Genetic Mapping of QTLs Controlling Fatty Acids Provided Insights into the Genetic Control of Fatty Acid Synthesis Pathway in Peanut (Arachis hypogaea L.)

Peanut, a high-oil crop with about 50% oil content, is either crushed for oil or used as edible products. Fatty acid composition determines the oil quality which has high relevance to consumer health, flavor, and shelf life of commercial products. In addition to the major fatty acids, oleic acid (C18:1) and linoleic acid (C18:2) accounting for about 80% of peanut oil, the six other fatty acids namely palmitic acid (C16:0), stearic acid (C18:0), arachidic acid (C20:0), gadoleic acid (C20:1), behenic acid (C22:0), and lignoceric acid (C24:0) are accounted for the rest 20%. To determine the genetic basis and to improve further understanding on effect of FAD2 genes on these fatty acids, two recombinant inbred line (RIL) populations namely S-population (high oleic line ‘SunOleic 97R’ × low oleic line ‘NC94022’) and T-population (normal oleic line ‘Tifrunner’ × low oleic line ‘GT-C20’) were developed. Genetic maps with 206 and 378 marker loci for the S- and the T-population, respectively were used for quantitative trait locus (QTL) analysis. As a result, a total of 164 main-effect (M-QTLs) and 27 epistatic (E-QTLs) QTLs associated with the minor fatty acids were identified with 0.16% to 40.56% phenotypic variation explained (PVE). Thirty four major QTLs (>10% of PVE) mapped on five linkage groups and 28 clusters containing more than three QTLs were also identified. These results suggest that the major QTLs with large additive effects would play an important role in controlling composition of these minor fatty acids in addition to the oleic and linoleic acids in peanut oil. The interrelationship among these fatty acids should be considered while breeding for improved peanut genotypes with good oil quality and desired fatty acid composition.     

Quantitative trait locus analysis of unsaturated fatty acids in a recombinant inbred population of soybean

Soybean [Glycine max (L.) Merr.] is an important oilseed crop which produces about 30 % of the world’s edible vegetable oil. The quality of soybean oil is determined by its fatty acid composition. Soybean oil high in oleic and low in linolenic fatty acids is desirable for human consumption and other uses. The objectives of this study were to identify quantitative trait loci (QTLs) for unsaturated fatty acids and to evaluate the genetic effects of single QTL and QTL combinations in soybean. A population of recombinant inbred lines derived from the cross of SD02-4-59 × A02-381100 was evaluated for fatty acid content in seven environments. In total, 516 polymorphic single nucleotide polymorphism markers, 477 polymorphic simple sequence repeat markers and three GmFAD3 genes were used to genotype the mapping population. By using the composite interval mapping and/or the interval mapping method, a total of 15 QTLs for the three unsaturated fatty acids were detected in more than two environments. Two QTLs for oleic acid on linkage groups G [chromosome (Chr) 18] (qOLE-G) and J (Chr 16) (qOLE-J), three QTLs for linoleic acid on linkage groups A1 (Chr 5) (qLLE-A1) and G (Chr 18) (qLLE-G-1 and qLLE-G-2), and five QTLs for linolenic acid on linkage groups C2 (Chr 6), D1a (Chr 1), D1b (Chr 2), F (Chr 13) and G (Chr 18) were consistently detected in at least three individual environments and the average data over all environments. Significant QTL × QTL interactions were not detected. However, significant QTL × environment interactions were detected for all the QTLs which were repeatedly detected. Some QTLs reported previously were confirmed, and seven new QTLs (two for oleic acid, two for linoleic acid and three for linolenic acid) were identified in this study. Comparisons of two-locus and three-locus combinations indicated that cumulative effects of QTLs were significant for all the three unsaturated fatty acids. QTL pyramiding by molecular marker-assisted breeding would be an appropriate strategy for the improvement of unsaturated fatty acids in soybean.     

