (CaS). The trial lasted 90 days following two weeks adaptation period. The body weights, average daily gain and gain to feed ratio were not affected by treatments. The intake and digestibilities of dry matter, organic matter, crude protein and neutral detergent fibre were not affected, while those for ether extract and crude fibre differed (p < 0.05). RPF had no effect on concentrations of ammonia nitrogen, total volatile fatty acids and total bacterial population. The concentrations of rumen total saturated fatty acids, unsaturated fatty acids, total n − 3, total n − 6, unsaturated fatty acids:saturated fatty acids and polyunsaturated fatty acids:saturated fatty acids differed (p < 0.05) among the treatments with RPF supplementation. Hence supplementation of different types of protected fats did not influence animal performance in Dorper sheep.

Effects of Condensed and Hydrolyzable Tannins on Rumen Metabolism with Emphasis on the Biohydrogenation of Unsaturated Fatty Acids

The hypothesis that condensed tannins have higher inhibitory effect on ruminal biohydrogenation than hydrolyzable tannins was tested. Condensed tannin extract from mimosa (CT) and hydrolyzable tannin extract from chestnut (HT) or their mixture (MIX) were incorporated (10%) into oil supplemented diets and fed to rumen fistulated sheep. Fatty acid and dimethyl acetal composition of rumen contents and bacterial biomass were determined. Selected rumen bacteria were analyzed by quantitative real time PCR. Lower ( P < 0.05) rumen volatile fatty acids concentrations were observed with CT compared to HT. Moreover, lower concentration ( P < 0.05) of Fibrobacter succinogenes, Ruminococcus flavefaciens, Ruminococcus albus, and Butyrivibrio proteoclasticus were observed with CT compared to HT. The extension of biohydrogenation of 18:2n-6 and 18:3n-3 did not differ among treatments but was much more variable with CT and MIX than with HT. The trans-/ cis-18:1 ratio in bacterial biomass was higher ( P < 0.05) with HT than CT. Thus, mimosa condensed tannins had a higher inhibitory effect on ruminal metabolism and biohydrogenation than chestnut hydrolyzable tannins.

Promising perspectives for ruminal protection of polyunsaturated fatty acids through polyphenol-oxidase-mediated crosslinking of interfacial protein in emulsions

Previously, polyunsaturated fatty acids (PUFA) from linseed oil were effectively protected (>80%) against biohydrogenation through polyphenol-oxidase-mediated protein crosslinking of an emulsion, prepared with polyphenol oxidase (PPO) extract from potato tuber peelings. However, until now, emulsions of only 2 wt% oil have been successfully protected, which implies serious limitations both from a research perspective (e.g. in vivo trials) as well as for further upscaling toward practical applications. Therefore, the aim of this study was to increase the oil/PPO ratio. In the original protocol, the PPO extract served both an emulsifying function as well as a crosslinking function. Here, it was first evaluated whether alternative protein sources could replace the emulsifying function of the PPO extract, with addition of PPO extract and 4-methylcatechol (4MC) to induce crosslinking after emulsion preparation. This approach was then further used to evaluate protection of emulsions with higher oil content. Five candidate emulsifiers (soy glycinin, gelatin, whey protein isolate (WPI), bovine serum albumin and sodium caseinate) were used to prepare 10 wt% oil emulsions, which were diluted five times (w/w) with PPO extract (experiment 1). As a positive control, 2 wt% oil emulsions were prepared directly with PPO extract according to the original protocol. Further, emulsions of 2, 4, 6, 8 and 10 wt% oil were prepared, with 80 wt% PPO extract (experiment 2), or with 90, 80, 70, 60 and 50 wt% PPO extract, respectively (experiment 3) starting from WPI-stabilized emulsions. Enzymatic crosslinking was induced by 24-h incubation with 4MC. Ruminal protection efficiency was evaluated by 24-h in vitro batch simulation of the rumen metabolism. In experiment 1, protection efficiencies were equal or higher than the control (85.5% to 92.5% v. 81.3%). In both experiments 2 and 3, high protection efficiencies (>80%) were achieved, except for emulsions containing 10 wt% oil emulsions (<50% protection), which showed oiling-off after enzymatic crosslinking. This study demonstrated that alternative emulsifier proteins can be used in combination with PPO extract to protect emulsified PUFA-rich oils against ruminal biohydrogenation. By applying the new protocol, 6.5 times less PPO extract was required.

