Probiotic Bacillus amyloliquefaciens H57 ameliorates subclinical necrotic enteritis in broiler chicks by maintaining intestinal mucosal integrity and improving feed efficiency.

Subclinical necrotic enteritis (NE) was induced in broiler chicks using a high dose of Eimeria spp. vaccine in the drinking water on day 9, and Clostridium perfringens (Cp) culture mixed in the feed on days 14 and 15. The aim was to evaluate the effects of probiotic Bacillus amyloliquefaciens strain H57 (H57) in preventing NE in chicks. Day-old Ross 308, male broilers were weighed and randomly assigned to 6 treatment groups (6 replicate cages/treatment and 8 birds/cage). Birds in group 1 (control) were fed the basal wheat-soybean diet without H57 or NE infection; in group 2 (Eimeria) were treated with Eimeria alone; in group 3 (Cp) were treated with Cp alone; in group 4 (NE) received both Eimeria and Cp; in group 5 (NE-H57) received NE infection and H57; and group 6 (H57) received H57. The basal diet of chicks in groups 5 and 6 was supplemented with H57 at a density of 2 × 108 spores/g feed from 1 D of age. On day 21, there were no significant treatment effects on BW and feed intake between control and H57 birds. However, on day 21, the feed conversion ratio of NE-H57 birds was significantly improved when compared with NE birds (1.28 vs. 1.36; P < 0.001). Birds challenged with NE had a higher occurrence of pasty vent than birds infected with either Eimeria, Cp, or NE-H57 (41 vs. 27 vs. 29 vs. 19%, respectively; P < 0.001). Intestinal lesion scores of NE birds were also higher than those of Eimeria, Cp, and NE-H57 birds (5.67 vs. 2.56 vs. 2.78 vs. 2.10, respectively; P < 0.001) and correlated with pasty vent (Pearson's r = 0.56; P < 0.001). Microscopic evaluation showed mucosal damage and necrosis in NE birds. In contrast, villi from NE-H57 birds were normal, with no damage or infiltration with Eimeria or Cp. H57 appears to be effective in challenged birds, as it maintained epithelial barrier integrity and improved feed efficiency.

Fatty liver haemorrhagic syndrome occurrence in laying hens: impact of production system.

Surveys were conducted with cage and alternative layer production systems to assess the prevalence of fatty liver haemorrhagic syndrome (FLHS). Commercial caged laying hens of different ages from three farms in Queensland were monitored for three months. The mortality rate of flocks ranged from 0.8% (the youngest flock) to 11.6% (the oldest flock). Six hundred and fifty-one birds were necropsied, and approximately 40% of hens died due to FLHS. Hens kept in cages in a controlled environment shed, were at a similar risk of developing FLHS to hens kept in naturally controlled sheds, however, the heavier birds in a flock were more likely to have the condition than lighter birds. In another study, layer flocks kept in cage, barn and free-range housing systems at the University of Queensland facility, were monitored for 50 weeks. Data from necropsies and performance records showed no significant differences in mortality rates between the housing systems (6.1%, 6.4% and 5.8%, for cages, barns and free-range, respectively), but the cause of mortality was different. In cages, 74% of necropsied hens died due to FLHS. In the other systems, only 0-5% of dead hens were diagnosed with the condition. These results are in agreement with previous Australian and overseas findings which have shown that FLHS is one of the main causes of hen death in caged flocks. Factors associated with husbandry practices in different production systems, such as restricted movement, increased production and temperature variations, influence hepatic lipid metabolism and predispose hens to FLHS.

Effects of selenium and vitamin E on performance, physiological response, and selenium balance in heat-stressed sheep.

