Biomedical subjects

N C Rath

Publications and source records attributed to N C Rath.

At least 19 recordsLinked to original sources

PubMed2001

Inflammation-induced changes in serum modulate chicken macrophage function.

Inflammation-induced changes in serum protein profiles and the effects of such serum on a chicken macrophage cell line HD11 were studied to find whether the changes in serum affect cellular immunity. Four-week-old male broiler chickens were injected subcutaneously with either olive oil or 50% croton oil mixed in olive oil to induce inflammation. The birds were bled at 48h after injection, and serum protein profiles were compared using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and densitometric evaluation. At 48h post-injection the serum from croton oil-injected birds showed distinct changes in protein profiles characterized by a selective increase or decrease in levels of several serum proteins. The protein bands which showed increases had relative molecular weights (Mr) corresponding to 65kilo Daltons (kD), 42kD, and two or more proteins with Mr> or =200kD. The levels of serum albumin (49kD), and a 56kD protein were reduced in croton oil-injected birds. The modulating effects of such serum on HD11 cells were studied using bacterial lipopolysaccharide (LPS) or phorbol myristate acetate (PMA) induced functional activation of these cells. The LPS-induced interleukin-6 (IL-6) production by HD11 cells was not affected by the presence of either olive oil-treated control or croton oil-treated inflammatory serum but nitrite production was enhanced by the inflammatory serum. Similarly, inflammatory serum also enhanced PMA-induced respiratory burst measured using dichlorofluorescein diacetate (DCF-DA) oxidation mediated by reactive oxygen intermediates. These results suggest that inflammatory serum can modulate macrophage function by influencing the production of reactive oxygen and nitrogen species which could affect their phagocytic and bactericidal activities.

Animals↗

PubMed2001

Matrix metalloproteinase activities of turkey (Meleagris gallopavo) bile.

The bile from turkey (Meleagris gallopavo) gall bladders was found to contain substantial matrix metalloproteinase (MMP) activities using gelatin, collagen, and casein substrate zymography, [3H]labeled collagen degradation assays, and gelatin-agarose affinity purification. Five major bands corresponding to approximate M(w) of 64, 60, 46, 40 and 36 kDa showed gelatinolytic activities. On incubation with p-aminophenylmercuric acetate or thimerosal, the densities of both the 64- and 46-kDa bands decreased with increasing intensities of the 60- and 40-kDa bands. Both the 64- and 60-kDa bands showed collagenolytic activities whereas the caseinolytic activities appeared as diffuse bands corresponding to M(w) of approximately 60, 40 and 36 kDa. Using [3H]collagen as substrate, the bile enzymes showed both a time and concentration-dependent degradation, which could be inhibited by the MMP inhibitors such as EDTA, phenanthroline, and N-[(2R)-2-(hydroxyamido carbonylmethyl)-4-methylpentanonyl]-L-tryptophan methylamide, but not by serine and cysteine protease inhibitors like trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane, phenylmethylsulfonyl fluoride or leupeptin. Both 60- and the 40-kDa gelatinolytic bands showed affinity adsorption to a gelatin-agarose matrix. The physiological roles of bile MMPs are not clear, but their involvement in the digestive functions of birds are likely.

Animals↗

PubMed2001

Effect of early handling of turkey poults on later responses to a dexamethasone-Escherichia coli challenge. 1. Production values and physiological response.

