Algae-based feed ingredient protects intestinal health during Eimeria challenge and alters systemic immune responses with differential outcomes observed during acute feed restriction

Assessment of the Nutritional Composition, Antimicrobial Potential, Anticoccidial, and Antioxidant Activities of Arthospira platensis in Broilers

This study evaluates the chemical composition, fatty acid profiles, and bioactive properties of ethanolic (SPE), methanolic (SPM), and acetonic (SPA) extracts of Arthrospira platensis. The chemical analysis revealed a high protein content (72.08%), moderate lipid levels (6.49%), and a diverse fatty acid profile, dominated by polyunsaturated fatty acids. Antibacterial testing showed that SPE exhibited the strongest activity against Gram-negative bacteria, including Escherichia coli (ATCC 25922), Enterobacter cloacae (ATCC 49141), Proteus mirabilis (ATCC 25933), Salmonella typhi (ATCC 6539), Salmonella typhimurium (ATCC 14028), Salmonella enteritidis (ATCC 13076), Salmonella gallinarum (ATCC 9184), and Pseudomonas aeruginosa (ATCC 27853). The anticoccidial activity was also significant, with SPE reducing Eimeria sp. oocyst counts in poultry intestines and ceca. Antioxidant activity was highest in SPM, which also had the highest phenolic content. LC-MS/MS profiling of the methanolic extract revealed various bioactive compounds, including phenolic acids, flavonoids, carotenoids, chlorophylls, and phycobiliproteins. These results suggest that A. platensis has great potential as a nutraceutical supplement in poultry farming, offering a sustainable alternative to synthetic additives.

Supplementation of Parachlorella sp. in feed promote the gut microbiome colonization and fecal IgA response of broiler in both early and late period

This study evaluated the effects of Parachlorella sp. KSN1 (PA) supplementation on the gut microbiota and intestinal immunity of broilers of different ages. A total of 180 Ross 308 broiler chicks were weighed and divided into early (1 to 10 days post hatch) and late (11 to 28 days post hatch) periods, with six replicates of 10 chicks per cage assigned to two dietary groups. The experimental diets included a corn-soybean meal-based control diet and a treatment diet supplemented with 0.5% PA, replacing corn or corn starch, and fed ad libitum for the assigned experimental period. On days 10 and 28, two broilers from each of the six replicate cages, with 7 broilers per cage in each group, were selected and euthanized, and cecal feces and intestinal tissue samples were collected. PA supplementation did not significantly affect broilers growth performance during both the early and the late periods. However, PA supplementation altered the cecal microbiome, with Clostridiaceae and Clostridium exhibiting prominent and consistent changes. In terms of intestinal immunity, PA supplementation significantly increased the number of CD3+ and CD4+ T cells when administered only during the early period. Cecal IgA levels were significantly increased by PA supplementation during both the early and late periods. A significant positive correlation was observed between IgA, Clostridiaceae and Clostridium during the early and late periods. Gene expression analysis identified 40 upregulated genes, including polymeric immunoglobulin receptor (pIgR), and 142 downregulated genes, including marginal zone B and B1 cell specific protein and immunoglobulin lambda-like polypeptide 1 that were associated with the IgA response in PA-treated broilers during the early period. This study demonstrated that PA supplementation promotes gut microbial colonization and intestinal immunity development during the early age of broilers. These findings suggest that the early growth period of broilers is the optimal time for dietary immunomodulation to promote gut health in broilers.

Significance of successive feeding of sources of n-3 fatty acids to broiler breeders and their progeny on growth performance, intestinal lesion scores, lymphoid organs weight and plasma immunoglobulin A in broiler chickens challenged with Eimeria

