Hepatic activity of 3-hydroxy-3-methylglutaryl-CoA reductase in rats with alimentary zinc deficiency

Recent studies demonstrated that zinc deficiency lowers hepatic cholesterol concentrations in rats fed on diets that were rich in polyunsaturated fatty acids (PUFA); in contrast, in rats fed on diets that were rich in saturated fatty acids, zinc deficiency did not influence hepatic cholesterol concentrations (Eder and Kirchgessner 1993, 1994a,b, 1995). To date the mechanism underlying those effects is unclear. Based on ¹⁴C-incorporation into tissue lipids, a study by Patel et al. (1975) suggested that zinc deficiency impairs the hepatic synthesis of cholesterol. However, their investigation did not include studies on enzymes involved in cholesterol synthesis. The present study therefore was focused on the effects of zinc deficiency on the activity of hepatic 3-hydroxy-3-methylglutaryl-CoA reductase (HMG-CoA reductase) which is the key enzyme in the regulation of cholesterol biosynthesis. Therefore, rats were fed zinc-deficient diets containing either linseed oil or olive oil as sources of fat, and the activity of HMG-CoA reductase was assayed in hepatic microsomes.     

Consequences of eicosapentaenoic acid (n-3) and arachidonic acid (n-6) supplementation on mast cell mediators

Mast cells are important players in the pathogenesis of atopic diseases. These cells release immediate-phase and late-phase mediators of inflammation. Fatty acids are incorporated in cellular membranes and therefore seem to influence mediator production and release. A study was conducted to assess the effects of eicosapentaenoic acid (EPA, 20:5n-3) and arachidonic acid (AA, 20:4n-6) on mast cell mediators in a canine mastocytoma cell line (C2). Cells were cultured in a basic medium (Dulbecco's modified Eagle's medium/HAM's F12 1 : 1, DEH), DEH supplemented with 14.0 microm EPA (DEH-EPA) or 14 microm AA (DEH-AA). The DEH-AA cultured cells had increased spontaneous and mastoparan-stimulated PGE2 production and histamine release. Furthermore, the tryptase activity was increased. The DEH-EPA cultured cells rendered elevated levels of PGE2 and histamine release compared with DEH only after stimulation. These levels were significantly lower in comparison to DEH-AA. The increased PGE2 production of C2 cultured in DEH-AA is the consequence of the AA enrichment, because AA is the precursor of PGE2. However, the different effects by AA and EPA on mast cell mediators possibly reflect the higher susceptibility of long chain polyunsaturated fatty acids (PUFA) to undergo lipid peroxidation, because it is known that altered cellular redox state influences mediator production and release.     

Omega-3 Fatty Acid Supplementation Affects Selected Phospholipids in Peripheral White Blood Cells and in Plasma of Full-Sized and Miniature Mares

Dietary omega-3 fatty acids (n-3 PUFA), notably eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), impart health benefits in humans and animals. In horses, dietary n-3 PUFAs elevate EPA and DHA and may promote anti-inflammatory effects. No reports document effects of dietary n-3 PUFA on fatty acyl components of circulating and cellular phospholipids in horses nor whether responses to dietary n-3 PUFA are similar among horse breeds. Ten Quarter Horse and 10 American Miniature Horse mares were assigned to n-3 PUFA (64.4 mg· kg body weight [BW]⁻¹·d⁻¹) or control diet for 56 days. Blood was sampled at 0, 28, and 56 days. Apparent phospholipid molecular species from several classes (phosphatidylcholine [PC]; “ether-linked” phosphatidylcholine [i.e., alk(en)yl, acyl glycerophosphocholine] [ePC]; phosphatidylethanolamine [PE]; phosphatidylinositol [PI]; and phosphatidylserine [PS]) were determined in plasma and peripheral blood mononuclear cells (PBMC) by mass spectrometry. Statistical analysis showed that six phospholipid species had diet × day interactions (P < .05) for both plasma and PBMC. Further evaluation of these species demonstrated that the mole percentage of PC(38:6), PC(40:7), PC(42:10), PE(38:5), PE(40:6), and PE(40:7) (where x:y represents total acyl carbon:total carbon-carbon double bonds) in both plasma and PBMC phospholipids was elevated in horses fed n-3 PUFA (P < .001 for all). Analysis of the acyl product ions revealed that these contained an acyl chain of mass consistent with an n-3 PUFA. Thus, supplementation increased n-3 PUFA in selected plasma and PBMC phospholipids. The absence of breed effects suggests that miniature and full-size horses responded similarly to dietary treatment.     