高油酸油菜遗传育种研究进展

油酸（C18∶1）是双低菜籽油的主要脂肪酸之一,合理的高油酸菜籽油脂肪酸组分更有利于人体健康,因此提高油酸含量是双低油菜品质育种的一个重要方向。当前我国高油酸油菜品种选育相关研究进展缓慢,高油酸菜籽油产业化进程急需提速。围绕高油酸油菜主要从四个方面开展论述：国内外利用理化方法成功创建的油菜高油酸种质资源及其高油酸性状遗传模式;油菜高油酸性状的控制基因及其突变位点;世界上高油酸品种的培育以及我国高油酸品种的发展趋势;当前高油酸品种的不足及今后高油酸油菜品种的改良途径。为油菜育种工作者较全面地展示了国际上高油酸油菜在遗传育种方面的研究成果,也为今后我国高油酸油菜的进一步发展提供了参考。     

Mapping QTL controlling fatty acid composition in a doubled haploid rapeseed population segregating for oil content

Increasing oil content and improving the fatty acid composition in the seed oil are important breeding goals for rapeseed (Brassica napus L.). The objective of the study was to investigate a possible relationship between fatty acid composition and oil content in an oilseed rape doubled haploid (DH) population. The DH population was derived from a cross between the German cultivar Sollux and the Chinese cultivar Gaoyou, both having a high erucic acid and a very high oil content. In total, 282 DH lines were evaluated in replicated field experiments in four environments, two each in Germany and in China. Fatty acid composition of the seed oil was analyzed by gas liquid chromatography and oil content was determined by NIRS. Quantitative trait loci (QTL) for fatty acid contents were mapped and their additive main effects were determined by a mixed model approach using the program QTLMapper. For all fatty acids large and highly significant genetic variations among the genotypes were observed. High heritabilities were determined for oil content and for all fatty acids (h ² = 0.82 to 0.94), except for stearic acid content (h ²= 0.38). Significant correlations were found between the contents of all individual fatty acids and oil content. Closest genetic correlations were found between oil content and the sum of polyunsaturated fatty acids (18:2 + 18:3; r _G = −0.46), the sum of monounsaturated fatty acids (18:1 + 20:1 + 22:1; r _G = 0.46) and palmitic acid (16:0; r _G = −0.34), respectively. Between one and eight QTL for the contents of the different fatty acids were detected. Together, their additive main effects explained between 28% and 65% of the genetic variance for the individual fatty acids. Ten QTL for fatty acid contents mapped within a distance of 0 to 10 cM to QTL for oil content, which were previously identified in this DH population. QTL mapped within this distance to each other are likely to be identical. The results indicate a close interrelationship between fatty acid composition and oil content, which should be considered when breeding for increased oil content or improved oil composition in rapeseed.     

Genome-Wide Association Study Singles Out SCD and LEPR as the Two Main Loci Influencing Intramuscular Fat Content and Fatty Acid Composition in Duroc Pigs

Intramuscular fat (IMF) content and fatty acid composition affect the organoleptic quality and nutritional value of pork. A genome-wide association study was performed on 138 Duroc pigs genotyped with a 60k SNP chip to detect biologically relevant genomic variants influencing fat content and composition. Despite the limited sample size, the genome-wide association study was powerful enough to detect the association between fatty acid composition and a known haplotypic variant in SCD (SSC14) and to reveal an association of IMF and fatty acid composition in the LEPR region (SSC6). The association of LEPR was later validated with an independent set of 853 pigs using a candidate quantitative trait nucleotide. The SCD gene is responsible for the biosynthesis of oleic acid (C18:1) from stearic acid. This locus affected the stearic to oleic desaturation index (C18:1/C18:0), C18:1, and saturated (SFA) and monounsaturated (MUFA) fatty acids content. These effects were consistently detected in gluteus medius, longissimus dorsi, and subcutaneous fat. The association of LEPR with fatty acid composition was detected only in muscle and was, at least in part, a consequence of its effect on IMF content, with increased IMF resulting in more SFA, less polyunsaturated fatty acids (PUFA), and greater SFA/PUFA ratio. Marker substitution effects estimated with a subset of 65 animals were used to predict the genomic estimated breeding values of 70 animals born 7 years later. Although predictions with the whole SNP chip information were in relatively high correlation with observed SFA, MUFA, and C18:1/C18:0 (0.48–0.60), IMF content and composition were in general better predicted by using only SNPs at the SCD and LEPR loci, in which case the correlation between predicted and observed values was in the range of 0.36 to 0.54 for all traits. Results indicate that markers in the SCD and LEPR genes can be useful to select for optimum fatty acid profiles of pork.     