The study examined the effects of successive feeding of sources of n-3 PUFA to broiler breeders (BB) and their progeny in broiler chickens challenged with Eimeria. The BB were fed: 1) control (CON), corn-soybean meal diet, 2) CON + 1 % microalgae (DMA), as a source of DHA and 3) CON + 2.50% co-extruded full fat flaxseed (FFF), as a source of ALA. Eggs were hatched at 34, 44, and 54 wk of age. Posthatch treatments (BB-progeny) were: CON-CON, DMA-CON, FFF-CON, DMA-DMA and FFF-FFF with diets formulated for starter (d 1-10) and grower/finisher (d 11-42) phases. All chicks were orally challenged with Eimeria (E. acervulina and E. maxima) on d 10. Relative to CON, DMA and FFF increased concentration of n-3 PUFA by ≥ 2-fold in hatching eggs and progeny diets. There were no (P > 0.05) interactions between treatment and BB age on d 0 to 10 growth. In general, BB age affected (P < 0.05) growth performance throughout the study. In the starter phase, successive exposure to DHA and ALA improved FCR over CON-CON (P < 0.01). The interaction between treatment and BB age in grower/finisher was such that DHA exposure to younger BB resulted in poor growth performance (P < 0.05) relative to exposure to older BB. In contrast, exposure to ALA had similar (P > 0.05) growth performance irrespective of BB age. Moreover, successive exposure to ALA resulted in higher BWG, breast weight and lower FCR compared to successive exposure to DHA (P < 0.05). There were no (P > 0.05) interactions between treatment and BB age on the intestinal lesion scores, lymphoid organ weights and concentration of plasma immunoglobulin A (IgA). Successive exposure to DHA resulted in higher (P = 0.006) jejunal lesion scores than CON-CON birds. The results showed that successive exposure of DHA and ALA improved FCR relative to non-exposed birds in the starter phase. However, responses in the grower/finisher phase depended on n-3 PUFA type, with birds on successive ALA exposure supporting better growth and breast yield than birds on successive DHA exposure.

Bioefficacy of dietary inclusion of Nannochloropsis oculata on Eimeria spp. challenged chicks: clinical approaches, meat quality, and molecular docking

Although anticoccidial drugs have been used to treat avian coccidiosis for nearly a century, resistance, bird harm, and food residues have caused health concerns. Thus, Nannochloropsis oculata was investigated as a possible coccidiosis treatment for broilers. A total of 150 1-day-old male Cobb broiler chicks were treated as follows: G1-Ng: fed a basal diet; G2-Ps: challenged with Eimeria spp. oocysts and fed basal diet; G3-Clo: challenged and fed basal diet with clopidol; G4-NOa: challenged and fed 0.1% N. oculata in diet, and G5-NOb: challenged and fed 0.2% N. oculata. Compared to G2-Ps, N. oculata in the diet significantly (P < 0.05) decreased dropping scores, lesion scores, and oocyst shedding. Without affecting breast meat colour metrics, N. oculata improved meat quality characters. At 28 days of age, birds received 0.2% N. oculata had significantly (P < 0.05) higher serum levels of MDA, T-SOD, HDL, and LDL cholesterol compared to G2-Ps. Serum AST, ALT, and urea levels were all decreased when N. oculata (0.2%) was used as opposed to G2-Ps. Histopathological alterations and the number of developmental and degenerative stages of Eimeria spp. in the intestinal epithelium were dramatically reduced by 0.2% N. oculata compared to G2-Ps. Molecular docking revealed a higher binding affinity of N. oculata for E. tenella aldolase, EtAMA1, and EtMIC3, which hindered glucose metabolism, host cell adhesion, and invasion of Eimeria. Finally, N. oculata (0.2%) can be used in broiler diets to mitigate the deleterious effects of coccidiosis.

Algae as an alternative source of protein in poultry diets for sustainable production and disease resistance: present status and future considerations