Effects of dietary flaxseed oil supplementation on equine plasma fatty acid concentrations and whole blood platelet aggregation

An 18-week feeding trial was performed to investigate the effects of an omega-3 (n-3) fatty acid-enriched ration on plasma fatty acid concentrations and platelet aggregation in healthy horses. Flaxseed oil served as the source of the n-3 fatty acid alpha-linolenic acid (ALA). Twelve horses were fed dietary maintenance requirements using a complete pelleted ration (80%) and timothy grass hay (20%) for a 2-week acclimation period before being randomly assigned either to a treatment (group 1) or control (group 2) group. Group 2 horses (n = 6) were fed the diet described in the acclimation period, whereas group I horses (n = 6) were fed a 10% flaxseed oil-enriched complete pellet (80%) and grass hay (20%). Biological samples and physical measurements were collected at one point during the acclimation period (week 0) and every 4 weeks thereafter (weeks 4, 8, 12, and 16). Body weight, CBC (including platelet count), plasma fibrinogen. electrolyte (Na, K, and Cl) concentrations, and biochemical profile enzyme activities (aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltransferase, and creatine kinase) did not change markedly with diet. Platelet aggregation was not altered by the supplementation of flaxseed oil in these healthy horses, although increases in plasma cis-polyunsaturated 18-carbon fatty acids C18:3; n-3 (ALA) and C18:2; n-6 (linoleic acid), biologically active C20:5; n-3 (eicosapentaenoic acid [EPA]), and malondialdehyde (MDA) were evident. There were no marked decreases in C20:4; n-6 (arachidonic acid [AA]) or increases in C22:6; n-3 (docosahexaenoic acid [DHA]), signifying that flaxseed oil may have had a high percentage of omega-6 (n-6) fatty acids as well as n-3 fatty acids, and this relatively high n-6: n-3 fatty acid ratio may have affected the biochemical effect of n-3 fatty acids. In healthy horses supplemented with flaxseed oil, platelet aggregation was not altered, which may have been due to the limited biologic effect in healthy subjects or the inability of flaxseed oil to induce the necessary biochemical effect of replacing n-6 fatty acids with n-3 types.     

亚麻籽对鸡蛋中脂肪酸富集及蛋品质的影响

本试验旨在探讨日粮中亚麻籽添加水平和添加时间对蛋中n-3多不饱和脂肪酸的富集以及蛋品质的影响。选取46周龄京粉1号蛋鸡1 344只,随机分为4个组,每组6个重复,每个重复56只。4个处理组日粮中亚麻籽的添加水平分别为0%(对照组)、5%、10%、15%。试验期60 d。试验第10、20、30、45、60天测定蛋中α-亚麻酸、二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)等n-3多不饱和脂肪酸(n-3PUFA)含量。第30、60天测定蛋壳强度、蛋黄色度和哈氏单位。结果表明:亚麻籽的添加水平、时间以及二者互作均对蛋中n-3PUFA的富集产生显著影响,蛋中n-3PUFA含量随着亚麻籽添加水平和添加时间增加呈上升趋势,随后达到稳定;5%亚麻籽组中鸡蛋DHA含量最高,其他脂肪酸含量以15%亚麻籽组最高;蛋中EPA含量在20 d达到最高,其他脂肪酸在30 d达到最高;蛋黄色度随着日粮中亚麻籽添加水平升高而显著降低,其他蛋品质指标无显著变化。由此表明,给蛋鸡饲喂含15%亚麻籽日粮30 d以上,可获得理想n-3PUFA富集鸡蛋,但要保证日粮色素水平稳定。     

Lipid profile in eggs of Araucana hens compared with Lohmann Selected Leghorn and ISA Brown hens given diets with different fat sources

