Humoral immunity in the ewe. 2. The effect of pregnancy on the primary and secondary antibody response to protein antigen

This study examines the effect of pregnancy on the quantity and isotype of antibody in ewes immunised with a novel primary antigen. The primary and secondary antibody levels to bovine serum albumin (BSA) in alum adjuvant, were compared between non-pregnant ewes and ewes immunised at different stages of pregnancy. Anti-BSA isotype specific responses were measured using an indirect ELISA. Results show the levels of immunoglobulin M (IgM) increased and persisted in response to BSA during pregnancy (P less than 0.05). Secondary immunoglobulin G1 (IgG1) titres were significantly impaired in late pregnancy and during lactation (P less than 0.05). The lower levels of immunoglobulin G2 (IgG2) were unaffected by pregnancy under these experimental conditions. Ewes were also immunised with BSA in alum adjuvant for their primary inoculum and BSA in different adjuvants for the secondary inoculation. Primary IgM persisted at higher levels during pregnancy compared with the response in non-pregnant ewes (P less than 0.05). Following the secondary injection, lower levels of anti-BSA specific IgM, IgG1 and IgG2 antibodies were produced in late pregnancy and during lactation compared with the levels in non-pregnant control ewes (P less than 0.05). Alterations in regulatory T-cell function or effector B-cell activity would most readily explain the qualitative changes in antibody titre observed following primary injection during pregnancy. The results also suggest an associated impairment of immunological memory following primary immunisation during pregnancy.     

日粮中脂肪酸对羊牛猪肉中长链多不饱和脂肪酸和共轭亚油酸的影响

随着消费者健康意识的提高,越来越多的研究关注提高家养动物肉产品中多不饱和脂肪酸(PUFA)含量,尤其是n-3长链脂肪酸和共轭亚油酸(CLA)在羊、牛、猪肉肌内脂中的含量。研究结果表明通过添加鱼油或鱼粉能提高动物肉中n-3长链脂肪酸含量。富含亚麻油酸(LNA)的日粮能提高肉中LNA、二十碳五烯酸(EPA)和二十二碳五烯酸(DPA)水平,但大部分对肌肉中二十二碳六烯酸(DHA)水平没有影响。然而,在日粮中添加鱼油或鱼粉大部分能提高动物肌肉中DHA含量。大部分研究中提高n-3脂肪酸含量的同时n-6脂肪酸含量下降,这主要归因于试验组日粮中n-6脂肪酸降低。这样刚好可以使肉中两者比例更合理,但对多不饱和脂肪酸与饱和脂肪酸比例没什么影响。饲喂反刍动物富含n-3脂肪酸日粮(亚麻籽或加草料)、鱼油或富含LA的浓缩料可提高肌肉中c9t11CLA含量。牛肉、羊肉中c9t11CLA在总脂中含量介于0.2~1.0 g/100 g,不随营养因素提高到更高。相对应的,在单胃动物日粮中添加混合CLA油则显著提高CLA含量。     

A quantitative assessment of primary and secondary immune responses in cattle using a B cell ELISPOT assay

The aim of the study was to build a comprehensive picture of the appearance in the blood stream of Ag-specific plasma cells and memory B cells in the bovine model. For this purpose, we have developed a method allowing the detection and quantification of both cell types within individual calves immunised with ovalbumin. During the primary response, we detected a burst of ovalbumin-specific plasma cells at days 6 and 7 post-immunisation, which was followed by the production of specific Ab, whereas a gradual increase of memory B cells was only detected from day 15. As expected, a boost immunisation performed 7 weeks later induced a quicker and stronger secondary response. Indeed, a burst of plasma cells was detected in the blood at days 3 and 4, which was followed by a strong increase in Ab titres. Furthermore, a burst of memory B cells, and not a gradual increase, was detected at days 5 and 6 post-boost immunisation. Importantly, we showed a strong correlation between the anti-ovalbumin-specific IgG titres detected 5 months after secondary immunisation and the plasma cell numbers detected in the blood at the peak response after secondary immunisation. The detection and quantification of plasma cells following an mmunisation/vaccination strategy could constitute a very effective means for predicting the magnitude and longevity of an Ab response.     