Integrating algae into poultry diets offers a promising avenue for enhancing nutrition, boosting sustainability efforts, and potentially stimulating disease resistance. This comprehensive review delves into the essence, diversity, chemical composition, and nutritional merits of algae, spotlighting their emergence as innovative nutrient sources and health supplements for poultry. The growing interest in algae within poultry nutrition stems from their diverse nutritional profile, boasting a rich array of proteins, lipids, amino acids, vitamins, minerals, and antioxidants, thus positioning them as valuable feed constituents. A key highlight of incorporating both macroalgae and microalgae lies in their elevated protein content, with microalgae varieties like Spirulina and Chlorella exhibiting protein levels of up to 50-70%, outperforming traditional sources like soybean meal. This premium protein source not only furnishes vital amino acids crucial for muscular development and overall health in poultry but also serves as an exceptional reservoir of omega-3 fatty acids, notably eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), presenting multiple health benefits for both poultry and consumers alike. Moreover, algae boast antioxidant properties attributed to bioactive compounds like phycocyanin and astaxanthin, mitigating oxidative stress and boosting the bird's immune response, thereby fostering robust health and disease resilience. Incorporating macroalgae and microalgae into poultry diets yields positive impacts on performance metrics. Research evidence underscores the enhancement of growth rates, feed conversion ratios, carcass quality, and meat attributes in broilers, while in layers, supplementation promotes increased egg production, superior egg quality, and increased concentrations of beneficial nutrients such as omega-3 fatty acids. Furthermore, algae hold promise for mitigating the environmental footprint of poultry production, though significant outcomes from trials remain sporadic, necessitating further research to elucidate optimal dosages and blends for different algae species in poultry diets. Standardizing the composition of algae utilized in research is imperative, paving the way for potential applications in poultry nutrition as growth stimulants and substitutes for antibiotics. Nonetheless, a deeper understanding of dosage, combination, and mechanism of action through rigorous scientific investigation is key to unlocking algae's full potential within poultry nutrition.

Dietary Spirulina effects in Eimeria-challenged broiler chickens: growth performance, nutrient digestibility, intestinal morphology, serum biomarkers, and gene expression

This study investigated the growth performance, nutrient utilization, and intestinal health responses of Eimeria-challenged broiler chickens to dietary Spirulina (Arthrospira platensis). On day 1, birds were assigned to 2 diets supplemented with Spirulina (0 or 5 g/kg) in a randomized complete block design. The birds within each diet were divided into 2 Eimeria-challenge groups (challenge or no-challenge) and that resulted in a 2 × 2 factorial arrangement with 2 levels each of Spirulina and challenge on day 14. On day 15, the birds in the challenge or no-challenge groups were orally gavaged with a solution containing Eimeria oocysts or 1% PBS, respectively. Samples were collected on days 21 and 26 (6- and 11-d post-infection; dpi). Data collected from days 1 to 26 were analyzed using the MIXED procedure of SAS. Birds that were fed Spirulina-supplemented diets had increased (P < 0.05) BW gain, gain-to-feed ratio, and total tract retention nitrogen from days 14 to 21. The ileal villus perimeter and area, serum catalase, HMOX1 and SOD1 jejunal abundance were all increased (P < 0.05) in birds fed Spirulina-supplemented diets on day 21 (6 dpi). However, there was no effect on bone ash or oocyst count. From days 21 to 26, there was a tendency (P = 0.059) for a Spirulina × Challenge interaction on the BW gain of birds. Moreover, dietary Spirulina addition increased (P < 0.05) serum catalase, total antioxidant capacity, ileal villus perimeter, tibia bone ash, and the relative mRNA expression of HMOX1, SOD1, claudin 1, and TNFα in the jejunal mucosa of birds on day 26 (11 dpi). On both 6 and 11 dpi, the Eimeria challenge negatively (P < 0.05) impacted growth performance, gut morphology, and the relative mRNA expression of genes. Overall, assessing the impact of Spirulina in broilers revealed its positive antioxidant, immune-modulating, and health benefits. However, its dietary addition did not completely reverse the Eimeria-induced effects in these birds. Ultimately, this study outlines the positive properties of dietary Spirulina beyond its use in the diet of healthy broiler chickens.