1. In a cross-over trial, the egg cholesterol and fatty acid composition of Araucana hens was compared with those of two commercial breeds (Lohmann Selected Leghorn and ISA Brown) under two feeding regimes, either high (Hn-3) or low (Ln-3) in long-chain n-3 fatty acids. 2. The Hn-3 diet was formed by isocaloric substitution of animal fat in the control diet (Ln-3) by a dry product containing stabilised fish oil with standardised concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 3. Both breed and diet had influences on egg composition, without interactions. 4. The Araucana breed showed lower feed intake and lower egg weights than the other two breeds. The yolk weight was similar, leading to a much higher yolk:albumen ratio in the Araucana eggs. 5. In comparison to commercial breeds, Araucanas produced eggs with higher cholesterol content per g of yolk, which was even more pronounced when expressed per g of egg, due to the high yolk content of the eggs. The cholesterol content of an egg remained unchanged by the diet, irrespective of the dietary fat source. 6. Changing to the Hn-3 diet led to greater concentrations of polyunsaturated fatty acids (PUFA) and lower concentrations of monounsaturated fatty acids (MUFA) contents in the yolk, without a change in the ratio of saturated (SFA) to unsaturated fatty acids (UFA). 7. Within the PUFA, the n-3 fatty acids increased at the expense of the n-6 fatty acids, indicating a competition between n-3 and n-6 fatty acids for incorporation in the yolk.     

Polyunsaturated fatty acids influence inflammatory markers in a cellular model for canine osteoarthritis

Although it is well recognized that dietary supplementation with fish oil improves clinical symptoms in dogs suffering from osteoarthritis, the molecular basis for the dietary benefit is not yet completely resolved in dogs. This study was designed to further clarify how polyunsaturated fatty acids (PUFA) affect key factors of cartilage degeneration in a canine cell culture system mimicking osteoarthritis. Canine chondrocytes were incubated either without or with 10 μm of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), arachidonic acid (AA) or 3.6 μm ibuprofen (Ibu) as positive control for 6 days. After the supplementation, cells were stimulated with 10 ng/ml interleukin‐1β (IL‐1β) for another 48 hr to induce osteoarthritic changes, or left unstimulated. We analysed fatty acid uptake via gas–liquid chromatography, nitric oxide (NO) production via Griess assay, prostaglandin E (PGE) production via ELISA and relative gene expression of several cartilage matrix proteinases, inducible nitric oxide synthase (iNOS) and cyclooxygenase‐2 via RT‐qPCR. After supplementation, the chondrocytes rapidly incorporated the PUFA into their fatty acid pools. The stimulation with IL‐1β caused a marked increase of most of the inflammatory markers measured. N‐3 PUFA EPA reduced IL‐induced gene expression of iNOS and corresponding production of NO. N‐6 PUFA AA also decreased iNOS and NO, but furthermore lowered gene expression of matrix metalloproteinase‐3. On the other hand, AA upregulated the aggrecanase ADAMTS‐5 and augmented the release of PGE. The effect of n‐3 PUFA DHA turned out to be negligible. Our results reveal molecular mechanisms by which PUFA affect degenerative joint disease in dogs. Of particular importance is that not only EPA but also AA decreased several inflammatory markers in our model. Thus, we conclude that an appropriate balance of both n‐3 and n‐6 fatty acids deserves more attention in dietary interventions.     

Breed effects on growth performance, carcass characteristics, fatty acid composition, and palatability attributes in finishing steers

Crossbred steers (n = 136) were used to assess breed differences in growth performance, carcass characteristics, fatty acid composition (total lipids and phospholipids), and palatability attributes of longissimus muscle. A multiple regression model was applied to crossbreeding data to estimate genetic differences between Simmental and Red Angus at the same level of backfat finish (10 mm). Simmental spent 71 more (P < 0.001) days on feed to acquire the same degree of backfat thickness as Red Angus, had heavier (P < 0.001) slaughter weights, larger (P = 0.002) longissimus muscle area, and increased (P = 0.023) lean yield. Average daily gain did not differ (P = 0.297) between breeds. Simmental were less (P = 0.012) efficient in converting feed to gain than Red Angus. Generally, there were few breed differences in palatability attributes for longissimus and semitendinosus muscles, with the exception of increased (P < 0.05) beef flavor scores for Simmental beef vs Red Angus beef across both muscles. For total lipids, concentrations of myristoleic acid (14:1), palmitoleic acid (16:1), and vaccenic acid (18:1n-7), along with n-6 to n-3 fatty acid (n-6:n-3) ratio, were greater (P < 0.05) in Simmental than Red Angus. In contrast, concentrations of margaric acid (17:0), eicosapentaenoic acid (20:5n-3), and total n-3 polyunsaturated fatty acids (n-3 PUFA) were greater (P < 0.05) in Red Angus than Simmental. For phospholipids, Simmental had lower (P < 0.05) amounts of 20:5n-3, docosahexaenoic acid (22:6n-3), and n-3 PUFA, with a greater (P = 0.017) n-6:n-3 ratio. Activity of delta9-desaturase enzyme in the conversion of palmitic acid (16:0) to 16:1 was greater (P = 0.001) in total lipids from Simmental as compared with Red Angus. A genetic basis for fatty acid differences is suggested, although the biological and practical significance needs to be demonstrated.     