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.     

Effect of a linseed diet or a sunflower diet on performances, fatty acid composition, lipogenic enzyme activities and stearoyl-CoA-desaturase activity in the pig

The aim of this study was to compare the influence of a high α-linolenic acid (ALA) diet (linseed diet) and a high linoleic acid (LA) diet (sunflower diet) on performances of pigs, on the dietetical quality of their tissues (adipose tissues and muscles), and on the lipogenic potential of these tissues. Growth and carcass performances, and the lipid content of the tissues were not affected by the diet. Feeding the linseed diet increased the content of n-3 PUFA and decreased the LA/ALA ratios in all the tissues, while the sunflower diet led to an increase in the n-6 PUFA contents. Neither the stearoyl-CoA-desaturase and glucose-6-phosphate-dehydrogenase activities nor the β-hydroxyacyl-CoA-dehydrogenase activity were affected by the diet. Acetyl-CoA-carboxylase and fatty acid synthase activities were enhanced with the linseed diet in respectively subcutaneous adipose tissue and intermuscular adipose tissue, while malic enzyme activity was decreased in liver and subcutaneous adipose tissue of pigs fed the linseed diet.     

Influence of Dietary Fat and Short-Time Starvation on the Composition of Sow-Milk Fat

The influence of cottonseed oil and of linseed oil upon the fatty-acid composition of milk fat was each studied in one sow. Each oil was added to the basic diet in an amount of 6.3 % for two periods of the lactation. As cottonseed oil has a fatty-acid composition that is similar to that of the basic diet, the supplement with this oil will, in general, increase the same kind of fat in the diet. The linoleic-acid content in the milk fat will be nearly redoubled (11.7 % to 20.5 %) when the cottonseed oil is added. The supplement with linseed oil (of which linolenic acid constitutes about 58 %) to the food raised the linolenic-acid level in the milk fat from 1.1 % to 18.3 %. The increase of linoleic and linolenic acid is counterbalanced by a decrease of shorter fatty acids (G 14 and G 16 acids). The fatty-acid composition of the milk fat adjusts itself to the dietary changes within two or three days.By feeding a diet containing 16.7 % cottonseed oil to a sow, about 27 % linoleic acid was obtained in the sow’s milk fat.The influence of 30 hours of starvation upon the fatty-acid composition was studied in two sows. The content of G 18 acids rose during starvation and that of shorter acids (C14 and C16) diminished.     

Effects of forage and sunflower oil levels on ruminal biohydrogenation of fatty acids and conjugated linoleic acid formation in beef steers fed finishing diets

Six Hereford steers (295 kg) cannulated in the proximal duodenum were used to evaluate the effects of forage and sunflower oil level on ruminal biohydrogenation (BH) and conjugated linoleic acid (CLA) outflow. Steers were fed one of six treatment diets in a 3 x 2 factorial arrangement of treatments (grass hay level: 12, 24, or 36% of DM; and sunflower oil level: 2 or 4% of DM) in a 6 x 6 Latin square design. The remainder of the diet was made up of steam rolled corn and protein/mineral supplement. Duodenal samples were collected for 4 d following 10-d diet adaptation periods. Data were analyzed with animal, period, forage level, sunflower oil level, and two-way interaction between forage and sunflower oil level in the model. Dry matter intake showed a quadratic response (P < 0.04), with an increase in DMI as forage level increased from 12 to 24% followed by a decrease in DMI when 36% forage was fed. Flow of fatty acids at the duodenum was higher (P < 0.03) for 4 vs. 2% sunflower oil diets, and similar among forage levels. Apparent ruminal digestibility of NDF increased in a linear manner (P < 0.04) as dietary forage level increased. Ruminal BH of dietary unsaturated 18-C fatty acids, oleic acid, and linoleic acid increased linearly (P < 0.05) as dietary forage level increased. Linoleic acid BH tended (P < 0.07) to be greater for 4 than 2% sunflower oil level. Duodenal flow of pentadecyclic, stearic, linolenic, and arachidic acids increased linearly (P < 0.05) as dietary forage level increased from 12 to 36%. Duodenal flow of linoleic acid decreased in a linear manner (P < 0.03) with increasing dietary forage level. Flow of trans-10 octadecenoate decreased linearly (P < 0.03) as dietary forage level increased, whereas trans-11 vaccenic acid flow to the duodenum increased (P < 0.01) linearly with increased dietary forage. Dietary forage or sunflower oil levels did not alter the outflow of cis-9, trans-11 CLA. Flows of cis-11, trans-13, and cis-9, cis-11 CLA increased linearly (P < 0.05) with increased dietary forage. Flows of cis-11, cis-13, and trans-11, trans-13 CLA decreased linearly (P < 0.05) with increased dietary forage. Increasing dietary forage levels from 12 to 36% in beef cattle finishing diets increased BH of unsaturated 18-C fatty acid and outflow of trans-11 vaccenic acid to duodenum without altering cis-9, trans-11 CLA outflow.     

