Diets high in n-3 fatty acids reduce cecal lesion scores in chickens infected with Eimeria tenella

n-3 enriched Fish oil diet enhanced intestinal barrier integrity in broilers after Eimeria infection

Coccidiosis caused by Eimeria spp. results in substantial economic losses in the poultry industry. The objective of this study was to investigate the effects of dietary supplementation with n-3 polyunsaturated fatty acids-enriched fish oil on growth performance, intestinal barrier integrity, and intestinal immune response of broilers challenged with Eimeria spp. A total of 576 fourteen-day-old broilers were randomly assigned in a completely randomized design with a 3 × 2 factorial arrangement, comprising 2 diets supplemented with either 5% fish oil or 5% soybean oil, and 3 Eimeria spp. infection levels: a nonchallenge control, a low dose of Eimeria challenge, and a high challenge dose. The results of the study revealed significant interactions between diet and Eimeria challenge to parameters of gut barrier integrity and feed intake. A significant interaction was observed in feed intake between 5 and 8 d postinfection (DPI), where the fish oil groups exhibited a higher amount of feed intake compared to the soybean oil diet groups after coccidiosis infection. The effects of the fish oil diet resulted in enhanced gut barrier integrity, as evidenced by a trend of decreased gastrointestinal leakage and a lower mean of small intestine lesion scores after Eimeria challenge. Additionally, significant interactions were noted between Eimeria spp. challenge and diet regarding jejunal crypt depth. The positive impact of the fish oil diet was particularly noticeable with the high Eimeria challenge dose. Overall, these findings underscore the relationship between the fish oil diet and Eimeria challenge on broiler chicken intestinal health. Dietary supplementation of fish oil has the potential to maintain small intestine barrier integrity with severe Eimeria infection conditions.

Administration of Ethanolic Extract of Spinacia oleracea Rich in Omega-3 Improves Oxidative Stress and Goblet Cells in Broiler Chickens Infected with Eimeria tenella

This study investigated the anticoccidial activity of spinach (Spinacia oleracea) whole-plant extract against Eimeria tenella, both in vitro and in vivo. For this purpose, one hundred 8-day-old broiler chicks of both sexes were divided into four groups (n = 25 in each group). Chicks in the first group served as the negative control (non-treated-non-infected). Chicks in the second group were challenged at 18 days old with 5 × 104E. tenella sporulated oocysts. The third group was challenged with 5 × 104 sporulated E. tenella oocysts at 18 days old after receiving spinach extract at a dose of 50 mg/kg at 8 days old. The fourth group received 0.2 mg/kg diclazuril (Coxiril® 0.2%) in their diet two days before being orally infected with 5 × 104 sporulated E. tenella oocysts and this continued till day 10 post-infection (PI). The growth performance, clinical symptoms, oocyst shedding, histological findings, and biochemical parameters were used to evaluate the efficacy on day 8 PI when the infection was at its peak. A gas chromatography examination revealed that omega-3 fatty acids were the main constituents of the spinach extract, followed by oleic acid, palmitic acid, and phytol, with amounts of 23.37%, 17.53%, 11.26%, and 7.97%, respectively. The in vitro investigation revealed that the spinach extract at concentrations of 10% and 5% inhibited the oocyst sporulation by 52.1% and 45.1%, respectively. The 5% concentration was selected for the in vivo trial based on the results of the in vitro study. The infected-untreated group showed high levels of OPG; lower body weight; a greater number of parasite stages; few goblet cells; decreased SOD, CAT, and GPX levels; and increased MDA and NO levels. The spinach-treated group, on the other hand, showed a significant decrease in oocyst output per gram of feces (OPG), increased body weight, decreased parasitic stages, and a nearly normal number of goblet cells. Additionally, it reduced malondialdehyde (MDA) and nitric oxide (NO), while increasing superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPX). In conclusion, spinach produced significant antioxidant effects, increased body weight, reduced the number of oocysts and parasite stages in the caecum, and restored the number of goblet cells relative to those of an uninfected control. Furthermore, spinach extract inhibits the sporulation percentage of E. tenella oocysts. The ethanolic extract of S. oleracea (whole plant) contained high concentrations of fatty acids, palmitic acid, Phytol, betulin, and ursolic aldehyde, all of which are known to regulate the antioxidant pathway and modulate inflammatory processes and may be the main reason for its anticoccidial activity.

The influence of nutrition on intestinal disease with emphasis on coccidiosis

Ever since the poultry industry began to intensify early last century, coccidiosis has been a significant problem with which it has had to contend. Losses due to mortality and morbidity can be significant and before the advent of control agents there were several practices, some of which were nutritional, which were implemented to limit these losses. The development of coccidiostats reduced these problems considerably and as a result some of the more extreme intervention measures were no longer necessary. Modern day interpretation of what may have been happening with some of these early interventions provide interesting insights into what may be possible today should cocciodiostats be removed. More recent research has also indicated that the diet has a significant influence on the ability of poultry to resist and resolve an infection through direct and indirect effects on the pathogen, the immune system and on the litter. This paper reviews the role of dietary ingredients and nutrients on the pathogen to establish and the host to resist such an infection. There is clearly no panacea, but the combination of a few practices may reduce the overall challenge experienced by the poultry producer.