Effects of dietary flax seed and sunflower seed supplementation on normal canine serum polyunsaturated fatty acids and skin and hair coat condition scores

This prospective study involved supplementing 18 normal dogs with flax seed (FLX) and sunflower seed (SUN) and evaluating their effects on skin and hair coat condition scores and serum polyunsaturated fatty acids (PUFA) concentrations. Skin and hair coat were evaluated in a double-blinded fashion using a numeric scoring system and serum PUFA concentrations were determined. Our hypothesis was that changes in serum PUFA concentrations are associated with improvements in skin and hair coat and that serum PUFA would provide an objective method for making dietary fatty acid supplement recommendations. Although a numerical improvement was found in hair coat quality in both groups, this improvement was not sustained beyond 28 days. The relative per cent of 18:3n-3 concentrations in serum phospholipids increased in the FLX treated dogs but these concentrations remained unchanged in the SUN treated dogs. Also, elevations in relative per cent of 18:2n-6 concentrations in serum phospholipids were seen in the FLX group. The ratio of serum polyunsaturated to saturated fatty acids also showed a transient increase. These increases preceded the peak skin condition score peak value by approximately 14 days. It was concluded that a 1-month supplementation with either flax seed or sunflower seed in dogs provides temporary improvement in skin and hair coat. These changes appeared to be associated with increased serum 18 carbon PUFA.     

Qualitative Risk Assessment of Chronic Renal Failure Development in Healthy,Female Cats as Based on the Content of Eicosapentaenoic Acid in Adipose Tissue and That of Arachidonic Acid in Plasma Cholesteryl Esters

A study was carried out to assess the qualitative risk of development of chronic renal failure (CRF) in young healthy, female cats as based on the content of arachidonic acid (AA) in plasma cholesteryl esters (CE) and eicosapentaenoic acid (EPA) in adipose tissue. It has been suggested that the content of AA in CE should be <10% of total fatty acids (TFA) and of EPA in adipose tissue be >1.4% of TFA. Subcutaneous adipose tissue and blood samples were obtained from 48 female cats. There was a statistically significant correlation between linoleic acid content of adipose tissue and that of plasma CE. In all cats the EPA content of adipose tissue was lower than 1.4% of TFA and in 30 cats that of AA in plasma CE was higher than 10% of TFA. The EPA content of adipose tissue and the AA content of plasma CE are determined by the contents of these fatty acids in the diet. It is concluded that the fatty acid composition of cat foods should be determined and that, if deemed necessary, the ingredient composition should be altered so that the content of EPA is raised and that of AA is lowererd.     

The Effects of n-3 Fatty Acid Supplementation on Bleeding Time, Plasma Fatty Acid Composition, and In Vitro Platelet Aggregation in Cats

Dietary supplementation with fish and fish oils rich in the n-3 fatty acids eicosapentaenoic acid ( EPA ) and docosahexaenoic acid (DHA) has been shown to alter eicosanoid metabolism and impair platelet function in several species. As an initial step in evaluating the antithrombotic effect of these n-3 fatty acids in cats, purified EPA and DHA were administered daily to 8 clinically normal cats for 2 months. Platelet function was evaluated biweekly by determining mucosal bleeding time and in vitro platelet aggregation parameters. Plasma fatty acid profiles were obtained before fish oil supplementation and at the termination of the study. In spite of significant increases ( P < .0001) in the plasma concentrations of EPA and DHA after n-3 fatty acid supplementation, there were no significant changes in platelet aggregation or bleeding times. Although it is tempting, based on extrapolation of data from other species, to recommend dietary supplementation with fish oil for cats prone to arterial thromboembolism, these results indicate that administration of large doses of purified EPA and DHA once daily does not inhibit platelet function in normal cats and is unlikely to prevent thrombosis in cats with cardiovascular disease. Additional studies are recommended to ascertain whether more frequent administration of these purified n-3 fatty acids or continual feeding of diets high in n-3 fatty acid content will impair platelet function.     

