Interactions and antigen dependence of dietary n-3 and n-6 polyunsaturated fatty acids on antibody responsiveness in growing layer hens

Impact of dietary supplementation of unsaturated and saturated fatty acids on bone strength, fatty acids profile of thigh muscle and immune responses in broiler chickens under heat stress

BACKGROUND

There have been some reports that supplementation of fat could alleviate the negative effects of heat stress on performance in broilers. However, information regarding compensation for the adverse effects of heat stress with diets differing in fatty acids source on immune system, bone strength and carcass quality of heat-distressed broilers is limited.

OBJECTIVES

The objective of this study was to investigate the effects of diets differing in fat source on performance, immune system, bone strength, and carcass quality of heat-distressed broilers.

METHODS

In a completely randomized design with 4 × 2 factorial arrangement of the treatments, 320 24-day-old Ross 308 chickens, with average initial weight of 1220 ± 10 g were divided into eight treatments included sesame oil, tallow, sunflower oil and palm oil in either 22 or 32 degree of centigrade temperature. The broiler performance of each fat source-treated group was not different in this experiment and decreased significantly in heat stress condition.

RESULTS

Heat stress showed a significant increase on fat, energy and ash content of thigh muscle. Tibia absolute length, width, ash and bone breaking strength were affected by fat source and increased when sesame and sunflower oil were used. Data analysis revealed that hot temperature decreased tibia weight, length, width, ash and bone breaking strength. Heat stress led to decrease of immune system parameters.

CONCLUSION

Results suggest that there is no beneficial effect of broiler performance due to adding different sources of fat in broiler chicken diet under hot condition. Furthermore, the unsaturated fatty acids could improve the profile of fatty acids in thigh and enhance immune responses in broiler chickens.

Rubber (Hevea brasiliensis) seed oil supplementation attenuates immunological stress and inflammatory response in lipopolysaccharide-challenged laying hens

This study was conducted to investigate the effect of PUFA-enriched rubber (Hevea brasiliensis) seed oil (RSO) supplementation in diets on the productive performance, plasma biochemical parameters, immune response, and inflammation in lipopolysaccharide (LPS)-challenged laying hens. Two hundred and forty 25-wk-old Lohmann Brown laying hens were randomly divided into 5 treatments, each including 4 replicates with 12 birds per replicate. The control group and LPS-challenged group were fed a corn-soybean-basal diet; 3 RSO-supplemented groups were fed experimental diets containing 1, 2, and 4% RSO for a feeding period of 4 wk. On the 15, 18, 21, 24, and 27 d of the RSO supplementation period of 4 wk, hens were injected intraperitoneally with LPS at 1 mg/kg body weight (challenge group and RSO-supplemented groups) or with the same amount of saline (control group). The results showed that the addition of RSO promoted laying performance by increasing egg production, total egg weight, daily egg mass, and feed intake in comparison to the LPS-challenged laying hens (P < 0.05). In addition, compared with laying hens stimulated with LPS, the analysis of blood cell and plasma parameters revealed that hens in RSO-supplemented groups had significantly lower levels (P < 0.05) of white blood cells (WBC), lymphocytes (LYM), aspartate aminotransferase (AST) activity, immunoglobulin A (IgA), triiodothyronine (T3), interleukin-2 (IL-2), and tumor necrosis factor-α (TNF-α). Further, RSO supplementation significantly reduced the mRNA expression of toll-like receptor 4 (TLR4), nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), interleukin-6 (IL-6), and interleukin-1β (IL-1β) of the ileum, spleen, and liver in LPS-challenged laying hens (P < 0.05), suggesting that the anti-inflammatory mechanism of RSO is related to the TLR4/NF-κB signaling pathway. In conclusion, RSO supplementation in diets could improve laying performance, attenuate immunological stress, and inhibit the inflammatory response in LPS-challenged laying hens, especially at the dietary inclusion of 4% RSO. This study will provide an insight into the application of RSO to positively contribute to overall health and welfare in laying hens.