Phytochemical control of poultry coccidiosis: a review

Avian coccidiosis is a major parasitic disorder in chickens resulting from the intracellular apicomplexan protozoa Eimeria that target the intestinal tract leading to a devastating disease. Eimeria life cycle is complex and consists of intra- and extracellular stages inducing a potent inflammatory response that results in tissue damage associated with oxidative stress and lipid peroxidation, diarrheal hemorrhage, poor growth, increased susceptibility to other disease agents, and in severe cases, mortality. Various anticoccidial drugs and vaccines have been used to prevent and control this disorder; however, many drawbacks have been reported. Drug residues concerning the consumers have directed research toward natural, safe, and effective alternative compounds. Phytochemical/herbal medicine is one of these natural alternatives to anticoccidial drugs, which is considered an attractive way to combat coccidiosis in compliance with the "anticoccidial chemical-free" regulations. The anticoccidial properties of several natural herbal products (or their extracts) have been reported. The effect of herbal additives on avian coccidiosis is based on diminishing the oocyst output through inhibition or impairment of the invasion, replication, and development of Eimeria species in the gut tissues of chickens; lowering oocyst counts due to the presence of phenolic compounds in herbal extracts which reacts with cytoplasmic membranes causing coccidial cell death; ameliorating the degree of intestinal lipid peroxidation; facilitating the repair of epithelial injuries; and decreasing the intestinal permeability induced by Eimeria species through the upregulation of epithelial turnover. This current review highlights the anticoccidial activity of several herbal products, and their other beneficial effects.

Omega polyunsaturated fatty acids and parasitic infections: An overview

Omega-3 and omega-6 polyunsaturated fatty acids are synthesized from the essential fatty acids alpha-linolenic acid and linoleic acid, respectively. They are pivotal components of all mammalian cells and were found to be useful in prevention and treatment of a variety of health problems owing to their anti-inflammatory and anti-microbial properties. Omega-3 and omega-6 polyunsaturated fatty acids are further metabolized to anti-inflammatory mediators, such as lipoxins, resolvins, and protectins. Moreover, these polyunsaturated fatty acids were found to have in vivo and in vitro protective efficacies against some parasitic infections. Therefore, dietary intake of polyunsaturated fatty acids should be encouraged because of their considerable beneficial effects.

Thymol efficacy against coccidiosis in pigeon (Columba livia domestica)

Investigation of thymol efficacy to control pigeon coccidiosis was performed using in-vitro and in-vivo studies. The in-vitro experiment was conducted by treatment of unsporulated oocysts of Eimeria species of pigeon by five concentrations (0.625-10%) from either thymol, eucalyptus essential oil or amprolium anticoccidial drug and incubation for 72 h. The in-vitro study revealed that thymol concentrations ≥1.25 % caused significant deformity on sporulated and unsporulated oocysts compared to the other two products. Eucalyptus oil was active at both 5 and 10 % concentrations on unsporulated oocysts but showed non-significant changes on sporulated ones at all tested concentration. Meanwhile, in-vivo testing of thymol was conducted using 45 squabs which were equally divided into three groups; untreated uninfected (UU) negative control, untreated infected (UI) positive control and thymol treated (TT). TT group received 40 mg/kg BWt thymol in feed for 15 days. At day five post thymol supplementation, the UI and TT groups were orally infected by 25 × 10³sporulated oocysts of pigeon Eimeria labbeana. The in-vivo study showed that thymol minimized the adverse effect of Eimeria infection in pigeon as observed by less severity of clinical signs, low oocysts count and improvement of body weight when compared with untreated infected birds. In addition, the biochemical parameters including liver and kidney functions tests proved thymol safety in pigeon. Moreover, thymol showed excellent antioxidant activity that was estimated by significantly lower value of malondialdehyde in TT than UI groups. The histopathological findings of TT group showed intact intestinal villi with mild sloughed epithelium, degenerated coccidian developmental stages and massive infiltrations of mononuclear cells in lamina propria. In conclusion, thymol can be safely used to control pigeon coccidiosis as a natural effective compound.

Effect of omega-3 fatty acids administered as monotherapy or combined with artemether on experimental Schistosoma mansoni infection

Schistosomiasis is on the top list of endemic diseases in sub-Saharan Africa. Praziquantel is the drug of choice for treatment of human schistosomiasis. Yet, the sole dependence on the drug raises concerns about the potential for increased drug resistance, which would subsequently result in searching for alternative preventive chemotherapy options, ideally among natural compounds. Therefore, we conducted this work to assess the effect of omega-3 polyunsaturated fatty acids [(ω-3) PUFAs] monotherapy or combined therapy with artemether (ART) against Schistosoma mansoni infection in a mouse model. A total of 42 mice were divided into 4 groups and infected with 50 ± 5 S. mansoni cercariae for 10 weeks. Mice were treated orally with either (ω-3) PUFAs as 273 mg/ kg, 4 times/ week throughout the experiment, ART as a single dose of 400 mg/ kg, 3 weeks post-infection, or combined ART + (ω-3) PUFAs using the same respective treatment regimen, while infected untreated mice were served as controls. The study explored that combined administration of (ω-3) PUFAs and ART has the best schistosomicidal efficacy as it significantly reduced liver and spleen indices, worm count, egg burdens, and granulomas count as well as diameter. Besides, the combined regimen was associated with a significant decrease in both hepatic nitric oxide and serum interleukin-4 level. The results highlighted the possibility of using (ω-3) PUFA combined with ART as a novel anti-schistosomal combination therapy. However, further researches should be conducted to clarify the possible synergistic mechanism/s between the two natural compounds.

Partial replacement of soybean meal with different protein sources in piglet feed during the nursery phase

Objective

Evaluate the partial replacement of soybean meal with different protein sources in piglet feed during the nursery phase in terms of digestibility of feed, nitrogen balance, growth performance and blood parameters.