The stress responses of mice and rats has been shown to be permanently altered by brief, gentle handling during the first 10 d of life, resulting in increased BW and resistance to stress-induced immunosuppression. The purpose of this study was to determine whether early handling of turkey poults could permanently affect production values and physiology of adult turkeys. Turkey poults were handled 0, 1 (1x), or 2 (2x) times daily for the first 10 d after hatch. Handling consisted of gently catching each poult and holding it for 10 s. On Day 11 after hatch, half of the birds from each handling treatment were treated with three injections of 2 mg dexamethasone (DEX)/kg BW on alternating days. On the day of the third DEX injection, duplicate pens of birds were also inoculated in the airsac with 0 or 50 cfu of Escherichia coli. The same birds were treated with a second series of DEX injections at 5 wk of age. Two weeks later, all birds were weighed, and 3 wk later four birds per pen were bled and 10 birds per pen were necropsied; relative organ weights were then determined. Surviving birds were treated with a third series of DEX injections at 10 wk of age; 2 wk later, all surviving turkeys were bled, weighed, and necropsied. Feed consumption was determined weekly. There were no differences due to handling treatment on the body weights or on the relative organ weights of birds that died after the first DEX treatment. Birds treated with a second DEX injection at 5 wk of age and handled 1x daily had decreased BW. Those handled 1x or 2x daily had higher feed conversion ratios. Surviving birds that were given a third DEX treatment had higher BW and no difference in feed conversion when handled 1x or 2x daily. Relative liver, heart, and spleen weights were affected by handling of DEX-E. coli-treated birds, as were serum chemistry values for calcium, iron, glucose, total protein, blood urea nitogen, uric acid, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and gamma-glutamyltransferase. Handling also affected the numbers of white blood cells of DEX-treated birds. These results indicate that brief and gentle handling of turkey poults during the first 10 d after hatch has lasting effects on production values and physiology of adult turkeys and that these effects can be positive or negative. These results suggest a genetic divergence in the response to stress and its effect on production values and physiology of commercial turkey populations.

Air Sacs↗

PubMed2001

Effect of early handling of turkey poults on later responses to multiple dexamethasone-Escherichia coli challenge. 2. Resistance to air sacculitis and turkey osteomyelitis complex.

Dexamethasone (DEX)-induced immunosuppression facilitates Escherichia coli pathogenesis leading to lesions of air sacculitis and turkey osteomyelitis complex (TOC). The purpose of this study was to determine if early handling could affect resistance to disease in this model. Seven hundred twenty male turkey poults were handled 0, 1 (1x), or 2 (2x) times daily for the first 10 d after hatch. Handling consisted of gently catching each individual poult, holding it for 10 s, and placing it into a basket. Starting on Day 11 after hatch, half of the birds from each handling treatment were treated with three injections of 2 mg DEX/kg BW on alternating days. On the day of the third DEX treatment, duplicate pens of birds were also inoculated in the air sac with 0 or 50 cfu of E. coli. All DEX-treated birds were given a second series of DEX injections at 5 wk of age, and 10 birds per pen were necropsied 3 wk later. Surviving birds were treated with a third series of DEX injections at 10 wk of age. Two weeks later, all surviving turkeys were necropsied. All mortalities and necropsied birds were scored for air sacculitis and examined for TOC lesions. All livers, air sacs, and TOC lesions were cultured for bacteria. There was increased mortality after the first series of DEX treatments of birds handled 2x. After the second series of DEX treatments, birds handled 1x had increased mortality, incidence of air sacculitis, and recovery of E. coli from tissues, whereas 2x handled birds were identical to unhandled controls. After the third series of DEX treatments, handling 1x resulted in decreased air sacculitis scores and decreased incidence of mortality, green liver, TOC lesions, and recovery of E. coli from tissues. The effects of early handling of turkey poults were variable, depending on the number of DEX treatments and the age of the birds. These results suggest that early handling can affect the susceptibility of stressed turkeys to E. coli air sacculitis and TOC and that differences in susceptibility may be influenced by age and individual variability in the stress response.

Air Sacs↗

PubMed2000

Effects of Salmonella typhimurium lipopolysaccharide on broiler chickens.