Effect of replacing calcium salts of palm oil with camelina seed at 2 dietary ether extract levels on digestion, ruminal fermentation, and nutrient flow in a dual-flow continuous culture system

Camelina is a drought- and salt-tolerant oil seed, which in total ether extract (EE) contains up to 74% polyunsaturated fatty acids. The objective of this study was to assess the effects of replacing calcium salts of palm oil (Megalac, Church & Dwight Co. Inc., Princeton, NJ) with camelina seed (CS) on ruminal fermentation, digestion, and flows of fatty acids (FA) and AA in a dual-flow continuous culture system when supplemented at 5 or 8% dietary EE. Diets were randomly assigned to 8 fermentors in a 2 × 2 factorial arrangement of treatments in a replicated 4 × 4 Latin square design, with four 10-d experimental periods consisting of 7 d for diet adaptation and 3 d for sample collection. Treatments were (1) calcium salts of palm oil supplementation at 5% EE (MEG5); (2) calcium salts of palm oil supplementation at 8% EE (MEG8); (3) 7.7% CS supplementation at 5% EE (CS5); and (4) 17.7% CS supplementation at 8% EE (CS8). Diets contained 55% orchardgrass hay, and fermentors were fed 72 g of dry matter/d. On d 8, 9, and 10 of each period, digesta effluent samples were taken for ruminal NH₃, volatile fatty acids, nitrogen metabolism analysis, and long-chain FA and AA flows. Statistical analysis was performed using the MIXED procedure (SAS Institute Inc., Cary, NC). We detected an interaction between FA source and dietary EE level for acetate, where MEG8 had the greatest molar proportion of acetate. Molar proportions of propionate were greater and total volatile fatty acids were lower on CS diets. Supplementation of CS decreased overall ruminal nutrient true digestibility, but dietary EE level did not affect it. Diets containing CS had greater biohydrogenation of 18:2 and 18:3; however, biohydrogenation of 18:1 was greater in MEG diets. Additionally, CS diets had greater ruminal concentrations of trans-10/11 18:1 and cis-9,trans-11 conjugated linoleic acid. Dietary EE level at 8% negatively affected flows of NH₃-N (g/d), nonammonia N, and bacterial N as well as the overall AA outflow. However, treatments had minor effects on individual ruminal AA digestibility. The shift from acetate to propionate observed on diets containing CS may be advantageous from an energetic standpoint. Moreover, CS diets had greater ruminal outflow of trans-10/11 18:1 and cis-9,trans-11 conjugated linoleic acid than MEG diets, suggesting a better FA profile available for postruminal absorption. However, dietary EE at 8% was deleterious to overall N metabolism and AA outflow, indicating that CS can be fed at 5% EE without compromising N metabolism.

Nutritional enhancement of sheep meat fatty acid profile for human health and wellbeing

