THE ROLE OF FEED ADDITIVES IN MITIGATING THE EFFECT OF STRESSORS ON GROWTH, DIGESTIBILITY, INTESTINAL MORPHOLOGY, PERMEABILITY, AND IMMUNE RESPONSE IN POULTRY

Three experiments were conducted to evaluate the interactive effects of dietary supplements in birds exposed to different stressors, on growth performance, nutrient, and energy digestibility, antioxidant status, intestinal permeability, and immune status. The first study was conducted to evaluate the effect of a commercially available algae-based antioxidant, containing Selenium yeast (EconomasE™, EcoE) and two inorganic sodium sources (NaCl and NaCl+NaHCO3) on growth performance, nutrient and energy digestibility and utilization, antioxidant, and immune status of broilers challenged with oral gavage of dexamethasone (DEX). The inclusion of either of the sodium sources did not affect plasma corticosterone and antioxidant status levels, growth performance, and the relative weights of the lymphoid organs. Homeostasis was altered with DEX, evident in the increased (P \u3c 0.05) levels of corticosterone in the plasma, reduced (P \u3c 0.05) growth performance, and nutrient digestibility. The EcoE supplementation did not mitigate the performance parameters however, its supplementation in the diet increased (P \u3c 0.05) nutrient and energy utilization and decreased corticosterone serum levels. The objective of the second study was to evaluate the effect of EconomasE™ (0 or 0.2 g/kg) and two inorganic sodium sources (NaCl or NaCl+NaHCO3) in layers exposed to different environmental temperatures. Dietary treatment did not improve performance, egg quality, intestinal morphology, keel bone, bone-breaking strength, and HSP 70 and 90 during ET1 and ET2. Exceptions to this were the increase (P \u3c 0.05) in the albumen height and Haugh unit with EcoE and NaCl+NaHCO3 during TN2 and EcoE alone during the ET2 regimen, which suggests that the supplementation can improve the fresh appearance of the egg during ET conditions. Similarly, NaCl+NaHCO3 as the sodium source helped limit the effects of respiratory alkalosis by reducing Cl- levels and increasing HCO3- during the ET regimen. In normal temperature conditions, EcoE and NaCl+NaHCO3 diet were able to improve (P \u3c 0.05) villus height and villus height: crypt depth ratio. The third study evaluated the effect of DEX and coccidia vaccine challenge in broiler chickens fed diets supplemented with or without Natustat™ (a natural plant-derived proprietary product composed of at least one yeast-derived MOS plus organic mineral nutrients and plant extracts) on growth performance, nutrient and energy digestibilities and utilization, intestinal barrier integrity, and immune response. Throughout the experiment, birds were fed a standard corn-SBM diet supplemented with or without Natustat™ at 1 g/kg. Within each diet group, the birds were randomly assigned to four treatments: CON (no-challenge), dexamethasone (DEX), coccidia vaccine (Cocci), and a combination of Cocci and DEX (CocciDex) challenge. The DEX and CocciDex groups received dexamethasone in the feed at 1.5mg/kg of diet for 7 days, while the Cocci and CocciDex groups were orally gavaged with 20x coccidia vaccine. The DEX and CocciDex-challenge were able to induce stress and reduce performance, digestibility, intestinal permeability, and immune response. The coccidia vaccine challenge did not affect performance. However, total tract nutrient and energy utilization were impaired and the jejunal mRNA expression of (TLR4) and pro-inflammatory cytokines 7-days post-challenge was observed. Finally, Natustat™ supplementation did not mitigate the negative effect of the stressors on performance, nutrient and energy digestibility and utilization, and intestinal morphology and permeability. The supplementation had a tendency to increase the expression of anti-inflammatory cytokine (IL-10) 7-days post-challenge. It also increased IL-10 and decreased the mRNA expression of IL-6, 14-days post-challenge. In conclusion, stress was induced in the birds especially with DEX and some with coccidia challenge and heat stress, and the supplements had a limited effect in mitigating the effect of the stressors

Evaluation of the Effect of a Lippia organoides Essential Oil Extract on Clostridium perfringens Proliferation In Vitro and Necrotic Enteritis in Broiler Chickens