饲粮n-6/n-3多不饱和脂肪酸比值对冬毛期北极狐生长性能及肝脏脂肪酸代谢相关蛋白基因表达的影响

本试验旨在研究饲粮n-6/n-3多不饱和脂肪酸(PUFA)比值对冬毛期北极狐生长性能、肝脏脂肪酸组成及肝脏型脂肪酸结合蛋白(L-FABP)和脂肪酸转运蛋白(FATP)基因表达的影响。试验选取48只157日龄、平均体重为(5 658±47)g的健康雄性北极狐,随机分成4组,每组12个重复,每个重复1只。Ⅰ组饲粮中添加12.00%鱼油和2.00%豆油,n-6/n-3 PUFA比值为3.00;Ⅱ组饲粮中添加9.38%玉米油和4.62%豆油,n-6/n-3 PUFA比值为18.03;Ⅲ组饲粮中添加12.00%玉米油和2.00%豆油,n-6/n-3 PUFA比值为40.83;Ⅳ组饲粮中添加1.50%鱼油和12.50%玉米油,n-6/n-3 PUFA比值为136.36。各组饲粮除油脂组成和配比不同外,其他原料一致。预试期7 d,正试期40 d。结果表明:1)饲粮n-6/n-3 PUFA比值对冬毛期北极狐的平均日增重(ADG)、平均日采食量(ADFI)和料重比(F/G)有极显著影响(P0.01)。Ⅰ和Ⅳ组的ADG极显著高于Ⅱ和Ⅲ组(P0.01),Ⅰ、Ⅱ和Ⅳ组的ADFI极显著高于Ⅲ组(P0.01),Ⅳ组的F/G极显著低于Ⅱ和Ⅲ组(P0.01)。2)饲粮n-6/n-3 PUFA比值对冬毛期北极狐肝脏单不饱和脂肪酸(MUFA)、PUFA、n-3 PUFA和n-6 PUFA的含量有显著或极显著影响(P0.05或P0.01),对肝脏饱和脂肪酸(SFA)含量无显著影响(P0.05)。Ⅰ和Ⅳ组肝脏n-3 PUFA含量极显著高于Ⅱ和Ⅲ组(P0.01),Ⅱ和Ⅲ组肝脏n-6 PUFA含量极显著高于Ⅰ和Ⅳ组(P0.01)。3)饲粮n-6/n-3 PUFA比值对冬毛期北极狐肝脏L-FABP mRNA相对表达量无显著影响(P0.05),但极显著影响肝脏FATP mRNA相对表达量(P0.01)。Ⅰ和Ⅳ组肝脏FATP mRNA相对表达量极显著高于Ⅱ和Ⅲ组(P0.01)。由此可见,饲粮添加1.50%鱼油与12.50%玉米油的混合油脂,即饲粮n-6/n-3 PUFA比值为136.36时,上调了肝脏中FATP基因的表达,增加了肝脏长链脂肪酸的转运及利用效率,促进了冬毛期北极狐的生长。     

长链n-3多不饱和脂肪酸对肠上皮细胞促炎细胞因子基因mRNA表达的影响

本试验旨在探讨长链n-3多不饱和脂肪酸(LC n-3 PUFA)对肠上皮细胞促炎细胞因子基因mRNA表达的影响.试验选用大鼠肠上皮细胞系IEC-6细胞为模型,分为4个处理,分别为对照、脂多糖(LPS,1μg/mL)、LPS(1μg/mL)+二十二碳六烯酸(DHA,100 μmol/L)和LPS(l μg/mL)+二十碳五烯酸(EPA,100μmol/L),每个处理3个重复,每孔为1个重复.细胞先用DHA、EPA或等量二甲基亚砜(DHA和EPA的溶剂,对照)预处理48h,再用LPS处理3h,收集细胞提取总RNA,采用实时定量PCR方法分析肿瘤坏死因子-α(TNF-α)、白介素-1β(IL-1β)和白介素-6(IL-6)的基因mRNA表达水平的差异.结果表明:LPS极显著上调了细胞中TNF-α、IL-1 β和IL-6的基因mRNA表达水平(P＜0.01),EPA均极显著或显著削弱了细胞内LPS诱导的TNF-α(P＜0.01)、IL-1β(P ＜0.01)和IL-6的基因mRNA水平(P＜0.05)的上调,而DHA仅显著削弱了细胞内LPS诱导的IL-1β的基因mRNA水平的上调(P＜0.05).结果提示,LC n-3 PUFA在肠上皮细胞中具有抗炎作用,且在本试验条件下EPA的抗炎效果要优于DHA.     