Evaluating the effect of Spirulina platensis on the immune response of broiler chickens to various vaccines and virulent Newcastle disease virus challenge

This study investigated the efficacy of co-administration of Spirulina platensis (SP) with vaccines on the immune response to Avian influenza (AI), Infectious bronchitis (IB), and Newcastle disease (ND), along with I/M challenging by virulent ND virus (vNDV) genotype VII. 126 one-day-old broiler chicks were allocated into six groups (21 birds/group with three replicates): G1: negative control; G2: positive control; G3: vaccinated, non-SP-supplemented; G4: vaccinated, SP-supplemented (0.1%); G5: vaccinated, SP-supplemented (0.3%); and G6: vaccinated, SP-supplemented (0.5%). G2-6 were challenged with a velogenic NDV genotype VII virus. Dietary SP administration prevented the ND-induced mortality compared to G2 (52.4%) and G3 (14.3%), in addition to alleviating the clinical disease. G3-6 showed significant improvement in body weight loss% and FCR during two weeks post vNDV challenge (pc), and the overall FCR (2.64 ± 0.28, 1.56 ± 0.03, 1.60 ± 0.05, 1.53 ± 0.04, and 1.54 ± 0.03 for G2, 3, 4, 5 and 6, respectively) (P<0.05). On the challenging day, the ND-HI titer (log2) of G3 (5.44 ± 0.24) was numerically higher than G6 (4.20 ± 0.55) and lower than G4 (6.10 ± 0.34) and G5 (6.00 ± 0.28). On the 10th day pc, ND-HI titer in G4-6 was numerically lower in a dose-dependent manner than that of G3, suggesting an antiviral efficacy of SP. G4-6 had lower viral shedding titer than G2 and G3 (P<0.05). In G3-6, viral shedding was reduced by 15, 27, 24, and 33.6%, respectively. In addition, the histopathological lesions in the trachea, lung, and spleen were severe in G2, moderately reduced in G3, and more relieved in G4-6. At three weeks after vaccination, the HI antibody titer of AIH5 was significantly higher after SP administration, especially at the 0.3% level, compared to the vaccine alone (P<0.05), demonstrating an immune-stimulating effect. In conclusion, dietary administration of SP, particularly a dose of 0.3%, for vaccinated chickens against NDV exerted an antiinflammatory and antiviral effects by preventing deaths, alleviating clinical disease and weight loss, and decreasing viral shedding post heterologous NDV challenge.

Effects of microalgae, with or without xylanase supplementation, on growth performance, organs development, and gut health parameters of broiler chickens

Microalgae are becoming potential sustainable feed ingredients, whereas terrestrial feedstuffs are becoming scarce and costly. They are rich in nutritional and functional values but have lower digestibility. This study evaluated the effects of microalgae with or without xylanase supplementation on growth performance and gut health of broiler chickens. A total of 162-day-old Cobb 500 chicks were raised for 35 d. Birds were fed with either 1 of the 3 dietary treatments: 1) corn-soybean meal-based diet (CON), 2) CON + 3% microalgae (MAG), and 3) MAG + xylanase (MAG+XYN) in 2 phases (starter: d 0-21 and finisher: d 22-35) in mash form. Each dietary treatment had 6 replicates, with 9 birds in each replicate. The level of significance was considered at the P value <0.05. The BW, ADG, and ADFI were significantly higher in MAG by 50%, 52.5%, and 42.4%, respectively, and MAG+XYN by 44.1%, 49.7%, and 38.6%, respectively, compared to the CON group. No significant difference was observed for FCR; however, FCR was reduced by 6.3% in both MAG and MAG+XYN groups compared to the CON group. The carcass and organ weight relative to the total body weight were not significantly different among the treatments. The expressions of Zonula occludens 1 (ZO1), Cluster of differentiation 56 (CD56), and Solute carrier family 7 member 7 (SLC7A7) were significantly modulated, for example, by 3.7, 3.9, and 3.3 folds, respectively, in the MAG group compared to CON and 0.8, 0.6, and 1.1 folds, respectively, in the MAG group compared to MAG+XYN groups on d 35. Villi surface area (VSA) of ileum tended to increase on d 3 (P = 0.0725) and d 35 (P = 0.0785) in the MAG and MAG+XYN groups, compared to the CON group. The results suggest that adding microalgae with or without xylanase to broiler's diet could promote growth performance and show a tendency to improve gut health parameters. The nutrient profile and its functional properties make microalgae a valuable resource to the poultry industry as a part substitution of corn and soybean meal and a functional feed supplement to modulate the gut health of broilers.