Changes in the growth, ileal digestibility, intestinal histology, behavior, fatty acid composition of the breast muscles, and blood biochemical parameters of broiler chickens by dietary inclusion of safflower oil and vitamin C

BACKGROUND

The effects of safflower oil and vitamin C (Vit. C) inclusion in broiler chicken diets on the growth performance, apparent ileal digestibility coefficient "AID%" of amino acids, intestinal histology, behavior, carcass traits, fatty acid composition of the breast muscle, antioxidant and immune status for a 35-day feeding period were evaluated. A total of 300 three-day-old Ross chicks (58.25 g ± 0.19) were randomly allotted in a 2 × 3 factorial design consisting of two levels of vitamin C (0 and 400 mg/kg diet) and three levels of safflower oil (0, 5, and 10 g/kg diet).

RESULTS

An increase in the final body weight, total body weight gain, total feed intake, and the relative growth rate (P <  0.05) were reported by safflower oil and vitamin C inclusion. Dietary supplementation of safflower oil and vitamin C had a positive effect (P <  0.05) on the ingestive, resting, and feather preening behavior. Vitamin C supplementation increased (P <  0.05) the AID% of lysine, threonine, tryptophan, arginine, and valine. Safflower inclusion (10 g/kg) increased (P <  0.05) the AID% of methionine and isoleucine. Safflower oil inclusion increased (P <  0.05) the levels of stearic acid, linoleic acid, saturated fatty acids, and omega-3 fatty acids (ω-3) in the breast muscle. In contrast, the supplementation of only 10 g of safflower oil/kg diet increased (P = 0.01) the omega-3/omega-6 (ω-3/ω-6) fatty acids ratio. Vit. C supplementation increased (P <  0.05) the CAT serum levels, SOD, and GSH enzymes. Dietary supplementation of safflower oil and vitamin C improved the intestinal histology. They increased the villous height and width, crypt depth, villous height/crypt depth ratio, mucosal thickness, goblet cell count, and intra-epithelium lymphocytic lick cell infiltrations. The serum levels of IgA and complement C3 were increased (P <  0.01) by Vit. C supplementation and prominent in the 400 vit. C +  10 safflower Oil group.

CONCLUSION

A dietary combination of safflower oil and vitamin C resulted in improved growth rate, amino acids AID%, intestinal histology, welfare, immune and antioxidant status of birds, and obtaining ω-3 and linoleic acid-enriched breast muscles. The best inclusion level was 400 vit. C +  10 safflower Oil.

Impact of feeding n-3 fatty acids to layer breeders and their offspring on concentration of antibody titres against infectious bronchitis, and Newcastle diseases and plasma fatty acids in the offspring

1. The impact of feeding sources of n-3 fatty acids (FA) to ISA Brown and Shaver White breeders and their offspring on antibody titres and plasma FA profile was examined.2. Breeders were fed either a control diet (CON); CON + 1% microalgae (DMA: Aurantiochytrium limacinum) as a source of docosahexaenoic acid; or CON + 2.6% of a co-extruded mixture of full-fat flaxseed (FFF) as a source of α-linolenic acid. Day-old female offspring were assigned to diets (breeder-offspring): 1) CON-CON, 2) CON-DMA, 3) CON - FFF, 4) DMA - CON, 5) DMA - DMA, 6) FFF - CON or 7) FFF - FFF, followed by a standard layer diet through 18 weeks of age (WOA) to 42 WOA.3. Antibody titres against infectious bronchitis (IBV) and Newcastle disease (NDV) were measured at six days and six WOA, and plasma FA profile was measured at 18 and 42 WOA.4. Pullets from FFF-fed breeders had higher antibody titres against IBV and NDV than pullets fed DMA (P < 0.05). Feeding FFF to offspring increased plasma ∑n-3 FA at 18 and 42 WOA, whereas feeding DMA to offspring reduced ∑n-6 FA at 18 WOA.5. In conclusion, independent of breeder strain, alpha linoleic acid (ALA) and DHA sources showed varied responses. Feeding breeders FFF increased plasma concentration of antibody titres and n-3 FA whereas DMA reduced plasma concentration of ∑n-6 FA.