Forty-two 7-mo-old Australian Merino wethers were used in a 50-d trial to investigate the effects of Se and vitamin E on the performance and physiological responses of heat-stressed sheep. Sheep were exposed to thermoneutral conditions (maximum = 24°C and minimum = 20°C) for 28 d followed by heat (maximum = 38°C and minimum = 28°C) for 22 d. Hot conditions were imposed between 0700 and 1800 h. Sheep were randomly allocated to diets containing 0.8 mg/kg Se (Sel-Plex), 150 mg/kg vitamin E, or 0.8 mg/kg Se and 150 mg/kg vitamin E for either the duration of the study (50 d) or from d 1 of the hot period until the end of the study. A control group that received no supplemental Se and vitamin E for the duration of the study was included. Feed intake was measured daily and sheep were weighed weekly. Blood samples were collected from all sheep before feeding on d 1, 21, and 49 for measurement of biochemical and enzymatic variables. The concentration of Se was determined in offered and refused feed, feces, urine, water, plasma, liver, and kidneys. Exposure to heat reduced ( < 0.05) DMI by 11.9%, ADG by 198 g, serum concentration of urea nitrogen and Se by 17.8%, and plasma total antioxidant status by 26.4%. During hot conditions, sheep receiving Se and vitamin E supplements for 50 d had reduced ( < 0.05) BW loss and elevated G:F compared to control sheep. Serum Se concentration and the plasma total antioxidant status were greatest in sheep receiving Se and vitamin E supplements for 50 d ( < 0.05). These results indicate that dietary supplementation with Se and vitamin E reduces the adverse effects of a high heat load. Additional studies are warranted to elucidate the mechanisms responsible for these effects.

Efficacy of a novel prebiotic and a commercial probiotic in reducing mortality and production losses due to cold stress and Escherichia coli challenge of broiler chicks 1.

Prebiotics consisting of resistant starch may alter intestinal ecology, thus modulating inflammation and increasing intestinal health through increased cecal production of short-chain fatty acids (SCFA). Probiotics may directly alter the intestinal microbiome, resulting in the same effects. We hypothesize that adding prebiotics and probiotics to feed may protect the gut of young chicks under stress. Studies 1, 2, and 3 evaluated treatments in a cold stress (CS) and Escherichia coli (EC) oral challenge to 430 day-old broiler chicks for 3 wk. In study 1, prebiotics were administered as 15% of the diet during the first week only and consisted of the following: Hi-Maize resistant starch (HM), potato starch (PS), or raw potato (RP). In studies 2 and 3, the PS treatment was identical to study 1, and an additional probiotic treatment (PRO) was administered in feed and water. In study 1, PS protected BW during the first week and decreased the mortality of CS/EC-challenged birds during the first week and wk 3, while RP decreased the mortality of warm-brooded birds challenged with EC during the first week. In study 2, PS decreased and PRO increased the main effect mean (MEM) of the first week BW. PS and PRO numerically decreased the feed conversion ratio (FCR) by 23 and 29 points, respectively, in CS/EC-challenged birds with no effects on mortality. In study 3, PS decreased and PRO increased the first week and wk 3 MEM BW. PS numerically increased FCR by 16 points, while PRO decreased FCR by 2 points. Both PS and PRO tended to increase overall mortality, and PRO significantly increased mortality in the CS/EC challenge. These results suggest that the effects of PS may be too variable in this challenge model for further study; however, the PRO treatment improved production values and may have potential as an alternative to antibiotics during the first weeks after hatch.

Effect of various doses of injected selenium on performance and physiological responses of sheep to heat load.

The aim of the study was to determine the effects of various doses of injected Se on the physiological responses of sheep to heat load. Fifteen 9-mo-old Australian Merino wethers (mean BW = 27.2 ± 2.1 kg) were randomly assigned to 1 of 3 treatments: 0 (control), 0.5, and 5 mg of Se, which was administered as a subcutaneous sodium selenate injection (5 mg/mL Se) on d 1, 8, and 15 of exposure to heat stress. The animals were housed individually in an environmental chamber and exposed to high temperature from 0700 to 1800 h (maximum = 38°C; minimum = 24°C) and to thermoneutral temperature from 1800 to 0700 h (maximum = 24°C; minimum = 20°C) for 21 d. Rectal temperature (RT) and respiration rate (RR) were measured daily at 0800, 1200, and 1600 h. Feed intake was measured daily, and sheep were weighed on d 1, 8, 15, and 21. Blood samples were collected on d 1 and 21. The 5 mg Se treatment decreased RT by 0.3°C (P = 0.02) and BW loss by 4.5% (P < 0.05) and increased eosinophil count (P < 0.05). There were no differences (P > 0.05) between treatments in RR and DMI, serum concentrations of glucose, total protein, cholesterol, and NEFA or in blood hematology variables. The findings of this study have important implications for the sheep industry. Further studies are warranted to elucidate the dynamics of Se on productivity and health during hot conditions.

