Effects of density and perch availability on the immune status of broilers

Comparative evaluation of Lactobacillus strains with different adhesion ability on growth performance and immunomodulatory activity in broiler chickens

The study was designed to assess the effect of 2 Lactobacillus strains (Lactobacillus kefiri 1.3207 and Lactobacillus plantarum 1.2567) with different adherence ability on growth performance and immunomodulatory activity in broiler. The BW and FCR were higher in L. kefiri 1.3207 and L. plantarum 1.2567 groups compared to control group at 42 days of age, and BW of broilers in L. kefiri 1.3207 group was significantly higher than that in L. plantarum 1.2567 group. IgA and IgG contents and the spleen and bursa of Fabricius indices in significantly increased in the L. kefiri 1.3207 group, but not in the L. plantarum 1.2567-treated group. L. kefiri 1.3207 had more significant effect on growth performance, plasma IgA and IgG levels and immune organs indices because it had better adhesion ability.

Effects of stale maize on growth performance, immunity, intestinal morphology and antioxidant capacity in broilers

OBJECTIVE

This study was conducted to determine the effects of stale maize on growth performance, immunity, intestinal morphology, and antioxidant capacity in broilers.

METHODS

A total of 800 one-day-old male Arbor Acres broilers (45.4±0.5 g) were blocked based on body weight, and then allocated randomly to 2 treatments with 20 cages per treatment and 20 broilers per cage in this 6-week experiment. Dietary treatments included a basal diet and diets with 100% of control maize replaced by stale maize.

RESULTS

The content of fat acidity value was higher (p<0.05) while the starch, activities of catalase and peroxidase were lower (p<0.05) than the control maize. Feeding stale maize diets reduced (p<0.05) average daily feed intake (ADFI) throughout the experiment, feed conversion ratio (FCR) during d 0 to 21 and the whole experiment as well as relative weight of liver, spleen, bursa of Fabricius and thymus (p<0.05) on d 21. Feeding stale maize diets decreased jejunum villus height (VH) and VH/crypt depth (CD) (p<0.05) on d 21 and 42 as well as ileum VH/CD on d 42. The levels of immunoglobulin G, acid α-naphthylacetate esterase positive ratios and lymphocyte proliferation on d 21 and 42 as well as lysozyme activity and avian influenza antibody H5N1 titer on d 21 decreased (p<0.05) by the stale maize. Feeding stale maize diets reduced (p<0.05) serum interferon-γ, tumor necrosis factor-α, interleukin-2 on d 21 and interleukin-6 on d 21 and 42. Broilers fed stale maize diets had lower levels of (p<0.05) total antioxidative capacity on d 42, superoxide dismutase and glutathione peroxidase on d 21 and 42, but higher (p<0.05) levels of malondialdehyde on d 21 and 42.

CONCLUSION

Feeding 100% stale maize decreased ADFI and FCR, caused adverse effects on immunity and antioxidant function and altered intestinal morphology in broilers.

Dietary Tea Tree (Melaleuca alternifolia) Oil Supplementation Improves Growth Performance, Cecal Microflora, Immunity, and Antioxidant Capacity of Partridge Shank Chickens

The aim of this study was to investigate the effects of tea tree oil (TTO) supplementation on the growth performance, cecal microflora composition, immunity, and antioxidant status of Partridge Shank chickens. A total of 144 one-day-old chicks were allocated into three treatments with six replicates of eight chicks each and fed with a basal diet supplemented with 0 (Control group), 500, and 1000 mg/kg TTO for 50 days. Compared with the control group, the broilers fed with the basal diet supplemented with 1000 mg/kg TTO exhibited an increase in average daily gain from 22 to 50 days (P=0.035) and in both relative thymus weight (P<0.001) and Lactobacillus colonies in the cecal contents (P=0.045) at 50 days of age, but a reduction in the feed/gain ratio during 1 to 50 days (P=0.048). Additionally, dietary TTO supplementation, irrespective of dosage, increased the relative spleen weight (P=0.003) and total antioxidant capacity in the jejunum (P=0.049) and ileum (P=0.001) at 21 days, but decreased the malondialdehyde content in the ileum at both 21 (P=0.003) and 50 days (P<0.001) and in the jejunum at 50 days (P=0.012). The results suggested that TTO supplementation could improve the growth performance, cecal microflora composition, immunity, and antioxidant capacity of Partridge Shank chickens.

Dietary supplementation with free methionine or methionine dipeptide mitigates intestinal oxidative stress induced by Eimeria spp. challenge in broiler chickens

Background

This study evaluated the effects of Eimeria spp. challenge and dietary supplementation with free methionine or methionine dipeptide on animal performance; expression of genes associated with the immune system, antioxidant system, and amino acid transport in the jejunum; and redox status of the jejunum of broiler chickens.

Methods

A randomized, 2 × 3 factorial design was used, in which Eimeria spp. challenge was the first factor (Eimeria-challenged, EC, or unchallenged, UC, broilers) and methionine supplementation was the second factor (non-supplemented, NS; free dl-methionine, dl-Met; and methionine dipeptide, dl-methionyl-dl-methionine, dl-MMet). At 14 days of age, chickens were inoculated orally with sporulated oocysts of Eimeria acervulina, Eimeria praecox, Eimeria maxima, and Eimeria mitis. Birds were killed by cervical dislocation 144 h post-inoculation (PI), and the jejunum was collected for biochemical and molecular analyses.