High feeding intensity increases the severity of fatty liver in the American mink (Neovison vison) with potential ameliorating role for long-chain n-3 polyunsaturated fatty acids

Background

Rapid body fat mobilization, obesity, and an inadequate supply of n-3 polyunsaturated fatty acids (PUFA) have been suggested to play roles in the etiology of fatty liver in the American mink (Neovison vison). This study examined the effects of feeding intensity and dietary fat source on fatty liver induced by fasting. In a multi-factorial design, 3 different fat sources (herring oil, rich in n-3 PUFA, soya oil, rich in n-6 PUFA, and canola oil, rich in n-9 monounsaturated fatty acids) were fed to mink at a low and high feeding intensity for 10 weeks, followed by an overnight or a 5-day fasting treatment to induce fatty liver.

Results

Fasting led to the development of fatty liver with increased severity in the mink fed at the high feeding intensity. The herring oil diet, high in long-chain n-3 PUFA, was found to decrease the severity of fatty liver in the mink at the high feeding intensity.

Conclusion

Preventing excessive weight gain and increasing dietary intake of n-3 long-chain PUFA may help prevent excessive lipid accumulation during prolonged periods of fasting or inappetence by promoting hepatic fatty acid oxidation.     

Circulating fatty acid profiles in response to three levels of dietary omega-3 fatty acid supplementation in horses

Fatty acids of the n-3 type confer health benefits to humans and other species. Their importance to equine physiology could include improved exercise tolerance, decreased inflammation, and improved reproductive function. The circulating fatty acid profile and the acquisition and washout of fatty acids in response to n-3 supplementation were determined for horses in the current study. A fatty acid supplement high in eicosapentaenoic (EPA) and docosahexaenoic (DHA) acid was fed to deliver EPA plus DHA at 0 (control), 10, 20, or 40 g/d to 16 mares (n = 4/group) for 28 d. Plasma was collected at -11, 3, 7, 10, 16, 23, 30, 37, 44, 70, and 87 d relative to the beginning of supplementation. Plasma was analyzed for the presence of 35 fatty acids by gas chromatography. Plasma EPA and DHA increased (P < 0.05) in a dose-responsive manner by 3 d of feeding and reached peak concentrations by 7 d. Peak EPA and DHA concentrations of the 40 g/d supplement group were approximately 13x and 10x those of controls, respectively. Plasma EPA and DHA demonstrated a steep decline (P < 0.05) from peak values by 9 d after cessation of supplementation and were near presupplementation values by 42 d. Omega-3 supplementation also increased (P < 0.05) concentrations of fatty acids C14:0, C17:1n-7, C18:1trans-11, C18:3n-6, C18:4n-3, C20:3n-6, C20:4n-6, and C22:5n-3 and decreased (P < 0.05) concentrations of C18:1cis-9 fatty acid. Seasonal effects, apparently unrelated to supplementation and likely due to the availability of fresh forage, were also noted. Unlike ruminants, there were no detectable concentrations of CLA in equine plasma. These results indicate that the circulating fatty acid milieu in horses can be influenced through targeted supplementation. Possible implications of increased n-3 plasma and tissue concentrations on specific physiological function in the equine remain to be elucidated.     

亚麻油对育肥猪肉品质及脂肪组织脂肪酸组成的影响

本试验旨在研究饲料添加亚麻油(linseed oil,LO)对育肥猪胴体指标、肉质及脂肪组织脂肪酸组成的影响.选用平均体质量为63 kg左右的健康大白猪84头(其中21头阉公猪),按体质量相近、性别比例一致原则随机分为3组,每组设4个重复,每个重复7头猪(1或2头阉公猪).3个处理口粮为玉米-豆粕型日粮,分别添加0%、1.5%和3.0%LO,饲养试验时间为50 d.结果显示,与对照组相比,日粮中添加LO对猪胴体和肉晶质指标均没有显著影响(P＞0.05);日粮中添加LO显著提高皮下脂肪的α-亚麻酸(ALA)(P＜0.01)、EPA(P＜0.01)、DPA(P＜0.05)含量,以及多不饱和脂肪酸(PUFA)(P＜0.05)和n-3PUFA(P＜0.01)总含量,同时显著降低花生四烯酸(P＜0.01)和二十二碳四烯酸(P＜0.01)含量,而对n-6PUFA总含量无显著影响(P＞0.05).结果表明,猪不但可以直接沉积α-亚麻酸,而且能将其进行进一步延长和脱饱和;饲料中添加1. 5% LO可将猪皮下脂肪n-6:n-3PUFA比值降至4.1:1,接近人类健康饮食推荐水平,而日粮中添加3.0%LO则能降低皮下脂肪n-6:n-3PUFA比值至2.5:1,大大增加了猪脂肪组织的保健价值.     