The purpose of the present research was to assess the effects of essential oils derived from the plant Lippia organoides on performance parameters, intestinal integrity, and necrotic enteritis (NE) in broiler chickens. To do this, a previously established challenge model for NE was utilized which included challenging with Salmonella Typhimurium on day 0, Eimeria maxima on day 18, and Clostridium perfringens on days 22 and 23. Treatment groups included a 1) non-challenged, negative control, 2) challenged control, and 3) challenged, Lippia origanoides (37ppm in the diet). Group 1 (negative control) had significantly (P \u3c 0.05) higher body weight gain from d8-25 and d0-25 compared to both challenged groups. Feed intake was significantly different for all three groups (P \u3c 0.05) at 8-25 days and 0-25 days with group 1 having the highest feed intake for both time periods. Total mortality was greater in the positive control when compared to both the negative and treatment groups. NE lesion scores were significantly different between all groups with the positive control having the highest mean lesion scores and the negative control having a mean lesion score of 0. The positive control group had the highest FITC-d amounts detected in the sera, being statistically higher than both the treatment group and negative group which were both statistically different from each other. At the present inclusion rate for the essential oil (37 ppm), there was an overall reduction in the negative impact from the NE infection. Further studies should be conducted to reach more significant conclusions

Splenic gene expression signatures in slow-growing chickens stimulated in ovo with galactooligosaccharides and challenged with heat

open9siGalactooligosaccharides (GOS) that are delivered in ovo improve intestinal microbiota composition and mitigate the negative effects of heat stress in broiler chickens. Hubbard hybrids are slow-growing chickens with a high resistance to heat. In this paper, we determined the impact of GOS delivered in ovo on slow-growing chickens that are challenged with heat. The experiment was a 2 × 2 × 2 factorial design. On day 12 of incubation, GOS (3.5 mg/egg) was delivered into the egg (n = 300). Controls (C) were mock-injected with physiological saline (n = 300). After hatching, the GOS and C groups were split into thermal groups: thermoneutral (TN) and heat stress (HS). HS (30 °C) lasted for 14 days (days 36–50 post-hatching). The spleen (n = 8) was sampled after acute (8.5 h) and chronic (14 days) HS. The gene expression of immune-related (IL-2, IL-4, IL-6, IL-10, IL-12p40, and IL-17) and stress-related genes (HSP25, HSP90AA1, BAG3, CAT, and SOD) was detected with RT-qPCR. Chronic HS up-regulated the expression of the genes: IL-10, IL-12p40, SOD (p < 0.05), and CAT (p < 0.01). GOS delivered in ovo down-regulated IL-4 (acute p < 0.001; chronic p < 0.01), IL-12p40, CAT and SOD (chronic p < 0.05). The obtained results suggest that slow-growing hybrids are resistant to acute heat and tolerant to chronic heat, which can be supported with in ovo GOS administration.openPietrzak E.; Dunislawska A.; Siwek M.; Zampiga M.; Sirri F.; Meluzzi A.; Tavaniello S.; Maiorano G.; Slawinska A.Pietrzak E.; Dunislawska A.; Siwek M.; Zampiga M.; Sirri F.; Meluzzi A.; Tavaniello S.; Maiorano G.; Slawinska A

In ovo injection of a galacto-oligosaccharide prebiotic in broiler chickens submitted to heat-stress: Impact on transcriptomic profile and plasma immune parameters.

This study investigated the effects of a galactooligosaccharide (GOS) prebiotic in ovo injected on intestinal transcriptome and plasma immune parameters of broiler chickens kept under thermoneutral (TN) or heat stress (HS) conditions. Fertilized Ross 308 eggs were injected in ovo with 0.2 mL physiological saline without (control, CON) or with 3.5 mg of GOS (GOS). Three-hundred male chicks/injection treatment (25 birds/pen) were kept in TN or HS (30\ub0 C) conditions during the last growing phase, in a 2 x 2 factorial design. At slaughter, from 20 birds/injection group (half from TN and half from HS), jejunum and cecum were collected for transcriptome analysis, and plasma was collected. No differences in plasma parameters (IgA and IgG, serum amyloid) and no interaction between injection treatment and environment condition were found. GOS-enriched gene sets related to energetic metabolism in jejunum, and to lipid metabolism in cecum, were involved in gut barrier maintenance. A homogeneous reaction to heat stress was determined along the gut, which showed downregulation of the genes related to energy and immunity, irrespective of in ovo treatment. GOS efficacy in counteracting heat stress was scarce after ten days of environmental treatment, but the in ovo supplementation modulates group of genes in jejunum and cecum of broiler chickens

