Biohydrogenation of linolenic acid to stearic acid by the rumen microbial population yields multiple intermediate conjugated diene isomers

Lithium Chloride Promotes Endogenous Synthesis of CLA in Bovine Mammary Epithelial Cells

Although conjugated linoleic acid (CLA) can promote human health, its content in milk is insufficient to have a significant impact. The majority of the CLA in milk is produced endogenously by the mammary gland. However, research on improving its content through nutrient-induced endogenous synthesis is relatively scarce. Previous research found that the key enzyme, stearoyl-CoA desaturase (SCD) for the synthesis of CLA, can be expressed more actively in bovine mammary epithelial cells (MAC-T) when lithium chloride (LiCl) is present. This study investigated whether LiCl can encourage CLA synthesis in MAC-T cells. The results showed that LiCl effectively increased SCD and proteasome α5 subunit (PSMA5) protein expression in MAC-T cells as well as the content of CLA and its endogenous synthesis index. LiCl enhanced the expression of proliferator-activated receptor-γ (PPARγ), sterol regulatory element-binding protein 1 (SREBP1), and its downstream enzymes acetyl CoA carboxylase (ACC), fatty acid synthase (FASN), lipoprotein lipase (LPL), and Perilipin 2 (PLIN2). The addition of LiCl significantly enhanced p-GSK-3β, β-catenin, p-β-catenin protein expression, hypoxia-inducible factor-1α (HIF-1α), and downregulation factor genes for mRNA expression (P < 0.05). These findings highlight that LiCl can increase the expression of SCD and PSMA5 by activating the transcription of HIF-1α, Wnt/β-catenin, and the SREBP1 signaling pathways to promote the conversion of trans-vaccenic acid (TVA) to the endogenous synthesis of CLA. This data suggests that the exogenous addition of nutrients can increase CLA content in milk through pertinent signaling pathways.

Short-communication: Study of fatty acid metabolites in microbial conjugated fatty acids-enrichment of milk and discovery of additional undescribed conjugated linolenic acid isomers

Microbially enriched food in conjugated linoleic (CLA) and conjugated linolenic (CLNA) acids is intensively studied nowadays. The conversion of linoleic (LA) and α-linolenic acids (α-LNA) into these compounds may involve different fatty acid (FA) intermediates. This research aimed to investigate potential FA byproducts in milk during microbial CLA/CLNA-enrichment using Bifidobacterium breve DSM 20091. Milk fermented with pure α-LNA showed a decrease in free myristic acid, while pure LA led to an increase in free stearic acid. No additional FA compounds were found alongside CLA/CLNA isomers. The strain produced several CLA isomers from LA, but only when administered alone. Nonetheless, when α-LNA was assayed, additional CLNA isomers, never reported before for bifidobacteria, were observed. In conclusion, except for stearic acid in the presence of LA, no side-FA metabolites were released during milk microbial CLA/CLNA-enrichment. Results suggest either CLA/CLNA production occurs in one single-step or intermediates biotransformation is very fast.

Comparison of milk and grass composition from grazing Irish dairy herds with and without milk fat depression

BACKGROUND

This study investigated the factors relating to pasture chemical and fatty acid (FA) composition that influence the milk fat percentage of spring calving, grazing dairy cows. The relationship between milk fat percentage and FA composition of the milk in these herds was also investigated.

RESULTS

Milk protein percentage, milk casein percentage and cheddar cheese yield were increased in milk from HMF herds. Cows from LMF herds did not have negatively altered milk processability including rennet coagulation time (RCT), pH and ethanol stability. Crude protein, NDF, ADF, ether extract and total FA content of pasture was not different between LMF and HMF herds. Milk fat concentration of conjugated linoleic acid (CLA) t10, c12 was not different between HMF and LMF herds. Pre-grazing herbage mass and pasture content of crude protein, neutral detergent fibre (NDF) and total FA were similar between HMF and LMF herds. Pasture offered to LMF herds had a higher concentration of monounsaturated fatty acids (MUFA). A strong negative relationship (r = -0.40) was evident between milk fat percentage and pasture crude protein content for MMF herds (3.31-3.94% milk fat).

CONCLUSIONS

This research reports improved milk protein percentage, milk casein percentage and cheddar cheese yield from HMF herds compared to LMF herds. Milk processability was not impacted by low milk fat percentage. Pasture NDF and total fatty acid content was similar in HMF herds and LMF herds. Milk fat percentage had a strong negative association (r = -0.40) with pasture crude protein content in MMF herds (MF 3.31-3.94%). Correlation values between pasture chemical and FA composition and milk fat percentage in LMF herds and HMF herds were low, indicating that diet is not the only causative factor for variation in milk fat of grazing dairy cows. Comparison of milk fatty acid composition from herds with and without milk fat depression suggests that there may be other fatty acids apart from CLA t10, c12 that contribute to the inhibition of milk fat synthesis during milk fat depression in grazing herds.

Milk yield and composition in dairy goats fed extruded flaxseed or a high-palmitic acid fat supplement

We compared the potential of dietary lipid supplements of different fatty acid compositions to affect milk performance when early lactation dairy goats were fed a high-concentrate diet. Thirty Alpine goats at 23 ± 5 d in milk were allocated to 1 of 10 blocks according to parity and milk fat concentration. Within each block, goats were randomly assigned to receive, during a period of 41 d, either CONT) a basal diet with a forage to concentrate ratio of 45:55, used as control, or PALM) the basal diet + 2% of a palmitic acid-enriched fat supplement, or FLAX) the basal diet + 7% of extruded flaxseed. Body weight, dry matter intake and milk yield were not different between treatments. As compared with CONT, goats fed PALM and FLAX had a greater milk fat concentration. Moreover, milk fat yield was numerically (but non-significantly) greater with PALM than with CONT. Milk fat from goats receiving PALM had a greater concentration of 16:0 as compared with CONT and FLAX, whereas a greater concentration of cis-9, cis-12, cis-15 18:3 was observed when goats were fed FLAX as compared with CONT and PALM. Under the conditions of the current experiment, dietary fat supplementation had only minor impacts on the yield of major milk constituents, with the exception of a modest increase in fat yield when goats were fed PALM. The impact of a greater concentration of 16:0 in milk fat of goats receiving this feed ingredient on the nutritive value of dairy products remains to be determined.