Dietary fatty acids (FA) consumed by sheep, like other ruminants, can undergo biohydrogenation resulting in high proportions of saturated FA (SFA) in meat. Biohydrogenation is typically less extensive in sheep than cattle, and consequently, sheep meat can contain higher proportions of omega (n)-3 polyunsaturated FA (PUFA), and PUFA biohydrogenation intermediates (PUFA-BHI) including conjugated linoleic acid (CLA) and trans-monounsaturated FAs (t-MUFA). Sheep meat is also noted for having characteristically higher contents of branched chain FA (BCFA). From a human health and wellness perspective, some SFA and trans-MUFA have been found to negatively affect blood lipid profiles, and are associated with increased risk of cardiovascular disease (CVD). On the other hand, n-3 PUFA, BCFA and some PUFA-BHI may have many potential beneficial effects on human health and wellbeing. In particular, vaccenic acid (VA), rumenic acid (RA) and BCFA may have potential for protecting against cancer and inflammatory disorders among other human health benefits. Several innovative strategies have been evaluated for their potential to enrich sheep meat with FA which may have human health benefits. To this end, dietary manipulation has been found to be the most effective strategy of improving the FA profile of sheep meat. However, there is a missing link between the FA profile of sheep meat, human consumption patterns of sheep FA and chronic diseases. The current review provides an overview of the nutritional strategies used to enhance the FA profile of sheep meat for human consumption.

Effect of Propionibacterium freudenreichii in diets containing rapeseed or flaxseed oil on in vitro ruminal fermentation, methane production and fatty acid biohydrogenation

The objectives of the present study were to determine the effect of inoculating Propionibacterium freudenreichii subsp. shermanii ATCC 8262 (1 × 109 colony-forming units per vial) in a barley silage-based diet supplemented with flaxseed oil or rapeseed oil (60 g/kg DM), on in vitro proportions and yield of volatile fatty acids, methane production and fatty acid (FA) biohydrogenation. Total volatile fatty acid production (mM) and proportions of individual FAs were not affected (P ≥ 0.10) by P. freudenreichii. Similarly, propionibacteria had little impact on FA biohydrogenation, resulting only in an increased accumulation (P < 0.01) of C18:1 cis-15 (g/kg total FA) at 6 h of incubation, compared with the control (CON). Compared with the CON, an increased (P < 0.01) accumulation of vaccenic acid was observed at 48 h in all oil-containing treatments, regardless of the oil type. Similarly, the apparent biohydrogenation of flaxseed oil resulted in an increased (P ≤ 0.04) accumulation of conjugated linoleic acid cis-9, trans-11, compared with all other treatments. Additionally, flaxseed oil produced a greater (P ≤ 0.01) accumulation of beneficial biohydrogenation intermediates (C18:2 trans-11, cis-15; C18:1 cis-15 and vaccenic acid), reflecting its ability to produce a more desirable FA profile than that of rapeseed oil or CON. The inability of P. freudenreichii subsp. shermanii ATCC 8262 to alter ruminal fermentation in a manner that lowered methane production, along with only minor effects on FA profiles through biohydrogenation, suggests that the biological activity of this strain was not realised under in vitro batch-culture conditions.

Polyphenol Oxidase Containing Sidestreams as Emulsifiers of Rumen Bypass Linseed Oil Emulsions: Interfacial Characterization and Efficacy of Protection against in Vitro Ruminal Biohydrogenation

The low transfer in ruminants of dietary polyunsaturated fatty acids to the milk or peripheral tissues is largely due to ruminal biohydrogenation. Lipids emulsified by a polyphenol oxidase (PPO) rich protein extract of red clover were shown before to be protected against this breakdown after cross-linking with 4-methylcatechol. Protein extracts of 13 other vegetal resources were tested. Surprisingly, the effectiveness to protect emulsified lipids against in vitro ruminal biohydrogenation largely depended on the origin of the extract and its protein concentration but was not related to PPO activity. Moreover, PPO isoforms in vegetal sources, effectively protecting emulsified lipids, were diverse and their presence at the emulsion interface did not seem essential. Potato tuber peels were identified as an interesting biological source of emulsifying proteins and PPO, particularly since protein extracts of industrial potato sidestreams proved to be suitable for the current application.

Is ruminal trans-11-18:1 accumulation a prerequisite for trans-10-18:1 production?

