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PubMed2006

Pathological features in dead on arrival broilers with special reference to heart disorders.

A gross postmortem investigation was done on 302 broilers that died between catching and slaughter to establish predisposing factors for dying in this period. Special attention was paid to heart disorders, which were established by determining the ratio of the right ventricle mass to the total ventricle mass (RV:TV) and to postmortem changes in hearts and lungs of broilers that were dead on arrival (DOA). Macroscopic pathologic lesions were found in 89.4% of DOA broilers. Signs of infectious diseases appeared to be most frequent (64.9%), followed by heart and circulation disorders (42.4%), and trauma (29.5%). The RV:TV was significantly higher for DOA broilers in comparison with slaughtered broilers. The prevalence of hearts with an abnormal RV:TV in DOA broilers was 34.4 vs. 4.1% in slaughtered broilers. The DOA broilers with an abnormal heart ratio more frequently showed ascites and hydropericardium. Postmortem changes in lungs depend on the position of the carcass the first several hours after death. Broilers, which remain in dorsal recumbency for several hours after death, develop engorged lungs. A good health status as well as more attention for the catching and crating process is crucial in decreasing the percentage of DOA broilers. Prevention of an increased heart ratio and of ascites will improve the livability in the broiler house and also decrease the DOA rate enormously.

Abattoirs↗

PubMed2005

The role of first line of defence mechanisms in the pathogenesis of cellulitis in broiler chickens: skin structural, physiological and cellular response factors.

The present study examined several basic attributes of first-line defence mechanisms in the skin as potential factors that may explain the susceptibility of broiler chickens to cellulitis. The variables including structural characteristics of the skin, physicochemical properties and cellular responses to the challenge with pathogens were compared between two categories of chickens, a strain of fast-growing commercial broiler chickens (susceptible to cellulitis) and leghorn chickens (resistant to cellulitis). There were substantial differences between leghorns and broilers with regard to physiological characteristics of the skin. Broiler skin was more amenable to injury and the wound-healing process was slow. Compared with leghorns, the lesions resulting from sub-dermal challenge in broilers were more severe and disseminated over a larger area. Mobilization of phagocytic cells (heterophils and macrophages) in leghorns was brisk even in the areas distant from the site of infection, whereas only few heterophils were recruited in the skin of broilers. The functional competence of heterophils in broilers was inferior when compared with leghorns. Based on the present finding, the predisposition of broilers to cellulitis appears to be primarily associated with the inferior first line of defence of their skin. Broilers in commercial situations may be at higher risk to succumb to even minor infection and eventually develop cellulitis because: (1) structural weaknesses of the skin may predispose broilers to skin injury and thus the risk of skin infection by pathogens is increased; (2) broiler skin surface is more likely to provide a conducive environment for colonization of Escherichia coli; (3) in the event of infection, poor recruitment of phagocytic cells to the site of infection may readily lead to widespread colonization of the tissue by pathogens causing cellulitis and (4) poor functional quality of the phagocytic cells that are mobilized compromise the ability of the host to contain the spread of infection.

Animals↗

PubMed2003

Effect of spray-dried bovine serum on intake, health, and growth of broilers housed in different environments.

Three experiments utilizing broilers were conducted in different environments to evaluate the effects of Innavax (INX; spray-dried serum) administered in drinking water on broiler performance. In Exp. 1 (1 to 42 d), 252 Ross x Cobb male broilers were assigned randomly to one of six treatments consisting of tap water mixed with 0, 0.25, 0.50, 0.75, 1.0, or 1.25% (wt/wt) INX. Broilers (six broilers per pen; seven pens per treatment) were housed in Petersime battery cages (raised wire flooring) in temperature-controlled rooms. Average daily gain, and feed and water intake (as-fed) were not affected (P > 0.05) by experimental treatments. Feed efficiency tended to improve linearly (P = 0.076) from d 0 to 7 with increasing levels of INX, but was unaffected (P > 0.05) during the remaining periods. In Exp. 2 and 3, 800 Ross x Ross 308 male broilers (400 broilers in each trial; 10 broilers per pen; 10 pens per treatment) in two 21-d experiments were assigned randomly to one of four treatments consisting of tap water mixed with 0, 0.45, 0.90, or 1.35% (wt/wt) INX. Broilers were housed in floor pens containing clean (Exp. 2) or used (Exp. 3) litter. In Exp. 2, intake, ADG, and feed efficiency were linearly improved (P < 0.05) during the first week with increasing levels of INX. During the second week (d 8 to 14), ADG, water intake, and feed efficiency were linearly improved (P < 0.05) with increasing levels of INX. In the third week (d 15 to 21), ADG and feed and water intake were not affected (P > 0.10) by level of INX. Overall (d 0 to 21), ADG, intake, and feed efficiency were linearly improved (P < 0.05) with INX. In Exp. 3, ADG, water intake, and feed efficiency were linearly improved (P < 0.05) during each period. Feed intake was not affected (P > 0.05) by experimental treatment during d 0 to 7, but was linearly increased (P < 0.05) from d 8 to 14 and 15 to 21. The greatest growth response of broilers to INX was observed when broilers were housed in floor pens with used litter, followed by floor pens with clean litter and battery pens. Further research on the relationship between the response to INX and housing conditions seems warranted.