Methods

Experiment I involved 24 crossbred entire male pigs with an initial body weight (BW) of 18.28±0.7 kg and used a randomized complete block design consisting of 3 treatments (fish meal, FM; soybean protein concentrate, SPC; and soybean meal, SBM) and 8 replicates, with 1 pig per experimental unit. Experiment II involved 1,843 crossbred male and female pigs with an initial BW of 6.79±0.90 kg and was based on a completely randomized design with a 2×3 factorial arrangement (2 sexes and 3 protein sources) and 13 replicates.

Results

The results of Exp. I indicate effects (p<0.05) of dietary protein sources on digestible protein (FM, 17.84%; SPC, 16.72%, and SBM, 18.13%) and on total nitrogen excretion (TNE, g/kg BW^0.75/d) in which pigs fed with SBM-based feed had TNE values that were 5.36% and 3.72% greater than SPC and FM, respectively. In the Exp. II, there was difference (p<0.01) between sexes in the pre-starter I and starter phases, and total period in average daily feed intake (ADFI), which were greater in females, and between the protein sources, ADFI, final weight and daily weight gain. For urea in the pre-starter II and starter phases and glucose in the pre-starter II phase, there was a difference (p<0.05) between protein sources and between sexes, in starter phase in urea concentrations (females: 57.11 mg/dL and males: 50.60 mg/dL).

Conclusion

The use of SBM as only protein source influences larger TNE (g/kg BW^0.75/d), reduces the growth performance of piglets and increases plasma urea concentrations in pre-starter II phase.

Synergistic approach for treatment of chicken coccidiosis using berberine--A plant natural product

Despite the advent of anticoccidial drugs and vaccines, coccidiosis continues to result in substantial economic losses to the poultry industry. Berberine, a natural alkaloid is well known in studies involving synergistic approaches, thereby reducing the dosage of principal drugs. Therefore, a study was designed to see whether a synergistic anticoccidial effect could be obtained between amprolium and berberine, in vivo using broiler chicken. Anticoccidial activity was measured in comparison to the reference drug amprolium on the basis of oocyst output reduction, mean weight gain and feed conversion ratio. Oocyst output was measured using Mc-Masters counting technique. Different combinations of berberine and amprolium were tested and out of which 1:1 ratio was the most effective for controlling these parasites. Oral gavaging of 100(50 + 50) mg/kg body weight of 1:1 ratio of amprolium and berberine caused the equivalent reduction in number of oocysts (38.85 ± 9.61) one day prior to that of standard drug amprolium (49.95 ± 16.65) as well as pure berberine (44.4 ± 9.61) used in the study. Weight gain of birds was also highest in the synergistic group (1547.43 ± 12.86) among all the infected groups. Besides feed conversion ratio in the synergistic group was also better (1.387 ± 0.026). The results of this study proved the effectiveness of both amprolium and berberine and revealed synergism between amprolium and berberine against coccidian oocysts, confirmed by significant reduction in the number of coccidian oocysts shed in the feces, leading to better weight gain and improved feed conversion ratio. The study deep-rooted the synergistic potential of berberine, a natural bioactive compound for controlling a protozoan parasite and the results of this study corroborate with its use for treatment of severe diarrhoea, amoebiasis and intestinal infections.

Influence of Flaxseed Oil on Fecal Microbiota, Egg Quality and Fatty Acid Composition of Egg Yolks in Laying Hens

Although there have been many attempts to produce ω-3 fatty acid-rich eggs using alpha-linolenic acid (ALA) that is a popular fatty acid in the poultry feed industry, only limited knowledge about the effects of ALA-enriched diets on chicken fecal microbiota is currently available. Herein we examined the changes in the fecal microbiota composition, egg quality traits and fatty acid composition of the egg yolks of laying hens fed ALA-rich flaxseed oil for 8 weeks. The animals fed the experimental diets that contained 0 % (group C), 0.5 % (group T1), and 1.0 % (group T2) of flaxseed oil, respectively, and eggs and feces were obtained for the analyses. ω-3 fatty acids, including ALA, were increased in T1 and T2 compared with C. Furthermore, the freshness of eggs was improved with no side effects on the eggs. The diet also changed the fecal microbiota; Firmicutes was increased in T1 and T2 (48.6 to 83 and 79.6 %) and Bacteroidetes was decreased (40.2 to 8.8 and 4.2 %). Principal coordinate analysis revealed that Lactobacillus, among the 56 examined genera, was the most influenced bacterial group in terms of the fecal microbial community shifts. These results indicate that ALA-rich diets influenced both the egg and fecal microbiota in beneficial manners in laying hens although the association between the fatty acid composition of the egg yolk and the fecal microbiota was not clear. This study is a first step to understand the effect of flaxseed oil as well as intestinal microbiota of laying hens.

Control of avian coccidiosis: future and present natural alternatives

Numerous efforts to date have been implemented in the control of avian coccidiosis caused by the Eimeria parasite. Since the appearance of anticoccidial chemical compounds, the search for new alternatives continues. Today, no product is available to cope with the disease; however, the number of products commercially available is constantly increasing. In this review, we focus on natural products and their anticoccidial activity. This group comprises fatty acids, antioxidants, fungal and herbal extracts, and immune response modulators with proven anticoccidial activity, many of which exist as dietary supplements. Additionally, we offer an overview of the poultry industry and the economic cost of coccidiosis as well as the classical strategies used to control the disease.