The effects of Salmonella typhimurium lipopolysaccharide (LPS) on the physiology of 3-wk-old broiler chickens were studied at 12, 24, and 48 h after a single intravenous injection of saline or LPS. Lipopolysaccharide elevated cloacal temperature by 3 h after injection, induced a diuretic response, and decreased BW gain. An increase in the relative liver weight was evident in LPS-treated birds at all time intervals, whereas a decrease in the relative weight of bursa of Fabricius was observed only at the 48-h time point. The plasma interleukin (IL)-6 and the blood heterophil concentrations were elevated at 12 and 24 h following LPS administration. These changes were not observed in control chickens or in LPS-treated chickens at 48 h. A decrease in the blood glucose concentration in LPS-treated birds at 12 h was accompanied by an elevation in the blood phosphate level. An increase in total plasma protein concentration was observed only at 24 and 48 h after LPS treatment. Comparative SDS-PAGE analysis of plasma proteins from these birds under nonreducing conditions showed some quantitative differences in four bands of proteins between saline and LPS-treated chickens. A protein corresponding to an approximate molecular weight (MW) of 65 kDa increased in LPS-treated chickens, and three other proteins with MW of approximately 39, 49, and 56 kDa showed reductions in concentration compared with saline-treated controls. These results show that LPS induces a number of physiological changes that may be responsible for the regulation of the acute phase response in chickens.

Animals↗

PubMed2000

Ascites syndrome and related pathologies in feed restricted broilers raised in a hypobaric chamber.

It has been demonstrated that the incidence of ascites can be significantly reduced through feed restriction. This method is thought to have an effect by slowing the growth rate of the birds. Interestingly, when birds are grown in a hypobaric chamber, ascites incidence increases while the overall growth rate of the birds is decreased. Unfortunately, the restriction programs practiced also have a detrimental effect on growth characteristics. An experiment was conducted to determine if the timing and duration of feed restriction can be used to reduce the incidence of ascites for broilers reared under high altitude and local elevation without having a negative impact on growth. A total of 600 commercial broiler males were used. Birds were divided, placing 360 birds in the hypobaric chamber at a simulated 2900 m (9,500 ft) above sea level, and 240 birds were placed at local elevation [390 m (1,300 ft) above sea level]. At each altitude there were four treatments: 1) fully fed controls; 2) feed available for 8 h/d for 6 wk (the duration of the study); 3) feed available for 8 h/d during the first 3 wk, then full feed for the remaining 3 wk; and 4) full feed for the first wk, then 3 wk of 8 h of feed availability, then 2 wk of full feed. Birds and feed were weighed weekly, and mortalities were necropsied to determine the cause of death. At the end of 6 wk, blood samples were taken, and the birds were weighed, necropsied, and scored for ascites, and organ weights were recorded. All feed restriction treatments significantly reduced ascites incidence, when compared with the fully fed controls. Treatment 2 birds were significantly lighter than any other group at both altitudes. The fully fed controls at local elevation were heavier than the fully fed controls at simulated high altitude, as seen in past experiments.

Animals↗

PubMed2000

The effect of vitamin D3 on resistance to stress-related infection in an experimental model of turkey osteomyelitis complex.

Male turkeys immunosuppressed by injection with dexamethasone (DEX) were given supplemental vitamin D3 in their drinking water in two experiments. In Experiment 1, vitamin D3 was supplemented at a dosage of either 2,064 IU/kg (low level) or 4,128 IU/kg (high level) in drinking water provided ad libitum only from Days 1 through 5 after hatch. In Experiment 2, vitamin D3 was provided at the low dosage for the first 5 d after hatch, followed by treatment with the high dosage for 12 h before and 12 h after each stressful event, which included weekly weighings and two DEX treatments. In both experiments, at 5 wk of age half of the birds were given intramuscular injections of 2 mg/kg DEX on 3 alternating d. In Experiment 1, 100 cfu of Escherichia coli was inoculated into the left thoracic airsac at the time of the third DEX injection. All mortalities were examined, and 10 birds per pen were necropsied 2 wk after treatment and examined for lesions of airsacculitis and turkey osteomyelitis complex (TOC). Four birds per pen were bled before necropsy, and white blood cell total counts, differential white blood cell counts, and clinical chemistry values were determined. In Experiment 2, healthy surviving birds were grown for an additional 5-wk period, after which the DEX-treated birds were given a second series of DEX injections and were bled and necropsied 2 wk later. There were no significant effects of vitamin D3 treatment in combined general linear models analysis of Experiment 1; however, when birds not treated with DEX or E. coli were compared with those treated with both DEX and E. coli, supplementation with the low level of vitamin D3 significantly decreased TOC incidence. There were no significant effects of vitamin D3 treatment in birds treated with DEX at 5 wk of age in Experiment 2. However, when surviving birds were given a second DEX treatment at 12 wk, vitamin D3 treatment resulted in significantly lower incidence of mortality, TOC, green liver, isolation of bacteria from tissues, and lower airsacculitis scores and heterophil-to-lymphocyte ratios than controls. Vitamin D3 also improved BW, relative weights of the liver and heart, and serum levels of glucose and alanine aminotransferase (ALT) of birds receiving two treatments with DEX. The ability of vitamin D3 supplementation to protect turkeys from the immunosuppressive effects of multiple DEX treatments emphasizes the role of vitamin D3 as a prohormone that affects health and disease resistance in turkeys.