Comparative evaluation of rumen‐protected fat,coconut oil and various oilseeds supplemented to fattening bulls

The effects of five different dietary fat supplements on fatty acid composition and oxidative stability of subcutaneous and kidney fat were evaluated in 36 Brown Swiss bulls and compared to a low fat diet in a monofactorial design. The following fat supplements were provided as additional fat at 30 g per kg feed dry matter: crystalline rumen‐protected fat, coconut oil, and three types of crushed whole oilseeds (rapeseed, sunflower seed and linseed). Adipose tissues reflected differences (P < 0.05) in dietary fatty acid composition although to a lower extent. Using protected fat, which contained elevated levels of trans fatty acids, and sunflower seed, containing a high proportion of linoleic acid, significantly increased C18:1 trans fatty acid proportion in the adipose tissues. The use of sunflower seed increased conjugated linoleic acid. The oilseeds resulted in lower amounts of C16:0 in favour of C18:0. Except for linseed, all fat supplemented groups improved oxidative stability of adipose tissues as compared with control. This was explained by lower proportions of unsaturated fatty acids in adipose tissue (protected fat), by elevated α‐tocopherol contents (rapeseed, sunflower seed) or by a combination of both (coconut oil). Fat colour remained unaffected by treatments. Compared to other fat supplements oilseeds, especially sunflower seed and rapeseed, can therefore be recommended to be fed to bulls in order to increase the proportions of C18 unsaturated fatty acids in adipose tissues and to maintain or improve oxidative stability.     

Stearoyl-ACP and oleoyl-PC desaturase genes cosegregate with quantitative trait loci underlying high stearic and high oleic acid mutant phenotypes in sunflower

The genetic control of the synthesis of stearic acid (C18:0) and oleic acid (C18:1) in the seed oil of sunflower was studied through candidate-gene and QTL analysis. Two F₂ mapping populations were developed using the high C18:0 mutant CAS-3 crossed to either HA-89 (standard, high linoleic fatty acid profile), or HAOL-9 (high C18:1 version of HA-89). A stearoyl-ACP desaturase locus (SAD17A), and an oleoyl-PC de-saturase locus (OLD7) were found to cosegregate with the previously described Es1 and Ol genes controlling the high C18:0 and the high C18:1 traits, respectively. Using linkage maps constructed from AFLP and RFLP markers, these loci mapped to LG1 (SAD17A) and to LG14 (OLD7) and were found to underlie the major QTLs affecting the concentrations of C18:0 and C18:1, explaining around 80% and 56% of the phenotypic variance of these fatty acids, respectively. These QTLs pleiotropically affected the levels of other primary fatty acids in the seed storage lipids. A minor QTL affecting both C18:0 and C18:1 levels was identified on LG8 in the HAOL-9×CAS-3 F₂. This QTL showed a significant epistatic interaction for C18:1 with the QTL at the OLD7 locus, and was hypothesized to be a modifier of Ol. Two additional minor C18:0 QTLs were also detected on LG7 and LG3 in the HA-89×CAS-3 and the HAOL-9×CAS-3 F₂ populations, respectively. No association between a mapped FatB thioesterase locus and fatty acid concentration was found. These results provide strong support about the role of fatty acid desaturase genes in determining fatty acid composition in the seed oil of sunflower. Received: 7 December 2000 / Accepted: 21 May 2001     

Increasing erucic acid content through combination of endogenous low polyunsaturated fatty acids alleles with Ld-LPAAT + Bn-fae1 transgenes in rapeseed (Brassica napus L.)