In vivo anticoccidial activity of berberine [18, 5,6-dihydro-9,10-dimethoxybenzo(g)-1,3-benzodioxolo(5,6-a) quinolizinium]--an isoquinoline alkaloid present in the root bark of Berberis lycium

Coccidiosis, caused by various Eimeria species, is a major parasitic disease in chicken. However the increasing resistance of these parasites to currently used anticoccidial drugs has stimulated the search for new methods of control. As part of this effort we investigated the root bark of Berberis lycium (barberry) as a potential source of compounds with anticoccidial activity. In the present study anticoccidial activity of different solvent extracts of the root bark of B. lycium and berberine was evaluated in vivo using broiler chicken. Results of the study demonstrated equipotent efficacy of pure berberine in comparison to that of standard drug amprolium on the basis of reduction in coccidian oocyst output, body weight gain of chicken and feed conversion ratio. Among the extracts crude methanolic extract showed highest anticoccidial activity tested at 300 mg/kg body weight which could be due to the presence of alcohol-soluble active ingredients in root bark of B. lycium. Toxicological studies revealed that B. lycium extracts as well as berberine were not lethal up to dosage of 2000 mg/kg body weight. LD(50) was not determined as mortalities were not recorded in any of the five groups of chicken. From the present study it can be concluded that root bark of B. lycium has the immense potential to contribute to the control of coccidian parasites of chicken. Our results corroborate the use of berberine for treatment of severe diarrhoea, amoebiasis and intestinal infections and could justify its use in folk medicine for treatment of haemorrhagic dysentery.

Coccidian infection causes oxidative damage in greenfinches

The main tenet of immunoecology is that individual variation in immune responsiveness is caused by the costs of immune responses to the hosts. Oxidative damage resulting from the excessive production of reactive oxygen species during immune response is hypothesized to form one of such costs. We tested this hypothesis in experimental coccidian infection model in greenfinches Carduelis chloris. Administration of isosporan coccidians to experimental birds did not affect indices of antioxidant protection (TAC and OXY), plasma triglyceride and carotenoid levels or body mass, indicating that pathological consequences of infection were generally mild. Infected birds had on average 8% higher levels of plasma malondialdehyde (MDA, a toxic end-product of lipid peroxidation) than un-infected birds. The birds that had highest MDA levels subsequent to experimental infection experienced the highest decrease in infection intensity. This observation is consistent with the idea that oxidative stress is a causative agent in the control of coccidiosis and supports the concept of oxidative costs of immune responses and parasite resistance. The finding that oxidative damage accompanies even the mild infection with a common parasite highlights the relevance of oxidative stress biology for the immunoecological research.

Fatty acids and coccidiosis: effects of dietary supplementation with different oils on coccidiosis in chickens

This study was undertaken to investigate the effects of dietary oils on coccidiosis of chickens infected with Eimeria tenella. Five hundred and four 1-day-old male Arbor Acres chicks were randomly assigned to seven groups. Seven diets were supplemented with poultry oil at 25 and 45 g/kg, corn oil at 25 and 45 g/kg, fish oil at 25 and 45 g/kg, and without oils, respectively, from 1 to 42 days of age. Chickens were inoculated by gavage with 3 x 10(5) sporulated oocysts at 21 days of age. Diets supplemented with oils at 45 g/kg resulted in higher body weight gain than with oils at 25 g/kg or without oils. The packed cell volume in chicks fed with diets supplemented with poultry oil was lower than that in chicks fed with diets supplemented with fish oil, corn oil and without oil. Chickens fed with diets supplemented with poultry oil had higher mortality than that of chickens fed with diets without oil. At 7 days post infection, the chickens consuming fish or corn oil diets had lower levels of plasma carotenoids than those fed with poultry oil supplement or without oils. Fish oil supplementation increased serum interleukin-6 levels in chickens compared with poultry oil at 25 and 45 g/kg and corn oil at 25 g/kg. Fish oil or corn oil enhanced secretory IgA levels in the lumen of the caecum, and oil supplementation tended to decrease serum IgG levels. In conclusion, the diets supplemented with saturated fatty acids aggravated mortality in chickens infected with E. tenella. The deleterious effects on coccidiosis of the diets supplemented with poultry oils might be related to the decreased levels of caecal E. tenella antigen-binding-specific secretory IgA or serum IgG.

Prooxidant diet provides protection during murine infection with Toxoplasma gondii

Toxoplasmosis, particularly toxoplasmic encephalitis, has emerged as a major cause of morbidity and mortality in patients with acquired immunodeficiency syndrome. Patients infected with human immunodeficiency virus typically experience chronic oxidative stress, and concurrent infection with the intracellular parasite Toxoplasma gondii would be expected to further exacerbate this condition. The present study was conducted to determine whether vitamin E and selenium supplementation might be beneficial in a murine model of toxoplasmosis. To investigate the effect of these antioxidants on the severity of parasitic infection. Swiss Webster (SW) or C57Bl/6J mice infected with oocysts of the ME49 strain of T. gondii were maintained on diets containing no vitamin E or selenium, no vitamin E and 8 ppm selenium, 400 IU/kg vitamin E plus 8 ppm selenium, or vitamin E and selenium at the levels present in standard rodent chow (16 IU/kg and 0.2 ppm, respectively). The results of the study showed that increased dietary supplementation with vitamin E and selenium resulted in trends toward increased tissue cyst number, tissue pathology, and weight loss during infection. In contrast, both resistant SW and susceptible C57Bl/6J mice fed a deficient diet (complete absence of vitamin E and selenium) showed the lowest mean numbers of tissue cysts and very little evidence of tissue pathology during chronic infection.