Alanine Transaminase↗

PubMed2000

Factors regulating bone maturity and strength in poultry.

Adolescent meat-type poultry and cage layers exhibit a high incidence of bone problems that include bone weakness, deformity, breakage, and infection and osteoporosis-related mortalities. These problems include economic and welfare issues. To improve bone quality in poultry, it is essential to understand the physiological basis of bone maturity and strength in poultry. A complex array of factors that include structural, architectural, compositional, physiological, and nutritional factors interactively determine bone quality and strength. Bone is approximately 70% mineral, 20% organic, and 10% water. Collagen is the major organic matrix that confers tensile strength to the bone, whereas hydroxyapatite provides compressional strength. In recent years, the roles of different collagen crosslinks have been shown to be important in the increase of bone mechanical strength. Similarly, age-related glyco-oxidative modifications of collagen have been shown to increase the stiffness of collagen. These posttranslational modifications of matrix can affect bone quality as it would be affected by the changes in the mineralization process. Our studies show that the growth in the tibia continued until 25 wk of age, which correlated with the increase in the content of hydroxylysylpridinoline (HP) and lysylpyridinoline (LP), the collagen crosslinks. The tibia from 5-wk-old chicks were strong but brittle because of low collagen crosslinks and high mineral content. Bone maturity may relate to its crosslink content. Compared to crosslink content, bone density and ash content showed moderate increases during growth. The bones from younger turkeys were more susceptible to corticosteroid-induced stunting of growth, which also resulted in decreased bone strength. This review discusses how different factors can compromise bone strength by reducing growth, altering shape, affecting mineralization, and affecting collagen crosslinking.

Aging↗

PubMed2000

Turkey osteomyelitis complex.

Turkey osteomyelitis complex (TOC) is defined by the US Food Safety Inspection Service (FSIS) to include normal-appearing processed turkey carcasses that contain lesions including green discoloration of the liver, arthritis/synovitis, soft-tissue abscesses, and osteomyelitis of the proximal tibia. The lesions are associated with many different opportunistic organisms, mainly Staphylococcus aureus and Escherichia coli, suggesting that TOC incidence may be influenced more by deficiencies in the host immune response rather than by the virulence of any one organism. This syndrome is primarily a disease of adolescent male turkeys, and birds with TOC lesions have decreased indices of cell-mediated immunity, leading to the hypothesis that defects in the immune response of individuals within flocks of male turkeys may be responsible for the occurrence of these opportunistic infections. We have developed an experimental model for this disease in which treatment with dexamethasone (DEX), either with or without air sac inoculation with Escherichia coli, produces all of the lesions associated with TOC. These studies suggest that TOC is a result of stress-induced immunosuppression in a subpopulation of male turkeys that respond to the stressors in modern poultry production in a detrimental manner. Supplemental vitamin D3 treatment protected male turkeys from the immunosuppression induced by multiple treatments with DEX and resulted in decreased incidence of mortality, TOC, green liver, and isolation of bacteria from tissues, lower air sacculitis scores, and lower heterophil to lymphocyte ratios than nonsupplemented controls. Vitamin D3 also protected BW; relative weights of the liver, heart, spleen, and bursa; and clinical chemistry values from the effects of DEX treatment. The ability of vitamin D3 supplementation to protect turkeys from the immunosuppressive effects of severe stress emphasizes its role as a prohormone that affects health and disease resistance in turkeys and suggests that variation in the vitamin D receptor genotype may be involved in this disease process. This model has potential value in the identification of other nutritional and physiological immunomodulators that can decrease TOC incidence and will provide a means for the divergent selection of birds more resistant to the stressors of turkey production. In addition, this model will provide justification for management options designed to minimize stress.