Results

EC broilers had a 13% lower feed intake (FI), 37% lower body weight gain (BWG), and 39% higher feed conversion ratio (FCR) than UC broilers. Chickens fed the dl-Met diet had higher BWG (about 12% higher) and better FCR (about 12% lower) than chickens fed the NS diet. EC chickens had lower relative weight of the bursa of Fabricius (51.8%) and higher relative weights of the spleen and whole intestine (53.6% and 26.3%, respectively) than UC chickens. Eimeria spp. challenge led to an increase in the levels of oxidative substances, such as nitrite and thiobarbituric acid reactive substances (TBARS), in the jejunum of chickens 144 h PI. Among UC chickens, those fed the dl-Met diet had higher total antioxidant capacity (TAC) and lower catalase (CAT) and superoxide dismutase (SOD) activities. EC chickens that received the NS diet had higher carbonylated protein content (CP). This result was associated with their lower TAC and catalase activity. The lower TAC in EC chickens might have been due to reduced expression of catalase (CAT) and superoxide dismutase 1 (SOD1) genes. Chickens fed the dl-Met and dl-MMet diets had lower nitrite content. Eimeria spp. challenge suppressed neutral amino acid transporter 1 (B⁰AT1), peptide transporter 1 (PEPT1), toll-like receptor 5 (TLR5), interleukin 2 (IL2), and occludin (OCLN) gene expression and enhanced cationic amino acid transporter 1 (CAT-1) and interferon gamma (IFNG) gene expression. The highest PEPT1 expression level was observed in broilers fed the dl-MMet diet, and the lowest TLR5 expression level was found in broilers fed the NS diet.

Conclusion

Our results show for the first time that supplementation with methionine as free amino acid or dipeptide helps protect the intestinal cells of broilers under Eimeria spp. challenge from the oxidative damage induced by free radicals, mainly through modulation of the antioxidant system.

Evaluation of the blend of organic acids and medium-chain fatty acids in matrix coating as antibiotic growth promoter alternative on growth performance, nutrient digestibility, blood profiles, excreta microflora, and carcass quality in broilers

This study was conducted to evaluate the effects of the blend of organic acids (OAs) and medium-chain fatty acids (MCFAs) in broiler chickens. A total of 816 1-d-old male Ross 308 broiler chickens (35 ± 0.44 g) were randomly allocated into 1 of the following 6 dietary treatments (17 broilers per pen with 8 pens per treatment): dietary treatments consisted of corn-soybean meal-based basal diet and the basal diet supplemented with 0.02, 0.03, 0.04, 0.05, and 0.06% blend of OAs and MCFAs. The study lasted 5 wk during which growth performance was determined. In the current study, the inclusion of 0.02, 0.03, 0.04, 0.05, and 0.06% blend of OAs and MCFAs in the basal diet linearly increased (P < 0.05) body weight gain and improved feed conversion ratio (P < 0.0001) on day 7 to 14, day 14 to 35, as well as overall. Increasing inclusion of the blend of OAs and MCFAs levels in the diets also linearly increased (P = 0.001) the digestibility of dry matter on day 35. Broilers fed with different levels of the blend of OAs and MCFAs showed a linear increment (P = 0.042) in Lactobacillus concentration and decrease (P = 0.002) in Escherichia coli concentration. With regard to relative organ weight, a trend of linear reduction (P = 0.052) in bursa of Fabricius weight of broilers fed the blend of OAs and MCFAs was observed. There was a significant linear improvement (P = 0.011) in the IgG concentration associated with the inclusion of the blend of OAs and MCFAs levels in the diets. In conclusion, the blend of OAs and MCFAs supplementation positively influenced growth performance, nutrient digestibility, and excreta microflora in broiler chickens.

Effects of reduced-protein diets supplemented with protease in broiler chickens under high stocking density

The effects of protease supplementation on productive performance and physiological responses were investigated in broiler chickens fed reduced crude-protein (low-CP) diets and reared under normal or high stocking densities (SD). Chicks were housed in pens with two stocking densities (≈10 birds/m2 or ≈15 birds/m2) and fed diets with either the recommended or reduced level of CP and metabolisable energy (ME) from 1 to 21 days. From 22 to 42 days, an equal number of birds from each dietary group was fed one of the following finisher diets: (1) recommended-CP and ME, (2) low-CP and recommended-ME or (3) low-CP and recommended-ME supplemented with protease. No interactions (P &gt; 0.05) were observed between diet and SD for feed intake (FI), weight gain (WG), feed conversion ratio (FCR), Newcastle disease antibody titre, pododermatitis, caecal clostridia, Escherichia coli, lactobacilli, serum corticosterone or acute-phase proteins. Diet had no effect (P &gt; 0.05) on FI, WG or FCR during the finisher period nor on FI and WG during the overall (1–42 days) period. High SD resulted in lower FI (P &lt; 0.05) and Newcastle disease antibody titre (P &lt; 0.05) and higher FCR (P &lt; 0.05), pododermatitis incidence (P &lt; 0.05), caecal population of clostridia (P &lt; 0.05) and E. Coli (P &lt; 0.05), and acute-phase protein and corticosterone concentrations than did normal SD. In conclusion, the supplementation of protease to a low-CP diet during the finisher period had no effect on the performance and immunity of overcrowded broiler chickens. Regardless of dietary CP and protease supplementation, a high SD negatively affected the growth performance, immunity, caecal microflora and welfare of the broiler chickens.