Animal Husbandry↗

PubMed2002

Microbial profile and antibiotic susceptibility of Campylobacter spp. and Salmonella spp. in broilers processed in air-chilled and immersion-chilled environments.

Carcass chilling is considered a critical step for inhibiting bacterial growth during poultry processing. The objective of this study was to compare microbiological loads and the incidence of Salmonella spp. and Campylobacter spp. on broiler carcasses subjected to immersion chilling and air chilling. Additionally, the antibiotic resistance patterns of pathogen isolates were determined. The results of this study indicated that the incidence of Salmonella spp. and Campylobacter spp. tends to be significantly lower in air-chilled broilers, suggesting that cross-contamination may be more prevalent for immersion-chilled broilers. No significant differences were detected between chilling treatments for total aerobic populations or for generic E. coli or coliform counts. Psychrotrophic populations were significantly larger (P < 0.05) in immersion-chilled broilers than in their air-chilled counterparts. Campylobacter isolates from immersion-chilled broilers had a higher incidence of resistance to nalidixic acid (NAL) and related fluoroquinolones than isolates from air-chilled broilers did. Additionally, Campylobacter isolates from air-chilled broilers had a higher frequency of resistance to tetracycline than isolates from immersion-chilled broilers did. With regard to Salmonella, isolates from immersion-chilled broilers had a higher incidence of resistance to NAL than isolates from air-chilled samples did. No Salmonella isolates from immersion- or air-chilled broilers were resistant to the fluoroquinolones tested. The chilling method used during processing may influence the microbial profile of postchilled broilers.

Adaptation, Physiological↗

PubMed2002

Risk factors for foot-pad dermatitis in chicken and turkey broilers in France.

A prospective cohort study was conducted in the Brittany region to identify the risk factors related to foot-pad dermatitis (considered an indicator of animal well-being) in chicken and turkey broilers reared under commercial conditions. Factors related to the shed, equipment, litter management and stocking density were recorded; the dependent variable was the prevalence of lesions observed on the slaughterhouse chain. Lesions were scored from 0 (no lesion) to 3 (severe lesion). Our survey lasted from May 1999 to October 2000. Fifty flocks of chicken broilers (15 farms), 27 flocks of female turkey broilers (21 farms) and 41 flocks of male turkey broilers (27 farms) were surveyed. In chicken broilers, 10% of flocks were of high quality (80% of birds with score 0) and this was related to the use of concrete floors with a thin layer of wood shavings. In turkey broilers, 48% of female and 46% of male flocks were of bad quality (>10% of birds with score 3). A poor fan ventilation system (<150m(3)/h/kg) was a significant risk factor. Turkey flocks of high quality were not observed. Stocking density had no influence on the prevalence of foot-pad dermatitis. We concluded that it is possible under high commercial stocking densities to have flocks with a low prevalence of foot-pad dermatitis in chicken broilers, whereas it is not in turkey broilers. Hence in chicken broilers, implementing a monitoring system based on the observation of foot-pad dermatitis prevalence at slaughter appears to be more appropriate than to legislate stocking density. In turkey broilers, it would probably be necessary either to reduce the stocking density drastically or to investigate new systems of floor drainage.

Animal Husbandry↗

PubMed1996

Epidemiological study on risk factors and risk reducing measures for campylobacter infections in Dutch broiler flocks.