Animals↗

PubMed2000

Effect of dietary aspirin on ascites in broilers raised in a hypobaric chamber.

During the course of ascites development in broilers, many factors can interact to cause hypoxia. To counteract hypoxia, birds with ascites develop greatly increased hematocrit and red cell counts. Increasing hematocrits result in more viscous blood. Prostaglandins are involved in the regulation of constriction and dilation of pulmonary blood vessels and in the formation of blood clots. Dietary aspirin, a prostaglandin inhibitor, was used in an attempt to promote vasodilation and inhibit blood clotting in broilers, with the objective of determining the effect of aspirin on ascites progression. The experimental design consisted of two trials with a total of 1,360, 1-d-old male broiler chicks, which were placed at either local altitude (390 m above sea level) or in a hypobaric chamber that simulated an altitude of 2,900 m above sea level. At each elevation, five dietary treatments were employed: [control, 0.025% crystalline acetylsalicylic acid (aspirin), 0.05% aspirin, 0.10% aspirin, and 0.20% aspirin]. Bird and feed weights were recorded weekly. At the end of 5 wk, blood samples and organ weights were collected, and all birds were examined for signs of ascites. In both trials, birds raised at high altitudes were significantly lighter, had a higher incidence of ascites, and had differences in hematology, compared with birds raised at local elevation. Only in Trial 2, however, did dietary aspirin appear to have any effect on ascites incidence. At the 0.20% aspirin level, a reduction in ascites incidence approached significance compared with controls (34% vs. 56%, P < or = 0.06). Unfortunately, birds fed 0.20% aspirin also were significantly (P < or = 0.01) lighter than controls. Because slowing growth rate is known to reduce ascites, this decrease in BW may have been partially responsible for any beneficial effect on ascites development and progression obtained through feeding aspirin.

Altitude↗

PubMed1999

Sex differences in the resistance of turkeys to Escherichia coli challenge after immunosuppression with dexamethasone.

Five-week-old male and female commercial turkeys were immunosuppressed with two levels of dexamethasone (DEX) and challenged by airsac inoculation with 100 cfu of Escherichia coli. Mortality and airsacculitis (AS) scores were significantly higher in challenged birds treated with DEX and marginally higher in males than in females. Male mortalities had significantly higher AS scores than females. Recovery of E. coli from blood and tissues was significantly higher in challenged birds treated with DEX, marginally higher in males (P = 0.09), and significantly higher in male mortalities than in female mortalities. The low level of DEX seemed to have a protective effect against bacterial challenge in males, whereas the high level of DEX had a more adverse effect in males than in females. Body weights 2 wk postchallenge were significantly decreased by both DEX and E. coli, challenge. Relative liver and heart weights were increased by both DEX and E. coli, challenge, whereas bursal:spleen ratios were decreased by both treatments. Total leukocyte counts and relative heterophil counts from blood samples taken 24 h postinfection were significantly higher in DEX-treated birds and in unchallenged DEX-treated females than in males. The DEX treatment resulted in significantly higher heterophil:lymphocyte ratios, but there was no difference between sexes. Males had significantly lower serum levels of uric acid, total protein, albumin, aspartate aminotransferase, and lactate dehydrogenase than did females. Dexamethasone treatment also resulted in lower levels of total protein, albumin, and aspartate aminotransferase. These data suggest that male turkeys may be more susceptible to colisepticemia than female turkeys, especially when under severe stress.