Effects of fumonisin B1 and mycotoxin binders on growth performance, tibia characteristics, gut physiology, and stress indicators in broiler chickens raised in different stocking densities

The present study was carried out to investigate the effects of stocking density, fumonisin B1 (FB), and mycotoxin binder (TB) on growth performance, bone quality, physiological stress indicators, and gut health in broiler chickens. Day-old Ross 308 male broiler chicks (n = 1,440/experiment) were randomly allocated to 72 floor pens in a 3 × 2 × 2 factorial arrangement, using 3 stocking densities (12.5 birds/m2 [HSD], 10 birds/m2 [MSD], or 7.5 birds/m2 [LSD]), 2 levels of purified FB (0 or 10 ppm), and 2 levels of TB (0 or 0.2%). Each treatment had 6 replicates (n = 6/treatment) and experiments lasted 34 days. All data were analyzed using 3-way ANOVA with stocking density level, FB, and TB as main factors. Body weight gain and feed intake were lower (P < 0.05) in broilers kept at HSD and MSD compared to LSD-housed counterparts. Birds fed an FB-contaminated diet exhibited a higher feed-to-gain ratio compared with those fed an FB-free diet (P < 0.05). None of the treatments affected intestinal morphology or ileal secretory immunoglobulin A levels. Stocking density affected tibia breaking strength (P < 0.05), which was lower in chickens housed at HSD compared with LSD-housed chickens. The heterophil/lymphocyte ratio (H/L ratio) was elevated (P < 0.05) in HSD and MSD groups compared with the LSD group. Serum nitric oxide (NO) levels were elevated (P < 0.05) in chickens fed the FB-contaminated diet compared with the control diet-fed counterparts. Significant interaction (P < 0.05) between FB and TB on serum NO levels was noted. In summary, increasing stocking density lowered growth performance and bone quality, but increased the H/L ratio. Dietary TB did not affect FB-induced increases in the feed-to-gain ratio. No interaction was observed between stocking density and FB for the measured variables.

Effect of stocking density vis-à-vis dietary protein supply on growth performance, immune-competence and cost economics of growing turkey poults

A 10-week biological experiment was undertaken to evaluate the response of Beltsvilie Small White turkey poults to different floor space (0.6, 0.8, and 1.0 ft2/bird) and dietary protein levels (22%, 24% and 26% with similar dietary energy) in terms of growth performance, immune response, and serum biochemistry, following 3 × 3 factorial design. Each treatment was allocated 4 replicates out of which one replicate was maintained for the replacement of the dead birds, if any, to maintain the required stocking density. The body weight gain (BWG), feed intake (FI) and performance index (PI) of poults was significantly higher in 1.0 ft2 floor space during 0–4 weeks and 4–10 weeks of age. Similarly, higher BWG, FI, and PI were observed at 26% dietary protein level. The interaction effect between stocking density and protein levels during 0–4 week resulted in significantly higher FI at 0.8 ft2 floor space with 26% protein level and 1.0 ft2 floor space with 24% as well as 26% protein level. The feed conversion ratio (FCR), mortality pattern, immune response and immune organ weights of poults did not reveal any significant treatment effect. The feed cost/bird increased linearly with increasing floor space, and feed cost/kg weight gain and feed cost/ kg meat increased linearly with increasing protein levels. However, profit potential per meter square decreased linearly with decreasing stocking density. The study concluded that increasing the stocking density and decreasing the dietary protein level decrease the performance of poults, but the profit potential per meter square increases with increasing stocking density. Thus, the study recommends either the floor space of 0.8 ft2/bird with 26% dietary protein level or the floor space of 1.0 sq2/bird with 24% dietary protein level for growing turkey poults.

Effects of dietary vitamin C, vitamin E, and alpha-lipoic acid supplementation on the antioxidant defense system and immune-related gene expression in broilers exposed to oxidative stress by dexamethasone

Vitamin C, vitamin E, and alpha-lipoic acid (ALA) are potent nutritional antioxidants, which are important for enhancing immunity. This study compared the effects of supplementation with vitamin C, vitamin E, or ALA on the antioxidant defense system and the expression of immune-related genes under oxidative stress induced by dexamethasone (DEX) in broilers. In total, 240 one-day-old female Recessive White Rock chickens were assigned randomly to either a basal diet (control group) or basal diet supplemented with vitamin C (200 mg/kg diet), vitamin E (100 mg/kg), or ALA (500 mg/kg) for 28 d starting from hatching. At 21 d of age, birds fed the ALA-supplemented diet had the highest plasma total antioxidant capacity (T-AOC) and superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-PX) enzyme activities, and the lowest plasma malondialdehyde (MDA) activity, as well as the lowest mRNA gene expression levels of interferon gamma (IFN-γ) and lipopolysaccharide-induced tumor necrosis factor-alpha factor (LITAF). At 23 d of age, the broilers in the 3 treatment groups were injected in the thigh muscle with DEX for 3 alternating days. In addition, the control group was divided into 2 equal groups, in which one was injected with saline and the other was injected with DEX. At 28 d of age, the DEX-ALA group (P < 0.05) had the highest activity levels for T-AOC, T-SOD, and GSH-PX in the plasma and liver (P < 0.05), and the greatest reduction in the MDA level. Dietary ALA significantly decreased the mRNA expression levels of the interleukin 1 β (IL-1β), IL-6, IFN-γ, and LITAF genes compared with the other groups during oxidative stress by DEX. In conclusion, this study suggests that in broilers, ALA is more effective for normalizing the oxidative stress induced by DEX than vitamin C or vitamin E.