Using canonical correlation analysis to understand the rumen biohydrogenation patterns of linoleic and alpha-linolenic acids in the rumen fluid of bovines

The objective of this study was to determine the multivariate relationship among linoleic acid, alpha-linolenic acid, and their main rumen biohydrogenation (BH) intermediates and products in bovine rumen fluid using canonical correlation analysis (CCA). A dataset consisting of 1177 observations generated by 107 in vitro rumen incubation systems of pure and mixed linoleic acid (18:2-c9, c12) and alpha-linolenic acid (18:3-c9, c12, c15) was gathered. Two canonical variates were defined: A: composed of the nine main BH intermediates and products (18:2-c9, t11; 18:2-t11, c15; 18:1-t11; 18:1-t9; 18:1-t6; 18:1-c11; 18:1-c6; 18:1-c9; 18:0) of 18:2-c9, c12 and 18:3-c9, c12, c15 and B: composed of 18:2-c9, c12 and 18:3-c9, c12, c15. Two canonical functions between A and B with significant canonical correlations (R1=0.990 and R2=0.738; p <0.01) were obtained. However, only the first function was selected for CCA. Exploration of canonical loadings for first function, revealed the following quantitative significance (absolute value) order for fatty acids (FA) within their respective canonical variates: A: 18:0(0.958)>18:1-t9(0.837)>18:1-c11(0.835)>18:1-c6(0.824)>18:1-t11(0.747)>18:1-c9(0.738)>18:1-t6(0.415)>18:2-t11, c15(0.387)> 18:2-c9, t11(0.239); B: 18:2-c9, c12(0.667)>18:3-c9, c12, c15(0.488). The CCA showed that 18:2-c9, c12 has a greater contribution than that of 18:3-c9, c12, c15 on the production of the aforementioned BH intermediates, in which 18:0, as well as the groups of 18:1 cis and trans-FA were mainly affected.

Stearic acid induces CCK and GLP-1 upregulation via GPR120/PLC-β, leading to reduced appetite in Hu sheep fed with rice straw

Due to the poor palatability of straw, feeding untreated rice straw reduces ruminant feed intake, thus affecting the production efficiency of animal husbandry. However, the detailed mechanism by which straw affects ruminants' feed intake is unclear. Therefore, this study aimed to elucidate the molecular mechanism by which a rice straw (RS)-based diet affects appetite regulation in Hu sheep. We found that RS promoted the secretion of cholecystokinin (CCK) and glucagon-like peptide-1 (GLP-1) and decreased feed intake. Blood metabolomics showed that RS activated the arachidonic acid metabolism, biosynthesis of unsaturated fatty acids, linoleic acid metabolism, and alpha-linolenic acid metabolism pathways, and the secretion of stearic acid (SA), their metabolic end product, increased significantly. GPR120, one of the classical receptors of long-chain fatty acids (LCFAs), can be involved in appetite regulation. However, the role of SA in satiety hormone regulation mediated by GPR120 in ruminants is unclear. In this study, in vivo experiments showed that in sheep fed with RS, SA increased significantly and activated GPR120/Ca²⁺, increasing the secretion of the satiety hormones CCK and GLP-1. In vitro mechanism studies showed that SA promotes GLP-1 and CCK secretion by activating GPR120-mediated downstream PKC and IP3R signaling pathways of PLCβ.

Effects of the herbal preparation AyuFertin, used for anestrus overcome, on fatty acids composition of milk in Bulgarian Murrah buffaloes

The herbal protocols, used instead of hormones in buffalo breeding for reproduction optimisation, do not provide information of their effect on the milk quality of treated animals. This research analysed whether the herbal preparation AyuFertin (Indian Herbs Specialities Pvt. Ltd, Saharanpur), applied in postpartum period for recovering the ovary cycling, had a side effect on the milk composition. The experiment was conducted with buffaloes of the Bulgarian Murrah breed at average age of 50 months during May-June 2019, divided into control (n=6) and experimental (n=7) groups. The experimental buffaloes received AyuFertin orally for three consecutive days at a dose of 3 g/100 kg live weight since the 21st postpartum day. The animals without signs of estrus were treated again after 10 days. The milk samples were collected at test-days, before and after treatments. The fatty acid composition of the milk and Ayufertin was evaluated by gas chromatography-mass spectrometry analysis. Quantification of the identified fatty acids in milk was made by the area normalisation method. In general, the fatty acids composition did not differ after the treatment with AyuFertin. Deviation in the amounts of some fatty acids was established. The content of medium-chain fatty acids such as lauric and capric was decreased, while the amount of long-chain acids such as 11-hexadecanoic and stearic was increased in the experimental group. The main active components of AyuFertin - trienoic acids were not transferred into the milk of treated animals. In conclusion, due to the ability of AyuFertin to affect the fatty acids amount in the milk of treated buffaloes, farmers should strictly follow the manufacturer’s recommendation for the dose and duration of AyuFertin treatment to avoid negative effects on milk quality.

Fatty Acid Profile, Conjugated Linoleic Acid Content, and Lipid Quality Indices in Selected Yogurts Available on the Polish Market

The aim of the present study was to determine the fatty acid composition, the content of cis9trans11 C18:2 acid (CLA), and lipid quality indices in yogurts made of cow's milk, available on the Polish market. The test material consisted of: natural yogurts, natural yogurts with additives (muesli, cereal grains), bio yogurts, bio yogurts with additives (millet groats, quinoa, chestnuts), probiotic yogurts, and eco yogurts. All the products were bought in the period from May to June 2021. The conducted research showed that the analyzed yoghurts were characterized by a varying content of fatty acid groups, different values of the calculated lipid quality indices, as well as a different content of conjugated linoleic acid cis9trans11 C18: 2 (CLA). Natural yogurts with additives had the highest content of polyunsaturated fatty acids (PUFAs) and n-3 PUFAs. Natural and bio yogurts with additives had a higher content of n-6 PUF than the other analyzed yogurts. The n-6/n-3 ratio was lower in bio yogurts and eco yogurts. Natural yogurts with additives featured the lowest index of atherogenicity (AI) and index of thrombogenicity (TI) and the highest hypocholesterolemic/hypercholesterolemic ratio (H/H). The fat extracted from the bio yogurts had the highest (0.90% of total fatty acids) mean content of cis9trans11 C18:2 (CLA). In fat of the other analyzed yogurts, mean CLA content in total content of fatty acids varied from 0.48% in natural yogurts with additives to 0.81% in bio yogurts with additives.