High erucic acid rapeseed (HEAR) oil is of interest for industrial purposes because erucic acid (22:1) and its derivatives are important renewable raw materials for the oleochemical industry. Currently available cultivars contain only about 50% erucic acid in the seed oil. A substantial increase in erucic acid content would significantly reduce processing costs and could increase market prospects of HEAR oil. It has been proposed that erucic acid content in rapeseed is limited because of insufficient fatty acid elongation, lack of insertion of erucic acid into the central sn-2 position of the triaclyglycerol backbone and due to competitive desaturation of the precursor oleic acid (18:1) to linoleic acid (18:2). The objective of the present study was to increase erucic content of HEAR winter rapeseed through over expression of the rapeseed fatty acid elongase gene (fae1) in combination with expression of the lysophosphatidic acid acyltransferase gene from Limnanthes douglasii (Ld-LPAAT), which enables insertion of erucic acid into the sn-2 glycerol position. Furthermore, mutant alleles for low contents of polyunsaturated fatty acids (18:2 + 18:3) were combined with the transgenic material. Selected transgenic lines showed up to 63% erucic acid in the seed oil in comparison to a mean of 54% erucic acid of segregating non-transgenic HEAR plants. Amongst 220 F₂ plants derived from the cross between a transgenic HEAR line and a non-transgenic HEAR line with a low content of polyunsaturated fatty acids, recombinant F₂ plants were identified with an erucic acid content of up to 72% and a polyunsaturated fatty acid content as low as 6%. Regression analysis revealed that a reduction of 10% in polyunsaturated fatty acids content led to a 6.5% increase in erucic acid content. Results from selected F₂ plants were confirmed in the next generation by analysing F₄ seeds harvested from five F₃ plants per selected F₂ plant. F₃ lines contained up to 72% erucic acid and as little as 4% polyunsaturated fatty acids content in the seed oil. The 72% erucic acid content of rapeseed oil achieved in the present study represents a major breakthrough in breeding high erucic acid rapeseed.     

Comparative analysis of fatty acids in pollen and seed of rapeseed

Lipids accounted for 31.7% of the dry wt of mature, viable pollen of rapeseed (Brassica napus). External lipids of the pollen coat, specified by the diploid parental genome, and internal cytoplasmic lipids, presumably specified by the haploid pollen genome, were separated by differential extraction. External lipids and paraffins represented 9.8 % of pollen dry wt, and contained predominantly linolenic (18:3) with significant amounts of palmitic (16:0), stearic (18:0) and myristic (14:0) acids, as well as paraffins. Internal lipids accounted for 21.9% of pollen dry wt and comprised predominantly 18:3 and 16:0. Mature seeds of B. napus comprised 45.0 % lipid, with a fatty acid composition different from that of either pollen fraction. Decanoic (10:0), lauric (12:0) and hexadecatrienoic (16:3) acids were detected in pollen but not in seeds. These data are discussed in relation to pollen biochemistry and the potential for pollen selection in rapeseed breeding.     

Influence of DGAT1 K232A Polymorphism on Milk Fat Percentage and Fatty Acid Profiles in Romanian Holstein Cattle