Animals↗

PubMed1999

Research on the probable cause of an outbreak of field rickets in turkeys.

An outbreak of field rickets in turkeys prompted studies on the cause. In Experiment 1, there were four treatments with two replicate pens of 10 poults per pen. The treatments consisted of poults fed newly manufactured feed (control), poults fed a diet containing control feed and 5% clean litter, poults fed control feed and 5% litter from the pens of affected poults, and poults challenged with an intestinal homogenate by gavage. Field rickets did not develop with these treatments. The feed was suspect, and, in Experiment 2, poults were either fed the suspect feed or newly manufactured feed. There were four replicate pens of 25 poults per pen. Poults fed the suspect feed had a decrease (P < or = 0.05) in BW at 1, 2, 3, and 4 wk of age; an increase in the relative weight of the liver, pancreas, kidney, and bursa of Fabricius; and a decrease in bone ash. There were changes in clinical chemistries. In the third study, there were five dietary treatments with two replicate pens of 25 poults per treatment. The treatments consisted of poults fed newly manufactured feed; new feed mixed with 25, 50, or 75% suspect feed; or 100% suspect feed. Body weights of poults fed 100% suspect feed were decreased at 2, 3, and 4 wk as was the relative weight of the liver, pancreas, and bursa of Fabricius. The relative weight of the kidney increased. Lameness, a decrease in bone ash, and changes in hematology and blood chemistry were observed in the poults consuming 100% suspect feed. These data demonstrate that feed from the original outbreak could induce field rickets and was toxic. Because the feed contained adequate vitamin D, calcium, and phosphorus, the cause of this outbreak of field rickets is thought to be a toxic feed contaminant affecting bone development.

Alkaline Phosphatase↗

PubMed1999

The effect of a second dexamethasone treatment on turkeys previously challenged in an experimental Escherichia coli respiratory model of turkey osteomyelitis complex.

In two separate experiments, turkeys that had survived immunosuppression with dexamethasone (DEX) and air sac inoculation with low numbers of Escherichia coli at 5 wk of age were maintained until 13 wk of age, at which time they were given a second treatment with DEX. All mortalities and birds that were necropsied 8 and 15 d (Experiment 1) and 21 d (Experiment 2) after the last DEX injection were scored for air sacculitis/pericarditis and turkey osteomyelitis complex (TOC). In both experiments, all of the lesions that characterize TOC were reproduced, including osteomyelitis of the proximal tibia, synovitis/tendonitis, abscesses in the soft tissues, and green liver. In Experiment 1, all mortalities after Day 7 had TOC lesions, whereas 44% of mortalities had green livers. Staphylococcus aureus was isolated from 90% of all TOC lesions cultured. In Experiment 2, the incidence of mortality, air sacculitis, TOC, and green liver as well as the heterophil:lymphocyte ratio were significantly higher in birds that had previously been treated with DEX but had never been challenged with E. coli than in birds that had survived both treatment with DEX and challenge with 25 or 50 cfu of E. coli. Staphylococcus aureus was isolated from 73% of TOC lesions cultured, whereas E. coli was isolated from only 5.4% of the lesions. These studies suggest that TOC incidence may be related to a stress-induced susceptibility to opportunistic infection.

Animals↗

PubMed1999

Comparative differences in the composition and biomechanical properties of tibiae of seven- and seventy-two-week-old male and female broiler breeder chickens.