Effect of lipid supplementation on the endogenous synthesis of milk cis-9,trans-11 conjugated linoleic acid in dairy sheep and goats: A tracer assay with 13C-vaccenic acid

A major proportion of milk rumenic acid (RA; cis-9,trans-11 CLA) is synthesized through mammary Δ⁹-desaturation of vaccenic acid (VA; trans-11 18:1). Diet composition may determine the relative contribution of this endogenous synthesis to milk RA content, with effects that might differ between ruminant species. However, this hypothesis is mostly based on estimated values, proxies of stearoyl-CoA desaturase (SCD) activity, and indirect comparisons between publications in the literature. With the aim of providing new insights into this issue, in vivo Δ⁹-desaturation of ¹³C-labeled VA (measured via milk ¹³C-VA and -RA secretion) was directly compared in sheep and goats fed a diet without lipid supplementation or including 2% of linseed oil. Four Assaf sheep and 4 Murciano-Granadina goats were used in a replicated 2 × 2 crossover design to test the effects of the 2 dietary treatments during 2 consecutive 25-d periods. On d 22 of each period, 500 mg of ¹³C-VA were i.v. injected to each animal. Dairy performance, milk fatty acid profile, including isotope analysis, and mammary mRNA abundance of genes coding for SCD were examined on d 21 to 25 of each period. Supplementation with linseed oil improved milk fat concentration and increased the content of milk VA and RA. However, the isotopic tracer assay suggested no variation in the relative proportion of VA desaturated to milk RA, and the percentage of this CLA isomer deriving from SCD activity would remain constant regardless of dietary treatment. These results put into question a major effect of lipid supplementation on the endogenous synthesis of milk RA and support that mammary Δ⁹-desaturation capacity would not represent a limiting factor when designing feeding strategies to increase milk RA content. The lack of diet-induced effects was common to caprines and ovines, but inherent interspecies differences in mammary lipogenesis were found. Thus, the higher proportions of VA desaturation and endogenous synthesis of milk RA in sheep supported a greater SCD activity compared with goats, a finding that was not associated with the similar mRNA abundance of SCD1 in the 2 species. On the other hand, transfer efficiency of the isotopic tracer to milk was 37% higher in caprine than in ovine, suggesting a greater efficiency in mammary fatty acid uptake from plasma in caprine.

Miúda (Nopalea cochenillifera (L.) Salm-Dyck)-The Best Forage Cactus Genotype for Feeding Lactating Dairy Cows in Semiarid Regions

Simple Summary

The usage of forage cactus is essential for the maintenance of livestock activity in semiarid regions as an alternative to conventional crops. Cactaceae have adaptive characteristics that ensure their development progress under drought conditions. Four genotypes of forage cactus (Gigante, Miúda, IPA Sertânia, and Orelha de Elefante Mexicana) were fed to lactating dairy cows and the diets were then evaluated based on animal performance, milk fatty acid profile, and microbial protein synthesis. Miúda forage cactus led to a higher nutrient intake and milk yield, as well as greater microbial protein synthesis. Higher saturated fatty acids were observed when the Gigante and IPA Sertânia forage cactus genotypes were fed to dairy cows. Orelha de Elefante Mexicana forage cactus caused lower milk yield along with protein yields and content; however, it improved the milk fatty acid profile by promoting a higher ratio of unsaturated to saturated fatty acids and desirable fatty acids. It is concluded that the Miúda forage cactus is the genotype most suitable for the diets of lactating dairy cows.

Abstract

This study aimed to investigate the effects on nutrient intake and digestibility, milk yield (MY) and composition, milk fatty acids profile, and microbial protein synthesis caused by feeding lactating dairy cows four different forage cactus genotypes. Eight Girolando cows (5/8 Holstein × 3/8 Gyr), weighing 490 ± 69.0 kg (means ± standard deviation), and producing 15.5 ± 1.0 kg/d of milk during pretrial were distributed to two contemporaneous 4 × 4 Latin squares. The cows were fed a total mixed ration composed of sorghum silage (385 g/kg of dry matter (DM)), concentrated mix (175 g/kg DM), and forage cactus (440 g/kg DM). The experimental treatments consisted of different cactus genotypes, such as Gigante cactus (GC), Miúda cactus (MC), IPA Sertânia cactus (SC), and Orelha de Elefante Mexicana cactus (OEMC). The feeding of MC provided a higher intake of DM, organic matter (OM), and total digestible nutrients, as well as higher MY, energy-corrected milk, and microbial protein synthesis in comparison with those resulting from the other genotypes tested. The GC promoted lower DM and OM, and the apparent digestibility of neutral detergent fiber. The cows fed with OEMC showed lower MY and milk protein yield and content, and higher unsaturated over saturated fatty acid ratio in milk. Miúda forage cactus increased nutrient intake, digestibility of DM and OM, and microbial synthesis without impairing the milk fatty acid profile.

Characterisation of Formaggella della Valle di Scalve Cheese Produced From Cows Reared in Valley Floor Stall or in Mountain Pasture: Fatty Acids Profile and Sensory Properties

An important problem in mountain areas is the abandonment of pasture. This trend can be combated by the valorisation of typical dairy products, such as “Formaggella della Valle di Scalve”, a semi-cooked traditional cheese made from whole milk in a mountain area in Italy. The aim of the present research was to compare the fatty acid (FA) profile and the sensory properties of this cheese as manufactured under different conditions: i) from the milk of cows grazing on mountain or valley pasture or fed indoors; ii) from the milk of cows fed hay or fed silage. In the first case, five cheesemaking trials were conducted during two years for each of the following situations: mountain pasture (A); pasture at the bottom of the valley (P) (about 1000m asl); stall (S). In the second case, three cheesemaking trials were conducted for each of the following situations: cows fed silage (I); cows fed hay (F). S cheese was richer in medium-chain FAs, while long-chain FAs were higher in P and A cheeses. On the other hand, long chain fatty acids (LCFA) were more abundant in P and A cheeses than in S. In general, MUFA, PUFA and, consequently, total unsaturated FA (UFA), were significantly higher in the P and A cheeses than S (UFA: 36.55 and 38.34, respectively, vs. 31.13; p < 0.001), while SFA showed higher values in S (68.85 vs. 63.41 and 61.68 in P and A, respectively; p < 0.001). Conjugated linoleic acid isomers (CLA) were more represented in the P and A samples (1.86 in P and 1.52 in A, vs. 0.80 in S; p < 0.001); Omega 3 fatty acids, and in particular α-linolenic acid, were more abundant in P than in S cheese. In winter, the I sample (silage) presented higher percentages of myristic (C14), myristoleic (C14:1) and omega 6 acids, whereas F cheese (hay) contained higher concentrations of CLA. The triangular test of sensory analysis showed that, in general, F cheeses were judged as “sweeter” than I, with aromatic profiles characterized by higher content of 2- butanol and ethyl capronate.

