Probiotic feed additives with potential to enhance performance, health, and immunity have gained considerable popularity in commercial broiler production. The study objectives were to measure broiler performance, gut integrity, and splenic immune cell profiles in birds fed one of two probiotics at two inclusion levels. Nine hundred sixty Ross 708 broilers (12 per pen) were randomly assigned to no additive control, 0.05% or 0.10% LactoCare (Lactobacillus reuteri), or 0.05% or 0.10% LactoPlan (Lactobacillus plantarum) dietary treatments for 6 wk. On day 27, a 20-pen subset was utilized for a fluorescein isothiocyanate dextran (FITC-d) assay, where half of the pens were subject to a 12-h feed restriction (FR) pregavage. Serum collected from blood drawn 1-h postgavage was analyzed for relative fluorescence of FITC-d absorbed across the intestinal barrier as a gut leakiness indicator. On day 42, spleens from eight birds per treatment were collected for immune cell profile analysis by multicolor flow cytometry. Although performance outcomes were not affected by dietary treatment, FITC-d absorption post-FR was increased 57% in the 0.05% LactoPlan treatment, and was decreased by 12.6% in the 0.05% LactoCare diet, 12% in the 0.10% LactoCare diet, and 22% in the 0.10% LactoPlan diet compared with the control. This indicates a positive impact in barrier integrity maintenance due to 0.05% and 0.10% LactoCare and 0.10% LactoPlan diet following a challenge. Immune cell profiles varied between the two probiotic compositions, with an approximately 50% reduction in splenic innate immune cells (monocyte/macrophage+) in birds fed LactoPlan (P < 0.0001) and greater overall percentages of CD45+ leukocytes and CD3+ T cells in birds fed 0.10% LactoCare (P < 0.0001). LactoPlan diets shifted splenic T-cell populations in favor of CD8α + cytotoxic T cells (TC; P = 0.007), while higher inclusions (0.10%) of either probiotic increased the percentage of activated CD4+ helper T cells (TH; P < 0.0001). These results indicate that compositionally different probiotics had varying effects on the gut permeability and splenic immune cell profiles in broiler chickens, particularly at higher inclusion rates, but observed changes to underlying physiology did not negatively impact performance outcomes. The ability of a probiotic to alter gut permeability and immune cell profile, therefore, may depend on the compositional complexity of the product as well as inclusion rate.
1. New production processes and additional uses for corn co-products have increased the availability of distiller's dried grains with solubles (DDGS) with varying energy and amino acid digestibility, for use in poultry feed. The objective of this study was to determine the performance, N-corrected metabolisable energy (AMEn), and amino acid (AA) digestibility of a 34% CP (as fed) high-protein DDGS (HP-DDGS) included in poultry diets for Cobb 500 broiler chickens. 2. A total of 832 Cobb 500 broilers were randomly assigned to four dietary treatments containing 5% conventional DDGS (CV-DDGS) as a control or 10, 15, and 20% HPDDGS and fed for 42 d. After the performance trial, 240 birds from the original 832 were selected for a concurrent AMEn and AA digestibility experiment consisting of two AMEn diets and two AA diets. 3. Birds fed diets containing 15 and 20% HP-DDGS gained less weight than birds fed the CV-DDGS (P <0.05) but did not differ in feed intake (FI), and therefore had a less efficient FCR than the control (P<0.05). The AMEn of HP-DDGS was determined to be 11.4 MJ/kg. The standardised ileal amino acid digestibility (SIAAD) of the essential amino acids Lys and Met were determined to be 80.9 and 88.6%, respectively. 4. HP-DDGS can be included in broiler diets up to 10% without any negative impact on performance or requiring supplemental Lys and Arg. The results from the AA digestibility study indicated that HP-DDGS could be a good source of digestible Lys.