Understanding ruminal biohydrogenation of linoleic and linolenic acid is important in relation to physiological responses in the animal and the fatty acid profile of ruminant meat and milk. Alterations in ruminal biohydrogenation pathways leading to an increased formation of trans-10-18:1 are known to occur with high-concentrate diets and marine supplements. We hypothesised that accumulation of trans-11-18:1 is a prerequisite for trans-10-18:1 production. To evaluate this hypothesis, a batch-culture method, using rumen fluid from wethers, was used which consisted of two periods. Period 1 (10 h) was used to induce changes in trans-11-18:1 accumulation using a 2 × 2 factorial design, with 18:2n-6 (0 vs 6.40 mg) and 22:6n-3 (0 vs 2.50 mg) replicated with three substrates (starch, glucose or cellobiose). As planned, the addition of 18:2n-6 in combination with 22:6n-3 resulted in greater accumulation of trans-11-18:1 than did the other treatments (2.73 ± 0.125 vs 0.37 ± 0.157 mg/flask). After P1, 18:2n-6 (3.20 mg) was added to all flasks and after 14 h of incubation, formation of trans-10-18:1 and trans-11-18:1 was evaluated. The apparent production of both trans-10-18:1 (0.057 vs 0.812 mg/flask) and trans-11-18:1 (–0.013 vs 1.100 mg/flask) for cultures receiving 22:6n-3 in P1 was greater independent of 18:2n-6 addition in P1 (P > 0.10). This lack of a significant interaction suggests that trans-11-18:1 accumulation was not a major factor explaining trans-10-18:1 production under the studied conditions.

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.

Substrates enriched by the fungus Cunninghamella echinulata: an in vitro study of nutrient composition, sheep rumen fermentation and lipid metabolism

AIMS

Enrichment of wheat bran (WB), corn meal (CM) and barley flakes (BF) with the oleaginous fungus Cunninghamella echinulata (CE) might lead to effective use of these by-products in ruminant nutrition. We examined their effects on rumen fermentation and lipid metabolism.

METHODS AND RESULTS

WB, CM and BF substrates without or with brewer's grains (WBG, CMG, BFG) and enriched with CE were incubated with meadow hay (MH, 500 : 500, w/w) in rumen fluid in vitro for 24 h. The dry matter of the CE-enriched substrates increased (by 2-4%); however, digestibility decreased (P < 0·01). Adverse effects of CE-enriched substrates on the rumen ciliate population were observed. Little effect on the rumen eubacterial population was detected by the 16S-polymerase chain reaction/denaturizing gradient gel electrophoresis method. The increase in γ-linolenic acid output in the MH + BFGCE diet (800 : 200, w/w) was accompanied by an increase in rumen biohydrogenation of polyunsaturated fatty acids.

CONCLUSION

The diet substrates enriched with the fungus CE were less digestible than the untreated cereal substrates; no appreciable positive effect was observed on rumen fermentation patterns or the eubacterial and ciliate populations.

SIGNIFICANCE AND IMPACT OF THE STUDY

The in vitro study showed that adding CE-enriched substrates to ruminant diets is not effective for improving rumen fermentation.

Changes in fatty acid composition of various full fat crushed oilseeds and their free oils when incubated with rumen liquor in vitro

The fatty acid pattern of dietary lipids can be modified during rumen biohydrogenation (BH). The objective of the present study was to assess changes in the FA pattern of different oilseed products supplied either as crushed full fat oilseed or as free oil after in vitro incubation with buffered rumen liquor. The FA patterns were determined at the beginning and compared with those measured after 24 h of incubation. The contents of fatty acids (FA) < C18 increased (p < 0.05) in nearly all treatments, eventually due to microbial de novo synthesis and fermentation of carbohydrates and proteins during incubation. In contrast, the contents of the dominating C18 FA, (oleic acid - C18:1c9, linoleic acid - C18:2c9,12, linolenic acid - C18:3c9,12,15) were reduced due to BH, resulting in the accumulation of characteristic BH intermediates, such as conjugated linoleic acid (CLA) isomer C18:2c9t11 (rumenic acid). However, both for crushed full fat oilseeds and their free oils the process of BH was not completed at the end of incubation. The disappearance was highest for C18:3c9,12,15, followed by C18:2c9,12 and C18:1c9. The rate of BH of unsaturated FA was higher in the crushed form compared to the oil form. Higher amounts of BH intermediates accumulated in the crushed form. Obviously, the physical form affects the degree of BH in vitro. The current results suggest that feeding crushed full fat seeds instead of their free oils to dairy cows might stimulate the formation of beneficial BH intermediates such as CLA in the rumen.