Bioactivity and health effects of ruminant meat lipids. Invited Review

Ruminant meat (RM) is an excellent source of high-quality protein, B vitamins and trace minerals and plays an important role in global food and nutrition security. However, nutritional guidelines commonly recommend reduced intake of RM mainly because of its high saturated fatty acid (SFA) content, and more recently because of its perceived negative environmental impacts. RM is, however, rich in heart healthy cis-monounsaturated fatty acids and can be an important source of long-chain omega-3 (n-3) fatty acids in populations with low fish consumption. In addition, RM is a source of bioactive phospholipids, as well as rumen-derived bioactive fatty acids including branched-chain, vaccenic and rumenic acids, which have been associated with several health benefits. However, the role of bioactive RM lipids in maintaining and improving consumers' health have been generally ignored in nutritional guidelines. The present review examines RM lipids in relation to human health, and evaluates the effectiveness of different feeding strategies and possibilities for future profile and content improvement.

Influence of Feeding Linseed on SCD Activity in Grazing Goat Mammary Glands

Simple Summary

The effect of linseed feeding on stearoyl-CoA desaturase (SCD) activity was studied in dairy goats. SCD acts on the synthesis of milk conjugated linoleic acids (CLAs), considered highly important for human health. Linseed feeding significantly changed SCD activity, milk fat, and fatty acid profile; in particular, CLAs were higher in treated animals with potential benefits for human health. Because of the increasing care of consumers for the healthy aspects of foods, results increase the knowledge of beneficial effects of goat milk due to animal nutrition.

Abstract

The effects of linseed feeding on the stearoyl-CoA desaturase (SCD) activity were evaluated on grazing dairy goats divided into two homogeneous groups (C, control, and L, treated) fed the same amount of concentrate which, for group L was supplemented with linseed. Milk yield was unaffected by the treatment. Group L showed significantly higher milk fat (4.10% vs 2.94%, p < 0.01) than group S. Within milk fatty acids, group C showed significantly higher levels of saturated fatty acids and lower values of mono-unsaturated and polyunsaturated fatty acids. In group L, total CLAs were higher than in group S (0.646% vs 0.311%; p < 0.01) mainly because of the differences in CLA cis9 trans 11 (0.623% vs 0.304%; p < 0.01). In treated animals, SCD activity, measured as cis9 C14:1/C14:0, was lower than in the control group, mainly in July and August.

Effect of Feeding Cold-Pressed Sunflower Cake on Ruminal Fermentation, Lipid Metabolism and Bacterial Community in Dairy Cows

Cold-pressed sunflower cake (CPSC), by-product of oil-manufacturing, has high crude fat and linoleic acid concentrations, being a promising supplement to modulate rumen fatty acid (FA) profile. This trial studied CPSC effects on ruminal fermentation, biohydrogenation and the bacterial community in dairy cows. Ten cows were used in a crossover design with two experimental diets and fed during two 63-day periods. The cows were group fed forage ad libitum and the concentrate individually. The concentrates, control and CPSC, were isoenergetic, isoproteic and isofat. The ruminal samples collected at the end of each experimental period were analyzed for short-chain fatty acid, FA and DNA sequencing. CPSC decreased butyrate molar proportion (4%, p = 0.005). CPSC decreased C16:0 (28%, p < 0.001) and increased C18:0 (14%, p < 0.001) and total monounsaturated FA, especially C18:1 trans-11 (13%, p = 0.023). The total purine derivative excretion tended to be greater (5%, p = 0.05) with CPSC, resulting in a 6% greater daily microbial N flow. CPSC did not affect the diversity indices but increased the relative abundances of Treponema and Coprococcus, and decreased Enterococcus, Ruminococcus and Succinivibrio. In conclusion, the changes in ruminal fermentation and the FA profile were not associated with changes in microbial diversity or abundance of dominant populations, however, they might be associated with less abundant genera.

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.

Dynamic Alterations in Yak Rumen Bacteria Community and Metabolome Characteristics in Response to Feed Type

Current knowledge about the relationships between ruminal bacterial communities and metabolite profiles in the yak rumen is limited. This is due to differences in the nutritional and metabolic features between yak and other ordinary cattle combined with difficulties associated with farm-based research and a lack of technical guidance. A comprehensive analysis of the composition and alterations in ruminal metabolites is required to advance the development of modern yak husbandry. In the current study, we characterized the effect of feed type on the ruminal fluid microbiota and metabolites in yak using 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS). Bacteroidetes and Firmicutes were the predominant bacterial phyla in the yak rumen. At the genus level, the relative abundance of Bacteroidales BS11 gut group, Prevotellaceae UCG-003, Ruminococcaceae UCG-011, Bacteroidales RF16 group and Ruminococcaceae UCG-010 was significantly (P < 0.01) higher in the forage group compared to that in the concentrate group, while the concentrate group harbored higher proportions of Bacteroidales S24-7 group, Ruminococcaceae NK4A214, Succiniclasticum and Ruminococcus 2. Yak rumen metabolomics analysis combined with enrichment analysis revealed that feed type altered the concentrations of ruminal metabolites as well as the metabolic pattern, and significantly (P < 0.01) affected the concentrations of ruminal metabolites involved in protein digestion and absorption (e.g., L-arginine, ornithine, L-threonine, L-proline and β-alanine), purine metabolism (e.g., xanthine, hypoxanthine, deoxyadenosine and deoxyadenosine monophosphate) and fatty acid biosynthesis (e.g., stearic acid, myristic acid and arachidonic acid). Correlation analysis of the association of microorganisms with metabolite features provides us with a comprehensive understanding of the composition and function of microbial communities. Associations between utilization or production were widely identified between affected microbiota and certain metabolites, and these findings will contribute to the direction of future research in yak.