In 2018 and 2019, Staphylococcus aureus was isolated from multiple post-molt commercial laying hens with unusually high mortality. A challenge study was conducted to elucidate the role of S. aureus in this disease outbreak and the work herein represents the assessment of immunological responses in laying hens experimentally infected with S. aureus isolates from these cases. A total of 200 laying hens at 22 or 96 weeks of age (100/ age group) were assigned to 1 of 4 experimental inoculation groups (negative control, oral gavage, subcutaneous injection, or intravenous injection) after a 72 h acclimation period. Blood samples were taken prior to inoculation (baseline), 6 h post-inoculation (pi), 24 hpi, 3 dpi, and 7 dpi. Additional spleen samples to further assess systemic immunity were taken at baseline, 3 and 8 dpi. Metabolic phenotypes of peripheral blood mononuclear cells (PBMC) were isolated and assessed by Seahorse metabolic assay. Immune cell profiles in the spleen and PBMC were assessed by multicolor flow cytometry. At baseline, 96-week-old laying hens had 26.7% fewer PBMC-derived T cells compared to 22-week-old birds. Older hens had 28.9% increased helper T cell (TH) populations and 60.5% reduced γδ T cells (P = 0.03 and < 0.0001) which may contribute to variable clinical responses between age groups; however, no age-related differences in metabolic potential were observed. Metabolic outcomes showed that birds remained stressed from transport and re-housing past a 72 h acclimation period and through 24 h- 3 days post-inoculation. Inoculation with S. aureus generally reduced oxidative and glycolytic potentials compared to the control, with the greatest reductions observed in birds inoculated by intravenous injection (P < 0.05). Overall CD3+ T cell populations showed significant reductions in the intravenous group compared to other inoculation routes from 24 hpi to 7 dpi (23.6–39.0%; P ≤ 0.0001). These results suggest that age-related baseline differences in T cell populations and changes to T cell subpopulations and other immune cells due to inoculation route may have an additive effect on S. aureus- induced reductions in metabolic potential; however, further research linking metabolic potential and immune cell profiles is needed.
Compounds in microalgae-derived feed ingredients in poultry diets may improve intestinal physiology and immunity to protect against damage induced by physiological and pathogen challenges, but mechanisms are examined sparingly. The study objective was to evaluate changes to intestinal morphology, permeability, and systemic immunity in broilers fed a proprietary microalgae ingredient during 2 separate challenge studies. In study 1, two replicate 28 d battery cage trials used 200 Ross 308 broilers each (n = 400) fed a control diet ± 0.175% algae ingredient. Half of the birds were subjected to a 12 h feed restriction challenge and fluorescein isothiocyanate dextran ( FITC-D ) intestinal permeability assay on d 28. Study 2 used 800 broilers randomly assigned to the same dietary treatments and housed in floor pens for 42 d. At d 14, intestine and spleen samples were collected from 10 birds/ diet. Half of the remainder was orally inoculated with 10X Coccivac-B52 vaccine in a 2 × 2 factorial treatment design (diet and Eimeria inoculation). The FITC-D assay was conducted at 1, 3, 7, and 14 d post-inoculation ( pi ) while intestinal and spleen samples were collected at 3, 7, 14, and 28 dpi for histomorphology and flow cytometric immune cell assessment. Study 1 validated intestinal leakage via FITC-D absorbance induced by feed restriction but showed no algae-associated protective effects. In study 2, algae preserved intestinal integrity during coccidiosis ( P = 0.04) and simultaneously protected jejunal villus height as early as 7dpi ( P < 0.0001), whereas intestinal damage resolution in control birds did not occur until 14 dpi. Algae inclusion increased splenic T cells in unchallenged broilers at d 14 by 29.6% vs. control ( P < 0.0001), specifically γδ T cell populations, without impacting performance ( P < 0.03). During Eimeria challenge, splenic T cells in algae-fed birds did not show evidence of recruitment to peripheral tissues, while control birds showed a 16.7% reduction compared to their uninoculated counterparts from 3 to 7 dpi ( P < 0.0001). This evidence suggests the algae ingredient altered the immune response in a manner that reduced recruitment from secondary lymphoid organs in addition to protecting intestinal physiology.
Background Restaurant oil in poultry diets increases energy content, reduces production costs, and promotes sustainability within the food supply chain. However, variable oil composition and heating temperatures among restaurant oil sources can impact broiler chicken health due to heat-induced lipid modifications. Objectives A 21-d experiment was conducted to evaluate ileal morphology, liver cytokine gene expression, and ileal immune cell populations in broilers fed control or peroxidized lipids with varying chain and saturation characteristics. Methods Day-old broilers were housed in battery cages (5 birds per cage) and fed diets containing 5% control or peroxidized oils. Eight diets were randomly assigned in a 4 × 2 factorial arrangement consisting of oil source (palm, soybean, flaxseed, or fish) and peroxidation status (control or peroxidized). At day 21, samples were collected for ileal histomorphology [villus height (VH), crypt depth (CrD), and the VH:CrD ratio], and liver cytokine expression (qPCR). Ileum cytokine expression and T-cell markers were analyzed by RNAscope in situ hybridization (ISH). Data were analyzed as a mixed model (SAS 9.4) with fixed effects of lipid source, peroxidation, and lipid × peroxidation interaction. Results CD3+ T-cells in the ileum decreased 16.2% due to peroxidation (P = 0.001) with 30.3% reductions observed in birds fed peroxidized flaxseed oil (P = 0.01). Peroxidation increased IL6+ and IL1B+ cells by 62.0% and 40.3%, respectively (P = 0.01). Soybean oil increased IFNG+ cells by 55.1% compared with palm oil, regardless of peroxidation status (P = 0.007). Lipid source and peroxidation did not alter ileal histomorphology or liver cytokine expression. Conclusions Lipid peroxidation increased ileal IL1B and IL6 in broiler chickens, whereas soybean oil diets increased IFNG. Generally, peroxidation decreased overall CD3+ T-cell populations, suggesting impaired T-cell presence or recruitment. These results identify potential immunomodulatory lipid profiles in restaurant oil while supporting RNAscope-ISH as a method to describe avian tissue-level immune responses.