Effects of feeding different linseed sources on omasal fatty acid flows and fatty acid profiles of plasma and milk fat in lactating dairy cows

The aim of this experiment was to study the effects of feeding different linseed sources on omasal fatty acid (FA) flows, and plasma and milk FA profiles in dairy cows. Four ruminally cannulated lactating Holstein-Friesian cows were assigned to 4 dietary treatments in a 4×4 Latin square design. Dietary treatments consisted of supplementing crushed linseed (CL), extruded whole linseed (EL), formaldehyde-treated linseed oil (FL) and linseed oil in combination with marine algae rich in docosahexaenoic acid (DL). Each period in the Latin square design lasted 21 d, with the first 16 d for adaptation. Omasal flow was estimated by the omasal sampling technique using Cr-EDTA, Yb-acetate, and acid detergent lignin as digesta flow markers. The average DM intake was 20.6 ± 2.5 kg/d, C18:3n-3 intake was 341 ± 51 g/d, and milk yield was 32.0 ± 4.6 kg/d. Milk fat yield was lower for the DL treatment (0.96 kg/d) compared with the other linseed treatments (CL, 1.36 kg/d; EL, 1.49 kg/d; FL, 1.54 kg/d). Omasal flow of C18:3n-3 was higher and C18:3n-3 biohydrogenation was lower for the EL treatment (33.8 g/d; 90.9%) compared with the CL (21.8 g/d; 94.0%), FL (15.5 g/d; 95.4%), and DL (4.6 g/d; 98.5%) treatments, whereas whole-tract digestibility of crude fat was lower for the EL treatment (64.8%) compared with the CL (71.3%), FL (78.5%), and DL (80.4%) treatments. The proportion of C18:3n-3 (g/100 g of FA) was higher for the FL treatment compared with the other treatments in plasma triacylglycerols (FL, 3.60; CL, 1.22; EL, 1.35; DL, 1.12) and milk fat (FL, 3.19; CL, 0.87; EL, 0.83; DL, 0.46). Omasal flow and proportion of C18:0 in plasma and milk fat were lower, whereas omasal flow and proportions of biohydrogenation intermediates in plasma and milk fat were higher for the DL treatment compared with the other linseed treatments. The results demonstrate that feeding EL did not result in a higher C18:3n-3 proportion in plasma and milk fat despite the higher omasal C18:3n-3 flow. This was related to the decreased total-tract digestibility of crude fat. Feeding FL resulted in a higher C18:3n-3 proportion in plasma and milk fat, although the omasal C18:3n-3 flow was similar or lower than for the CL and EL treatment, respectively. Feeding DL inhibited biohydrogenation of trans-11,cis-15-C18:2 to C18:0, as indicated by the increased omasal flows and proportions of biohydrogenation intermediates in plasma and milk fat.