Conjugated Linoleic Acid Effects on Cancer, Obesity, and Atherosclerosis: A Review of Pre-Clinical and Human Trials with Current Perspectives

Obesity and its comorbidities, including type 2 diabetes and cardiovascular disease, are straining our healthcare system, necessitating the development of novel strategies for weight loss. Lifestyle modifications, such as exercise and caloric restriction, have proven effective against obesity in the short term, yet obesity persists because of the high predilection for weight regain. Therefore, alternative approaches to achieve long term sustainable weight loss are urgently needed. Conjugated linoleic acid (CLA), a fatty acid found naturally in ruminant animal food products, has been identified as a potential anti-obesogenic agent, with substantial efficacy in mice, and modest efficacy in obese human populations. Originally described as an anti-carcinogenic fatty acid, in addition to its anti-obesogenic effects, CLA has now been shown to possess anti-atherosclerotic properties. This review summarizes the pre-clinical and human studies conducted using CLA to date, which collectively suggest that CLA has efficacy against cancer, obesity, and atherosclerosis. In addition, the potential mechanisms for the many integrative physiological effects of CLA supplementation will be discussed in detail, including an introduction to the gut microbiota as a potential mediator of CLA effects on obesity and atherosclerosis.

Microbial Production of Conjugated Linoleic Acid and Conjugated Linolenic Acid Relies on a Multienzymatic System

Conjugated linoleic acids (CLAs) and conjugated linolenic acids (CLNAs) have gained significant attention due to their anticarcinogenic and lipid/energy metabolism-modulatory effects. However, their concentration in foodstuffs is insufficient for any therapeutic application to be implemented. From a biotechnological standpoint, microbial production of these conjugated fatty acids (CFAs) has been explored as an alternative, and strains of the genera Propionibacterium, Lactobacillus, and Bifidobacterium have shown promising producing capacities. Current screening research works are generally based on direct analytical determination of production capacity (e.g., trial and error), representing an important bottleneck in these studies. This review aims to summarize the available information regarding identified genes and proteins involved in CLA/CLNA production by these groups of bacteria and, consequently, the possible enzymatic reactions behind such metabolic processes. Linoleate isomerase (LAI) was the first enzyme to be described to be involved in the microbiological transformation of linoleic acids (LAs) and linolenic acids (LNAs) into CFA isomers. Thus, the availability of lai gene sequences has allowed the development of genetic screening tools. Nevertheless, several studies have reported that LAIs have significant homology with myosin-cross-reactive antigen (MCRA) proteins, which are involved in the synthesis of hydroxy fatty acids, as shown by hydratase activity. Furthermore, it has been suggested that CLA and/or CLNA production results from a stress response performed by the activation of more than one gene in a multiple-step reaction. Studies on CFA biochemical pathways are essential to understand and characterize the metabolic mechanism behind this process, unraveling all the gene products that may be involved. As some of these bacteria have shown modulation of lipid metabolism in vivo, further research to be focused on this topic may help us to understand the role of the gut microbiota in human health.

Implication of trans-11,trans-13 conjugated linoleic acid in the development of hepatic steatosis

SCOPE

Conjugated linoleic acids are linoleic acid isomers found in the diet that can also be produced through bacterial metabolism of polyunsaturated fatty acids. Our objective was to evaluate the contribution of fatty acid metabolites produced from polyunsaturated fatty acids by the gut microbiota in vivo to regulation of hepatic lipid metabolism and steatosis.

METHODS AND RESULTS

In mice with depleted n-3 polyunsaturated fatty acids, we observed an accumulation of trans-11,trans-13 CLA and cis-9,cis-11 conjugated linoleic acids in the liver tissue that were associated with an increased triglyceride content and expression of lipogenic genes. We used an in vitro model to evaluate the impact of these two conjugated linoleic acids on hepatic lipid metabolism. In HepG2 cells, we observed that only trans-11,trans-13 conjugated linoleic acids recapitulated triglyceride accumulation and increased lipogenic gene expression, which is a phenomenon that may implicate the nuclear factors sterol regulatory element binding protein 1c (SREBP-1c) and carbohydrate-responsive element-binding protein (ChREBP).

CONCLUSION

The trans-11,trans-13 conjugated linoleic acids can stimulate hepatic lipogenesis, which supports the conclusion that gut microbiota and related metabolites should be considered in the treatment of non-alcoholic liver disease.

Evidence for the Initial Steps of DHA Biohydrogenation by Mixed Ruminal Microorganisms from Sheep Involves Formation of Conjugated Fatty Acids

Incubation of DHA with sheep rumen fluid resulted in 80% disappearance in 6 h. The products were analyzed as their fatty acid (FA) methyl esters by GC-FID on SP-2560 and SLB-IL111 columns. The GC-online reduction × GC and GC-MS techniques demonstrated that all DHA metabolites retained the C22 structure (no evidence of chain-shortening). Two new transient DHA products were identified: mono-trans methylene interrupted-DHA and monoconjugated DHA (MC-DHA) isomers. Identification of MC-DHA was confirmed by their predicted elution using equivalent chain length differences from C18 FA, their molecular ions, and the 22:5 products formed which were the most abundant at 6 h. The 22:5 structures were established by fragmentation of their 4,4-dimethyloxazoline derivatives, and all 22:5 products contained an isolated double bond, suggesting formation via MC-DHA. The most abundant c4,c7,c10,t14,c19-22:5 appeared to be formed by unknown isomerases. Results suggest that the initial biohydrogenation of DHA was analogous to that of C18 FA.

Impact of ground soybean and starch levels on the quality of meat from feedlot young Nellore bulls

Twenty-eight young Nellore bulls (395±32kg initial body weight) were assigned to a completely randomized design (2×2 factorial design with 7 animals per treatment) to evaluate effects on the quality of meat. Diet treatments consisted of high (about 25%) or low (about 16%) starch levels, with or without ground soybean addition. Shear force was decreased in the meat from animals fed a low-starch diet (P=0.0016). Meat from animals fed a high-starch diet had increased total concentrations of unsaturated (P=0.0029) and monounsaturated fatty acids (P=0.0253). Polyunsaturated fatty acid content increased in the meat from animals fed a diet containing soybean (P=0.0121). High starch diets (>25%) decreased the concentration of saturated fatty acids and increased the amount of unsaturated fatty acids in the meat from young Nellore bulls.