Effects of dietary conjugated linoleic acid and fish oil supplementation on performance and egg quality in laying hens

1. Laying hen performance, yolk fat fatty acid concentrations and firmness of eggs were evaluated with respect to the inclusion in the diet of conjugated linoleic acid (CLA) and fish oil. 2. Nine diets were arranged factorially, with three levels of supplementation of CLA (1, 3 and 5 g/kg) and fish oil (0, 14 and 20 g/kg). 3. Type of diet did not affect egg production traits. 4. CLA addition increased yolk weight and yolk fat concentrations of CLA, saturated and total long-chain n-3 fatty acids, but decreased those of monounsaturated and total long-chain n-6 fatty acids. 5. Fish oil addition increased long-chain n-3 fatty acids yolk fat concentrations but decreased those of CLA, saturated and long-chain n-6 fatty acids. 6. Effects of CLA addition on yolk fat concentrations of C22:4 n-6 and C20:5 n-3 were greater when no fish oil was added to the diet. 7. CLA supplementation increased linearly yolk moisture and firmness and altered albumen and yolk pH.     

The influence of dietary fish oil vs. sunflower oil on the fatty acid composition of plasma cholesteryl-esters in healthy, adult cats

The question addressed was whether the fatty acid composition of plasma cholesteryl esters (CEs) in cats reflects the intake of fatty acids. Diets containing either fish oil or sunflower oil were fed to six healthy, adult cats in a cross-over trial. The dry cat foods contained approximately 18.5% crude fat, of which two-third was in the form of the variable oil. Blood samples were collected at the end of each 4-week feeding period, and the fatty acid composition of plasma CEs and plasma concentrations of lipoproteins were determined. Consumption of the diet with fish oil was associated with significantly greater proportions of eicosapentaenoic acid, arachidonic acid, alpha-linolenic acid, oleic acid, palmitic acid and myristic acid in plasma CEs. The intake of fish oil instead of sunflower oil reduced the percentage of linoleic acid in CEs. The plasma concentrations of total cholesterol, high-density lipoprotein cholesterol, phospholipids and triglycerides were not affected by fish oil vs. sunflower oil feeding.     

Effect of dietary fat sources on systemic and intrauterine synthesis of prostaglandins during early pregnancy in gilts