Polyunsaturated fatty acids and parasitism: effect of a diet supplemented with fish oil on the course of rat trichinellosis

Dietary fish oil has a beneficial effect on heart and some bacterial diseases and apart from other effects, some studies have revealed their ability to modulate the course of inflammatory and autoimmune diseases. The study here reported was designed to evaluate the possible influence of a fish oil supplement on the course of a Trichinella infection. Nutritional, parasitological and immunological parameters were analyzed. Two groups of 20 Wistar rats, one fed a standard diet and the other one a standard diet supplemented with fish oil, were infected with 1000 L1 larvae. Other two uninfected groups served as control. Results were as follows: fish oil diet intake and infection have, respectively, a positive and a negative effect on growth and food utilization. The negative effect is detected later in animals fed the fish oil diet. A reduction of 30.9 and 36.6% in the number of adult worms and L1 larvae, respectively, was observed in the fish oil group as compared to the standard diet group. Production of IFNgamma (Th1 response) and IL4 (Th2) response was measured in stimulated splenic cells. The fish oil diet increased both IFNgamma and IL4 levels. At 6 days after infection both IFNgamma and IL4 responses were detected, but at 36 days after infection only IL4 was detected in the standard group. The level of somatic and cuticular antibodies was not affected by the diet.

Resistance to anticoccidial drugs of Dutch avianEimeriaspp. field isolates originating from 1996, 1999 and 2001

Fifteen Eimeria spp. field isolates sampled on Dutch broiler farms were subjected to an Anticoccidial Sensitivity Test (AST) in a battery cage study. Four isolates dated from 1996, another four from 1999 and the last seven isolates from 2001. The selected anticoccidial drugs were monensin, narasin, salinomycin, lasalocid, nicarbazin, diclazuril, halofuginone, maduramicin and meticlorpindol/methylbenzoquate. Maduramicin and halofuginone were not included in the ASTs of 1999 and 2001, while meticlorpindol/methylbenzoquate was not tested in 1996 and 1999. Eimeria acervulina present in each of the four 1996 field isolates showed resistance for almost all products tested except maduramicin (1/4) and salinomycin (114), which appeared to be reduced sensitive. In 1999 the same species presented a similar resistance pattern for most products, although reduced sensitivity occurred for salinomycin (1/4), and sensitivity was found for diclazuril (2/4), monensin (1/4) and narasin (1/4). In the year 2001 increased sensitivity to various products was found. Higher sensitivity was found for meticlorpindol/ methylbenzoquate (7/7) and salinomycin and narasin (both 4/7), followed by nicarbazin (3/7) and monensin (2/7). Reduced sensitivity was found for monensin (3/7), lasalocid (2/7), salinomycin and narasin (1/7). E. maxima was only found in one field isolate per year. The E. maxima from 1996 was resistant to all products except narasin (sensitive) and halofuginone (reduced sensitive). In 1999 this species was reduced sensitive to narasin and lasalocid, showing resistance for the other products. The strain originating from the 2001 isolate was reduced sensitive to most products except monensin and narasin (resistant). Full sensitivity was found for meticlorpindol/ methylbenzoquate. E. tenella was present in one isolate of 1996, two of 1999 and four isolates of 2001. The AST of 1996 showed reduced sensitivity for nicarbazin, and sensitive to narasin, maduramicin and halofuginone. All other products showed resistance. In 1999 both strains showed resistance to all products tested. For the year 2001 full sensitivity was found to meticlorpindol/methylbenzoquate. Sensitivity was also found for salinomycin (1/4), nicarbazin (2/4), diclazuril (2/4) and lasalocid (2/4), monensin (1/4) and narasin (1/4). Reduced sensitivity was found for nicarbazin (1/4), lasalocid (1/4) and narasin (1/4). The different resistance patterns of Dutch coccidiosis isolates and resistance of coccidia in general is discussed.

(n-3) Fatty acids and infectious disease resistance

The current view of the manner in which (n-3) polyunsaturated fatty acids (PUFA) affect the immune system is centered on their ability to alter cytokine production and secondarily to diminish eicosanoid biosynthesis. The purpose of this article is to review the evidence that (n-3) PUFA affect host infectious disease resistance. Although there have been a few human clinical trials involving (n-3) PUFA and human infectious disease, the data are equivocal and the study designs confounded by the simultaneous inclusion of other immunonutrients (i.e., arginine and nucleotides) with the (n-3) PUFA. Thus, this review focuses on animal feeding trials that include an in vivo challenge of the host with a live infectious agent. Host survival and pathogen clearance are the most common end points measured in these studies. The data suggest that (n-3) PUFA can both improve and impair host resistance to a number of pathogens. However, the data are still quite limited in breadth and depth. For those pathogens for which data exist, the number of published studies in general does not exceed two or three. Emphasis is placed on defining important microbiological and immunological differences in various host-pathogen interactions that might help explain the incongruity in the findings published to date. The authors believe that direct examination of (n-3) PUFA on human infectious disease resistance is warranted.