Effects of chronic thermal stress on growth performance, carcass traits, antioxidant indices and the expression of HSP70, growth hormone and superoxide dismutase genes in two broiler strains

The objective was to investigate the effects of genetic type and the duration of chronic thermal stress (36 °C) on the growing efficiency, carcass traits, antioxidant status, and the expression of liver heat shock protein 70 (HSP70), growth hormone (GH) and superoxide dismutase (SOD) genes. Two hundred and seventy one-day-old chicks (135 male chicks of each breed; Ross 308 and Cobb 500) were used in this work. On the 21st day of age, birds were allocated randomly into 3 equal groups till the 42 days of age (CON:raised in a thermoneutral condition; HS₁ and HS₂ groups were subjected to 4 and 6 h of daily thermal stress, respectively). Regardless of genetic type, thermal stress decreased the dressing percentage in broilers when compared with the thermoneutral conditions (p = 0.039). In both broiler strains, thermal stress for 6 h (HS₂) increased the heterophil to lymphocyte ratio (p = 0.036) and the serum albumin, cholesterol and triglyceride levels (p = 0.023, 0.012 and 0.005, respectively) compared with the thermoneutral group. Under the thermonuteral and heat stress conditions, the Ross broiler chickens showed a significant lower serum triiodothyronine level compared with the Cobb boilers (p = 0.042). It is interesting to note that the expression of HSP70 in the liver of heat-stressed Ross broilers, either 4 or 6 h, was significantly (p = 0.002) higher than that reported in the heat-stressed Cobb broilers. In both broiler strains, the thermal stress for 6 h up-regulate the expression of SOD gene (p = 0.001), but down-regulate the expression of GH gene (p = 0.021) when compared with the CON group. In conclusion, chronic thermal stress down-regulate the mRNA expression of liver GH, concomitantly with an increase in the expression of HSP70 and SOD genes in both broiler strains. This could be useful in the identification of molecular genetic markers to assist in selecting broilers that are more tolerant to heat stress.

Effects of dietary supplementation with oridonin on the growth performance, relative organ weight, lymphocyte proliferation, and cytokine concentration in broiler chickens

Background

The present study was conducted to investigate the effects of oridonin (ORI) on growth performance, relative organ weight, lymphocyte proliferation, phagocytic function of neutrophils, and cytokine concentration in broiler chickens. A total of 240 one-day-old Arbor Acres male broilers were randomly assigned to four treatments with six replicate pens of 10 broiler chickens per pen. Broiler chickens were fed diets based on four levels of dietary ORI (0, 50, 80 and 100 mg/kg) for a 42-d feeding trial. The experimental diets were fed in three phases: 1 to 14 d, 15 to 28 d and 29 to 42 d.

Results

The results indicated that ORI has no influence on the growth performance (P > 0.05). However, ORI increased the relative weights of spleen and bursa, the number of proliferation peripheral blood T and B lymphocytes, the phagocytic rate of neutrophils, as well as the Interleukin-2 (IL-2), Interleukin-4 (IL-4) and tumor necrosis factor-a (TNF-a) serum concentrations in serum in broilers at days 14, 28 and 42 (P < 0.05).

Conclusions

In conclusion, ORI can enhance immune function and resistance to disease in broiler chickens by stimulating T and B lymphocyte formation, division, and proliferation, as well as the modulation of Th1/Th2 cytokine secretion profiles.

Lipopolysaccharide induces acute bursal atrophy in broiler chicks by activating TLR4-MAPK-NF-κB/AP-1 signaling

We investigated the mechanisms that induce atrophy of the chicken bursa of Fabricius (BF) upon lipopolysaccharide (LPS) treatment in young chicks. LPS treatment resulted in ∼36% decrease in bursal weight within 36 h (P < 0.01). Histological analysis showed infiltration of eosinophilic heterophils and nucleated oval shaped RBCs in or near blood vessels of the BF from LPS-treated chicks. Scanning electron micrographs showed severe erosion and breaks in the mucosal membrane at 12 h and complete exuviation of bursal mucosal epithelial cells at 36 h. We observed decreased cell proliferation (low PCNA positivity) and increased apoptosis (high TUNEL and ssDNA positivity) in the BF 12-72 h after LPS treatment. RNA-seq analysis of the BF transcriptome showed 736 differentially expressed genes with most expression changes (637/736) 12 h after LPS treatment. KEGG pathway analysis identified TLR4-MAPK-NF-κB/AP-1 as the key signaling pathway affected in response to LPS stimulation. These findings indicate LPS activates the TLR4-MAPK-NF-κB/AP-1 signaling pathway that mediates acute atrophy of the chicken bursa of Fabricius by inducing inflammation and apoptosis.