Physiological responses of Australian Merino wethers exposed to high heat load.

Twelve 9-mo-old Merino wethers (30.4 ± 3.2 kg of BW) were used in a crossover study to investigate the heat tolerance of Australian Merino sheep by testing their physiological responses to repeated heat loads that occurred during summer months. Wethers were randomly divided into 2 groups of 6 wethers each, housed individually in an environmental chamber, and subjected to 2 d of thermoneutral conditions (TNC) followed by either 7 d of TNC (maximum temperature of 24°C, minimum temperature of 16°C) or 7 d of hot conditions (maximum temperature of 38°C, minimum temperature of 28°C), and then 2 d of TNC. These treatments were applied in 2 replicates, with each replicate in a separate environmental chamber. Rectal temperature (RT) and respiration rate were measured daily at 0600, 0800, 1000, 1200, 1400, 1600, and 1800 h. Feed and water intakes were measured daily, and wethers were weighed on d 1 and 11. Blood samples were collected from each whether on d 2 and 6, and serum was assayed for concentrations of creatine, glucose, total protein, cholesterol, NEFA, calcium, sodium, and potassium. Exposure to a high ambient temperature resulted in an 0.8°C increase in RT (P < 0.001), an increase in respiration rate (P < 0.001) by 66 breaths/min, and a 2.7 L/d increase in water intake (P < 0.0001). Feed intake decreased by 22% (P < 0.0001), BW decreased by 5.2% (P < 0.03), and creatine concentration was reduced (P < 0.05). No differences (P > 0.05) between treatments were observed for any of the remaining serum variables. These results indicate that Australian Merino sheep were able to maintain RT within the normal range during exposure to a prolonged increase in heat and that they recovered quickly from the negative effect of heat stress within 2 d of conditions returning to TNC. It would appear that they have a high heat tolerance, and further studies are needed to examine the effects of a greater heat load to determine the temperature-humidity index thresholds for Australian Merino sheep.

Heregulin expression and prognosis in prostate adenocarcinoma.

BACKGROUND: Heregulins (HRG) are a family of growth factors acting as ligands to HER3, HER4 and HER family signalling. HRG has a concentration-dependent differential growth effect--low levels mitogenic, high levels inhibitory. HRG differentially affects hormone-naïve (inhibitory) and castrate-resistant (proliferative) prostate adenocarcinoma (CaP) cell lines. We postulate that differential HRG expression in CaP will be associated with alteration in tumour growth, development and prognosis. PATIENTS AND METHODS: HRG expression was assessed in 2 cohorts: cohort 1 of 45 patients with paired hormone-naïve and castrate-resistant samples, and cohort 2 of 357 hormone-naïve samples. Correlations between HRG expression and biochemical relapse and survival were determined. RESULTS: In cohort 1, hormone-naïve samples' high membranous HRG expression was associated with increased time to relapse (p = 0.036), time to death from relapse (p = 0.002) and overall survival (p = 0.001). Membrane HRG fell significantly in post-relapse specimens. In cohort 2, high membranous HRG was associated with increased time to relapse (p = 0.004) and overall survival (p = 0.044) in patients treated with castration therapy but only with overall survival (p = 0.002) in the full cohort. CONCLUSION: High HRG expression is associated with improved prognosis in hormone-naïve CaP and a fall in expression occurs at castration escape indicating a protective role against castrate resistance.