Impact of galactooligosaccharides delivered in ovo on mitigating negative effects of heat stress on performance and welfare of broilers

Galactooligosaccharides (GOS) delivered in ovo improve intestinal health of broiler chickens. This study aimed to demonstrate the impact of in ovo stimulation with GOS prebiotic on day 12 of egg incubation on performance and welfare traits in broiler chickens. The incubating eggs were divided into 3 groups, based on the substance injected in ovo: 3.5 mg of GOS dissolved in 0.2 mL physiological saline (GOS), 0.2 mL physiological saline (S), or uninjected controls (C). Constant heat stress (HS) was induced on days 32 to 42 post-hatch by increasing environmental temperature to 30\ub0C. Thermoneutral (TN) animals were kept at 25\ub0C. The performance (body weight [BW], daily feed intake [DFI], daily weight gain [DWG], and feed conversion rate [FCR]) were measured and mortality was scored for starter (days 0 to 13), grower (days 14 to 27), and finisher (days 28 to 42) feeding phases. Rectal temperature was scored on days 32 to 42. Food-pad dermatitis (FPD) was scored post-mortem (day 42). GOS increased (P < 0.01) BW on day 42 (2.892 kg in GOS vs. 2.758 kg in C). Heat stress significantly reduced (P < 0.01) final BW (2.516 kg in TN vs. 3.110 kg in HS). During finisher phase, DFI was significantly higher in GOS vs. C (173.2 g vs. 165.7 g; P < 0.05). FCR calculated for the entire rearing period (days 0 to 42) ranged from 1.701 in C to 1.653 in GOS (P < 0.05). GOS improved FCR in HS animals during finisher phase (P < 0.05). Rectal temperature of GOS chickens under HS reached 42.5\ub0C 1 day earlier than C and S (P < 0.05), which suggests that those birds recovered earlier from the high environmental temperature. Heat stress increased (P < 0.05) mortality about 5 times compared to TN during finisher phase (from 1.59% in TN to 7.69% in HS). GOS decreased FPD in TN conditions by 20% (no lesions in 81% in GOS vs. 60% in C). GOS delivered in ovo mitigated negative effects of HS on performance and welfare in broiler chickens

A review of heat stress in chickens. Part I: Insights into physiology and gut health

Heat stress (HS) compromises the yield and quality of poultry products and endangers the sustainability of the poultry industry. Despite being homeothermic, chickens, especially fast-growing broiler lines, are particularly sensitive to HS due to the phylogenetic absence of sweat glands, along with the artificial selection-caused increase in metabolic rates and limited development of cardiovascular and respiratory systems. Clinical signs and consequences of HS are multifaceted and include alterations in behavior (e.g., lethargy, decreased feed intake, and panting), metabolism (e.g., catabolic state, fat accumulation, and reduced skeletal muscle accretion), general homeostasis (e.g., alkalosis, hormonal imbalance, immunodeficiency, inflammation, and oxidative stress), and gastrointestinal tract function (e.g., digestive and absorptive disorders, enteritis, paracellular barrier failure, and dysbiosis). Poultry scientists and companies have made great efforts to develop effective solutions to counteract the detrimental effects of HS on health and performance of chickens. Feeding and nutrition have been shown to play a key role in combating HS in chicken husbandry. Nutritional strategies that enhance protein and energy utilization as well as dietary interventions intended to restore intestinal eubiosis are of increasing interest because of the marked effects of HS on feed intake, nutrient metabolism, and gut health. Hence, the present review series, divided into Part I and Part II, seeks to synthesize information on the effects of HS on physiology, gut health, and performance of chickens, with emphasis on potential solutions adopted in broiler chicken nutrition to alleviate these effects. Part I provides introductory knowledge on HS physiology to make good use of the nutritional themes covered by Part II