Comparison of different dietary sources of n-3 polyunsaturated fatty acids on immune response in broiler chickens

The study aims to research the effects of varied dietary sources of n-3 polyunsaturated fatty acids (PUFA) on the immune response in broiler chickens with stress on natural killer (NK) cell activity. Diets supplemented with one of the four sources of n-3 PUFA: linseed oil-, echium oil-, fish oil (FO) or algal biomass-enriched diets at levels of 18, 18, 50 and 15 g/kg fresh weight, were provided for one-d-old male Ross 308 broilers, totaling 340 in number, until they were slaughtered. The analyses included total lipid profile using gas chromatography (GC) for plasma, spleen, thymus, and blood. Additionally, NK cell activity and cell proliferation were investigated for thymocytes and splenocytes. The results indicated that the source of n-3 PUFA had a strong influence on fatty acid composition across all tissues. NK activity was highest in splenocytes and PBMCs from broilers fed linseed oil, followed by those fed algal biomass or echium oil, and lowest for those from broilers fed FO. The proliferative response of lymphocytes from algal biomass-fed chickens tended to be the highest, followed by those fed linseed oil in most cases. Lymphocytes from chickens fed fish oil showed the lowest proliferative response. These results could mean that a docosahexaenoic acid (DHA)-rich algal product might enrich chicken meat with n-3 PUFA without significant damaging effects on chicken immunity.

The growing feather as a dermal test site: Comparison of leukocyte profiles during the response to Mycobacterium butyricum in growing feathers, wattles, and wing webs

Using the response to Mycobacterium butyricum as the test-immune response, the main goal of this study was to demonstrate the suitability of the growing feather (GF) as a dermal test site and window into in vivo cellular/tissue responses (US-Patent 8,216,551). Using M. butyricum immunized chickens, the specific objectives were to: 1) compare the leukocyte infiltration response to intra-dermally injected M. butyricum in GF, wattles, and wing webs; 2) use GF as the test site to monitor leukocyte response profiles to recall antigen in the same individuals; and 3) gain new knowledge regarding the local response to M. butyricum in chickens. For objective 1, chickens were euthanized for tissue collection at 4 to 6, 24, 48, and 72 h after intra-dermal antigen injection. Leukocyte infiltration profiles were determined using immunochemical and conventional histology. Data from this study established the similarities between the cellular response in GF, wattles, and wing webs and uncovered many advantages of working with GF. For objective 2, antigen was injected into multiple GF per individual. GF were collected before and at 0.25, 1, 2, 3, and 7 d post injection and processed for cell population analysis by flow cytometry. Advantages of the approach used in objective 2 included a technically easier, more comprehensive, and more objective leukocyte profile analysis; same-day data acquisition; and, most importantly, easy, minimally invasive sample collection from the same individual throughout the study. Both studies contributed new knowledge regarding the local cutaneous response to M. butyricum in M. butyricum immunized chickens and confirmed the cell-mediated nature of the immune response to M. butyricum (e.g., elevated levels [P < 0.05] of T cells [CD4+ and CD8+], macrophages and MHC class II+-cells on days one to 3 post injection in M. butyricum- compared to PBS-injected tissues). The use of GF as an "in vivo test tube" to monitor local innate and adaptive immune activities will find direct application in vaccine development, as well as in the assessment and optimization of immune system development and function in poultry.