The present experiment was conducted to determine the influence of dietary fatty acids C18:2n-6 and C18:3n-3 on the modulation of intrauterine synthesis of prostaglandin E2 (PGE2) and F2alpha (PGF2alpha) during early pregnancy in pigs. Prostaglandin E2 in uterine fluid has been previously reported to be associated with embryo survival and development. Thirty-two Yorkshire-Landrace nulliparous gilts were randomly allocated to four diets containing 5% supplemental fat. The four dietary treatments were: HT, hydrogenated tallow (26.5% C16:0 and 54.8% C18:0); SO, sunflower oil (61.3% C18:2n-6); LO, linseed oil (50.4% C18:3n-3); and SO(CLA), a mixture of sunflower oil and conjugated linoleic acids to provide 20% CLA. Treatments started 2 d after the first pubertal estrus (d -21) and lasted for 36 d (slaughter), which was 15 d after the second estrus (d 0; insemination). Fatty acids and PGE2 were measured in the peripheral blood plasma on d -19, d -7, d 0, and d 14. Fatty acids in endometrial tissues and PGE2 and PGF2alpha in the uterine fluid collected on d 15 were also measured. Concentrations of fatty acids in the plasma reflected the content of fatty acids in the diet as early as d -7. From d -7, PGE2 concentrations in the plasma were higher in gilts fed SO compared with HT (P < 0.05). Plasma PGE2 concentrations were lower (P < 0.01) on d 14 in gilts fed LO compared with HT. Total PGF2alpha contents in the uterine fluid of gilts fed LO were more than 70% lower (P < 0.05) than for the HT group. A similar trend was observed for total PGE2 content and for the ratio PGF2alpha:PGE2, but the effect (LO vs HT) was less marked (P < 0.07 and P < 0.10, respectively). There was no effect of SO or SO(CLA) on total PGE2 contents in the uterine fluid. Dietary enrichment in C18:2n-6 and/or C18:3n-3 for early pregnant gilts can influence fatty acids in plasma and endometrial tissue and can modulate circulatory and intrauterine prostaglandins.     

Effect of different fat sources on in vitro degradation of nutrients and certain blood parameters in sheep

This study was designed to determine the effects of calcium salt of palm oil fatty acids (CS), hydroxyethylsoyamide (HESA), butylsoyamide (BSA) and soybean oil (SO) on degradation of crude protein and fibre in vitro, and on the blood plasma lipid parameters in vivo. Five mature wethers (body weight 75 kg) were fed five diets in a 5 x 5 Latin square experiment. The control diet consisted of 50% meadow hay and 50% concentrate with no added fat. The control diet was supplemented with CS, HESA, BSA, or SO. Fat was added at 3.5% of dietary dry matter (DM). The final ether extract content of the ration was near 6%. Each period lasted 20 days. Fat supplements, except HESA, consistently decreased the in vitro DM disappearance of soybean meal as compared to control. In contrast to the effect of other treatments, crude protein degradation was greatest in the test tubes with inocula obtained from sheep fed diet with HESA. Fat supplements equally inhibited the DM and fibre breakdown of alfalfa pellet. CS and HESA seemed to be less detrimental to in vitro fermentation of neutral detergent fibre (NDF) than BSA and SO. All fat supplements increased blood plasma triglyceride, cholesterol and total lipid content. Plasma concentration of cholesterol and total lipid was highest with SO. The inclusion of CS in the diet increased 16:0, while all fat supplements increased plasma 18:0 and decreased 16:1 and 18:1 fatty acid content. Plasma 18:2n-6 was not changed by feeding CS and SO. However, compared to the control diet, 18:2n-6 increased with 12 and 41% in plasma fatty acids when sheep were fed HESA and BSA, respectively. The results showed that plasma concentration of linoleic acid was enhanced more when the amide was synthesised from butylamine than when from ethanolamine.     

Leukoencephalomyelopathy in cats linked to abnormal fatty acid composition of the white matter of the spinal cord and of irradiated dry cat food

Four outbreaks of leukoencephalomyelopathy in colonies of SPF cats on a long‐term diet of irradiated dry cat food were observed in the Netherlands between 1989 and 2001. As a primary defect in myelin formation was suspected to be the cause of the disease and myelin consists mainly of lipids and their fatty acids, we investigated the fatty acid composition of the white matter of the spinal cord of affected and control cats and of irradiated and non‐irradiated food. The irradiated food had low levels of alpha‐linolenic acid compared to linoleic acid as well as a high total omega‐6:omega‐3 ratio of 7:1 in the irradiated and of 2:1 in the non‐irradiated food. The white matter of the spinal cord showed low levels of linoleic acid and absence of alpha‐linolenic acid in affected cats as well as absence of lignoceric and nervonic acid in both affected and control cats. These abnormalities in fatty acid composition of the white matter of the spinal cord may reflect an increased need for alpha‐linolenic acid as a substrate for longer chain omega‐3 fatty acids to compose myelin and thus indicate a particular species sensitivity to dietary deficiency in omega‐3 polyunsaturated fatty acids, particularly alpha‐linolenic acid in cats. Our findings indicate that abnormalities in fatty acid metabolism in myelin play an essential role in the pathogenesis of this acquired form of leukoencephalomyelopathy in cats.     