Dietary alfalfa hay or lipid-soluble alfalfa extract may improve broiler growth, but fiber presence may be detrimental during Eimeria vaccine challenge

Lipid-soluble components in late-cutting alfalfa are linked to beneficial immune and microbiota responses in mouse challenge models; therefore, responses in a comparative poultry Eimeria challenge model were investigated. The study objective was to evaluate performance, immunity, and the cecal microbiota in broilers fed ground hay or lipid-soluble extract from late (fifth) cutting alfalfa during Eimeria challenge. At hatch, 432 Ross 708 broilers were placed in 24 floor pens (18 birds/pen) and assigned to 3 isocaloric/isonitrogenous dietary treatments consisting of control, 5% ground hay, or 0.25% lipid-soluble extract for a 42-d trial divided into 14 d starter, grower, and finisher periods. On d 14, 4 birds/treatment were euthanized to collect blood and cecal contents before half the remainder were inoculated with 10X Merck Coccivac-B52 (Kenilworth, NJ). Tissue samples were collected at 3, 7, 14, and 28 d postinoculation (pi; 4 birds/diet × Eimeria group) with body weight (BW) and feed intake (FI) recorded weekly. Immune populations within peripheral blood mononuclear cells were characterized by flow cytometry while cecal microbial communities were profiled by 16S rRNA gene amplicon sequencing. Data were normalized when appropriate and analyzed to evaluate the effects of diet, Eimeria challenge, and timepoint (SAS 9.4; P ≤ 0.05). Before challenge, dietary alfalfa hay or extract increased FI 6.9 to 8.0% and increased CD3+ T cells 19.3 to 24.9% compared to control-fed birds (P ≤ 0.007). Alfalfa did not significantly affect post-Eimeria performance, but Eimeria-challenged birds fed hay showed the greatest numeric reduction in final BW compared to their unchallenged counterparts (0.17 kg) vs. control and extract-fed birds (0.02-0.04 kg). Immune cell changes did not indicate recruitment from peripheral blood to local infection sites; however, alfalfa hay may have accelerated Bu-1+ B cell development by 7 d in unchallenged birds (P < 0.0001). During Eimeria-challenge, dietary alfalfa extract preserved alpha diversity measures related to species richness (P ≤ 0.007). Collectively, these results indicate potential benefits of feeding lipid-soluble extract from late cutting alfalfa to broilers during Eimeria challenge.

Microalgae as a Sustainable Source of Antioxidants in Animal Nutrition, Health and Livestock Development

Microalgae are a renewable and sustainable source of bioactive compounds, such as essential amino acids, polyunsaturated fatty acids, and antioxidant compounds, that have been documented to have beneficial effects on nutrition and health. Among these natural products, the demand for natural antioxidants, as an alternative to synthetic antioxidants, has increased. The antioxidant activity of microalgae significantly varies between species and depends on growth conditions. In the last decade, microalgae have been explored in livestock animals as feed additives with the aim of improving both animals' health and performance as well as product quality and the environmental impact of livestock. These findings are highly dependent on the composition of microalgae strain and their amount in the diet. The use of carbohydrate-active enzymes can increase nutrient bioavailability as a consequence of recalcitrant microalgae cell wall degradation, making it a promising strategy for monogastric nutrition for improving livestock productivity. The use of microalgae as an alternative to conventional feedstuffs is becoming increasingly important due to food-feed competition, land degradation, water deprivation, and climate change. However, the cost-effective production and use of microalgae is a major challenge in the near future, and their cultivation technology should be improved by reducing production costs, thus increasing profitability.