Effect of dietary combination of methionine and fish oil on cellular immunity and plasma fatty acids in infectious bursal disease challenged chickens

This study was carried out to investigate the modulatory effects of dietary methionine and fish oil on immune response, plasma fatty acid profile, and blood parameters of infectious bursal disease (IBD) challenged broiler chickens. A total of 300 one-day-old male broiler chicks were assigned to one of six dietary treatment groups in a 3 × 2 factorial arrangement. There were three levels of fish oil (0, 2.5 and 5.5%), and two levels of methionine (NRC recommendation and twice NRC recommendation). The results showed that the birds fed with 5.5% fish oil had higher total protein, white blood cell count, and IL-2 concentration than those of other groups at 7 days after IBD challenge. Inclusion of fish oil in diet had no effect on IFN- γ concentration. However, supplementation of methionine twice the recommendation enhanced the serum IFN- γ and globulin concentration. Neither of fish oil nor methionine supplementation affected the liver enzymes concentration. It can be suggested that a balance of moderate level of fish oil (2.5%) and methionine level (twice NRC recommendation) might enhance immune response in IBD challenged broiler chickens.

Effect of n-3 fatty acids on immune function in broiler chickens

There is interest in the enrichment of poultry meat with long-chain n-3 polyunsaturated fatty acids in order to increase the consumption of these fatty acids by humans. However, there is concern that high levels of n-3 polyunsaturated fatty acids may have detrimental effects on immune function in chickens. The effect of feeding increasing levels of fish oil (FO) on immune function was investigated in broiler chickens. Three-week-old broilers were fed 1 of 4 wheat-soybean basal diets that contained 0, 30, 50, or 60 g/kg of FO until slaughter. At slaughter, samples of blood, bursa of Fabricius, spleen, and thymus were collected from each bird. A range of immune parameters, including immune tissue weight, immuno-phenotyping, phagocytosis, and cell proliferation, were assessed. The pattern of fatty acid incorporation reflected the fatty acid composition of the diet. The FO did not affect the weight of the spleen, but it did increase thymus weight when fed at 50 g/kg (P < 0.001). Fish oil also lowered bursal weights when fed at 50 or 60 g/kg (P < 0.001). There was no significant effect of FO on immune cell phenotypes in the spleen, thymus, bursa, or blood. Feeding 60 g/kg of FO significantly decreased the percentage of monocytes engaged in phagocytosis, but it increased their mean fluorescence intensity relative to that of broilers fed 50 g/kg of FO. Lymphocyte proliferation was significantly decreased after feeding broiler chickens diets rich in FO when expressed as division index or proliferation index, although there was no significant effect of FO on the percentage of divided cells. In conclusion, dietary n-3 polyunsaturated fatty acids decrease phagocytosis and lymphocyte proliferation in broiler chickens, highlighting the need for the poultry industry to consider the health status of poultry when poultry meat is being enriched with FO.

Effects of dietary n-6:n-3 ratio on immune and reproductive systems of pullet chicks

The objective of this study was to examine the effects of dietary n-6:n-3 ratio on immune and reproduction systems of Leghorn pullet chicks. A total of 216 Hy-Line W-36 pullet chicks (1 d old) were randomly assigned to 3 diets (n-6:n-3 ratios of 10, 6, and 2) until 22 wk of age. The Optomega-50 (Optivite International Ltd., Nottinghamshire, UK) containing 50% salmon fish oil was used as an n-3 source. Pullets were injected with SRBC suspension at 6 and 9 wk and anti-SRBC titers were measured 7 and 14 d after each immunization. The antibody (Ab) titers for Newcastle disease (ND), avian influenza, infectious bronchitis (IB), and infectious bursal disease (IBD) were determined at 4, 6, 10, 14, and 18 wk of age. Pullets fed diet with the n-6:n-3 ratio of 2 had higher feed consumption and lower BW gain (P < 0.05) compared those fed diets with the ratios of 6 and 10. The results demonstrated that the different dietary n-6:n-3 ratios did not have a significant effect on the anti-SRBC titers in pullets serum (P > 0.05). The Ab production against avian influenza vaccine was increased in pullets fed diet containing the n-6:n-3 ratio of 10 at wk 10 and 14 and increased for ND at only 14 wk (P < 0.05). On the other hand, the Ab response to IBD (14 wk) and IB (14 wk) vaccines was increased when pullets were fed diet containing a ratio of 6 (P < 0.05). The pullets fed diet with the n-6:n-3 ratio of 2 showed lower egg production and late sexual maturity (P > 0.05) whereas ovary weight (P = 0.01) and number of large yellow follicles (P = 0.049) were significantly decreased at first oviposition. Our results revealed that the supplementation of Optomega-50 as a source of n-3 to decrease the n-6:n-3 ratio in diet significantly increased Ab production for ND, IB, and IBD in pullet chicks with slight reduction in reproductive organs weight at early production.