不同种类多不饱和脂肪酸对产蛋鸡抗体产生和淋巴细胞增殖的影响

选用360只60～70周龄海兰褐蛋鸡,研究不同种类的多不饱和脂肪酸(PUFA)在不同添加水平下对产蛋鸡免疫功能的影响。试验共设10个处理,其中n-3PUFA的来源分别为亚麻籽油和鱼油,在日粮中的添加水平分别为20、40、60和10、30、50g/kg。n-6PUFA的来源为玉米油,在日粮中的添加量为20、40和60g/kg,另设一处理为不添加脂肪酸的对照组。在试验开始后的第5周和第7周分别给每个处理组中的6只鸡注射牛血清白蛋白抗原(BSA)和绵羊红细胞(SRBC),并分别于注射后第6,10,14天和第5,9,13天翅静脉采血,测定BSA抗体效价和SRBC抗体滴度。在试验开始后的第5周和第10周,采血测定外周全血淋巴细胞增殖速度,同时每个处理杀3只鸡,取脾脏制备单核细胞,测定其增殖速度。试验结果表明,日粮中添加PUFA具有提高产蛋鸡一免及二免BSA抗体和SRBC抗体产量的趋势,并呈现剂量依赖性。其中高鱼油添加组在一免10天时能显著(P<0.05)提高SRBC抗体滴度,二免后高鱼油添加组和高亚麻籽油添加组都能够显著(P<0.10)提高SRBC抗体滴度;对于BSA抗体效价,高n-3PUFA添加组都能够显著(P<0.10)提高。产蛋鸡外周全血淋巴细胞和脾脏单核细胞增殖速度在饲喂添加高n-3PUFA日粮后受到明显抑制。鱼油来源的n-3PUFA对产蛋鸡免疫功能影响程度比亚麻籽油的大。     

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.     

Humoral immunity in the ewe. 1. The influence of adjuvancy and immunogenic substitution on immune reactivity following immunisation with protein antigens

The nature of antigen and presence of adjuvant are major factors which influence the level of immune reactivity following immunisation. This study examines the quantity and isotype of antibody produced in ewes immunised with different proteins in combination with different adjuvants. Results using indirect ELISA assays show that animals immunised with keyhole limpet haemocyanin (KLH) in adjuvant produced lower levels (P less than 0.05) of immunoglobulin M (IgM) and had increased levels and persistence of immunoglobulin G1 (IgG1) compared with ewes immunised with antigen in saline (P less than 0.005). The anti-KLH immunoglobulin G2 (IgG2) titre was significantly higher in animals given oil-emulsion adjuvant than all other groups (P less than 0.005). Ewes were also immunised with bovine serum albumin (BSA) or BSA haptenated with trinitrophenyl (TNP) for the primary injection and carrier BSA alone for the secondary inoculation. Chemical haptenation of BSA antigen reduced primary IgM (P less than 0.005), IgG1 (P less than 0.005) and IgG2 (P less than 0.005) levels compared with animals immunised with pure BSA. There was an increased secondary anti-BSA IgM response in all animals first immunised with TNP-BSA (P less than 0.05). The class of anti-hapten antibody produced to TNP determinants was influenced by the degree of TNP haptenation of the carrier BSA. Mid-range molar ratios of TNP produced the strongest IgM, IgG1 and IgG2 anti-TNP responses compared with all other groups (P less than 0.01).     