From September 1991 until August 1993 an epidemiological study involving 20 Dutch broiler farms was conducted to identify risk factors and risk reducing measures for campylobacter infections in broiler flocks. Campylobacter spp. were detected in 64 (57%) of the 112 broiler flocks and in 25 (63%) of the 40 broiler cycles examined. Univariate analysis of farm management data was performed followed by logistic regression analysis of selected risk and risk reducing factors. The presence of other farm animals, including pigs, cattle, sheep and fowl, other than broilers, was found to be independently associated with an increased risk of campylobacter infections in broiler flocks (odds ratio (OR) = 11.81; P = 0.041). Further, the results indicate that application of specific hygiene measures during the rearing period, such as washing hands before tending the broiler flocks, the use of separate boots for each broiler house and the use of footbath disinfection when entering a broiler house, may significantly reduce the risk of campylobacter infections in broiler flocks.

Analysis of Variance↗

PubMed2001

Evaluation of a pneumatically operated captive bolt for stunning/killing broiler chickens.

1. Two separate experiments were carried out in this study. In experiment 1, the effectiveness of stunning broilers, as determined from physical responses, with a 6 mm diameter bolt and an air line pressure of 827 kPa, when fired at 90 degrees (perpendicular to the skull) 110 degrees, 120 degrees and 130 degrees (leaning towards beak) was evaluated. 2. In experiment 2, the effects of perpendicular shooting with two bolt diameters (3 and 6 mm) and two air line pressures (620 and 827 kPa) on spontaneous behaviour, electroencephalogram (EEG) and visually evoked potentials (VEPs) were evaluated in broilers. 3. Only the perpendicular shooting was effective in stunning/killing broilers (n= 10) as indicated by the immediate cessation of breathing and loss of neck muscle tension and eye reflexes. Deviations from the perpendicular shooting failed to stun 5 out of 9 broilers. The perpendicular vs non-perpendicular effect was significant. 4. Shooting broilers with a 3 mm bolt at air line pressures of 620 kPa (n=2) or 827 kPa (n=2) failed stun as indicated by the unaltered physical reflexes, EEG and VEPs. Shooting of two broilers with a 6 mm bolt at 620 kPa resulted in effective stunning and a very rapid recovery of consciousness in one bird and death in the other. 5. Captive bolt stunning of broilers with a 6 mm bolt and air line pressure of 827 kPa resulted in an immediate stun leading to death in all 6 broilers tested. In these broilers, a profound EEG suppression and abolition of VEPs occurred immediately after shooting. 6. It is suggested that the appropriate variables for captive bolt stunning of broilers are a minimum of 6 mm bolt diameter driven at an air line pressure of 827 kPa and a penetration depth of 10 mm.

Animals↗

PubMed2001

Taurine, cardiopulmonary hemodynamics, and pulmonary hypertension syndrome in broilers.

Previous studies have suggested cardiac taurine is released into the plasma in response to hypoxemia (low blood oxygen levels) during the pathogenesis of pulmonary hypertension syndrome (PHS, ascites). In the present study, broilers reared under cool temperature conditions (16 C) were provided tap water (control group), tap water supplemented with taurine, or tap water supplemented with the taurine transport antagonist beta-alanine. When compared with control values, taurine supplementation consistently elevated free taurine concentrations in the plasma but not in cardiac tissues, whereas beta-alanine supplementation consistently reduced free taurine concentrations in cardiac tissues but not in the plasma. Neither the incidence of PHS nor specific predictors of PHS susceptibility (electrocardiogram Lead II S-wave amplitude, % saturation of hemoglobin with oxygen, heart rate, right to total ventricular weight ratio) were affected by taurine or beta-alanine supplementation. Cardiopulmonary hemodynamic evaluations were conducted to compare control and beta-alanine supplemented broilers breathing room air or air containing 12% oxygen (low oxygen challenge). While breathing room air, the betaalanine-supplemented broilers had higher baseline values for cardiac output (186.2 vs. 146.9 mL/min/kg BW) and pulmonary arterial pressure (27.4 vs. 22.4 mm Hg), similar values for mean systemic arterial pressure (100 vs. 104 mm Hg) and pulmonary vascular resistance (0.062 vs. 0.064 resistance units), and lower values for total peripheral resistance (0.228 vs. 0.296 resistance units) when compared with control broilers breathing room air. During low oxygen challenges, the beta-alanine-supplemented broilers exhibited larger reductions in cardiac output, mean systemic arterial pressure, and pulmonary arterial pressure and greater increases in pulmonary vascular resistance than control broilers. These observations indicate that beta-alanine-supplemented broilers breathing room air had a higher systemic demand for oxygen as evidenced by their lower total peripheral resistance (systemic vasodilation) and had a capacity sufficient to pump a higher cardiac output and, thereby, maintain a similar mean systemic arterial pressure when compared with control broilers. However, cardiac function rapidly deteriorated in beta-alanine-supplemented broilers during low oxygen challenges, leading to substantially greater reductions in cardiac output, stroke volume, and mean systemic arterial pressure when compared with control broilers. Concurrent changes in pulmonary arterial pressure within the beta-alanine group reflect interactions between cardiac output and pulmonary vascular resistance. Overall, depleting cardiac taurine did not appear to initiate PHS, but systemic hypoxemia developing during the mid- to late-pathogenesis of PHS may expose and incipient cardiac weakness attributable to depleted taurine reserves.