Feed-additive probiotics accelerate yet antibiotics delay intestinal microbiota maturation in broiler chicken

BACKGROUND

Reducing antibiotics overuse in animal agriculture is one key in combat against the spread of antibiotic resistance. Probiotics are a potential replacement of antibiotics in animal feed; however, it is not clear whether and how probiotics and antibiotics differ in impact on physiology and microbial ecology of host animals.

RESULTS

Host phenotype and fecal microbiota of broilers with either antibiotics or probiotics as feed additive were simultaneously sampled at four time points from birth to slaughter and then compared. Probiotic feeding resulted in a lower feed conversion ratio (FCR) and induced the highest level of immunity response, suggesting greater economic benefits in broiler farming. Probiotic use but not antibiotic use recapitulated the characteristics of age-dependent development of gut microbiota in the control group. The maturation of intestinal microbiota was greatly accelerated by probiotic feeding, yet significantly retarded and eventually delayed by antibiotic feeding. LP-8 stimulated the growth of many intestinal Lactobacillus spp. and led to an altered bacterial correlation network where Lactobacillus spp. are negatively correlated with 14 genera and positively linked with none, yet from the start antibiotic feeding featured a less-organized network where such inter-genera interactions were fewer and weaker. Consistently, microbiota-encoded functions as revealed by metagenome sequencing were highly distinct between the two groups. Thus, "intestinal microbiota maturation index" was proposed to quantitatively compare impact of feed additives on animal microecology.

CONCLUSIONS

Our results reveal a tremendous potential of probiotics as antibiotics' substitute in poultry farming.

Effects of Kluyveromyces marxianus supplementation on immune responses, intestinal structure and microbiota in broiler chickens

To investigate the effects of Kluyveromyces marxianus on immune responses, intestinal structure and microbiota in broilers, 840 1-d-old broiler chicks were randomly divided into seven groups (eight replicates) and were fed basal diets without or with 0.25, 0.50, 1.0, 1.5, 2.0, and 2.5 g/kg of K. marxianus (2.0×10¹⁰ CFU/g). Serum and intestine samples were collected at 21 d of age. The results showed that increasing K. marxianus addition linearly reduced feed conversion ratio but linearly elevated relative thymus weight, as well as quadratically increased serum lysozyme and IgG levels, with the medium dose (1.0 g/kg) being the most effective. The ratio of villus height to crypt depth of jejunum and ileum, ileal villus height and sucrase activity, as well as the mRNA expression of ileal mucin-2, claudin-1 and sodium glucose cotransporter 1 linearly responded to the increasing K. marxianus addition. Supplemental K. marxianus at low (0.5 g/kg), medium (1.5 g/kg) and high (2.5 g/kg) dose all decreased the abundance of phylum Cyanobacteria, increased the abundance of phylum Firmicutes and genus Lactobacillus in ileum. The high dose of K. marxianus addition also reduced the abundance of order Rickettsiales and Pseudomonadales along with species Acinetobacter junii. Ileal bacterial communities between K. marxianus-treated and untreated groups formed distinctly different clusters. In summary, K. marxianus supplementation benefits feed efficiency and immune function, as well as intestinal structure in broilers, which might be attributed to the improved ileal microbial structure. Supplemental K. marxianus at high dose (2.5 g/kg) was more effective for feed efficiency and intestinal health of broilers, while the innate immunity was optimized at a medium dose (1.0 g/kg).

Influence of probiotic supplementation on immune response in broilers raised under hot climate

1. The objective of the study was to evaluate the potential effects of dietary probiotic supplementation and stocking density and their interaction on growth performance, humoral and cellular immune responses of broiler chickens raised under hot climate conditions. 2. A total of 1800 1-d-old unsexed broiler chicks (Ross 308) were allocated in a completely randomised 3 × 2 factorial design, with three concentrations of dietary probiotic (0, 200 and 400 mg/kg) containing 4 × 10⁹ cfu/g of Bacillus subtilis and two stocking densities (12 or 18 birds/m²) in a total of 6 treatment subgroups. 3. Dietary probiotic and stocking density had no significant effect on live body weight, feed consumption and feed conversion ratio. 4. Dietary probiotic supplementation had a positive effect on serum immunoglobulin M (IgM) and cell-mediated immunity when compared to the control at 6 weeks of age, whereas serum immunoglobulin A (IgA) and immunoglobulin Y (IgY) were improved, but not significantly so. Dietary probiotic and stocking density had no effect on relative weights of the bursa of Fabricius and spleen. 5. Dietary probiotic supplementation had a positive significant effect on serum IgM concentration and cell-mediated immunity without penalising growth performance in broilers raised under high ambient temperature.

Dietary Administration of Bacillus subtilis Enhances Growth Performance, Immune Response and Disease Resistance in Cherry Valley Ducks

Given the promising results of applying Bacillus subtilis (B.subtilis) as a probiotic in both humans and animals, the aim of this study was to systematically investigate the effects of B. subtilis on growth performance, immune response and disease resistance in Cherry Valley ducks. At 28 d post-hatch (dph), ducks fed a diet with B. subtilis weighed significantly more, had higher relative immune organ weights (e.g., bursa of Fabricius, thymus, and spleen), and exhibited greater villus heights, villus height to crypt depth ratios (duodenum and jejunum), and shallower crypt depths in the duodenum than controls fed a normal diet (p < 0.05). Moreover, the major pro-inflammatory factors and antiviral proteins, as measured in the thymus and the spleen, were higher at 28 dph in ducks fed probiotics than those of 14 dph. After 28 d of feeding, the ducks were challenged with Escherichia coli (E. coli) and novel duck reovirus (NDRV), and ducks fed B. subtilis achieved survival rates of 43.3 and 100%, respectively, which were significantly greater than the control group's 20 and 83.3%. Altogether, diets with B. subtilis can improve Cherry Valley ducks' growth performance, innate immune response, and resistance against E. coli and NDRV.