瘤胃保护共轭亚油酸和亚油酸对奶牛产奶性能的影响

选择健康、泌乳月份与产奶量相近的多胎荷斯坦泌乳牛20头,随机分成5组,每组4头,研究日粮中添加商业来源的瘤胃保护共轭亚油酸钙盐(Ca-CLA)同时添加自然来源亚油酸(葵花油)对奶牛生产性能的影响。试验期为52d。对照组基础日粮为60%粗饲料(苜蓿、羊草、青贮)和40%精料(以DM为基础),处理组在对照组日粮基础上分别添加Ca-CLA100g/d·头(CLA)、葵花油350g/d·头(Sunf);Ca-CLA100g/d·头 葵花油350g/d·头(CLA Sunf),Ca-CLA50g/d·头 葵花油175g/d·头(1/2CLA 1/2Sunf)。结果表明:在奶牛日粮中,单独添加自然来源亚油酸产奶量较对照组差异不显著(P>0.05),而单独添加共轭亚油酸钙盐或与自然来源亚油酸高低不同剂量添加产奶量较对照组都分别显著提高2.20%、9.95%、11.16%,无论单独添加自然来源亚油酸或Ca-CLA或二者以高低不同剂量同时添加,牛奶的乳脂率较对照组都分别显著降低15.0%,6.24%,21.74%,14.35%。总之,奶牛日粮中同时添加Ca-CLA和自然来源亚油酸能显著提高产奶量,降低乳脂率,并且,减少Ca-CLA的添加量同时添加自然来源亚油酸可以达到高剂量添加Ca-CLA相同的效果。     

Effect of diets containing linoleic acid- or oleic acid-rich oils on ruminal fermentation and nutrient digestibility, and performance and fatty acid composition of adipose and muscle tissues of finishing cattle

Two trials were conducted to determine the effect of linoleic acid- or oleic acid-rich safflower oil on ruminal fermentation, nutrient digestion, feedlot performance, carcass characteristics, and fatty acid composition of adipose and muscle tissues of beef cattle. In both trials, cattle were fed a finishing diet based on barley grain, wheat silage, and alfalfa hay. Oils were fed at 5% of dietary DM. In a metabolism trial, four ruminally and duodenally cannulated Angus crossbred steers were subjected to linoleic acid-rich oil or oleic acid-rich oil in a crossover design with covariate periods (no oil supplementation). In a finishing trial, 16 individually fed Angus crossbred steers and heifers (eight per diet) received linoleic acid- or oleic acid-rich oils during the last 86 d of a 116-d feeding period. Ruminal pH, ammonia concentration, protozoal counts, major VFA concentrations, acetate-to-propionate ratio, polysaccharide-degrading activities, microbial N flow to the duodenum, and the efficiency of microbial N synthesis in the rumen were not affected (P = 0.18 to 0.96) by type of oil. Type of oil had no effect on total-tract apparent digestion of nutrients (P = 0.46 to 0.98). Ruminal true nutrient digestibilities did not differ between oils (P = 0.15 to 0.99), except that the linoleic acid-rich oil decreased (P = 0.05) NDF digestibility. Dry matter intake, ADG, G:F, and carcass characteristics did not differ (P = 0.11 to 0.84) between the two oils. Overall, the difference in dietary fatty acids provided to the cattle produced few changes in tissue fatty acids. Weight percentages of c9t11 CLA were unaltered by the addition of linoleic acid to the diet compared with oleic acid, probably as a result of low vaccenic acid production in the rumen, as the pathway of biohydrogenation was apparently primarily through the t10 pathway.     

Effect of dietary α -tocopherol concentration on performance and some immune responses in broiler chickens fed on diets containing oils from different sources

1. An investigation was carried out into the effects of dietary α-tocopherol (α-T) concentration and source of supplemental oil on performance, activity of anti-oxidative enzymes and some immune responses in broilers from day-old to 41 d of age. 2. Three dietary concentrations of α-T (10, 50 and 100 mg/kg) with three sources of supplemental oil (sunflower - SFO, palm - PMO and safflower - SAO) were provided using a 3 × 3 experimental design. 3. Body weight gain and food conversion efficiency were not affected by either interaction or concentrations of α-T and sources of oil in diet. 4. Concentrations of total protein, globulin, triglycerides and cholesterol in sera increased significantly with dietary α-T concentration irrespective of the source of oil. Significantly higher concentration of serum albumin was evident in broilers fed on the SFO-based diet and the concentration of globulin was higher in groups fed on those diets containing PMO and SAO. 5. The lipid peroxidation (LP), measured as MDA release, decreased with the concentration of α-T in a dose-related manner with SFO- and SAO-based diets, although not with the PMO-based diet. With different oil sources, LP was significantly lower with the PMO-based diet compared to the others. Activities of glutathione peroxidase and RBC catalase increased and heterophil: lymphocyte ratio was reduced with concentration of α-T for each source of oil tested. 6. Assays for humoral and cell-mediated immune responses indicated no effect of the source of dietary supplemental oil or interaction, although an increasing concentration of dietary α-T improved cell-mediated immune responses. 7. It is concluded that sunflower oil, palm oil and safflower oil can be used as sources of oil for broiler diets without having any effect on performance, immune responses or the activity of anti-oxidizing enzymes. Higher concentrations of dietary α-tocopherol (50 or 100 mg/kg) reduced lipid peroxidation activity and enhanced activities of anti-oxidative enzymes, they also improved the cell-mediated immune responses in commercial broilers.     