Changes in the rumen microbiome and metabolites reveal the effect of host genetics on hybrid crosses

The rumen microbiota plays important roles in nutrient metabolism and absorption of the host. However, it is poorly understood how host genetic variation shapes the community structure of the rumen microbiota and its metabolic phenotype. Here, we used sika deer (Cervus nippon) and elk (Cervus elaphus) to produce the following two types of hybrid offspring: sika deer ♀ × elk ♂ (SEH) and elk ♀ × sika deer ♂ (ESH). Then, we examined the rumen microbiome and metabolites in the parents and their hybrid offspring. The rumen microbiota in the hybrids differed from that in their parents, suggesting a significant effect of host genetics on the rumen microbiome that may have resulted from vertical transmission. The rumen metabolites displayed patterns similar to the structure of the rumen microbiome, with changes in the amounts of volatile fatty acids and metabolites of amino acids. The alanine, arginine, proline and phenylalanine pathways were enriched in the rumen of hybrid animals. The enriched metabolites in the above pathways were positively correlated with the bacteria Prevotella spp., Acetitomaculum spp., Quinella spp., Succinivibrio spp. and Ruminobacter spp. These results suggest that host genetics has a major impact on the rumen microbiome and metabolites in hybrid animals.

Effects of feeding whole linseed on ruminal fatty acid composition and microbial population in goats

The objective of the present study was to evaluate the effect of feeding different levels of whole linseed, as a source of n-3 polyunsaturated fatty acids (PUFA), on ruminal fatty acid composition and microbial population in the goat. Twenty-four crossbred Boer goats were assigned to 3 dietary treatments: L0 (control), L10 and L20 containing 0, 10%, or 20% whole linseed, respectively. The ruminal pH and concentration of total volatile fatty acids (VFA) were not affected by dietary treatments. The feeding of L10 and L20 diets produced higher (P < 0.05) molar proportions of acetate and lower (P < 0.05) molar proportions of butyrate and valerate than the L0 diet. Molar proportions of myristic acid (C14:0) and palmitic acid (C16:0) were lower (P < 0.05) in the rumen of goats offered L10 and L20 diets than the control diet. However, stearic acid (C18:0), vaccenic acid (C18:1 trans-11), conjugated linoleic acid (CLA, C18:2 trans-10, cis-12) and α-lenolenic acid (C18:3 n-3) were higher (P < 0.05) in the rumen of goats fed L10 and L20 than L0. Both inclusion levels of linseed in the diet (L10 and L20) reduced the ruminal total bacteria, methanogens, and protozoa compared with L0 (P < 0.05). The effect of the dietary treatments on cellulolytic bacteria, varied between the individual species. Both inclusion levels of linseed resulted in a significant decrease (P < 0.05) in the population of Fibrobacter succinogenes, and Rumunococus flavefaciens compared with L0, with no significant difference between the groups fed linseed diets. The population of Rumunococus albus was not affected by the different dietary treatments. It was concluded that inclusion of whole linseed in the diet of goats could increase the concentration of PUFA in the rumen, and decrease the population of F. succinogenes, R. flavefaciens, methanogens and protozoa in rumen liquid of goats.

Metabolism ofα-linolenic acid during incubations with strained bovine rumen contents: products and mechanisms

Description ofα-linolenic acid (cis-9,cis-12,cis-15-18 : 3, ALA) metabolism in the rumen is incomplete. Ruminal digesta samples were incubated with ALA and buffer containing water or deuterium oxide to investigate the products and mechanisms of ALA biohydrogenation. Geometric Δ9,11,15-18 : 3 isomers were the main intermediates formed from ALA. An increase in then+1 isotopomers of Δ9,11,15-18 : 3 was due to2H labelling at C-13. Isomers of Δ9,11,13-18 : 3,cis-7,cis-12,cis-15-18 : 3 andcis-8,cis-12,cis-15-18 : 3 were also formed. No increase inn+1 isotopomers of Δ7,12,15-18 : 3 or Δ8,12,15-18 : 3 was detected. Enrichment inn+2 isotopomers of 18 : 2 products indicated that ALA metabolism continued via the reduction of 18 : 3 intermediates. Isomers of Δ9,11,15-18 : 3 were reduced to Δ11,15-18 : 2 labelled at C-9 and C-13. ALA resulted in the formation of Δ11,13-18 : 2 and Δ12,14-18 : 2 containing multiple2H labels. Enrichment of then+3 isotopomer of Δ12,15-18 : 2 was also detected. Metabolism of ALA during incubations with rumen contents occurs by one of three distinct pathways. Formation of Δ9,11,15-18 : 3 appears to be initiated by H abstraction on C-13. Octadecatrienoic intermediates containingcis-12 andcis-15 double bonds are formed without an apparent H exchange with water. Labelling of Δ9,11,13-18 : 3 was inconclusive, suggesting formation by an alternative mechanism. These findings explain the appearance of several bioactive fatty acids in muscle and milk that influence the nutritional value of ruminant-derived foods.

Sources and Bioactive Properties of Conjugated Dietary Fatty Acids

The group of conjugated fatty acids known as conjugated linoleic acid (CLA) isomers have been extensively studied with regard to their bioactive potential in treating some of the most prominent human health malignancies. However, CLA isomers are not the only group of potentially bioactive conjugated fatty acids currently undergoing study. In this regard, isomers of conjugated α-linolenic acid, conjugated nonadecadienoic acid and conjugated eicosapentaenoic acid, to name but a few, have undergone experimental assessment. These studies have indicated many of these conjugated fatty acid isomers commonly possess anti-carcinogenic, anti-adipogenic, anti-inflammatory and immune modulating properties, a number of which will be discussed in this review. The mechanisms through which these bioactivities are mediated have not yet been fully elucidated. However, existing evidence indicates that these fatty acids may play a role in modulating the expression of several oncogenes, cell cycle regulators, and genes associated with energy metabolism. Despite such bioactive potential, interest in these conjugated fatty acids has remained low relative to the CLA isomers. This may be partly attributed to the relatively recent emergence of these fatty acids as bioactives, but also due to a lack of awareness regarding sources from which they can be produced. In this review, we will also highlight the common sources of these conjugated fatty acids, including plants, algae, microbes and chemosynthesis.