Understanding stress-induced immunosuppression: exploration of cytokine and chemokine gene profiles in chicken peripheral leukocytes.

At present, the poultry meat and egg industry has gained a lot of ground, being viewed as a provider of a healthy alternative to red meat and other protein sources. If this trend is to be maintained, solutions must be found to improve resistance of chickens to disease, which often is weakened by stressful conditions. In poultry, stress-induced immunosuppression is manifested by failures in vaccination and increased morbidity and mortality of flocks. Currently, several modern cellular and molecular approaches are being used to explore the status of the immune system during stress and disease. It is likely that these new techniques will lead to the development of new strategies for preventing and controlling immunosuppression in poultry. Using quantitative reverse transcription-PCR assays, a broad spectrum of cytokine, chemokine, and their receptor genes can be quantified in birds and then be used as markers to assess the effects of stress on the immune system. Currently, we are investigating immune and endocrine interactions in the chicken, in particular the cells and molecules that are known to be involved in such interactions in mammals. We have evaluated the effects of corticosterone administration in drinking water on peripheral lymphocyte and heterophil cytokine and chemokine gene profiles. In particular, there seems to be effects on cytokine and chemokine mRNA expression levels in both lymphocytes and heterophils, especially expression of the proinflammatory cytokines interleukin (IL)-1beta, IL-6, and IL-18 and chemokines C-C motif, ligand 1 inflammatory (CCLi1); C-C motif, ligand 2 inflammatory (CCLi2); C-C motif, ligand 5 (CCL5); C-C motif, ligand 16 (CCL16); C-X-C motif ligand 1 inflammatory (CXCLi1); and C-X-C motif ligand 2 inflammatory (CXCLi2), which are initially upregulated and are potentially involved in modulating the adaptive immune response. A chronic treatment with corticosterone downregulates proinflammatory cytokines and chemokines, suggesting that the delayed effects of chronic stress can suppress the immune response. Messenger RNA expression levels of transforming growth factor-beta4 (TGF-beta4) are also upregulated in cortisosterone-treated birds. It appears that the balance between T-helper (Th) 1 and Th2/T regulatory cytokine production is altered in conditions associated with significant changes in plasma corticosterone concentration. Experiments are underway to decipher the cytokine and chemokine responses to vaccination and bacterial challenge on the background of stress-induced immunosuppression.

Effects of housing conditions during the rearing and laying period on adrenal reactivity, immune response and heterophil to lymphocyte (H/L) ratios in laying hens.

This study was conducted to evaluate the effect of early rearing conditions on physiological, haematological and immunological responses relevant to adaptation and long-term stress in white Leghorn hens with intact beaks housed in furnished cages (FC) or conventional cages (CC) during the laying period. Pullets were cage reared (CR) or litter floor reared (FR). From 16 to 76 weeks of age, hens were housed in FC (eight hens per cage) or in CC (three hens per cage). As measures of long-term stress at the end of the laying period, adrenal reactivity was quantified by assessing corticosterone responses to adrenocorticotropin challenge, and immune response was assessed by measuring antibody responses after immunization with sheep red blood cells (SRBC) and keyhole limpet haemocyanin (KLH). Heterophil to lymphocyte (H/L) ratio was employed as an indicator of stress. Rearing conditions significantly affected anti-SRBC titres (P < 0.0001) and tended to affect H/L ratios (P = 0.07), with the highest values found in FR hens. Layer housing affected H/L ratio (P < 0.01); the highest ratio was found in FR birds housed in FC during the laying period. This study shows that early rearing environment affects immunological indicators that are widely used to assess stress in laying hens. However, while results on H/L ratio indicated that FR birds experienced more stress particularly when they were housed in FC during the laying period, the immune responses to SRBC in FR hens was improved, indicating the opposite. This contradiction suggests that the effects on immune response may have been associated with pathogenic load due to environmental complexity in FR and FC hens rather than stress due to rearing system or housing system per se.