Milk and dairy products are considered the main sources of saturated fatty acids, which are a valuable source of nutrients in the human diet. Fat composition can be adjusted through guided nutrition of dairy animals but also through selective breeding. Recently, a dinucleotide substitution located in the exon 8 of the gene coding for acyl CoA: diacylglycerol acyltransferase 1 (DGAT1), that alters the amino acid sequence from a lysine to an alanine (p.Lys232Ala) in the mature protein, was shown to have a strong effect on milk fat content in some cattle breeds. Therefore, the objectives of this work were to study the occurrence of the DGAT1 p.Lys232Ala polymorphism in Romanian Holstein cattle and Romanian Buffalo breeds and to further investigate its possible influence on fat percentage and fatty acid profiles. The results obtained in this study show that in Romanian Holstein cattle the K allele is associated with increased fat percentage and higher levels of C16:0 and C18:0 fatty acids. The ratio of saturated fatty acids versus unsaturated fatty acids (SFA/UFA) was also higher in KK homozygous individuals, whereas the fractions of C14:0, unsaturated C18 decreased. The DGAT1 p.Lys232Ala polymorphism revealed a high genetic variance for fat percentage, unsaturated C18, C16:0, and SFA/UFA. Although the effect of this polymorphism was not so evident for short chain fatty acids such as C4:0–C8:0, it was significant for C14:0 fatty acids. We concluded that selective breeding of carriers of the A allele in Romanian Holsteins can contribute to improvement in unsaturated fatty acids content of milk. However, in buffalo, the lack of the A allele makes selection inapplicable because only the K allele, associated with higher saturated fatty acids contents in milk, was identified.     

Physicochemical properties of cold pressed sunflower,peanut, rapeseed,mustard and olive oils grown in the Eastern Mediterranean region

Fatty acid composition and stability of vegetable oils have taken more attention as an essential source of biologically active compounds in a good balanced diet. The purpose of the study was to determine peroxide value, free fatty acids, unsaponifiable matter, total carotenoid content, iodine value and fatty acid composition of sunflower, rapeseed, mustard, peanut and olive oils. Rapeseed and peanut oils had the highest peroxide values, while sunflower oil had the lowest peroxide values. The free fatty acid value of the tested oils varied between 0.43 and 1.36% oleic. The peanut oil had the highest free acid value and the mustard oil had the lowest one. Total carotenoid contents of mustard and rape seed oil were higher than those of the other oils tested. Palmitic acid (C16:0), oleic acid (C18:1) and stearic acid (C18:0) were the common main fatty acid components of the vegetable oils tested. Followed by linoleic acid, the amount of oleic acid was the highest among other fatty acid components. Mustard oil had the highest erucic acid (C22:1) with the amount of 11.38%, indicating that it cannot be used for human consumption. Among the oils investigated, sunflower and mustard oils were more stable than rapeseed, peanut and olive oils.     

Separation of some mono-, di- and tri-unsaturated fatty acids containing 18 carbon atoms by high-performance liquid chromatography and photodiode array detection

Positional and geometric isomers of mono-, di- and tri-unsaturated fatty acids containing 18 carbon atoms were separated on commercially available reversed-phase columns in gradient systems composed of acetonitrile and water, utilizing photodiode array detection. The biological samples were hydrolyzed with 2 M NaOH for 35–40 min at 85–90°C. After cooling, the hydrolysates were acidified with 4 M HCl and the free fatty acids were extracted with dichloromethane. The organic solvent was removed in a gentle stream of argon. The fatty acids were determined after pre-column derivatization with dibromacetophenone in the presence of triethylamine. The reaction components were mixed and reacted for 2 h at 50°C. Separations of derivatized fatty acids were performed on two C₁₈ columns (Nova Pak C₁₈, 4 μm, 250×4.6 mm, Waters) by binary or ternate gradient programs and UV detection at 254 and 235 nm. The geometric and positional isomers of some unsaturated fatty acids were substantially retained on the C₁₈ columns and were distinct from some saturated fatty acids, endogenous substances in biological samples or background interference. Only slight separation of critical pairs of cis-9 C_18:1/cis-11 C_18:1 and cis-6 C_18:1/trans-11 C_18:1 was obtained. A ternate gradient program can be used for complete fractionation of a mixture of conjugated linoleic acid isomers (CLA) from cis-9, cis-12 and trans-9, trans-12 isomers of C_18:2. The CLA isomers in the effluent were monitored at 235 nm. The CLA isomers were differentiated from saturated and unsaturated fatty acids using a photodiode array detector. The utility of the method was demonstrated by evaluating the fatty acid composition of duodenal digesta, rapeseed and maize oils.     