Mechanistic Understanding of Leaky Gut Syndrome in Heat Stressed Broiler Chickens

Abstract Broilers, meat-type chickens, are bred for high growth rate and meat yield. These chickens have specific challenges due to heat stress. The adverse effects that impact these chickens have lead us to study the mechanisms involved. The objective of this study is to evaluate the expression of genes involved in intestinal permeability of heat- stressed broiler chickens. All analyses are on previously collected tissues. A total of 600 one day old Cobb 500 male chicks were weighed and randomly assigned to 12 environmental chambers. Ambient temperature in the chambers was gradually decreased from 32˚C on d 1 to 24˚C at d 21. At 8am on d 21, the temperature was increased to 35˚C in 6 of the chambers to induce HS. All chambers reached 35°C within 15 minutes of temperature adjustment. Thermoneutral (TN) chambers were maintained at 24°C. After 2h of HS, the thermologger birds were humanely euthanized via cervical dislocation. The gut was dissected and a ~2cm portion of the duodenum, jejunum, and ileum were collected. These samples underwent RNA extraction and cDNA reverse transcription to prepare for quantification using real-time PCR. This is an additional study to evaluating what genes play a role in leaky gut syndrome in heat stress broiler chickens to further understand the genetic potential of regulating heat-stress. The results of this study showed a down-regulation of HSP 70 in the duodenum under heat-stress and mostly no significant change of HSP 90, HSP 60, HSP27, GRP75, Claudin, Occludin, and Zo-1

Effect of Morinda citrifolia (Noni)-Enriched Diet on Hepatic Heat Shock Protein and Lipid Metabolism-Related Genes in Heat Stressed Broiler Chickens

Heat stress (HS) has been reported to alter fat deposition in broilers, however the underlying molecular mechanisms are not well-defined; therefore, the objectives of the current study were to: (1) determine the effects of acute (2 h) and chronic (3 wk) HS on the expression of key molecular signatures involved in hepatic lipogenic and lipolytic programs; and (2) assess if diet supplementation with dried Noni medicinal plant (0.2% of the diet) modulates these effects. Broilers (n=480 males, 1 d) were randomly assigned to 12 environmental chambers, subjected to two environmental conditions (HS at 35°C vs. thermoneutral condition [TN] at 24°C) and fed two diets (control vs. Noni) in a 2 × 2 factorial design. Feed intake and body weights were recorded, and blood and liver samples were collected at 2 h and 3 wk post-heat exposure. HS depressed feed intake, reduced body weight, and up-regulated the hepatic expression of heat shock protein HSP60, HSP70, HSP90, as well as key lipogenic proteins fatty acid synthase (FASN), acetyl co-A carboxylase alpha (ACCα), and ATP citrate lyase (ACLY). HS down-regulated the hepatic expression of lipoprotein lipase (LPL) and hepatic triacylglycerol lipase (LIPC), but up-regulated adipose triglyceride lipase (ATGL). Although it did not affect growth performance, Noni supplementation regulated the hepatic expression of lipogenic proteins in a time- and gene-specific manner. Prior to HS, Noni increased ACLY and FASN in acute and chronic experimental conditions, respectively. During acute HS, Noni increased ACCα, but reduced FASN and ACLY expression. Under chronic HS, Noni up-regulated ACCα and FASN but it down-regulated ACLY. In cells, HS exposure to 45°C for 2 hours down-regulated ACCα, FASN, and ACLY compared to TN exposure at 37°C. Treatment with quercetin, one bioactive ingredient in Noni, up-regulated the expression of ACCα, FASN, and ACLY under TN conditions, but it appeared to down-regulate ACCα and increase ACLY levels under HS exposure. In conclusion, our findings indicate that HS induces hepatic lipogenesis in chickens and this effect is probably mediated via HSPs. The modulation of hepatic heat-shock protein HSP expression suggests that Noni might be involved in modulating the stress response in chicken liver