Animals↗

PubMed2001

Threonine requirements of different broiler genotypes.

The objectives of this work were to study the responses of one Leghorn and two broiler stocks and sexes to different levels of Thr and to estimate their requirements for this amino acid. All experiments were conducted with birds from 1 to 18 d of age. Body weight gain (BWG) and feed consumption were measured on the eighteenth day, and feed conversion ratio (FCR) was calculated. At Day 18, three birds per replicate were killed, and liver and fat pads were collected and weighed. The data were analyzed by the general linear model and nonlinear model procedures of SAS software, and the broken-line linear model was used to estimate Thr requirements of chicks. Experiment 1 had a 5 x 3 factorial design with five levels of Thr (0.63, 0.70, 0.77, 0.84, and 0.91% of the diet), two broiler genotypes (Arbor Acres Classic and High Yield), and one Leghorn genotype (Hy-line W-36), with three replicate pens of eight male birds each. The basal diet was composed of corn, peanut meal (PNM), poultry by-product meal, poultry fat, DL-Met, L-Lys, and L-Ile (23% CP and 3.2 kcal/g of ME). The Leghorn chicks did not respond to Thr supplementation, indicating their requirement was < or = 0.63%. High Yield birds had better BWG and FCR than Classic. The BWG and FCR were reduced more in Classic than High Yield strains by the lowest Thr level. The percentage of liver was higher in the Classic than High Yield strain broilers with Thr supplementation. The second experiment (2 x 2 x 2 factorial design) was conducted to evaluate the effects of two levels of Thr (0.63 and 0.90%), two levels of Ile (0.72 and 0.90%), and two broiler strains (as Experiment 1). There were no responses to Ile for any parameters measured. Experiment 3 (6 x 2 factorial design, corn, PNM-based basal diet) had six Thr levels (0.63, 0.67, 0.71, 0.75, 0.79, and 0.83%) and two broiler strains (as Experiment 1), with four replicate pens of eight male birds each. The High Yield strain broilers grew significantly better at the lowest Thr level, but performance was similar at the higher Thr levels (significant interaction, P = 0.018). FCR was affected by Thr level but not by strain. The Thr requirement of the Classic strain broilers was 0.69 +/- 0.01% for BWG and 0.68 +/- 0.01% for FCR. The Thr requirement of the High Yield strain broilers was 0.68 +/- 0.01% for BWG and 0.69 +/- 0.01% for FCR. The Thr requirements of male versus female High Yield strain broilers were evaluated in a 6 x 2 factorial design, with six Thr levels (Experiment 4), with four replicate pens of eight birds each. Males and females had the same performance and carcass composition results (P > 0.05), except for percentage abdominal fat pads. The Thr requirement was 0.71 +/- 0.01% for BWG and 0.71 +/- 0.01% for FCR for the males and 0.72 +/- 0.008% for BWG and 0.71 +/- 0.001% for FCR for females. Excellent performance was observed from the corn- and PNM-based diet supplemented to contain 0.72% Thr. The Thr requirements of High Yield and Classic broilers (males and females) were similar and greater than for the Leghorn strain studied.