Intestinal Immune Cell Populations, Barrier Function, and Microbiomes in Broilers Fed a Diet Supplemented with Chlorella vulgaris

This study aimed to evaluate the effects of dietary Chlorella vulgaris (CV) on the distribution of immune cells, intestinal morphology, intestinal barrier function, antioxidant markers, and the cecal microbiome in 10-day-old broiler chickens. A total of 120 day-old Ross 308 male broiler chicks were assigned to two dietary treatments using a randomized complete block design, with body weight as the blocking factor. Birds fed a diet containing CV showed an increase in CD4⁺ T cells (p < 0.05) compared to those fed the control diet. The relative mRNA expression of intestinal epithelial barrier function-related markers (occludin and avian β-defensin 5) was elevated (p < 0.05) in the CV-supplemented group compared to the control group. The alpha diversity indices (Chao1 and observed features) of the cecal microbiome in 10-day-old birds increased (p < 0.05), indicating higher richness within the cecal bacterial community. In the microbiome analysis, enriched genera abundance of Clostridium ASF356 and Coriobacteriaceae CHKCI002 was observed in birds fed the diet containing CV compared to those fed the control diet. Taken together, dietary CV supplementation might alter intestinal barrier function, immunity, and microbiomes in 10-day-old broiler chickens.

Effect of Dietary Chlorella vulgaris or Tetradesmus obliquus on Laying Performance and Intestinal Immune Cell Parameters

A feeding trial was conducted to investigate the effect of dietary supplementation of Chlorella vulgaris (CV) or Tetradesmus obliquus (TO) on laying performance, egg quality, and gut health indicators of laying hens. A total of 144 Hy-Line Brown laying hens aged 21 weeks were randomly assigned to one of three dietary treatments with eight replicates of six hens. Dietary treatments were as follows: CON, basal diet; CV, basal diet + 5 g C. vulgaris/kg of diet; TO, basal diet + 5 g T. obliquus/kg of diet. The results showed that diets supplemented with CV or TO had insignificant effects on laying performance, egg quality (i.e., Haugh unit and eggshell strength and thickness), jejunal histology, cecal short-chain fatty acids, and antioxidant/immune markers in ileal mucosa samples of laying hens. Compared with the control group, the egg yolk color score was higher (p < 0.05) in laying hens fed on diets containing CV and TO, although the former was a more intense yellow than the latter. Small intestinal lamina propria cells were isolated using flow cytometry to examine the percentages of immune cell subpopulations. Dietary microalgae did not affect B cells or monocytes/macrophages but altered the percentage of CD4+ T cells and CD8- TCR γδ T cells. Collectively, diets supplemented with C. vulgaris or T. obliquus can improve egg yolk color and would modulate host immune development and competence in laying hens.

Characterization of the eukaryotic microbial communities in the chicken ileum in cage-free and conventional commercial housing systems

The current shift from conventional cage (CC) hen housing facilities towards cage-free (CF) hen housing in the egg industry has left many questions regarding how level of fecal exposure and exposure to other hens may influence the hen intestinal microbiota. In a previous publication we reported differences in the bacterial ileal communities and ileal morphology between hens in CC and CF production environments at a single commercial site. Here, we present the first 18S rRNA gene amplicon sequencing-based characterization of the eukaryotic ileal microbiota of adult layer hens, and their associations with intestinal health parameters and the bacterial microbiota. DNA was extracted from the ileal digesta of hens (n = 32 CC, n = 48 CF) using the Qiagen Powerlyzer Powersoil kit, followed by amplification of the V9 region of the 18S rRNA gene. Paired end sequencing was performed with the Illumina MiSeq platform, and the resulting reads were processed according to the Mothur MiSeq protocol in Mothur v1.43.0. De novo operational taxonomic unit (OTU) clustering was performed in mothur with a 99% similarity threshold, and OTUs were taxonomically classified with the SILVA SSU v138 reference database. OTUs classified as vertebrate, plant, or arthropod were removed, resulting in 3,136,400 high quality reads and 1,370 OTUs. Associations between OTUs and intestinal parameters were calculated using PROC GLIMMIX. PERMANOVA over Bray-Curtis distances revealed differences between CC and CF eukaryotic ileal microbiota at the whole community level, but no OTUs were differentially abundant after correcting for false discovery (P > 0.05; q > 0.1). Kazachstania and Saccharomyces, closely related genera of yeast, represented 77.1% and 9.7% of sequences respectively. Two Kazachstania OTUs and 1 Saccharomycetaceae OTU were positively correlated with intestinal permeability (r² ≥ 0.35). Eimeria accounted for 7.6% of sequences across all samples. Intriguingly, 15 OTUs classified as Eimeria were inversely associated with intestinal permeability (r² ≤ -0.35), suggesting Eimeria may play a more complex role in the microbiota of healthy birds than has been observed in disease challenges.