Effect of ruminally unprotected Echium oil on milk yield, composition and fatty acid profile in mid-lactation goats

This study investigated the effects on goat milk yield and composition of a diet supplemented with Echium plantagineum oil (EPO). Twenty-four mid-lactation multiparous Camosciata goats were divided into two balanced groups and fed for 44 d a diet based on hay and concentrate, supplemented (EPO group, Echium) or not (CON group, control) with 40 ml of ruminally unprotected EPO. Individual milk yield was recorded and individual milk samples were collected at 11, 22, 33, and 44 d after supplementation. Milk samples were analysed for milk components and fatty acids (FA). Data were statistically analysed by repeated-measures analysis of variance. Milk yield, protein and lactose contents were significantly higher in EPO than CON group. The inclusion of EPO significantly decreased total saturated FA and total branched-chain FA, and contemporarily sharply increased trans biohydrogenation intermediates (P ⩽ 0.001). Milk concentration of α-linolenic, stearidonic and γ-linolenic acids increased by 23, 1000 and 67%, respectively (P ⩽ 0.001). Due to extensive ruminal biohydrogenation, their apparent transfer rate was less than 3%. As a consequence, the milk concentrations of very long-chain (VLC) polyunsaturated fatty acids (PUFA), such as eicosapentaenoic (20:5 n-3) and dihomo-γ-linolenic (20:3 n-6) acids, significantly increased with EPO treatment, but values remained very low. Docosahexaenoic acid (22:6 n-3) was undetectable in all analysed milk samples. Results show that ruminally unprotected EPO can enhance milk yield and protein and improve the overall goat milk FA profile. However, this kind of supplementation cannot be considered a valuable strategy to develop goat functional dairy products enriched with VLC n-3 PUFA for human consumption.

Transcriptome adaptation of the bovine mammary gland to diets rich in unsaturated fatty acids shows greater impact of linseed oil over safflower oil on gene expression and metabolic pathways

BACKGROUND

Nutritional strategies can decrease saturated fatty acids (SFAs) and increase health beneficial fatty acids (FAs) in bovine milk. The pathways/genes involved in these processes are not properly defined. Next-generation RNA-sequencing was used to investigate the bovine mammary gland transcriptome following supplemental feeding with 5% linseed oil (LSO) or 5% safflower oil (SFO). Holstein cows in mid-lactation were fed a control diet for 28 days (control period) followed by supplementation with 5% LSO (12 cows) or 5% SFO (12 cows) for 28 days (treatment period). Milk and mammary gland biopsies were sampled on days-14 (control period), +7 and +28 (treatment period). Milk was used to measure fat(FP)/protein(PP) percentages and individual FAs while RNA was subjected to sequencing.

RESULTS

Milk FP was decreased by 30.38% (LSO) or 32.42% (SFO) while PP was unaffected (LSO) or increased (SFO). Several beneficial FAs were increased by LSO (C18:1n11t, CLA:10t12c, CLA:9c11t, C20:3n3, C20:5n3, C22:5n3) and SFO (C18:1n11t, CLA:10t12c, C20:1c11, C20:2, C20:3n3) while several SFAs (C4:0, C6:0, C8:0, C14:0, C16:0, C17:0, C24:0) were decreased by both treatments (P < 0.05). 1006 (460 up- and 546 down-regulated) and 199 (127 up- and 72 down-regulated) genes were significantly differentially regulated (DE) by LSO and SFO, respectively. Top regulated genes (≥ 2 fold change) by both treatments (FBP2, UCP2, TIEG2, ANGPTL4, ALDH1L2) are potential candidate genes for milk fat traits. Involvement of SCP2, PDK4, NQO1, F2RL1, DBI, CPT1A, CNTFR, CALB1, ACADVL, SPTLC3, PIK3CG, PIGZ, ADORA2B, TRIB3, HPGD, IGFBP2 and TXN in FA/lipid metabolism in dairy cows is being reported for the first time. Functional analysis indicated similar and different top enriched functions for DE genes. DE genes were predicted to significantly decrease synthesis of FA/lipid by both treatments and FA metabolism by LSO. Top canonical pathways associated with DE genes of both treatments might be involved in lipid/cholesterol metabolism.

CONCLUSION

This study shows that rich α-linolenic acid LSO has a greater impact on mammary gland transcriptome by affecting more genes, pathways and processes as compared to SFO, rich in linoleic acid. Our study suggest that decrease in milk SFAs was due to down-regulation of genes in the FA/lipid synthesis and lipid metabolism pathways while increase in PUFAs was due to increased availability of ruminal biohydrogenation metabolites that were up taken and incorporated into milk or used as substrate for the synthesis of PUFAs.

Effects of long-term dietary supplementation with conjugated linoleic acid on bovine oocyte lipid profile

Nutritional and environmental conditions around conception and during early embryonic development may have significant effects on health and well-being in adult life. Here, a bovine heifer model was used to investigate the effects of rumen-protected fat supplementation on oocyte quality and embryo development. Holstein-Friesian heifers (n=84) received a dietary supplement consisting of rumen-protected conjugated linoleic acid (CLA) or stearic acid (SA), each on top of an isocaloric basic diet. Oocytes were collected via ultrasound-guided follicular aspiration and subjected to in vitro maturation followed by either desorption electrospray ionisation mass spectrometry (DESI-MS) for lipid profiling of individual oocytes or in vitro fertilisation and embryo culture. The type of supplement significantly affected lipid profiles of in vitro-matured oocytes. Palmitic acid and plasmalogen species were more abundant in the mass spectra of in vitro-matured oocytes after rumen-protected SA supplementation when compared with those collected from animals supplemented with CLA. Lipid concentrations in blood and follicular fluid were significantly affected by both supplements. Results show that rumen-protected fatty-acid supplementation affects oocyte lipid content and may pave the way for the establishment of a large-animal model for studies towards a better understanding of reproductive disorders associated with nutritional impairments.

Substituting redberry juniper for oat hay in lamb feedlot diets: Carcass characteristics, adipose tissue fatty acid composition, and sensory panel traits

We hypothesized that ground juniper and dried distillers grains with solubles (DDGS) fed to lambs would have no negative effects on end products. Lambs were individually fed diets containing mainly sorghum grain and oat hay (control) or DDGS-based diets consisting mainly of DDGS, sorghum grain, and oat hay (0JUN), or 33% (33JUN), 66% (66JUN), or 100% (100JUN) of the hay replaced by juniper. Lambs fed control had greater (P<0.03) shrunk BW and HCW vs. lambs fed 0JUN, but other carcass characteristics and sensory panel traits were similar (P>0.23). As juniper increased in the DDGS-based diets, HCW increased quadratically (P=0.01) and LM fatty acid composition was altered. Feeding juniper did not negatively affect (P>0.57) off-flavor in chops, but enhanced (linear, P<0.05) juiciness, tenderness, and flavor intensity. Lambs fed diets with a combination of oat hay and ground juniper appeared to produce the most acceptable carcasses and lamb chops.