Aging↗

PubMed2002

Genetic diversity at the major histocompatibility complex (B) and microsatellite loci in three commercial broiler pure lines.

Genetic diversity at the MHC and non-MHC loci was investigated in three commercial broiler chicken pure lines. The MHC class II and IV loci were evaluated in Southern hybridizations and molecular genotypes based on RFLP were interpreted from pedigreed families. Four MHC class II and eight class IV genotypes were identified in the broiler lines, and their frequencies differed among the lines. Line-specific MHC genotypes were identified. The observed heterozygosities (59 to 67%) suggest that the MHC loci are highly polymorphic in the broiler lines. At least 9% of the genetic variation at the MHC was due to line differences; the remainder reflected individual variations. To characterize non-MHC genes, 41 microsatellite loci located throughout the chicken genome were evaluated in the broiler lines. Genetic variation was also observed at the microsatellite loci for the broiler lines; the number of alleles at a single locus ranged from one to eight, and the average number of alleles per locus was 3.5, 2.8, and 3.1 for each of the lines, respectively. The observed heterozygosities for microsatellite loci ranged between 0 and 89% in the lines. Based on the fixation index (Fst), about 19% of the genetic variation at microsatellite loci was attributed to broiler line differences. Deviations from Hardy-Weinberg equilibrium were detected at both MHC and non-MHC loci. Possible explanations for these deviations include genetic selection by the primary broiler breeder or the presence of null alleles that were not identified by the typing procedures described in this report. This study contributes to our knowledge on the molecular characteristics and genetic structure of a commercial broiler chicken population. Analysis of MHC and non-MHC loci suggests that there is still sufficient genetic diversity in the broiler lines to continue the progress toward improved broiler chicken production.

Animals↗

PubMed2002

Campylobacter isolation trends of cage versus floor broiler chickens: a one-year study.

An experiment was carried out over a 1-yr period with broiler chickens to assess the influence of cage and floor rearing environments on the isolation trends of Campylobacter jejuni. The study used 36 7-wk-old broiler chickens that were raised in floor pens and naturally infected with or exposed to C. jejuni during the growout period. These broilers were then leg-banded and split into two groups with 18 per group. The groups were placed in wire cages or in a floor pen with unused litter in separate houses on the same farm. Each broiler was swabbed cloacally monthly to determine the presence of C. jejuni. The yearly average percentage isolation rates were significantly (P < 0.05) higher for the broilers held in the litter floor pen (130/185;66%) when compared to the broilers kept in wire cages (67/193;35%). There was a trend for higher isolation rates in the fall for caged and floor broilers and a decrease in rates near the end of the experimental year (summer) in the caged broilers. Isolation rates for both treatments reached their lowest level for the month of March. No caged broilers tested positive during the last 4 mo of the trial. The long-term cage isolation was linked to a reduced prevalence of C. jejuni. The results from this study suggest that housing environment and time spent in that environment play a major role in the continuing shedding and isolation of C. jejuni in broiler chickens.

Animals↗

PubMed2003

Dietary sodium bicarbonate, cool temperatures, and feed withdrawal: impact on arterial and venous blood-gas values in broilers.