Maternal dietary N-3 fatty acids alter the spleen fatty acid composition and bovine serum albumin-induced wing web swelling in broilers

Effects of maternal dietary polyunsaturated fatty acids (PUFA) on the spleen fatty acid composition and BSA-induced wing web swellings were investigated in broilers. One hundred twenty broiler breeder hens 26 wk of age were randomly assigned to diets containing mainly wheat, corn, soy meal, barley, oat and 5% (wt/wt) added sunflower oil, fish oil, or a mix of sunflower and fish oils (1:1). After 2 wk on the experimental diets, birds were inseminated, eggs were collected and incubated. Progeny chicks were then fed identical diets for 6 wk. The maternal dietary oils affected (P < 0.05) n-6 and n-3 PUFA in the spleens of hatching chicks. After 2 wk, n-6 PUFA did not differ among the groups; n-3 PUFA, docosapentaenoic, and docosahexaenoic (DHA) acids were higher (P < 0.05) in the spleens of broilers from hens fed 2.5 or 5% fish oil. After 4 wk, broilers from hens fed 5% fish oil still had higher levels of DHA (P < 0.05) in their spleens than those from hens fed 5% sunflower oil. The BSA-induced wing web swelling response was suppressed (P < 0.05) by n-3 PUFA in breeder hens. Broilers from hens fed high levels of n-3 PUFA had lower (P < 0.05) wing web swelling reactions to BSA at 2 wk (2.5% fish oil) and 4 wk (2.5 and 5% fish oil). In conclusion, n-3 PUFA in breeder hen diets suppressed the BSA-induced wing web swellings of the hens, increased the spleen n-3 fatty acids (especially DHA), and decreased BSA-induced wing web swellings of progeny up to 4 wk of age.

Recent advances in biology and immunobiology of Eimeria species and in diagnosis and control of infection with these coccidian parasites of poultry

Avian coccidiosis, an intestinal disease caused by protozoan parasites of the genus Eimeria, occurs worldwide. It is considered to be one of the most economically important diseases of domestic poultry. For many years, prophylactic use of anticoccidial feed additives has been the primary means of controlling coccidiosis in the broiler industry and has played a major role in the growth of this industry, which now can produce about 7.6 billion chickens annually. However, development of anticoccidial resistance has threatened the economic stability of the broiler industry. Although there has been little effort by the pharmaceutical industry to develop new anticoccidials, the mounting problem of drug resistance of Eimeria species has prompted major research efforts to seek alternative means of control through increased knowledge of parasite biology, host response, and nutritional modulation. As a consequence, important advancements have been made, particularly in defining parasite antigens that have potential use in vaccines, defining the Eimeria genome, understanding the immunology of coccidial infections, and the practical applications of live vaccines. This review describes the progress in these areas, most of which has occurred within the past 10 to 15 years.

Effects of nutritionally balanced and stabilized flaxmeal-based diets on Eimeria tenella infections in chickens

Twenty Sex Sal cockerels were randomly assigned to each of eight groups; each of four nutritionally balanced diets were fed to two groups from 1 d through 4 wk of age. These diets contained 0, 2, 5, or 10% stabilized flaxseed meal that provided a calculated 0, 0.45, 1.11, or 2.22% n-3 fatty acids, primarily linolenic acid. At 3 wk of age, one group of chickens from each diet treatment was infected with Eimeria tenella and was housed in separate but similar conditions to uninfected control chickens. At 6 d postinfection, chickens were weighed, bled, killed, and scored for lesions. No level of dietary flaxmeal tested provided protection against weight gain depression, increased feed conversion ratios, or lesions. We concluded that these diets did not protect against E. tenella infection because levels of linolenic acid were not high enough, and the oxidative potentials were well suppressed by vitamin E and other stabilizers present.

Effects of dietary supplementation with n-3 fatty acid ethyl esters on coccidiosis in chickens

The ethyl esters of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids were added to a broiler starter diet singly or in combination [as bulk purified ethyl ester concentrate from menhaden oil (n3FAC)] in quantities similar to those found in a diet supplemented with 5% menhaden oil (MO). Diets were fed to chickens from 1 d of age through 3 wk of age. At 2 wk of age, the chickens were infected with Eimeria tenella, Eimeria acervulina, or Eimeria maxima. At 6 d postinfection (PI), the effects of the diets were assessed on weight gains, plasma carotenoids, gross lesion scores, and histological parasite scores in gut cross sections, or oocyst output. Significant ameliorating effects of diet on lesion scores and parasite scores were only seen in E. tenella infections and were only produced by the n3FAC and MO supplements. These two supplements, which contained higher molar concentrations of double bonds than the other supplements, also significantly reduced plasma carotenoids in uninfected chickens, indicating that they promoted a state of oxidative stress. These results are consistent with previous reports on the interaction of coccidiosis with dietary n-3 fatty acids and strengthen the hypotheses that dietary-induced oxidative stress is an effective deterrent against cecal coccidiosis in chickens.

Dietary modulation of avian coccidiosis

During the past several years, our laboratory has been investigating the anticoccidial activities of various natural products that have potential use as dietary supplements for coccidiosis control. Sources of fats containing high concentrations of n-3 fatty acids such as menhaden oil and flaxseed oil and flaxseed, when added to starter rations and fed to chicks from one day of age, effectively reduce lesions caused by the caecal parasite Eimeria tenella, but not lesions caused by Eimeria maxima. Our results are consistent with reports of effects of diets high in n-3 fatty acids on other protozoan parasites which suggest that the state of oxidative stress induced by these diets in the cells of both host and parasites is responsible for their parasitic actions. Artemisinin, a naturally occurring (Artemisia annua) endoperoxide and effective antimalarial significantly lowers lesions from E. tenella when given at low levels as a feed additive. The mechanism of its action is also considered to involve induction of oxidative stress. Diets supplemented with 8 p.p.m. gamma-tocopherol (abundant in flaxseeds) or with 1% of the spice tumeric, reduce mid-small intestinal lesion scores and improve weight gains during E. maxima infections. These compounds may exert their anticoccidial activity because they are effective antioxidants. Betaine, a choline analogue found in high concentrations in sugar beets, improves nutrient utilisation by animals under stress. When provided as a dietary supplement at a level of 0.15% it has enhanced the anticoccidial activity of the ionophore, salinomycin. Betaine may act as an osmoprotectant whereby it improves the integrity and function of the infected intestinal mucosa. In in vivo studies, betaine plus salinomycin significantly inhibit invasion of both E. tenella and E. acervulina. However, subsequent development of E. acervulina is inhibited more effectively with this combination treatment than development of E. tenella.