Potential of Spirulina platensis as a feed supplement for poultry to enhance growth performance and immune modulation

Increase in drug resistance as well as ineffective immunization efforts against various pathogens (viruses, bacteria and fungi) pose a significant threat to the poultry industry. Spirulina is one of the most widely used natural ingredients which is becoming popular as a nutritional supplement in humans, animals, poultry and aquaculture. It contains protein, vitamins, minerals, fatty acids, pigments, and essential amino acids. Moreover, it also has considerable quantities of unique natural antioxidants including polyphenols, carotenoids, and phycocyanin. Dietary supplementation of Spirulina can beneficially affect gut microbial population, serum biochemical parameters, and growth performance of chicken. Additionally, it contains polyphenolic contents having antibacterial effects. Spirulina extracts might inhibit bacterial motility, invasion, biofilm formation, and quorum sensing in addition to acting directly on the bacterium by weakening and making the bacterial cell walls more porous, subsequently resulting in cytoplasmic content leakage. Additionally, Spirulina has shown antiviral activities against certain common human or animal viruses and this capability can be considered to exhibit potential benefits against avian viruses also. Spirulan, a calcium-rich internal polysaccharide of Spirulina, is potentially responsible for its antiviral effect through inhibiting the entry of several viruses into the host cells, boosting the production of nitric oxide in macrophages, and stimulating the generation of cytokines. Comparatively a greater emphasis has been given to the immune modulatory effects of Spirulina as a feed additive in chicken which might boost disease resistance and improve survival and growth rates, particularly under stress conditions. This manuscript reviews biological activities and immune-stimulating properties of Spirulina and its potential use as a dietary supplement in poultry to enhance growth, gut health and disease resistance.

Basal diet composition contributes to differential performance, intestinal health, and immunological responses to a microalgae-based feed ingredient in broiler chickens

Novel feed ingredients may improve poultry health, but functionality of these ingredients may vary across basal diet formulations. This study evaluated a proprietary algae ingredient's effects on broiler performance, intestinal health, systemic immunity, and metabolic/immune kinotypes between corn- or wheat-based diets. Ross 308 broilers were housed in 80 floor pens (14 birds/pen) and assigned to 1 of 4 corn or wheat-based diets ± 0.175% algae ingredient for 42 d. At the end of each 14 d starter, grower, and finisher period, 10 birds/treatment were euthanized for tissue collection to assess intestinal histomorphology, systemic immune cell populations by flow cytometry and kinotypes by peptide arrays. On d 28 and 29, forty-three birds/treatment underwent a 12 h feed restriction challenge followed by a fluorescein isothiocyanate-dextran intestinal permeability assay. For the entire 42 d study, wheat-based diets improved feed conversion rate (FCR) by 5 points compared to corn-based diets (P < 0.0001). Performance benefits related to algae inclusion were diet dependent, with algae inclusion improving 42 d FCR by 6 points only in corn-based diets (P = 0.006). Birds fed wheat-based diets had reduced splenic monocyte/macrophage, CD1.1⁺, and T cell populations in the first 14 d (P < 0.0001) and reduced serum fluorescence on d 28/29 (P = 0.0002). Algae inclusion in the corn-based diet increased villus height in the duodenum on d 28 and jejunum on d 42, while reducing splenic CD3⁺CD8α⁺ cytotoxic T cells 13.4 to 27.5% compared to the corn-based control at the same timepoints (P < 0.0001). Kinome results showed a significant innate immune toll-like receptor (TLR) response via MyD88 at d 14 in the small intestine of birds fed corn-based diets with algae that shifted to a more growth factor and adaptive immune-oriented response by d 42. Concurrent with immune changes, signaling changes indicative of lipid metabolism in the small intestine, ceca, and liver were seen in birds fed the corn-based diet with algae. The observed differential responses to basal diet composition and algae inclusion emphasize the need to comparatively evaluate feed ingredients in various diet formulations.