Parity and litter size effects on maternal behavior of Small Tail Han sheep in China

The effects of parity and litter size on maternal behavior of Small Tail Han sheep was investigated at Linyi University, China. Sixty-eight ewes were observed from parturition to weaning. Continuous focal animal sampling was used to quantify the duration of maternal behaviors. Ewe feces were collected every 2 days and estradiol concentration was measured with an enzyme immunoassay kit. All lambs were weighed 24 h after parturition and again at 35 days of age. Parity increased sucking, following, grooming, low-pitched bleat, head-up and udder-refusal behavior and decreased aggressive behavior (P < 0.01, P < 0.01, P < 0.05, P < 0.05, P < 0.05, P < 0.05, P < 0.01, respectively), and litter size showed significant effect on sucking, following and low-pitched bleat behavior (P < 0.05, P < 0.01, P < 0.05, respectively). The lambs of multiparous ewes were significantly heavier than primiparous ewes at birth (P < 0.01) and were significantly heavier at weaning age (P < 0.01). Similar results were founded for birth weight and weaning weight gain in litter size (P < 0.01, P < 0.01, respectively). Estradiol concentration in feces was higher in multiparous ewes than primiparous ewes. Parity and litter size may have effects on maternal behavior during lactation. Ewes that have 2-3 lambs may be more suitable for production of Small Tail Han sheep in China.

Effects of tryptophan supplementation on growth performance, antioxidative activity, and meat quality of ducks under high stocking density

High stocking density (STD) could affect duck welfare and production. The objective of our study was to investigate whether dietary tryptophan (TRP) supplementation could alleviate the detrimental effects of high STD on ducks. White Pekin ducks at 4 to 6 wk of age were raised at 11 birds/m(2) and fed diets containing 0.18, 0.48, 0.78, or 1.08% TRP for 21 d. Growth performance, concentrations of TRP and metabolites in the blood and hypothalamus, antioxidative activities in serum and tissue, meat quality, serum uric acid, and urea nitrogen were measured. Weight gain and feed efficiency were significantly improved by TRP supplementation at ≥ 0.48 and ≥ 0.78% (P < 0.05 and P < 0.001, respectively). Serum TRP, hypothalamic TRP, 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacitic acid (5-HIAA), and 5-HIAA/5-HT were also increased significantly (P < 0.01). These increases plateaued at 0.48% TRP, and no further improvement was obtained by adding more TRP to the diet. Dietary TRP supplementation significantly increased levels of total antioxidant capacity, glutathione peroxidase (GSH-Px), and catalase (CAT) in serum; GSH-Px in liver; and GSH-Px and CAT in breast muscle (P < 0.05). Malondialdehyde levels in breast muscle decreased (P < 0.001). Drip loss of breast muscle and pH decline at 45 min postmortem were reduced by TRP supplementation (P < 0.01 and P < 0.05, respectively). Meat color was similar among different treatments (P > 0.05). Breast muscle shear force was increased significantly when dietary TRP level increased to 1.08% (P < 0.01). For ducks raised at 11 birds/m², dietary TRP supplementation could alleviate stress and improve growth performance, antioxidative activity, and meat quality.

Effects of outdoor access days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed

An experiment was conducted to evaluate the effect of outdoor access days on growth performance, carcass yield, meat quality, and lymphoid organ index of a local chicken breed. In total, 864 twenty one-day-old male Suqin yellow chickens, with similar body weight (536±36g), were selected and raised in indoor floor pens that measured 1.42×1.42 m (2 m2, 18 birds/m2) in conventional poultry research houses (36 birds per pen). Two hundred and sixteen birds were allowed outdoor access treatments at 21, 28, 35, and 42 d of age, respectively (access to outdoor for 35, 28, 21, and 14 days, respectively). Each treatment was represented by 6 replicates (pens) containing 36 birds (216 birds per treatment). In the outdoor access treatment, the birds had an outdoor free-range paddock that measured 3×8 m (24 m2, 1.5 birds/m2). The body weight of birds at 56 d of age increased linearly with increasing outdoor access days (P<0.001), but there was no effect of the outdoor access days on the body weight at 42 d of age (P=0.161). The daily weight gain, daily feed intake, and feed per gain from 21 to 42 d of age were unaffected by outdoor access days (P=0.401, P=0.463, P=0.223, respectively). However, the daily weight gain and daily feed intake from 42 to 56 and from 21 to 56 d of age increased linearly with increasing outdoor access days (P=0.002, P<0.001; P=0.001, P=0.004; respectively), while the feed per gain tended to decrease linearly from 21 to 56 d of age (P=0.060). The mortality from 21 to 56 d of age was unaffected by outdoor access days (P=0.261). At 56 d of age, the breast yield increased linearly with increasing outdoor access days (P<0.001), while the foot yield decreased linearly (P=0.016). The light (L*) and red (b*) values of leg meat color increased linearly with increasing outdoor access days (P=0.032, P=0.013, respectively). The spleen: the body weight ratio showed a decreasing and then increasing quadratic response to increasing outdoor access days (P=0.047). The litter moisture content at 42 and 56 d of age increased linearly with increasing outdoor access days (P<0.001, P=0.013, respectively). The findings of this study suggest that increasing outdoor access days advantageously affects the body weight, daily weight gain, feed per gain and breast yield as well as the light (L*) and red (b*) values of leg meat color, while decreasing foot yield.