Comparison of outbred lines of chickens for resistance to experimental infection with coccidiosis (Eimeria tenella)

Coccidiosis causes dramatic economic losses in the poultry industry. Next to the extensive use of anticoccidial drugs, improving genetic resistance of birds to this parasitic disease represents an attractive alternative. An experiment was run in order to identify lines of chickens resistant and susceptible to coccidiosis as a tool to search for genetic markers of resistance. Five outbred lines were used: two Egyptian lines (Mandarah and Fayoumi), a Rhode Island Red line, and two White Leghorn lines (WLB21 and WLDW). The WLDW line segregated for three MHC haplotypes, B15, B19, and B21, and for the sex-linked dwarf gene, DW. Chicks were challenged at 4 wk of age with a high dose of Eimeria tenella (150,000 oocysts) and slaughtered 8 d postinoculation. Innate resistance was assessed individually by measures of lesion score, mortality, and body weight gain at slaughter, and plasma coloration 4 d postinoculation. Large differences in resistance to E. tenella were observed between lines. The Fayoumi line appeared clearly as the most resistant line, showing no mortality, less severe lesions than other lines, and a 30% reduction of growth as compared to control birds. The WLDW line was the most susceptible, with 27% mortality and a 85% reduction in growth. No major effect of MHC or dwarfism on resistance to E. tenella was found.

Dietary fish oil or lofrin, a 5-lipoxygenase inhibitor, decrease the growth-suppressing effects of coccidiosis in broiler chicks

Broiler chicks were fed a diet containing 4% of either corn oil or fish oil from 3 to 14 d of age. From Days 15 to 23, half of the chicks in each dietary treatment were fed Lofrin (an experimental 5-lipoxygenase inhibitor) at 33 micrograms/kg feed. The remaining chicks within each dietary treatment were the untreated controls. At 24 d of age, half of the chicks within each diet-Lofrin treatment group were each infected with 4.6 x 10(4) sporulated Eimeria tenella oocysts, resulting in a 2 x 2 x 2 factorial arrangement of treatments. Body weight gain, feed consumption, and feed conversion efficiency were determined throughout the study. At 27 d of age, blood, liver, and ceca were sampled. Plasma tumor necrosis factor and hemopexin, hepatic fatty acid composition, and cecal inflammatory cell infiltration were determined. Liver fatty acid composition tended to reflect that of the diet. Chicks fed fish oil had livers that were enriched in (n-3) polyunsaturated fatty acids (PUFA) at the expense of (n-6) PUFA. Chicks fed fish oil gained body weight more rapidly than those fed corn oil. Infection of chicks with Eimeria decreased body weight gain of chicks fed corn oil, but not of chicks fed fish oil. The addition of Lofrin to the corn oil diets abrogated the growth-suppressing effects of infection, although there was no Lofrin effect among chicks fed fish oil. There was a diet by Lofrin interaction in which Lofrin treatment of birds fed corn oil decreased feed consumption and increased feed conversion efficiency, but had no effect on chicks fed diets containing fish oil. Plasma hemopexin was greater, but tumor necrosis factor was lower, in chicks fed fish oil than in chicks fed corn oil. Eimeria infection significantly increased cecal inflammatory cell infiltration across all dietary treatments. There were no clear relationships between growth rate or efficiency and the severity of the inflammatory response to Eimeria infection, as indicated by hemopexin levels and cecal inflammatory scores. These results indicate that Lofrin or fish oil, both of which modify eicosanoid metabolism, attenuate the growth-depressing effects of an Eimeria tenella infection.

Dietary unsaturated fatty acids affect antibody responses and growth of chickens divergently selected for humoral responses to sheep red blood cells

The effect of linoleic and linolenic acid on antibody (Ab) responses to SRBC and BSA and on growth performance were studied in pullets of three genetically different laying lines. Pullets were fed one of three diets: a control diet, a linoleic acid-enriched diet, or a linolenic acid enriched-diet. The linoleic and linolenic acid enriched-diets were the control diet enriched with either sunflower oil or linseed oil. Two chicken lines divergently selected for high (H) and low (L) Ab responses to SRBC, and a randombred control (C) line were used. Total Ab responses to SRBC were not affected by diet, but in the H line a tendency for higher IgG titers to SRBC after primary immunization were found when birds were fed the linoleic diet. The humoral response to BSA was significantly affected by a line by immunization by diet interaction. In the H line birds, the linoleic diet significantly enhanced Ab titers to BSA as compared to the normal diet and linolenic acid-enriched diet. The linolenic acid-enriched diet significantly decreased Ab titers to BSA in the C line birds. No dietary effects on the titer to BSA were found in the L line birds. During the first 3 wk of life, the linolenic acid-enriched diet resulted in reduced BW gain of H line birds. After that period, no effects of diet on BW gain was found. It is concluded that modulation of Ab responses of poultry to T cell-dependent antigens by essential fatty acids is affected by genotype. The relationship between magnitude of Ab responsiveness, BW, and essential fatty acids is discussed.