Yeast-derived 1,3/1,6 beta-glucans may alter host immunity to produce robust and quickly resolved responses that align with companion animal health goals. In adult dogs, immunomodulation by yeast 1,3/1,6 beta-glucans in extruded kibble diet have not been well-documented. The study objective was to evaluate systemic immune responses in dogs fed kibble diets with two yeast 1,3/1,6 beta-glucans doses before and after vaccine challenge. Twenty-four adult Labrador Retrievers were assigned to 3 dietary treatments consisting of a basal diet (control) supplemented with 0.012 or 0.023% (0.5 or 1X, respectively) yeast 1,3/1,6 beta-glucan with equal sex representation within each treatment (8 dogs/diet). Animals were fed experimental diets for a 29d acclimation period, after which baseline blood samples were collected before administration of a combination canine distemper virus, parvovirus, and adenovirus-2 vaccine. Blood samples were collected weekly for 21d following vaccination with whole blood for CBC analysis, serum for titer and cytokine assays, and peripheral blood mononuclear cells (PBMC) isolated for flow cytometric immune cell profiling. Data were analyzed using the MIXED procedure with diet and timepoint fixed effects. Serum titer was analyzed by Kruskal-Wallis test (SAS 9.4; P≤0.05). Prior to vaccination, beta-glucan diets did not affect serum cytokines, antibody titer, or immune cell populations. In the first 7 days post-vaccination (dpv), PBMC CD21 low B cells increased in 36.5-58.1% in all groups but the magnitude of change was lesser in the 0.5X beta-glucan diet resulting in 25.6% lower CD21 low populations compared to control-fed dogs (P=0.007). By 21dpv, B cell populations recovered to baseline levels in dogs fed 1X beta-glucan, but CD21 high cells remained elevated 50.5% in dogs fed 0.5X beta-glucan diets compared to baseline (P<0.0001). While no differences in serum titer or cytokines were observed, feeding both beta-glucan diets maintained stable blood monocytes whereas a 53.0% decrease between baseline and 14dpv was observed in control-fed dogs (P=0.01). Collectively, these outcomes suggest that a 1X dose of 1,3/1,6 yeast beta-glucan in extruded kibble diets altered monocytes associated with trained immunity, did not reduce PBMC CD21 low B cell responsiveness, and simultaneously contributed to B cell population resolution by 21dpv in adult dogs. Additional research to assess the functionality of these changes is needed.
and Implications Mouse models allow for detailed preliminary research into the health-promoting effects of novel feed additives to identify candidates for livestock application. Alfalfa is a potential source of health-promoting feed additives, but detailed findings on factors that maximize its benefits are lacking. The study objective was to evaluate the effects of feeding late and early alfalfa as hay, aqueous, and lipidsoluble extracts on the body weight (BW) and colon microbiota of mice before and after pathogen challenge. A total of 98 female 6-week-old C57BL/6J mice were weighed and assigned to 1 of 7 diets consisting of basal diet ± hay (9%), aqueous extract (0.25%), and chloroform extract (0.25%) of late and early cutting alfalfa. After 14d, 6 mice/treatment were euthanized for baseline colon digesta sampling. The remaining animals were orally inoculated with Citrobacter rodentium and 4 mice/ treatment were euthanized for colon digesta collection at 4 and 21d postinoculation (pi). While observed patterns in BW were not statistically significant, numerical improvements in early and late days post-inoculation (pi) indicated a protective effect of lipid-soluble extracts on BW during bacterial challenge. Corresponding to these observations, late cutting chloroform extracts significantly reduced pathogen abundance in the colon at 4dpi while increasing the abundance of beneficial community members at 21dpi (P = 0.02). These findings in mice support future research into the effects of late-cutting chloroform alfalfa extracts in livestock diets.
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