Sodium bicarbonate (NaHCO3) has been used successfully in mammals and birds to alleviate pulmonary hypertension. Experiment 1 was designed to provide measurements of arterial and venous blood-gas values from unanesthetized male broilers subjected to a cool temperature (16 degrees C) challenge and fed either a control diet or the same diet alkalinized by dilution with 1% NaHCO3. The incidences of pulmonary hypertension syndrome (PHS, ascites) for broilers fed the control or bicarbonate diets were 15.5 and 10.5%, respectively (P = 0.36, NS). Non-ascitic broilers fed the control diet were heavier than those fed the bicarbonate diet on d 49 (2,671 vs. 2,484 g, respectively); however, other comparisons failed to reveal diet-related differences in heart weight, pulse oximetry values, electrocardiogram amplitudes, or blood-gas values (P > 0.05). When the data were resorted into categories based on right:total ventricular weight ratios (RV:TV) indicative of normal (RV:TV < 0.28) or elevated (RV:TV > or = 0.28) pulmonary arterial pressures, broilers with elevated RV:TV ratios had poorly oxygenated arterial blood that was more acidic, had high partial pressure of CO2 (PCO2), and had higher HCO3 concentrations when compared with broilers with normal RV:TV ratios. Experiment 2 was conducted to determine if metabolic variations associated with differences in feed intake or environmental temperature potentially could mask an impact of diet composition on blood-gas values. Male broilers maintained at thermoneutral temperature (24 degrees C) either received feed ad libitum or had the feed withdrawn > or = 12 h prior to blood sampling. Broilers fed ad libitum had lower venous saturation of hemoglobin with O2, higher venous PCO2, and higher arterial HCO3 concentrations than broilers subjected to feed withdrawal. Broilers in experiment 2 fed ad libitum and exposed to cool temperatures (16 degrees C) had lower arterial partial pressure of O2 and higher venous PCO2 than broilers fed ad libitum and maintained at 24 degrees C. Overall, these results demonstrate that changes in diet composition (control vs. 1% NaHCO3 diets) had minimal impact on arterial and venous blood-gas variables when compared with the more dramatic differences associated with feed intake (ad libitum vs. > or = 12 h withdrawal), environmental temperature (24 vs. 16 degrees C), and the pathogenesis associated with PHS (RV:TV < 0.28 vs. > or = 0.28).

Acid-Base Equilibrium↗

PubMed2003

The effects of conjugated linoleic acids or an alpha-glucosidase inhibitor on tissue lipid concentrations and fatty acid composition of broiler chicks fed a low-protein diet.

The effects of dietary conjugated linoleic acid (CLA) and an alpha-glucosidase inhibitor--Bay g 5421--on tissue lipid concentrations and fatty acid composition were investigated in male broiler chicks fed a low-protein diet. The trial comprised six isoenergetic broiler diets. One diet (high-protein diet) was used as a control diet and contained 230 g crude protein per kilogram. The other five diets were low-protein diets (180 g crude protein/kg) without additional supplement, or supplemented with 20 or 40 g/kg of a CLA-enriched oil, or supplemented with 50 or 100 mg of Bay g 5421/kg. Broilers fed the low-protein diets had higher concentrations of triglycerides and cholesterol in the liver than broilers fed the high-protein diet. Broilers fed low-protein diets supplemented with CLA had a higher cholesterol concentration in plasma, lower hepatic triglyceride concentrations, higher relative concentrations of saturated fatty acids (SFA), and lower relative concentrations of monounsaturated fatty acids (MUFA) in lipids of liver, thigh muscle, and adipose than broilers fed low-protein diets without CLA supplement. Broilers fed the low-protein diets supplemented with Bay g 5421 had lower concentrations of triglycerides and cholesterol in the liver and lower concentrations of triglycerides in plasma than broilers fed the low-protein diet without supplementation. Moreover, broilers fed diets with Bay g 5421 had higher relative concentrations of polyunsaturated fatty acids and lower relative concentrations of MUFA in lipids of liver, muscle, and adipose tissue. The results show that supplementation of the low-protein diets with CLA and Bay g 5421 affected tissue lipid concentrations and fatty acid composition in broilers, which are of practical relevance with regards to meat quality.

Acarbose↗

PubMed2004

Comparison between broilers and layers for growth and protein use by embryos.

Three experiments were conducted to compare the growth and protein utilization of embryo between broilers and layers. In experiments 1 and 2, the average weight of eggs was the same for broilers and layers. Nothing or an amino acid (AA) solution was injected into the eggs of broilers at d 7 of incubation, and the plasma AA concentration of newly hatched chicks was determined in broilers in experiment 1. In experiment 2, the same treatments as experiment 1 were used on layer breeder eggs. Plasma Tau, Thr, and Lys concentrations of hatched chicks increased when AA solution was injected in broilers breeder eggs (P < 0.05) but not in layers (P > 0.05). The AA ratio to Lys was reduced by AA injection in broilers but not in layers. In experiment 3, weights of embryos and egg were recorded, and CP contents were analyzed over time during incubation (d 0, 7, 14, and 19 of incubation) in broilers and layers using eggs of the same weight. There were no differences in the weights and CP contents of embryos and eggs from broilers and layers. On d 14 and 19 of incubation, weights and CP contents of embryo were higher in broilers than layers (P < 0.05). These results suggested that the egg protein content might be adequate for hatching but insufficient for maximum growth of embryos from broilers.