The Fatty Acid Profile Analysis of Cyperus laxus Used for Phytoremediation of Soils from Aged Oil Spill-Impacted Sites Revealed That This Is a C18:3 Plant Species

The effect of recalcitrant hydrocarbons on the fatty acid profile from leaf, basal corm, and roots of Cyperus laxus plants cultivated in greenhouse phytoremediation systems of soils from aged oil spill-impacted sites containing from 16 to 340 g/Kg total hydrocarbons (THC) was assessed to investigate if this is a C18:3 species and if the hydrocarbon removal during the phytoremediation process has a relationship with the fatty acid profile of this plant. The fatty acid profile was specific to each vegetative organ and was strongly affected by the hydrocarbons level in the impacted sites. Leaf extracts of plants from uncontaminated soil produced palmitic acid (C16), octadecanoic acid (C18:0), unsaturated oleic acids (C18:1-C18:3), and unsaturated eichosanoic (C20:2-C20:3) acids with a noticeable absence of the unsaturated hexadecatrienoic acid (C16:3); this finding demonstrates, for the first time, that C. laxus is a C18:3 plant. In plants from the phytoremediation systems, the total fatty acid contents in the leaf and the corm were negatively affected by the hydrocarbons presence; however, the effect was positive in root. Interestingly, under contaminated conditions, unusual fatty acids such as odd numbered carbons (C15, C17, C21, and C23) and uncommon unsaturated chains (C20:3n6 and C20:4) were produced together with a remarkable quantity of C22:2 and C24:0 chains in the corm and the leaf. These results demonstrate that weathered hydrocarbons may drastically affect the lipidic composition of C. laxus at the fatty acid level, suggesting that this species adjusts the cover lipid composition in its vegetative organs, mainly in roots, in response to the weathered hydrocarbon presence and uptake during the phytoremediation process.     

Mapping of QTLs for oil content and fatty acid composition in Indian mustard [Brassica juncea (L.) Czern. and Coss.]

An AFLP linkage map of Brassica juncea (L.) Czern and Coss was constructed using 88 recombinant inbred lines (RILs) from a cross between an Indian cultivar ‘Varuna’ and an accession from Poland ‘BEC-144’. The map included 91 AFLP markers organized on 19 linkage groups covering a total map distance of 1679.1 cM. A total of 14 QTLs were detected for oil content (2 QTLs), erucic acid (2 QTLs), eicosenoic acid (2 QTLs), linolenic acid (3 QTLs), linoleic acid (3 QTLs) and palmitic acid (2 QTLs). A specific genomic region on LG2 was associated with contents of three fatty acids: erucic acid, eicosenoic acid and linoleic acid. Some of the markers showed absolute linkage with the QTLs associated with the levels of linolenic acid, linoleic acid and oil content. These markers may be used for improvement of fatty acid profile of B. juncea.     

Genetic Architecture of Palm Oil Fatty Acid Composition in Cultivated Oil Palm (Elaeis guineensis Jacq.) Compared to Its Wild Relative E. oleifera (H.B.K) Cortés

We searched for quantitative trait loci (QTL) associated with the palm oil fatty acid composition of mature fruits of the oil palm E. guineensis Jacq. in comparison with its wild relative E. oleifera (H.B.K) Cortés. The oil palm cross LM2T x DA10D between two heterozygous parents was considered in our experiment as an intraspecific representative of E. guineensis. Its QTLs were compared to QTLs published for the same traits in an interspecific Elaeis pseudo-backcross used as an indirect representative of E. oleifera. Few correlations were found in E. guineensis between pulp fatty acid proportions and yield traits, allowing for the rather independent selection of both types of traits. Sixteen QTLs affecting palm oil fatty acid proportions and iodine value were identified in oil palm. The phenotypic variation explained by the detected QTLs was low to medium in E. guineensis, ranging between 10% and 36%. The explained cumulative variation was 29% for palmitic acid C16:0 (one QTL), 68% for stearic acid C18:0 (two QTLs), 50% for oleic acid C18:1 (three QTLs), 25% for linoleic acid C18:2 (one QTL), and 40% (two QTLs) for the iodine value. Good marker co-linearity was observed between the intraspecific and interspecific Simple Sequence Repeat (SSR) linkage maps. Specific QTL regions for several traits were found in each mapping population. Our comparative QTL results in both E. guineensis and interspecific materials strongly suggest that, apart from two common QTL zones, there are two specific QTL regions with major effects, which might be one in E. guineensis, the other in E. oleifera, which are independent of each other and harbor QTLs for several traits, indicating either pleiotropic effects or linkage. Using QTL maps connected by highly transferable SSR markers, our study established a good basis to decipher in the future such hypothesis at the Elaeis genus level.     