Effects of components of Artemisia annua on coccidia infections in chickens

Four experiments were run to test the anticoccidial activity of dried Artemisia annua leaves and several of their chemical constituents for possible use as prophylactic feed additives. When fed over a period of 3 wk at a level of 5%, a dried leaf supplement of A. annua provided significant protection against lesions due to Eimeria tenella but not Eimeria acervulina or Eimeria maxima. When fed over a period of 5 wk at a level of 1% to chicks undergoing immunization with a live vaccine, it provided significant protection in partially immunized chicks against E. acervulina and E. tenella lesions from a dual species challenge infection. It also afforded lower mean lesion scores in challenged chicks immunized over a period of 5 wk. Artemisinin, an antimalarial component of A. annua, was present at a level of 0.034% in the dried leaf preparation. A 5% supplement thus afforded about 17 ppm artemisin. When the pure compound was fed at that level for a period of 3 wk, it protected weight gains and significantly reduced lesion scores attributable to E. tenella but not E. acervulina. Other components of A. annua, camphor and 1,8-cineole, at 119 ppm also protected weight gains, and reduced E. tenella lesion scores. Camphor reduced E. acervulina lesions. Artemisinin fed for 4 wk at levels of 2, 8.5, and 17 ppm significantly reduced oocyst output from separate E. acervulina and E. tenella infections and a dual species infection. Pure artemisinin thus appears to be effective against at least two coccidia species when used as a feed additive, and its activity may depend, in part, on the length of time it is administered before a challenge infection.

Interaction of dietary flaxseed with coccidia infections in chickens

Two experiments were conducted to determine effects of diets containing n-3 fatty acids (n-3FA) from whole as well as ground flaxseed on the performance of broilers during coccidia infections. Diets were fed from 1 d of age through 3 wk of age. Chickens were infected with coccidia at 2 wk of age and the effects of infection assessed at 6 d postinfection. The first experiment contrasted effects of several high n-3FA-containing diets, including one supplemented with whole flaxseed, on infections with Eimeria tenella or Eimeria maxima. Infected chickens that consumed the flaxseed-supplemented diet had the lowest weight gains, but they were not significantly different from gains of infected chickens on the control diet. Diets supplemented with 5% menhaden oil or 15% flaxseed significantly reduced lesions caused by E. tenella, but had no effect on lesions caused by E. maxima. In a second experiment, diets supplemented with 5 or 10% ground flaxseed were assessed for effects on the performance of broilers infected with three dose levels (500, 5,000, or 50,000 oocysts) of E. maxima. Neither flaxseed diet protected weight gain during infection with 50,000 oocysts. However, a 5% flax diet protected weight gains in chickens infected with 500 or 5,000 oocysts. Diets supplemented with 5 or 10% ground flaxseed exacerbated lesions in chickens infected with 5,000 or 50,000 E. maxima oocysts compared to the control diet. Thus, diets containing high amounts of n-3 fatty acids do not affect the development of all Eimeria sp. in the same manner. The oxidative stress produced by these diets may more adversely affect development of E. tenella, which infects the relatively oxygen-poor ceca, whereas it does not affect development of E. maxima which parasitizes the middle portion of the small intestine.

Vitamin E-deficient diets enriched with fish oil suppress lethal Plasmodium yoelii infections in athymic and scid/bg mice

Mice fed vitamin E-deficient diets containing omega-3 fatty acids survive infection with lethal Plasmodium yoelii. The current study sought to determine if antimalarial T- and B-cell responses were required for such dietary-mediated protection. In the first set of experiments, nu/nu mice (which lack alphabeta T-cell-receptor-positive T cells and do not produce antimalarial antibody) and nu/+ mice were fed casein-based diets containing 4% menhaden oil, with or without vitamin E supplementation, for 4 weeks prior to infection with lethal P. yoelii. All mice fed diets containing vitamin E developed fulminating parasitemias and quickly died, whereas both nu/nu and nu/+ mice fed diets deficient in vitamin E controlled their parasitemias for the first 18 days of infection. Thereafter, the nu/nu mice became anemic and died, whereas the nu/+ mice produced antimalarial antibodies and survived. In the second set of experiments, scid/scid.bg/bg mice (which lack B cells and alphabeta and gammadelta T cells and have reduced NK-cell activity) were fed the experimental diet for 6 weeks and then infected with the less virulent 17XNL strain of P. yoelii. Mice fed vitamin E-containing diets quickly died, whereas those fed the vitamin E-deficient diet survived without developing detectable parasitemias. Results from these experiments show that under prooxidant dietary conditions, mice were able to control and even survive malaria in the absence of malaria-primed T cells and antimalarial antibody. These results emphasize the importance of cellular oxidative processes in parasite elimination.

Association of lowered plasma carotenoids with protection against cecal coccidiosis by diets high in n-3 fatty acids

A series of four experiments was run to assess the effectiveness of diets containing high amounts of n-3 fatty acids in reducing the pathological effects of cecal coccidiosis in chickens caused by Eimeria tenella. To determine whether the dietary effects were related to development of oxidative stress, plasma samples were analyzed for tocopherols and carotenoids. Plasma vitamin E (alpha-tocopherol) values were not consistent between experiments. Total plasma carotenoids, however, were significantly decreased by 2.5 to 20% diet supplementation with fish oil in several experiments. These decreases coincided with significant reductions in lesion scores. Under the experimental conditions, total plasma carotenoid concentrations may serve as a sensitive indicator for oxidative stress, which may be a factor in reducing cecal lesions in E. tenella infections.