Using ecology to inform physiology studies: implications of high population density in the laboratory

Conspecific density is widely recognized as an important ecological factor across the animal kingdom; however, the physiological impacts are less thoroughly described. In fact, population density is rarely mentioned as a factor in physiological studies on captive animals and, when it is infrequently addressed, the animals used are reared and housed at densities far above those in nature, making the translation of results from the laboratory to natural systems difficult. We survey the literature to highlight this important ecophysiological gap and bring attention to the possibility that conspecific density prior to experimentation may be a critical factor influencing results. Across three taxa: mammals, birds, and fish, we present evidence from ecology that density influences glucocorticoid levels, immune function, and body condition with the intention of stimulating discussion and increasing consideration of population density in physiology studies. We conclude with several directives to improve the applicability of insights gained in the laboratory to organisms in the natural environment.

Response to dietary supplementation of L-glutamine and L-glutamate in broiler chickens reared at different stocking densities under hot, humid tropical conditions

A study was conducted to determine whether supplementing AminoGut (a commercial dietary supplement containing a mixture of l-glutamine and l-glutamic acid) to broiler chickens stocked at 2 different densities affected performance, physiological stress responses, foot pad dermatitis incidence, and intestinal morphology and microflora. A randomized design in a factorial arrangement with 4 diets [basal diet, basal diet + 0.5% AminoGut from d 1 to 21, basal diet + 0.5% AminoGut from d 1 to 42, and basal diet + virginiamycin (0.02%) for d 1 to 42] and 2 stocking densities [0.100 m(2)/bird (23 birds/pen; LD) or 0.067 m(2)/bird (35 birds/pen; HD)]. Results showed that villi length and crypt depth were not changed by different dietary treatments. However, birds in the HD group had smaller villi (P = 0.03) compared with those of the LD group. Regardless of diet, HD consistently increased the serum concentrations of ceruloplasmin, α-1 acid glycoprotein, ovotransferin, and corticosterone (P = 0.0007), and elevated heterophil to lymphocyte ratio (0.0005). Neither AminoGut supplementation nor stocking density affected cecal microflora counts. In conclusion, under the conditions of this study, dietary supplementation of AminoGut, irrespective of stocking density, had no beneficial effect on growth performance, intestinal morphology, and physiological adaptive responses of broiler chickens raised under hot and humid tropical conditions. However, AminoGut supplementation from d 1 to 42 was beneficial in reducing mortality rate. Also, the increased serum concentrations of a wide range of acute phase proteins together with elevated corticosterone and heterophil to lymphocyte ratio suggested that high stocking density induced an acute phase response either indirectly as a result of increased incidence of inflammatory diseases such as foot pad dermatitis or possibly as a direct physiological response to the stress of high stocking density.

Effects of Replacement of Soybean Meal by Fermented Cottonseed Meal on Growth Performance, Serum Biochemical Parameters and Immune Function of Yellow-feathered Broilers

The study was conducted to examine the effects of partially replacing soybean meal (SBM) by solid-state fermented cottonseed meal (FCSM) on growth performance, serum biochemical parameters and immune function of broilers. After inoculated with Bacillus subtilis BJ-1 for 48 h, the content of free gossypol in cottonseed meal was decreased from 0.82 to 0.21 g/kg. A total of 600, day-old male yellow-feathered broilers were randomly divided into four groups with three replicates of 50 chicks each. A corn-SBM based control diet was formulated and the experimental diets included 4, 8 or 12% FCSM, replacing SBM. Throughout the experiment, broilers fed 8% FCSM had higher (p<0.05) body weight gain than those fed 0, 4 and 12% FCSM. The feed intake in 8% FCSM group was superior (p<0.05) to other treatments from d 21 to 42. On d 21, the concentration of serum immunoglobin M in the 4% and 8% FCSM groups, as well as the content of complements (C3, C4) in 8% FCSM group were greater (p<0.05) than those in the SBM group. Besides, birds fed 8% FCSM had increased (p<0.05) serum immunoglobin M, immunoglobulin G and complement C4 levels on d 42 compared with bird fed control diet. No differences (p>0.05) were found between treatments regarding the serum biochemical parameters and the relative weights of immune organs. In conclusion, FCSM can be used in broiler diets at up to 12% of the total diet and an appropriate replacement of SBM with FCSM may improve growth performance and immunity in broilers.