Ruminal fermentation, milk fatty acid profiles, and productive performance of Holstein dairy cows fed 2 different safflower seeds

A lactation trial was conducted to determine the effects of supplementing whole safflower seeds (SS) on ruminal fermentation, lactational performance, and milk fatty acid (FA) profiles. Nine multiparous Holstein cows (days in milk = 110 ± 20) were used in a replicated 3 × 3 Latin square design. Each period lasted 21 d, with 14 d of adaptation and 7 d of data collection. Within square, cows were randomly assigned to a sequence of 3 dietary treatments as follows: cottonseed total mixed ration (TMR; CST), conventional SS (variety S-208) TMR (CSST), and NutraSaff SS (Safflower Technologies International, Sidney, MT) TMR (NSST). Diets contained approximately 63% forage (36% alfalfa hay, 4% grass hay, and 23% corn silage) and 37% concentrate supplemented with 2% cottonseed to the CST and 3% conventional or NutraSaff SS to the CSST or the NSST, respectively. Intake of dry matter (DM) averaged 21.8 kg/d and did not differ across diets, but feeding the NSST decreased intake of neutral detergent fiber (NDF) due to lower dietary concentration of NDF in the NSST. Digestibilities of DM and nutrients were similar among treatments. No differences in yields of milk or milk components were observed in response to supplementing SS. Dietary treatments did not affect ruminal pH, total or molar proportions of ruminal volatile FA, and ammonia-N. However, cows fed SS had a higher molar proportion of isobutyrate than those fed the CST diet. Ruminal C16:0 FA concentration increased with the CST, whereas C18:1 cis-9 and C18:2 n-6 tended to increase with SS supplementation, indicating that conventional and NutraSaff SS were partially protected from microbial biohydrogenation. Supplementing SS decreased milk C16:0 concentration, whereas it increased C18:1 cis-9 and C18:1 trans-9. Milk FA C18:1 trans-11 and cis-9, trans-11 conjugated linoleic acid increased and tended to increase with feeding the NSST, respectively, but not the CSST diet. In conclusion, supplementing diets with whole SS at 3% of dietary DM can be an effective strategy of fat supplementation to lactating dairy cows without negative effects on lactational performance and milk FA profiles.

Interactions of monensin with dietary fat and carbohydrate components on ruminal fermentation and production responses by dairy cows

Variation in milk fat percentage resulting from monensin supplementation to lactating dairy cows could be due to altered ruminal fermentation with interactions of monensin with ruminal biohydrogenation of fat and ruminal carbohydrate availability. The objective of the study was to determine the effects of feeding monensin as Rumensin (R) in diets differing in starch availability (ground or steam-flaked corn), effective fiber (long or short alfalfa hay, LAH or SAH), and 4% fat (F) from distillers grains, roasted soybeans, and an animal-vegetable blend on ruminal fermentation characteristics and milk production in lactating dairy cows. Six ruminally cannulated lactating Holstein cows were used in a balanced 6×6 Latin square design with 21-d periods. The cows were fed 6 diets: (1) C=control diet with ground corn and LAH, (2) CR=C plus R, (3) CRFL=CR plus F, (4) CRFS=ground corn, R, F, and SAH, (5) SRFL=steam-flaked corn, R, F, and LAH, and (6) SRFS=steam-flaked corn, R, F, and SAH. Mean particle size of LAH was 5.00 mm and 1.36 mm for SAH. All diets were formulated to have 21% forage NDF and 40% NFC. The R tended to decrease DMI, decreased milk fat yield, and numerically lowered milk fat percentage (3.41 vs. 2.98%). Addition of F to R diets did not affect milk fat percentage. By feeding diets containing R and F, SAH tended to increase milk fat percentage for the ground-corn diet, but SAH tended to decrease milk fat percentage with steam-flaked corn (CRFL+SRFS vs. CRFS+SRFL). The steam-flaked corn increased total-tract NDF digestibility (CRFL + CRFS vs. SRFL+SRFS; 51.1 vs. 56%). Addition of F with R decreased total VFA concentration and increased rumen pH. Fat addition with R decreased rumen NH3N and MUN (12.8 vs. 13.9 mg/dL), and SFC decreased NH3N concentration compared with ground corn. Although R caused milk fat depression, addition of F did not further exacerbate milk fat depression. Fatty acid analysis did not implicate any particular biohydrogenation intermediate as the causative factor for the milk fat depression.