Fatty acid profile differs between organic and conventionally produced cow milk independent of season or milking time

Differing amounts of fresh forage and concentrates fed, and level of input contributes to the differences reported in fatty acid (FA) composition of organic and conventionally produced cow milk. In many previous studies designed to investigate this phenomenon, comparisons were made between grazed organic cows and housed conventional cows. In the present study, we have investigated differences between organic and conventional milk produced using year-round pasture grazing, as practiced in New Zealand. The FA composition was determined in milk sampled at morning and evening milking in both spring and autumn. Samples were taken from 45 cows from the Massey University organic herd and compared with 50 cows from the corresponding conventional herd grazed and managed similarly at the same location. Forty-three out of 51 analyzed FA were influenced by season, whereas 28 were different between production systems. In addition, one-half were also different due to time of milking. Levels of linoleic acid and α-linolenic acid were higher in organic milk, whereas conjugated linoleic acid (CLA) and vaccenic acid were higher in conventional milk. The first 3 FA (linoleic acid, α-linolenic acid, and CLA) were more abundant in milk harvested during autumn, and the CLA concentration was also significantly influenced by time of milking. Our results confirm reports that the FA profile is affected by season and time of milking, and we also showed an effect due to the production system, when both sets of cows were kept continuously on pasture, even after taking milking time and seasonal effect into account.

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.

Changes in fatty acid composition and distribution of N-3 fatty acids in goat tissues fed different levels of whole linseed

The effects of feeding different levels of whole linseed on fatty acid (FA) composition of muscles and adipose tissues of goat were investigated. Twenty-four Crossed Boer bucks were assigned randomly into three treatment diets: L0, L10, or L20, containing 0%, 10%, or 20% whole linseed, respectively. The goats were slaughtered after 110 days of feeding. Samples from the longissimus dorsi, supraspinatus, semitendinosus, and subcutaneous fat (SF) and perirenal fat (PF) were taken for FA analyses. In muscles, the average increments in α-linolenic (ALA) and total n-3 PUFA were 6.48 and 3.4, and 11.48 and 4.78 for L10 and L20, respectively. In the adipose tissues, the increments in ALA and total n-3 PUFA were 3.07- and 6.92-fold and 3.00- and 7.54-fold in SF and PF for L10 and L20, respectively. The n-6 : n-3 ratio of the muscles was decreased from up to 8.86 in L0 to 2 or less in L10 and L20. The PUFA : SFA ratio was increased in all the tissues of L20 compared to L0. It is concluded that both inclusion levels (10% and 20%) of whole linseed in goat diets resulted in producing meat highly enriched with n-3 PUFA with desirable n-6 : n-3 ratio.

Influence of Carotino oil on in vitro rumen fermentation, metabolism and apparent biohydrogenation of fatty acids

The study appraised the effects of Carotino oil on in vitro rumen fermentation, gas production, metabolism and apparent biohydrogenation of oleic, linoleic and linolenic acids. Carotino oil was added to a basal diet (50% concentrate and 50% oil palm frond) at the rate of 0, 2, 4, 6 and 8% dry matter of the diet. Rumen inoculum was obtained from three fistulated Boer bucks and incubated with 200 mg of each treatment for 24 h at 39°C. Gas production, fermentation kinetics, in vitro organic matter digestibility (IVOMD), volatile fatty acids (VFA), in vitro dry matter digestibility (IVDMD), metabolizable energy and free fatty acids were determined. Carotino oil did not affect (P > 0.05) gas production, metabolizable energy, pH, IVOMD, IVDMD, methane, total and individual VFAs. However, Carotino oil decreased (P < 0.05) the biohydrogenation of linoleic and linolenic acids but enhanced (P < 0.05) the biohydrogenation of oleic acid. After 24 h incubation, the concentrations of stearic, palmitic, pentadecanoic, myristic, myristoleic and lauric acids decreased (P < 0.05) while the concentration of linolenic, linoleic, oleic and transvaccenic acids and conjugated linoleic acid (CLAc9t11) increased (P < 0.05) with increasing levels of Carotino oil. Carotino oil seems to enhance the accumulation of beneficial unsaturated fatty acids without disrupting rumen fermentation.

Subcutaneous adipose fatty acid profiles and related rumen bacterial populations of steers fed red clover or grass hay diets containing flax or sunflower-seed

Steers were fed 70∶30 forage∶concentrate diets for 205 days, with either grass hay (GH) or red clover silage (RC), and either sunflower-seed (SS) or flaxseed (FS), providing 5.4% oil in the diets. Compared to diets containing SS, FS diets had elevated (P<0.05) subcutaneous trans (t)-18:1 isomers, conjugated linoleic acids and n-6 polyunsaturated fatty acid (PUFA). Forage and oilseed type influenced total n-3 PUFA, especially α-linolenic acid (ALA) and total non-conjugated diene biohydrogenation (BH) in subcutaneous fat with proportions being greater (P<0.05) for FS or GH as compared to SS or RC. Of the 25 bacterial genera impacted by diet, 19 correlated with fatty acids (FA) profile. Clostridium were most abundant when levels of conjugated linolenic acids, and n-3 PUFA's were found to be the lowest in subcutaneous fat, suggestive of their role in BH. Anerophaga, Fibrobacter, Guggenheimella, Paludibacter and Pseudozobellia were more abundant in the rumen when the levels of VA in subcutaneous fat were low. This study clearly shows the impact of oilseeds and forage source on the deposition of subcutaneous FA in beef cattle. Significant correlations between rumen bacterial genera and the levels of specific FA in subcutaneous fat maybe indicative of their role in determining the FA profile of adipose tissue. However, despite numerous correlations, the dynamics of rumen bacteria in the BH of unsaturated fatty acid and synthesis of PUFA and FA tissue profiles require further experimentation to determine if these correlations are consistent over a range of diets of differing composition. Present results demonstrate that in order to achieve targeted FA profiles in beef, a multifactorial approach will be required that takes into consideration not only the PUFA profile of the diet, but also the non-oil fraction of the diet, type and level of feed processing, and the role of rumen microbes in the BH of unsaturated fatty acid.