Effects From Dietary Addition of Sargassum sp., Spirulina sp., or Gracilaria sp. Powder on Immune Status in Broiler Chickens

Algae are innovative and significant nutrient sources with various health benefits when used as additives in animal feed. The study aims to examine the effect of different inclusions of three algae species, Sargassum sp., Spirulina sp., and Gracilaria sp. on the immune response of broiler chickens, as measured by the cellular immune response, humoral immune response, intestinal microbial counts, hindgut acidosis, and hematological measures. Here is a list of the seven experimental treatments (TRT). TRT 1 was the control group without algae; TRT 2 was supplemented with Sargassum sp. at 1% of the diet; TRT 3 with Sargassum sp. at 2% of the diet; TRT 4 with Spirulina sp. at 5% of the diet; TRT 5 with Spirulina sp. at 7.5% of the diet; TRT 6 with Gracilaria sp. at 0.5% of the diet; and TRT 7 Gracilaria sp. at 1% of the diet. Each treatment involved five replicates with 17 broiler chickens each, and the analyses were triplicated. The results showed that including algae in the feed ration of broiler chickens induces a higher cellular response than the control group, represented by T-cell response in the wattle area (P = 0.037). Sargassum sp. at 1 and 2% enhanced IgA antibody titers significantly and Gracilaria sp. at 5% enhanced IgY antibody titers, P = 0.045 and P = 0.030, respectively. All algal inclusions inhibited the growth of Salmonella sp. and improved LAB counts in the intestine of broilers, excepting the Gracilaria sp. at 0.5%, where LAB counts were similar to the control group. The E. coli counts decreased numerically but not significantly. Blood lymphocytes were enhanced while white blood cells (WBC) and heterophils were decreased as a results of algal inclusions. In conclusion, supplementing broiler chickens with algae could enhance their cellular and humoral immune status and promote healthy microflora in their guts.

Body weight, organ development and jejunal histomorphology in broiler breeder pullets fed n-3 fatty acids enriched diets from hatch through to 22 weeks of age

Dietary long chain polyunsaturated n-3 fatty acids (n-3 FA) may be beneficial to broiler breeder (BB) development. Therefore, the effects of feeding sources of docosahexaenoic acid (DHA) and α-linolenic acid (ALA) from hatch through to 22 weeks of age (woa) on growth, organ weight, and jejunal histomorphology were investigated. A total of 588-day-old Ross × Ross 708 BB were reared on one of 3 diets: 1) control, corn-soybean meal diet, 2) Control + 1% microalgae (DMA, Aurantichytrium limacinum), as a source of DHA and 3) Control + 2.50% co-extruded full fat flaxseed and pulse mixture (FFF, 1:1 wt/wt), as a source of ALA. Diets DMA and FFF had similar total n-3 and n-6: n-3 ratio. Diets were allocated to floor pens (28 birds/pen) to give 9 or 6 replicates per diet for control or DMA and FFF, respectively and fed according to breeder curve in 3 phases: starter (0-4 woa), grower (5-19 woa), and pre-breeder (20-22 woa). Individual body weight (BW) was taken weekly and 6 birds/pen necropsied at 5 and 12 woa for gastrointestinal, spleen, bursa, and liver weight and samples for jejunal histomorphology. There was no (P > 0.05) diet effect on growth by 20 woa. With exception of 5 woa, pullets fed DMA showed (P < 0.001) lower BW coefficient of variation (C.V.) than pullets fed control between 2 and 7 woa. However, pullets fed DMA had higher BW CV at 20 woa than birds fed either control or FFF. At 5 woa, birds fed DMA had taller (P ≤ 0.01) villi and deeper crypt than birds fed either control or FFF but VH or CD were similar (P > 0.05) between CON and FFF pullets. At 12 woa, birds fed FFF had taller VH than birds fed control diet but similar (P > 0.05) to that of birds fed DMA. Therefore, different responses to sources of omega-3 FA may implicate other components, however, the BW uniformity and intestinal histomorphology responses suggested benefits of feeding omega-3 FA during rearing.