Brain, liver and plasma unsaturated aldehydes in nutritional encephalomalacia of chicks

Vitamin E deficiency and linoleic acid-feeding lead to nutritional encephalomalacia (NE) in chicks, affecting the cerebellum exclusively. The relevance of lipid peroxidation (LPO) products to the pathogenesis of the disease was studied. Laying hens received a diet low in vitamin E. Resulting chicks were assigned to four groups fed either with linoleic (C18: 2n-6) or linolenic (C18: 3n-3) acid together with 1 or 50 p.p.m. vitamin E. Nine days post-hatching NE occurred in the vitamin E-deficient group fed linoleic acid. With each chick showing NE, a healthy one from all four groups was killed. Unsaturated aldehydes were determined in plasma, liver, cerebrum and cerebellum. Results underlined that the type of dietary fat is decisive for the aldehyde pattern. In the liver of linoleic acid-fed animals total aldehydes were increased. Diseased animals had increased aldehydes stemming from n-3 fatty acids. In plasma, vitamin E deficiency led to higher malondialdehyde and OH-nonenal concentrations. In brain, neither vitamin E deficiency nor NE were accompanied by increased aldehyde concentrations. In consequence a direct role of unsaturated aldehydes for the development of NE in the cerebellum is not probable.     

Effect of dietary omega-3 fatty acids on red blood cell lipid composition and plasma metabolites in the cockatiel, Nymphicus hollandicus

Although dietary n-3 fatty acids have been extensively studied in poultry, they have not yet been prospectively investigated in psittacines, despite potential benefits for preventing and treating atherosclerosis, osteoarthritis, and other chronic disease processes. The objectives of this study were to investigate the incorporation of dietary n-3 fatty acids into red blood cells (RBC) and to determine the effects of supplementation of psittacine diets with fish or flax oil on plasma lipids and lipoproteins in the cockatiel. Adult cockatiels were fed a custom-formulated diet containing either 4% (wt/wt, as-fed) beef tallow (CON), 3% fish oil + 1% tallow (FSH), or 3.5% flax oil + 0.5% tallow (FLX; n = 20 per diet group). Baseline measurements were obtained for RBC fatty acid composition, triacylglycerides (TAG), and cholesterol. After 8 to 13 wk on the study diets, plasma chemistry profiles, lipoprotein density profiles, and RBC fatty acid composition were determined. At 8 wk, total plasma cholesterol was least in FSH birds (P < 0.05) and TAG concentrations were less in FSH birds than FLX birds (P < 0.05). Total n-3 fatty acids, docosahexaenoic acid, docosapentaenoic acid, and eicosapentaenoic acid were markedly greater in the RBC of FSH birds than FLX or CON birds (P < 0.05). Alpha linolenic acid was greatest in FLX (P < 0.05). Initial and final BW, and nonlipid plasma chemistry values did not differ among diet groups. No adverse effects of dietary supplementation of cockatiels with 3.5% flax oil or 3% fish oil were observed during the 13-wk feeding period. Although fish and flax oils provided similar total n-3 PUFA to the diets, fish oil caused greater reductions in cholesterol and TAG, and greater total RBC n-3 incorporation. Thus, dietary modification of psittacine diets with long chain n-3 PUFA from fish oil appears safe and may be beneficial to these long-lived companion birds.