Lipid content and fatty acid composition of the monogenean Neobenedenia girellae and comparison between the parasite and host fish species

Neobenedenia girellae, a capsalid monogenean, is a destructive fish parasite. We studied the lipid content and fatty acid composition of N. girellae and the skin and cutaneous mucus of a host fish, the amberjack Seriola dumerili (Carangidae). The lipid content of adult N. girellae was less than one-fourth that of both the skin and cutaneous mucus of its host. Adult N. girellae, S. dumerili skin and mucus had a relatively high weight-percentage of C16:0, C18:1(n-9), C18:0 and C22:6(n-3) fatty acids. When S. dumerili were fed a diet supplemented with [13C] fatty acids, [13C] fatty acids were detected in S. dumerili skin and adult N. girellae on S. dumerili, but no [13C] fatty acids were detected in the S. dumerili cutaneous mucus. In addition, the epidermis of S. dumerili, attached with N. girellae, was markedly thin. These results suggest that N. girellae feeds primarily on host epithelial cells. We then infected 2 host fishes, S. dumerili and the spotted halibut Verasper variegatus (Pleuronectidae; a host less susceptible to N. girellae infection), and compared the fatty acid composition of N. girellae with that of the skin and cutaneous mucus of the hosts. The fatty acid profiles from all samples were qualitatively and quantitatively similar. Thus, the fatty acid composition of the host may not contribute to the difference in susceptibility between S. dumerili and V. variegatus. These results may serve to develop new strategies for the control of N. girellae infections.     

Estimates of genetic parameters for fatty acid compositions in the longissimus dorsi muscle of Hanwoo cattle

We estimated the heritabilities (h²) and genetic and phenotypic correlations among individual and groups of fatty acids, as well as their correlations with six important carcass and meat-quality traits in Korean Hanwoo cattle. Meat samples were collected from the longissimus dorsi muscles of 1000 Hanwoo steers that were 30-month-old (progeny of 85 proven Hanwoo bulls) to determine intramuscular fatty acid profiles. Phenotypic data on carcass weight (CWT), eye muscle area (EMA), back fat thickness (BFT), marbling score (MS), Warner–Bratzler shear force (WBSF) and intramuscular fat content (IMF) were also investigated using this half-sib population. Variance and covari.ance components were estimated using restricted maximum likelihood procedures under univariate and pairwise bivariate animal models. Oleic acid (C18:1n-9) was the most abundant fatty acid, accounting for 50.69% of all investigated fatty acids, followed by palmitic (C16:0; 27.33%) and stearic acid (C18:0; 10.96%). The contents of saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs) and polyunsaturated fatty acids (PUFAs) were 41.64%, 56.24% and 2.10%, respectively, and the MUFA/SFA ratio, PUFA/SFA ratio, desaturation index (DI) and elongation index (EI) were 1.36, 0.05, 0.59 and 0.66, respectively. The h² estimates for individual fatty acids ranged from very low to high (0.03±0.14 to 0.63±0.14). The h² estimates for SFAs, MUFAs, PUFAs, DI and EI were 0.53±0.14, 0.49±0.14, 0.23±0.10, 0.51±0.13 and 0.53±0.13, respectively. The genetic and phenotypic correlations among individual fatty acids and fatty acid classes varied widely (−0.99 to 0.99). Notably, C18:1n-9 had favourable (negative) genetic correlations with two detrimental fatty acids, C14:0 (−0.76) and C16:0 (−0.92). Genetic correlations of individual and group fatty acids with CWT, EMA, BFT, MS, WBSF and IMF ranged from low to moderate (both positive and negative) with the exception of low-concentration PUFAs. Low or near-zero phenotypic correlations reflected potential non-genetic contributions. This study provides insights on genetic variability and correlations among intramuscular fatty acids as well as correlations between fatty acids and carcass and meat-quality traits, which could be used in Hanwoo breeding programmes to improve fatty acid compositions in meat.     