Amino Acids↗

PubMed2005

Pulmonary hypertensive responses of broilers to bacterial lipopolysaccharide (LPS): evaluation of LPS source and dose, and impact of pre-existing pulmonary hypertension and cellulose micro-particle selection.

Previous studies demonstrated that bacterial lipopolysaccharide (LPS, endotoxin) triggers pulmonary vasoconstriction leading to pulmonary hypertension (PHS, ascites) in broilers. The lungs of broilers are constantly challenged with LPS that can trigger pulmonary vasoconstriction. Among broilers from a single genetic line, some individuals respond to LPS with large increases in pulmonary arterial pressure (PAP), whereas others fail to exhibit any response to the same supramaximal dose of LPS. In the present study we evaluated the impact of a variety of factors on the magnitude of the PAP response of male broilers to LPS, including: (1) the role of the initial PAP (low vs. high initial PAP); (2) the source of the LPS (Salmonella typhimurium vs. Escherichia coli); (3) the dose of LPS (0.02, 0.1, and 0.5 mg/kg of BW); and (4) the role of micro-particle selection for improved pulmonary vascular capacity (cellulose survivors vs. saline-injected controls). Broilers in the low initial PAP group (21 +/- 0.34 mmHg, mean +/- SEM) did not differ in their pulmonary hypertensive response to LPS compared with broilers in the high initial PAP group (29 +/- 0.55 mmHg, mean +/- SEM). Lipopolysaccharide from S. typhimurium elicited pulmonary hypertensive responses qualitatively similar to those elicited by E. coli LPS. A detailed evaluation revealed that an LPS dose of 0.1 mg/kg of BW elicits a maximal pulmonary hypertensive response in male broilers, and broilers selected by micro-particle injection for a robust pulmonary vascular capacity did not differ in their pulmonary hypertensive response to LPS compared with unselected broilers. This research confirms that the variable pulmonary hypertensive responses among broilers cannot be attributed to the source or dosage of LPS, or to differences in the baseline pulmonary arterial pressure or micro-particle selection before injecting LPS. These findings are consistent with the hypothesis that innate rather than acquired variability may influence the profile of chemical mediators released during the inflammatory cascade.

Animals↗

PubMed2006

Response of broilers to feeding low-calcium and phosphorus diets plus phytase under different environmental conditions: body weight and tibiotarsus mineralization.

Three experiments on Ross broiler chickens were conducted in 3 locations: cages (Experiment 1), floor pens (Experiment 2), and commercial farms (Experiment 3). The effect of low-total P (TP) wheat-soybean based diets plus microbial phytase (Natuphos) was evaluated. Four experimental starter and finisher diets were used in a 2-phase feeding program, as follows: control diet (SC until 21 d, FC from 22 to 42 d); 2 diets (SL400 and SL600 until 21 d, FL400 and FL600 from 22 to 42 d) with low TP (0.61% for starter and 0.54% for finisher), including 400 and 600 U/kg of phytase, respectively; and a very low-TP (0.52% for starter and 0.44% for finisher) diet (SVL600 until 21 d, FVL600 from 22 to 42 d) with 600 U/kg of phytase. In Experiment 1 (broilers in cages had movement limitation and no access to litter), no differences in BW, tibiotarsus mineralization, or mineral metabolism were observed among diets. In Experiment 2 (broilers in floor pens had movement limitation and access to litter), at 21 d of age, the lowest tibiotarsus ash percentage and BW were shown by birds fed the SVL600 diet. At 42 d of age, broilers fed the FC diet were the lightest. For the rest of the parameters of tibiotarsus mineralization and mineral metabolism measured in Experiment 2, no differences were shown. In Experiment 3 (broilers in commercial farms had access to litter without movement limitation), the BW of broilers fed the SC diet was the highest at 21 d of age. At 42 d of age, the broilers fed FL400 and FL600 diets were the heaviest. At the end of Experiment 3, broilers fed the FC diet had the highest dry litter Ca and P, whereas broilers fed the FVL600 diet had the lowest values. In conclusion, the very low-TP wheat-soybean based diet supplemented with 600 U/kg of phytase was sufficient to optimize all the parameters measured in Experiment 1 but not in Experiments 2 and 3. Therefore, when evaluating Ca and P in phytase-supplemented diets for broilers, it is necessary to bear in mind the environmental conditions of experimentation.