Skeletal problems are common in both young and old poultry and are often related to bone weakness. They affect mortality on the farm and condemnations within processing plant and thus raise both welfare and economic concerns. To understand the basis of bone strength, the metaphyseal histology, composition, and the biomechanical properties of tibiae from 7- and 72-wk-old male and female broiler breeder chickens were compared. The biochemical constituents included ash, collagen, proteoglycan, transforming growth factor-beta (TGF-beta), pyridinium crosslinks, and the organic matrix-associated fluorescence. Blood variables were measured to determine the metabolic status of these birds as related to bone physiology. Although there were no differences in blood chemistry of 7-wk-old males and females, there were several differences between young and old birds. The levels of calcium, triglyceride, and iron were higher in older females than in older males. The collagen content was reduced, and the proteoglycan content increased in 72-wk-old hens. The TGF-beta content of bones from 7-wk-old females was higher than that of other groups of birds. Bone strength and stiffness, measured using loads at break and Young's modulus, respectively, were higher in older birds. The presence of medullary bones in 72-wk-old hens did not affect their bone strength, although it reduced strain values and increased Young's modulus. Compared to other groups, the 72-wk-old hens had a higher content of an inorganic matrix. The levels of hydroxylysylpyridinoline (HP) and lysylpyridinoline (LP) and the collagenase-extractable fluorescence of the organic matrix from older birds was higher. The decalcified bone matrix from older birds also showed higher susceptibility to bacterial collagenase than their younger counterparts. Bone strength showed positive correlations with its ash content, density, pyridinium crosslinks, and the fluorescence of the matrix. However, the correlation was strong with both pyridinium crosslinks and the fluorescence of the organic matrix. These results suggest that bone strength is influenced by the content of its collagen crosslinks.

Animal Welfare↗

PubMed1998

Fluorescein isothiocyanate staining and characterization of avian heterophils.

Fluorescein isothiocyanate (FITC) was found to stain cytoplasmic granules of avian heterophilgranulocytes. In tissue sections, the fluorescent granulocytes were predominantly distributed adjacent to trabecular bones. The fluorescein stained granulocytes were abundant in synovial fluids of chickens with synovitis. A significant correlation was observed in the percent of fluorescein labeled granulocytes in blood smears and the percent of heterophils determined using an automated counting method, in unstained blood from normal and Escherichia coli-infected turkeys. The fluorescein-binding heterophils purified from chickens showed a time dependent increases in the oxidation of 2',7'-dichlorofluorescin diacetate (DCF-DA) and the reduction of nitroblue tetrazolium (NBT) which were indicative of changes in oxidative burst in response to phorbol 12-myristate 13-acetate (PMA), Salmonella typhimurium lipopolysaccharide (LPS), and zymosan A (ZA). These heterophil-activating agents, also, caused significant degranulation at 16 h post-treatment, as indicated by the loss fluorescence. There were microscopically visible alterations in the cell shapes and a decrease in the density of granules due to treatment with LPS, PMA or ZA. In addition, these cells also showed phagocytic response which was evident at 30 min of incubation with fluorescent latex particles. Both chicken and turkey heterophils produced interleukin-6 in vitro at 24 h in response to LPS but not to PMA, FMLP or ZA. The chicken heterophils showed spontaneous production of matrix metalloproteinases (MMP) which was significantly enhanced by treatment with LPS, PMA, and ZA; however, LPS appeared to be most effective in inducing MMP production. These results demonstrate that the functions of heterophils can be differentially regulated by different activating agents and the fluorescein binding property of these cells may be useful for their histochemical identification.

Animals↗

PubMed1998

Effect of dietary phytase and high available phosphorus corn on broiler chicken performance.

Two trials were conducted to determine the effects on broiler chicken performance and health of reducing dietary phosphorus levels by treating feed with the enzyme phytase, formulating diets using high available phosphorus (HAP) corn, or when diets were formulated with HAP corn and treated with phytase. Cobb x Cobb male broiler chickens were placed in an experimental design consisting of four dietary treatments with six replicate pens of 50 broilers per pen. The dietary treatments consisted of untreated control feed, phytase-supplemented feed (500 U/kg), diets prepared with HAP corn, and diets prepared with HAP corn and supplemented with phytase. The chickens were maintained on these dietary treatments from 1 to 49 d of age with feed and water made available for ad libitum consumption. When the two trials were combined, there was a significant (P < or = 0.05) increase in body weight in the broilers fed the phytase treated diets at 49 d of age. The serum activity of alkaline phosphatase was significantly decreased in the diets supplemented with phytase, and serum cholesterol was significantly decreased in the diets prepared with HAP corn. These data indicate that total phosphorus can be reduced by at least 11% in diets prepared with HAP corn, or in diets supplemented with phytase, without affecting the performance or health of broiler chickens. When diets are prepared with HAP corn and supplemented with phytase, the dietary addition of total phosphorus can be reduced by at least 25% without affecting broiler chicken performance or health.