Avian hepatitis E virus in an outbreak of hepatitis–splenomegaly syndrome and fatty liver haemorrhage syndrome in two flaxseed-fed layer flocks in Ontario

Two commercial layer chicken flocks that were fed a flax-based diet beginning at 28 weeks of age for the production of omega-3 fatty-acid-enriched eggs experienced increased mortality when the birds reached 37 weeks. The average weekly mortality was 0.34% over a 20-week period, with peak mortality of 0.9% for 1 week. Reduced feed consumption, reduced body weight gain and poor peak production were noticed prior to the onset of increased mortality. A total of 245 birds were necropsied and 78% of these had lesions in the liver and spleen, with 44% of those necropsied having changes consistent with hepatitis-splenomegaly syndrome, with lesions ranging from acute periportal lymphoplasmacytic hepatitis to chronic severe cholangiohepatitis with haemorrhage, vasculitis and amyloidosis. A total of 11% of the birds had lesions typical of fatty liver haemorrhagic syndrome, and 22% had lesions found in both hepatitis-splenomegaly syndrome and fatty liver haemorrhagic syndrome. No significant bacteria or viruses were recovered from samples of the liver/bile or spleen but 11 of 21 bile samples contained avian hepatitis E virus RNA detectable with a reverse transcriptase-polymerase chain reaction assay. Comparative sequence analysis found identities of 82 to 92% and 78 to 80% between the helicase and capsid protein genes, respectively, of the virus detected in this outbreak and those of other avian hepatitis E virus isolates, suggesting extensive genetic heterogeneity in avian hepatitis E viruses in Ontario flocks.

Dietary lutein and fat interact to modify macrophage properties in chicks hatched from carotenoid deplete or replete eggs

Two experiments were conducted to study the interaction between dietary lutein and fat levels in broiler chicks hatched from lutein depleted (Experiment I) and repleted (Experiment II) eggs. In both experiments, a 2 x 3 factorial arrangement of treatments resulted in six dietary treatments (fat at 3% and 6% and lutein at 0, 25 and 50 mg/kg feed) that were fed for 23 days to 18 birds per treatment (in three replications). In Experiment I, the anti-dinitrophenyl-keyhole-lympet-hemocyanin (anti-DNP-KLM) serum antibody response at day 22 and macrophage phagocytotic index at day 17 did not differ among treatment groups (p > 0.05). The concavalin A and phytohaemagglutinin-P lymphocyte proliferation index at day 19 was greater in birds fed 50 mg of lutein and 3% fat than in birds fed all other diets (p < 0.05). Independent of the level of dietary fat, dietary lutein increased macrophage (day 23) nitrite production measured 46 h after in vitro stimulation with LPS (p < 0.05). Among the birds fed lutein at 25 or 50 mg/kg feed, birds fed 3% fat had higher LPS-induced nitrite production compared to the birds fed 6% fat after 46 (p = 0.014) or 70 h (p < 0.001). In Experiment II, macrophage nitrite production was measured at 54 h after LPS stimulation on days 11, 15, 19 and 23. An interaction between dietary lutein and fat levels on nitrite production was observed on day 19 (p = 0.012), where macrophages from birds fed 0 mg lutein and 3% fat had the highest nitrite production (p = 0.012). Macrophages from birds fed lutein at 25 and 50 mg/kg diet and 3% fat had higher (p = 0.012) nitrite production than birds fed 6% fat. Thus, in birds hatched from lutein deplete and replete eggs, modulation of macrophage nitrite production by lutein is dependent on the level of dietary fat.