Effects ofLactobacillus plantarumon production performance, immune characteristics, antioxidant status, and intestinal microflora of bursin-immunized broilers

Examples of probiotics that can promote host health by improving its intestinal microbial balance and intestinal immunity belong to the genus Lactobacillus. Bursin (BS) is a peptide isolated from the bursa of Fabricius for use as an adjuvant for a variety of immunogens. To investigate the synergistic effects of Lactobacillus plantarum (LP) dietary supplementation and BS immunization on production performance, immune characteristics, antioxidant status, and intestinal microflora in broilers, we randomly allocated 200 1-day-old broilers of mixed sex into 4 treatments in a 2 × 2 factorial arrangement (LP–/BS–, LP–/BS+, LP+/BS–, LP+/BS+) for 42 days. BS immunization enhanced immune response by increasing serum total immunoglobulin G concentration and interleukin-6 concentration, promoted antioxidant capacity by increasing catalase activities in serum and liver and by decreasing serum malondialdehyde (MDA) content at 42 days of age (DOA), and enriched intestinal microflora diversity. LP supplementation enhanced immune response by increasing interleukin-2 concentration at 42 DOA; promoted antioxidant capacity by increasing liver catalase activities, increasing glutathione peroxidase activities in serum and liver at 21 DOA, and decreasing serum MDA content at 42 DOA; promoted intestinal microflora composition by decreasing total aerobes and Escherichia coli counts at 21 DOA, by increasing total anaerobes count at 21 DOA, and by increasing Lactobacillus spp. and Bifidobacterium spp. counts at both 21 and 42 DOA. The interactions between BS and LP had a significant effect on daily body mass gain and feed conversion ratio in the starter period (1–21 DOA); on interleukin-2 concentration and liver MDA content at 21 DOA; and on thymus index, peripheral lymphocyte proliferation, and E. coli counts at 42 DOA. Overall, these data suggest that the combination of LP dietary supplementation and BS immunization promoted the production performance, immune characteristics, antioxidant status, and intestinal microflora of broilers.

Overcrowding stress decreases macrophage activity and increases Salmonella Enteritidis invasion in broiler chickens

Overcrowding stress is a reality in the poultry industry. Chickens exposed to long-term stressful situations present a reduction of welfare and immunosuppression. We designed this experiment to analyse the effects from overcrowding stress of 16 birds/m(2) on performance parameters, serum corticosterone levels, the relative weight of the bursa of Fabricius, plasma IgA and IgG levels, intestinal integrity, macrophage activity and experimental Salmonella Enteritidis invasion. The results of this study indicate that overcrowding stress decreased performance parameters, induced enteritis and decreased macrophage activity and the relative bursa weight in broiler chickens. When the chickens were similarly stressed and infected with Salmonella Enteritidis, there was an increase in feed conversion and a decrease in plasma IgG levels in the stressed and Salmonella-infected birds. We observed moderate enteritis throughout the duodenum of chickens stressed and infected with Salmonella. The overcrowding stress decreased the macrophage phagocytosis intensity and increased Salmonella Enteritidis counts in the livers of birds challenged with the pathogenic bacterium. Overcrowding stress via the hypothalamic-pituitary-adrenal axis that is associated with an increase in corticosterone and enteritis might influence the quality of the intestinal immune barrier and the integrity of the small intestine. This effect allowed pathogenic bacteria to migrate through the intestinal mucosa, resulting in inflammatory infiltration and decreased nutrient absorption. The data strengthen the hypothesis that control of the welfare of chickens and avoidance of stress from overcrowding in poultry production are relevant factors for the maintenance of intestinal integrity, performance and decreased susceptibility to Salmonella infection.

Evaluation of probiotics in diets with different nutrient densities on growth performance, blood characteristics, relative organ weight and breast meat characteristics in broilers

1. A total of 720 1-d-old broilers were used in a 28 d experiment to determine the effects of probiotic supplementation in diets with different dietary nutrient densities. 2. Birds were randomly allotted to one of the 4 treatments in a 2 × 2 factorial arrangement (12 replicateswith 15 broilers per replicate) with two levels of nutrient density [high nutrient density (metabolisable energy (ME) 12.7 MJ/kg and crude protein (CP) 230.3 g/kg for 1-7 d; ME 13.2 MJ/kg and CP 220.3 g/kg for 8-28 d) or low nutrient density (ME 12.1 MJ/kg and CP 220.2 g/kg for 0-7 d; ME 12.6 MJ/kg and CP 209.8 g/kg for 8-28 d)] and 0 or 2 g/kg probiotics (1.0 × 10(10) viable spores/g of Bacillus subtilis endospores and 1.0 × 10(9) viable spores/g of Clostridium butyricum). 3. The high-nutrient-density diet increased body weight gain (BWG), feed conversion ratio (FCR), serum cholesterol and triglyceride concentration relative to the low-nutrient-density diet. High-nutrient-density diet reduced water loss ratio of breast muscle, liver and fat relative to body weight compared to low-nutrient density-diet. The inclusion of probiotics increased BWG and feed intake throughout the experiment. Dietary probiotics increased the percentage of blood lymphocytes and relative weight of spleen and bursa of Fabricius when compared to the non-probiotic treatment. The inclusion of probiotics decreased serum cholesterol and triglyceride concentrations and lightness (L*) value of breast meat compared to the non-probiotic-supplemented diet. 4. In conclusion, high dietary nutrient density increased growth performance and serum cholesterol and triglyceride concentrations in broiler chickens. The inclusion of probiotics increased growth performance but reduced serum cholesterol and triglyceride concentrations. The positive effect of probiotic supplementation on growth performance was reduced by the high-nutrient-density diet during the first week of life.