Effects of chemically or technologically treated linseed products and docosahexaenoic acid addition to linseed oil on biohydrogenation of C18:3n-3 in vitro

Rumen biohydrogenation kinetics of C18:3n-3 from several chemically or technologically treated linseed products and docosahexaenoic acid (DHA; C22:6n-3) addition to linseed oil were evaluated in vitro. Linseed products evaluated were linseed oil, crushed linseed, formaldehyde treated crushed linseed, sodium hydroxide/formaldehyde treated crushed linseed, extruded whole linseed (2 processing variants), extruded crushed linseed (2 processing variants), micronized crushed linseed, commercially available extruded linseed, lipid encapsulated linseed oil, and DHA addition to linseed oil. Each product was incubated with rumen liquid using equal amounts of supplemented C18:3n-3 and fermentable substrate (freeze-dried total mixed ration) for 0, 0.5, 1, 2, 4, 6, 12, and 24h using a batch culture technique. Disappearance of C18:3n-3 was measured to estimate the fractional biohydrogenation rate and lag time according to an exponential model and to calculate effective biohydrogenation of C18:3n-3, assuming a fractional passage rate of 0.060/h. Treatments showed no differences in rumen fermentation parameters, including gas production rate and volatile fatty acid concentration. Technological pretreatment (crushing) followed by chemical treatment applied as formaldehyde of linseed resulted in effective protection of C18:3n-3 against biohydrogenation. Additional chemical pretreatment (sodium hydroxide) before applying formaldehyde treatment did not further improve the effectiveness of protection. Extrusion of whole linseed compared with extrusion of crushed linseed was effective in reducing C18:3n-3 biohydrogenation, whereas the processing variants were not different in C18:3n-3 biohydrogenation. Crushed linseed, micronized crushed linseed, lipid encapsulated linseed oil, and DHA addition to linseed oil did not reduce C18:3n-3 biohydrogenation. Compared with the other treatments, docosahexaenoic acid addition to linseed oil resulted in a comparable trans11,cis15-C18:2 biohydrogenation but a lesser trans10+11-C18:1 biohydrogenation. This suggests that addition of DHA in combination with linseed oil was effective only in inhibiting the last step of biohydrogenation from trans10+11-C18:1 to C18:0.

Significance of phenolic compounds in tropical forages for the ruminal bypass of polyunsaturated fatty acids and the appearance of biohydrogenation intermediates as examined in vitro

The purpose of the present study was to assess the influence of phenol-rich tropical ruminant feeds on the extent of ruminal biohydrogenation (BH) of polyunsaturated fatty acids (PUFA). Samples of 27 tropical forages (mainly tree and shrub leaves), characterised by different phenolic profiles, were incubated in vitro (n = 4 replicates) with buffered rumen fluid for 24 h using the Hohenheim gas test method. Linseed oil was added as a rich source of PUFA. In the plants, total extractable phenols (TEP), non-tannin phenols, condensed tannins, and fatty acids were determined. After terminating incubation, the fatty acid profile present in fermentation fluid (total syringe content) was analysed by gas chromatography. The relationship between TEP and the disappearance of α-linolenic acid from the incubation fluid was negative (R2 = 0.48, P < 0.001), indicating that TEP reduced the ruminal BH of this PUFA. Similarly, TEP were negatively related with the disappearances of linoleic acid (R2 = 0.52, P < 0.001) and oleic acid (R2 = 0.58, P < 0.001). The appearance of rumenic acid, an important conjugated linoleic acid isomer, was positively correlated with TEP (R2 = 0.30, P < 0.01), while the opposite result was seen with stearic acid (R2 = 0.22, P < 0.05). Leaves of avocado (Persea americana) were particularly interesting, because they changed the BH pattern at a moderate TEP content of 73 g/kg DM. It is concluded that, in the tropical feedstuffs investigated, TEP have an impact on ruminal fatty acid BH and are associated with an increased bypass of PUFA and the generation of conjugated linoleic acid.