Effects of chronic and repeated corticosterone administration in rearing chickens on physiology, the onset of lay and egg production of hens.

A corticosterone model was used to study the effects of chronic and repeated stress during the rearing phase on physiology, the onset of lay and performance of laying hens in the subsequent laying period. Two hundred and seventy Hy-line brown layer pullets were reared in environmentally controlled battery cages. At 7, 11, and 15 weeks of age birds were exposed for 1 week to the following treatments in drinking water: corticosterone dissolved in ethanol, ethanol, or untreated water. One week following each treatment, and at 35 weeks of age endocrine, metabolic and haematological tests were conducted. Body weight was measured throughout the study, and egg production was recorded daily throughout the laying period. Plasma corticosterone levels and heterophil to lymphocyte (H/L) ratio were increased after each corticosterone delivery, showing the effectiveness of the treatment. When corticosterone delivery was interrupted, plasma corticosterone and H/L ratio were significantly reduced. Exposing birds to repeated and long-term corticosterone treatment significantly affected BW (P<0.01), and relative organ weights (P<0.01). Corticosterone delivery also resulted in increased blood levels of glucose (GLU), cholesterol (CHOL), and triglyceride (TRG). Administration of corticosterone during the rearing phase delayed the onset of lay and decreased egg production at 35 weeks of age. These results demonstrate that oral corticosterone treatment affects hen physiology, reduces performance, and may model the effects of production stressors.

Effects of stress, mimicked by administration of corticosterone in drinking water, on the expression of chicken cytokine and chemokine genes in lymphocytes.

In this study, we identify molecular mediators that participate in the regulation of the immune response during corticosterone-induced stress in chickens. At 7 weeks of age, 120 chickens were exposed for 1 week to corticosterone treatment. Cytokine and chemokine mRNA expression levels were evaluated in peripheral blood and splenic lymphocytes. Expression levels of interleukin (IL)-1beta, IL-6, IL-18 and transforming growth factor (TGF)-beta4 mRNA were significantly up-regulated in lymphocytes 3 h after first treatment with corticosterone. TGF-beta4 and IL-18 remained elevated 1 week post-initial treatment. Compared with controls, corticosterone-treated birds showed greater expression levels of chemokine (CC) mRNA, particularly for CCLi2, CCL5 (RANTES), CCL16 and CXCLi1, in peripheral and splenic lymphocytes 3 h post-initial exposure. CCLi2 mRNA was highly expressed in splenocytes at all time-points. Administration of corticosterone significantly increased circulating corticosterone concentrations and decreased total lymphocyte counts at 3, 24 h and 1 week post-initiation of corticosterone treatment. There was a positive correlation between plasma corticosterone concentrations and CCL5 and CCL16 mRNA at 3 h post-initial administration. At 1 week post-initial treatment, corticosterone concentrations correlated positively with CCL5 and negatively with IL-18 mRNA level. Conditions associated with significant changes in corticosterone levels might therefore affect the immune response by increasing pro-inflammatory responses, leading to potential modulation of the Th1/Th2 balance.

[Kinetics of elimination of diazepam after intravenous injection in horses]. / Eliminationskinetik von Diazepam nach intravenöser Applikation beim Pferd.

Diazepam is used in veterinary medicine as sedative and pre-anaesthetic agent. This publication describes the plasma-concentration time curve for diazepam and its metabolite in horses suffering from colic after intravenous application as pre-anaesthetic agent. Elimination half-life (t1/2 beta) after a dose of 0.05-0.08 mg/kg (30-50 mg Diazepam per horse) was 7.5 to 13.2 h. Total clearance (Cltot) between 1.86 and 3.44 ml/min/kg was detected and apparent volume of distribution in steady state (Vdiss) was 1.98 to 2.25 l/kg. Diazepam was still found in serum after 24 h. The metabolite oxazepam could be found in plasma. Its elimination half-life was 14-16.5 hours.