Dietary 18:3ω3 influences immune function and the tissue fatty acid response to antigens and adjuvant

Alpha-linolenic acid (18:3omega3) has many important physiological functions including being beta-oxidized, serving a precursor to the synthesis of other lipids and it has immunomodulation properties. The objective of the present study was to test the effects of immunization and dietary 18:3omega3 on immune function and the fatty acid profile of immunized pig tissues. Piglets suckled from sows consuming either a control or high 18:3omega3 diet until 14 days old when they were weaned onto a similar diet as the sow and were moved to a segregated nursery for the remainder of the study. At 35 days of age, pigs on both diets (2 x 2 factorial design) received either an injection containing hen eggwhite lysozyme (HEWL), killed Mycobacterium tuberculosis and Freund's complete adjuvant (immunized) or phosphate buffered saline (PBS) (non-immunized) into the neck followed by a booster injection 2 weeks later and induction of delayed-type hypersensitivity (DTH) one week later. Immunization increased (compared to non-immunized) while the high 18:3omega3 diet decreased haptoglobin by 30% compared to pigs consuming the control diet. Immunized pigs had a seven-fold increase in antibodies to HEWL and pigs consuming the high 18:3omega3 diet also had transiently higher levels of serum antibodies. There was a diet by immunization interaction on the DTH reaction such that immunized pigs consuming the high 18:3omega3 had the largest DTH reaction. The neck muscle proximal to the site of injection of immunized pigs had 10-30% lower levels of triglyceride and phospholipid linoleic (18:2omega6) and 18:3omega3 compared to non-immunized pigs. Thus, a high 18:3omega3 intake in pigs modulates immune function and tissue fatty acids in response to immunization.

Detection of different quantitative trait loci for antibody responses to keyhole lympet hemocyanin and Mycobacterium butyricum in two unrelated populations of laying hens

Quantitative trait loci involved in the primary antibody response to keyhole lympet hemocyanin (KLH) and Mycobacterium butyricum were detected in two independent populations of laying hens. The first population was an F2 cross (H/L) of lines divergently selected for either high or low primary antibody responses to SRBC, and the second population was an F2 cross between 2 commercial layer lines displaying differences in feather pecking behavior (FP). Both populations were typed with microsatellite markers widely distributed over the genome with similar intervals between markers. Titers of antibodies binding KLH and M. butyricum were measured for all individuals by ELISA. Two genetic models were applied to detect QTL involved in the humoral immune response: a half-sib model and a line-cross model, both using the regression interval method. In the half-sib analysis, 2 QTL (on GGA14 and GGA27) were detected for the antibody response to KLH for the H/L population, and 2 QTL (on GGA14 and GGA18) were detected for the FP population. Only 1 QTL was detected for M. butyricum on GGA14 in the FP population using the half-sib analysis model. Two QTL were detected for the FP population on GGA2 and GGA3 using the line-cross analysis model. A QTL for the primary antibody response to KLH detected on GGA14 was validated in both populations under the half-sib analysis model. The present data suggest differences in the genetic regulation of antibody responses to two different T-cell dependent antigens.

Early in vivo cytokine genes expression in chickens after challenge with Salmonella typhimurium lipopolysaccharide and modulation by dietary n--3 polyunsaturated fatty acids