Effect of replacing calcium salts of palm oil distillate with rapeseed oil, milled or whole rapeseeds on milk fatty-acid composition in cows fed maize silage-based diets

Inclusion of rapeseed feeds in dairy cow diets has the potential to reduce milk fat saturated fatty acid (SFA) and increase cis-monounsaturated fatty acid (cis-MUFA) content, but effectiveness may depend on the form in which the rapeseed is presented. Four mid-lactation Holstein dairy cows were allocated to four maize silage-based dietary treatments according to a 4 × 4 Latin Square design, with 28-day experimental periods. Treatments consisted of a control diet (C) containing 49 g/kg dry matter (DM) of calcium salts of palm oil distillate (CPO), or 49 g/kg DM of oil supplied as whole rapeseeds (WR), rapeseeds milled with wheat (MR) or rapeseed oil (RO). Replacing CPO with rapeseed feeds had no effect (P > 0.05) on milk fat and protein content, while milk yields were higher (P < 0.05) for RO and MR compared with WR (37.1, 38.1 and 34.3 kg/day, respectively). Substituting CPO with RO or MR reduced (P < 0.05) milk fat total SFA content (69.6, 55.6, 71.7 and 61.5 g/100 g fatty acids for C, RO, WR and MR, respectively) and enhanced (P < 0.05) milk cis-9 18:1 MUFA concentrations (corresponding values 18.6, 24.3, 17.0 and 23.0 g/100 g fatty acids) compared with C and WR. Treatments RO and MR also increased (P < 0.05) milk trans-MUFA content (4.4, 6.8, 10.5 g/100 g fatty acids, C, MR and RO, respectively). A lack of significant changes in milk fat composition when replacing CPO with WR suggests limited bioavailability of fatty acids in intact rapeseeds. In conclusion, replacing a commercial palm oil-based fat supplement in the diet with milled rapeseeds or rapeseed oil represented an effective strategy to alter milk fatty acid composition with the potential to improve human health. Inclusion of processed rapeseeds offered a good compromise for reducing milk SFA and increasing cis-MUFA, whilst minimising milk trans-MUFA and negative effects on animal performance.     

Novel Mutations of the FASN Gene and Their Effect on Fatty Acid Composition in Japanese Black Beef

Eight novel and four known mutations were detected in the coding sequence of the bovine fatty acid synthase (FASN) gene of an F2 population from Japanese Black and Limousin cattle. Two mutations, g.16024A>G and g.16039T>C, detected in exon 34, which determine amino acid substitutions of threonine (T) to alanine (A) and tryptophan (W) to arginine (R), were clearly separated in the parental breeds. The haplotypes (TW and AR) segregated in F2 individuals and had a significant effect on the fatty acid composition of backfat, intermuscular fat, and intramuscular fat. The TW haplotype was associated with increasing C18:0 and C18:1 content and the ratio of monounsaturated to saturated fatty acids, and decreasing C14:0, C14:1, C16:0, and C16:1 content. The two mutations were screened in two commercial Japanese Black half-sibling populations and similarly determined the contribution to the fatty acid composition of intramuscular fat. The frequency of the TW haplotype was markedly higher in Japanese Black (0.67) than in Holstein (0.17), Angus (0.02), and Hereford (0.07). We conclude that these mutations may contribute to the characteristic fatty acid composition of Japanese Black beef.