6-Phytase↗

PubMed1998

Effects of roxarsone and monensin on digital flexoral tendons of broiler chickens.

Roxarsone and monensin are common poultry feed additives that are used alone or in combination with other drugs to improve growth and feed utilization in young birds. The effects of monensin and roxarsone on the physiology of flexoral tendons of broiler chickens were examined to understand their relationships to leg weakness that have been occasionally associated with these drugs. Day-old chickens were fed either roxarsone or monensin for a period of 6 wk with two regimens of each of the drugs (roxarsone, 45.4 or 90.8 g/ton feed; monensin, 100 or 150 g/ton feed). None of the treatments had any adverse effect on the growth of the birds or caused any significant leg problem. Roxarsone at 45.4 g/ton caused a significant gain in body weight. The biomechanical strength of digital flexoral tendons was measured in several ways. There were no statistical differences in load at break, the modulus of elasticity, or stress or strain levels between different treatment groups and birds that received no medication. There were no differences in collagen, proteoglycan, and pyridinoline content of tendons. Sequential extraction of tendons with different solvents revealed a significant increase in the percentage of guanidine HCl extractible collagens in monensin-treated birds, and a decrease in the acid extractible collagen in both roxarsone- and monensin-treated groups. The relative content of collagen in acid extractible collagens were significantly small relative to total collagen content. Majority of collagen (84 to 90%) was extractible with pepsin. About 8 to 11% of total collagen was resistant to pepsin that was extractible with collagenase; this did not differ between treatment groups. Roxarsone treatment had no effect on the guanidine soluble collagen pool. The effect of monensin on the increase in guanidine soluble pool of collagen may relate to its disruptive effects on cellular secretory processes, which may be of significance in modulating connective tissue function in conjunction with other factors. However, in the present study, neither roxarsone nor monensin alone produced any significant leg problems nor caused any significant differences in the physiology of flexoral tendons or altered their biomechanical properties.

Amino Acids↗

PubMed1998

The effects of dexamethasone immunosuppression on turkey osteomyelitis complex in an experimental Escherichia coli respiratory infection.

Six hundred male turkeys were maintained in floor pens for 5 wk at which time half of the birds were given three intramuscular injections of 2 mg/kg BW of dexamethasone (DEX) on alternating days. On the day of the third DEX injection, the left thoracic air sac of each bird was injected with sterile tryptose phosphate broth (TPB) or with TPB containing approximately 1 x 10(2), 1 x 10(3), 1 x 10(4), or 1 x 10(5) cfu of Escherichia coli. All mortalities and birds necropsied at 14 and 15 d postchallenge were scored for air sacculitis/pericarditis (AS) and turkey osteomyelitis complex (TOC). Cumulative mortality and AS score were both increased by either DEX treatment or E. coli. Although TOC incidence was significantly increased by the lowest titer of E. coli inoculation, increasing the number of bacteria inoculated did not increase TOC incidence due to increased mortality before TOC lesions developed. The DEX treatment by itself increased TOC incidence and there was a synergistic interaction between DEX treatment and E. coli on TOC incidence. Both DEX treatment and E. coli significantly decreased BW. Relative weights of liver, heart, and spleen were significantly increased by both E. coli and DEX, whereas both treatments significantly decreased relative weight of the bursa of Fabricius. The number of positive bacterial isolations from tissue and the heterophil to lymphocyte ratio were increased by both DEX treatment and E. coli challenge. These results suggest that stress-induced immunosuppression may be involved in the etiology of TOC, and that bacterial respiratory infection can lead to the development of TOC lesions.

Animals↗