6-Phytase↗

PubMed2006

Evaluation of the serotonin receptor blocker methiothepin in broilers injected intravenously with lipopolysaccharide and microparticles.

There has been considerable interest in the role of serotonin (5-hydroxytryptamine, 5-HT) in the pathogenesis of pulmonary hypertension due to episodes of primary pulmonary hypertension in humans linked to serotoninergic appetite-suppressant drugs. In this study, we investigated the effect of 5-HT on the development of pulmonary hypertension induced by injecting bacterial lipopolysaccharide (LPS; endotoxin) and cellulose microparticles intravenously, using the nonselective 5-HT(1/2)receptor, antagonist methiothepin. In Experiment 1, broilers selected for ascites susceptibility or resistance under conditions of hypobaric hypoxia were treated with methiothepin or saline, followed by injection of LPS, while recording pulmonary arterial pressure (PAP). In Experiment 2 ascites-susceptible broilers were treated with methiothepin or saline, followed by injection of cellulose microparticles, while recording PAP. In Experiment 3, an i.v. microparticle injection dose shown to cause 50% mortality was injected into ascites-susceptible and ascites-resistant broilers after methiothepin or saline treatment. Injecting methiothepin reduced PAP below baseline values in ascites-susceptible and ascites-resistant broilers, suggesting a role for 5-HT in maintaining the basal tone of the pulmonary vasculature in broilers. Injecting microparticles into the wing vein had no affect on the PAP in the broilers treated with methiothepin, suggesting that 5-HT is an important mediator in the pulmonary hypertensive response of broilers to microparticles. Furthermore, injecting an 50% lethal dose of microparticles into ascites-susceptible and ascites-resistant broilers pretreated with methiothepin resulted in reduced mortality. Serotonin appears to play a less prominent role in the pulmonary hypertensive response of broilers to intravenously injected LPS, indicating that other mediators within the innate response to inflammatory stimuli may also be involved. These results are consistent with our hypothesis that pulmonary hypertension syndrome ensues when vasoconstrictors, such as 5-HT, overwhelm the dilatory effects of vasodilators, such as NO, thereby effectively reducing the pulmonary vascular capacity of pulmonary hypertension syndrome-susceptible broilers.

Animals↗

PubMed1998

High incidence of cardiac arrhythmias in broiler chickens.

A study was completed to characterize cardiac arrhythmias in broiler chickens. The data were collected from 505 (265 males and 240 females) commercial broilers. Electrocardiograph (ECG) readings were obtained from all birds between 7 and 9, 21 and 23, and 42 and 44 days of age. For comparison, ECG recordings were also collected from 180 broiler breeders at 3 and 8 weeks of age, and from 100 6-week-old Brown Leghorn and 100 6-week-old Barred Plymouth Rock chicks. The measurements included evaluation of heart rhythm, and incidence of ascites and of sudden death syndrome (SDS). Heart arrhythmias in broiler breeders or in the two other breeds examined were sporadic. Cardiac arrhythmias in broiler chickens were seen as early as 7 days of age. The incidence of arrhythmias increased with age. At 42-44 days of age 17% of the broiler population showed disrhythmia. The incidence was higher in male broilers (P < 0.012) in comparison to females. The most frequently observed disturbances of the rhythm were ventricular arrhythmias (VA), the most common being premature ventricular contractions (PVC). In most cases PVC occurred as one or two episodes, but in several birds, runs of three or more consecutive PVCs occurred. Unifocal PVCs were considerably more frequent than multifocal PVCs. Sustained ventricular tachycardia (VT) was least frequent. Heart-related mortalities were observed only in broiler chickens. There were 23 SDS cases (4.55% of the population) and 13 birds developed ascites (2.25% of the population). Male broilers had a higher incidence of SDS (P < 0.027) and ascites (P = 0.064) compared to females. Males represented 74% of all SDS cases and 77% of all ascites cases. Whereas three birds that died of SDS and one bird that developed ascites had a history of VA, five birds that developed ascites had a history of conduction block. It has been concluded that, compared to other chickens, the hearts of broiler chickens are considerably more susceptible to arrhythmias. Cardiac arrhythmias are involved in the pathogenesis of SDS and are likely in some cases of ascites.

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