We studied the effects of Salmonella typhimurium lipopolysaccharide (LPS) on in vivo cytokine mRNA levels in chickens, and investigated whether these levels could be altered by different nutrients. Two hundred and forty chicks were assigned in a 2 x 4 factorial design of treatments. Factors were intravenous injection with S. typhimurium LPS, or saline (control), and four dietary fat sources: corn oil (CO), linseed oil (LO), menhaden oil and beef tallow (BT). Two hours after injection birds were killed and their spleens removed for RNA extraction. Quantitative real-time RT-PCR assays for mRNA of chicken IFN-gamma, IL-6, IL-8, IL-15, IL-18 and 28S rRNA were used to obtain the in vivo splenic cytokine profiles. Expression levels of IL-6, IL-8, IL-18 and IFN-gamma mRNA increased, but IL-15 mRNA decreased 2h after challenge with LPS compared with saline controls. In saline-injected control chickens, the dietary oil source did not affect the splenic mRNA level of any cytokine. In LPS challenged chickens IFN-gamma mRNA was significantly higher in the chickens fed the fish oil enriched diet compared with the LO, CO and BT enriched diets. The present data imply that avian IL-15 has, at least partially, a different function compared to its mammalian counterpart, and in addition, chicken innate immune responses might be affected differently by n-3 PUFA compared to mammals.

Different sources of dietary n-6 polyunsaturated fatty acids and their effects on antibody responses in chickens

1. Effects of linoleic and linolenic acid provided via different oil sources on total antibody (Ab) titres, Ab isotypes after primary and secondary immunisation, and cutaneous hypersensitivity (CH) responses to bovine serum albumin (BSA) and maleyl-BSA, respectively, were studied in pullets fed on one of 4 diets. The diets were the basal control diet enriched with either sunflower oil or safflower oil as sources of linoleic acid, and linseed oil as a source of linolenic acid, tested against a control diet supplemented with animal fat. 2. Total Ab and immunoglobulin (Ig) isotype responses to BSA were affected by diet after primary, and diet x immunisation effects after secondary immunisation. Higher total Ab and IgG titres to BSA were found especially after primary immunisation in birds given the sunflower oil enriched diet, whereas birds given sunflower oil mounted significantly lower IgM titres to BSA after primary and secondary immunisation. The antibody responses to maleyl-BSA were affected by diet after primary, and immunisation x diet interactions after secondary immunisation. Sunflower oil enhanced total and IgG Ab titres to maleyl-BSA after primary immunisation, but decreased IgM titres to maleyl-BSA after primary and secondary immunisation. Cutaneous hypersensitivity responses to BSA and maleyl-BSA were not affected by the diet. 3. It is concluded that modulation of the magnitude and isotype of Ab responses of poultry to T cell-dependent antigens is affected not only by type of essential fatty acids, but also by their source. In the present study the n-6 source, sunflower oil, showed strong enhancement of primary Ab responses, directed to both Th2 and Th1 antigens. On the other hand, the different effects of safflower oil imply that constituents other than n-6 acids within dietary plant oils may affect immune responsiveness. 4. The relationship between magnitude and isotype of Ab responsiveness, type of antigen, and essential fatty acids is discussed.

Interactions of dietary polyunsaturated fatty acids and vitamin E with regard to vitamin E status, fat composition and antibody responsiveness in layer hens

1. Effects of dietary polyunsaturated fatty acids (PUFA) and vitamin E (VE) on an immune response may interact because VE may protect PUFA from in vivo oxidation. The present study was designed to study the presence of such an interaction in growing layer chickens. 2. Three dietary concentration of linoleic acid (LA, 3.3, 6.6 and 10%), in combination with 4 concentration of dietary VE (5, 20, 40 and 80 mg/kg) were used. Effects of LA and VE on circulating VE concentration, fatty acid composition of bursal and adipose fat, and antibody kinetics against keyhole limpet hemocyanin and Mycobacterim butyricum were established. 3. At high dietary LA concentration, bursal and adipose LA were higher but bursal arachidonic acid and long chain n-3 PUFA decreased. The dietary VE level did not consistently affect the deposition of PUFA in tissue. Plasma VE concentrations were affected by the dietary VE and LA content, but not by their interaction. Antibody responses before and 7 d after immunisation were affected by the dietary treatments. Antibody concentration were not affected by tissue fatty acid content. 4. In conclusion, the interaction effects of dietary PUFA and VE on fat deposition and immune responses are of minor importance compared to separate PUFA and VE effects. This implies that, within the studied range, adding extra VE to preserve or affect the effects of dietary PUFA on antibody responsiveness is unnecessary.