A diet moderately deficient in zinc induces limited intestinal alterations in weaned pigs

The aim of this work was to test the hypothesis that a moderate zinc deficiency induces intestinal alterations in weaned piglets. A diet based on maize and soybean meal was formulated without supplemental zinc (33 ppm, zinc-deficient) or with added zinc (113 ppm, control). These diets were pair-fed for 18 or 27 d to intra-litter pairs of piglets weaned at 21 d of age. The feed intake and growth, plasma concentrations of zinc and alkaline phosphatase (ALP) activity, and morphometry, enzyme activities and the microflora of the mid-jejunum were investigated. Feed intake and growth were similar between diets and diarrhoea was not observed. By contrast, plasma zinc and ALP activity were much lower in zinc-deficient piglets at slaughter (P < 0.001). The weight of organs was unaffected, except colonic tissue that was lighter in piglets fed the zinc-deficient diet (P < 0.05). Neither villus-crypt intestinal architecture nor mucosal enzyme activities were altered. Jejunal counts of lactic acid bacteria and coliforms tended to be higher in the zinc-deficient pigs (P ≤ 0.10). In conclusion, feeding a diet moderately deficient in zinc for 18–27 d induced limited intestinal alterations in weaned pigs.     

Influence of swine genotype on fatty acid composition of phospholipids in longissimus muscle.

Our objective for this study was to determine whether there is a difference in the fatty acid composition of phospholipids in longissimus muscle from pigs of different genotypes. In Exp. 1, 15 Hampshire x Yorkshire-Landrace (YL), 15 Duroc x YL, and 15 Danbred x YL were used. Animals were of similar age and were fed identical diets. In Exp. 2, longissimus muscle samples from pigs of seven genetically different lines were analyzed. In both experiments, saturated fatty acids (SFA, 16:0 and 18:0) constituted approximately 31.5% of the total fatty acids. Monounsaturated fatty acid (MUFA, 18:1 and 20:1) levels ranged from 12.3 to 16.9%, and PUFA (mainly 18:2 and 20:4) accounted for 50.8 to 57.0% of the total fatty acids. Fatty acid composition of muscle phospholipids from Duroc and Hampshire x YL pigs was identical. Muscle phospholipids from Danbred x YL pigs contained more PUFA (approximately 3%, P < .05) and less SFA (approximately 2%, P < .05) than phospholipids from the two other genotypes. Differences in SFA and PUFA of muscle from the seven lines were of the same order of magnitude. Differences in MUFA content were not significant.     

Direct supplementation of diet is the most efficient way of enriching broiler meat with n-3 long-chain polyunsaturated fatty acids

1. Concentrations of beneficial omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFAs) in poultry meat can be improved by increasing the concentration of n-3 PUFA in poultry diets.

2. A decrease in flavour quality is, however, usually associated with the dietary supplementation with n-3 PUFA, which is due to the susceptibility of PUFA to oxidation.

3. This experiment was conducted to study the effects of introducing two different n-3 fatty acid sources (extruded linseed and DHA Gold?, a proprietary algal product rich in docosahexaenoic acid), either separately or together, on broiler productive performance, and meat quality, oxidative stability, sensory traits and LC-PUFA profile.

4. Birds given the algal product displayed better productive performances than animals from other groups.

5. The data revealed an improvement in the fatty acid nutritional value of meat from birds receiving the algal product and an inefficient conversion of α-linolenic acid (LNA) into LC-PUFA.

6. Metabolisation of LNA in vivo is not sufficient to improve meat quality in n-3 LC-PUFA and direct supplementation of the diet with n-3 LC-PUFA is a better alternative to modulate an increase in beneficial fatty acids of broiler meat.

7. The overall acceptability of meat was negatively affected by the dietary supplementation with 7.4% of DHA, in contrast to the supplementation with 3.7% of DHA, which showed to be efficient in improving LC-PUFA meat content without affecting its sensory properties.