Defining susceptibility of broiler chicks to colibacillosis.

This study aimed to define the susceptibility of broilers to colibacillosis through quantification of clinical responses and to examine the relationship between susceptibility and growth retardation. A challenge experiment was carried out twice. In each trial, 192 chicks were challenged intratracheally with Escherichia coli (E. coli) at 7 days of age and 160 chicks served as controls. Surviving chicks were euthanized at 14 or 15 days. Parameters measured were: daily mortality, lesion scores, body weight at 1, 4, 7, 10, 12 and 14 or 15 days and feeding behaviour at 6, 11 and 13 days. The results were reproducible, and increasing susceptibility to colibacillosis was defined by four categories: chicks without lesions, chicks with airsacculitis but no systemic lesions, chicks with systemic lesions, and chicks that die. Increasing susceptibility was associated with increasing growth retardation, but growth retardation was not inevitably linked to challenge with E. coli.     

Histopathology of monensin-tiamulin myopathy in broiler chicks

Thirty-six 7-day-old broiler chicks were simultaneously given food containing monensin, and water containing tiamulin, both drugs being at normal levels of usage. Equal numbers of chicks on a basal diet and plain water served as the controls. Anorexia, depression, drowsiness, leg weakness and a decrease in body weight appeared on days 2 to 3 of administration in several treated chicks. These clinical signs and growth retardation were prevalent and severe on days 4 to 7, at which time some chicks became recumbent. From day 9, chicks showed gradual recovery from the clinical signs and growth retardation. Histopathologically, the neck and leg skeletal muscles examined were severely affected in treated chicks, but cardiac and pectoral muscles were intact. Besides hyalinisation and floccular change which appeared infrequently in early stage of the experiment, muscle fibres showing an enlargement of the nuclei and a distention of a pale to basophilic sarcoplasm, suggestive of partial myofibrillar lysis and subsequent reparative change, dominated all affected muscles. These degenerative and reparative changes were considered to be distinctive for monensin-tiamulin myopathy in chicks.     

Haematological and morphological responses of broiler chicks to hypoxia

Broiler chicks were subjected to experimentally-induced hypoxia and the haematology, together with the histopathology and ultrastructure of heart, liver, lung and kidney and the ultracytochemistry of heart tissues were examined. The haemoglobin concentration, packed cell volume and red blood cell counts were significantly increased compared with controls. The results resembled the haematology of similar aged broilers with an ascitic syndrome and also 1-day-old chicks after induced hypoxia. The morphological changes were also similar in all organs examined and compared with those described in ascitic syndromes. Lactate dehydrogenase was increased in the hearts of hypoxic and ascitic birds indicating reduced oxygen utilisation. It was suggested that hypoxia may be an important factor in the aetiology ascitic syndromes of flocks kept at low altitude.     

Pathological effects of gentamicin administered intramuscularly to day-old broiler chicks

The aim of this experimental study was to investigate the pathological effects of gentamicin in birds. Broiler chicks at 1 day of age were intramuscularly administered gentamicin at dose levels varying from 0 to 180 mg/kg. Clinical signs comprising of depression, decreased feed consumption, increased water intake, loose watery droppings and reduced body weights appeared in a dose-related manner in chicks administered 30 mg/kg or higher dose levels. Mortality was 0% and 20% in chicks given 40 mg and 50 mg/kg gentamicin. It increased in a dose-related manner and was 100% in 100 mg/kg or higher dose groups. The LD50 calculated at total deaths in 5 weeks duration was 77.56 mg/kg. Kidneys and livers of chicks given 50 mg/kg or higher doses of gentamicin were congested, enlarged and had hemorrhages on the surfaces. Microscopically kidneys exhibited acute tubular necrosis. Livers showed fatty change, vacuolar degeneration, necrotic areas and cellular infiltration around portal triads. Serum total proteins and albumin decreased while creatinine and ALT increased in chicks given 20 mg/kg and higher doses. The no observable effect level (NOEL) of a single intramuscular administration of gentamicin in day-old broiler chicks was 10 mg/kg body weight.     

Ultrastructural changes of monensin-oleandomycin myopathy in broiler chicks

Light microscopical and ultrastructural changes of skeletal muscles were described in chicks treated with monensin and oleandomycin in the food and water for 3 to 6 days. Simultaneously, or slightly subsequent to necrosis of some myofibres on days 3 and 4 of treatment, many myofibres exhibited reversible alterations initiated by focal myofibrillar lysis and degeneration of mitochondria. Reparative changes appearing on day 6 of treatment showed proliferation of the mitochondria, marked increase of ribosomes and polysomes, and enlargement of the Golgi apparatus in the sarcoplasm of degenerated myofibres. The morphological findings of monensin-oleandomycin myopathy in chicks were indistinguishable from monensin-tiamulin myopathy. Possible factors contributing to the unique morphology of this myopathy were discussed.     

Immunosuppressive effects of arsenic in broiler chicks exposed to Newcastle disease virus

To assess the effects of prolonged exposure to arsenic (As, as arsenate) on host immune competence overall and resistance to Newcastle disease (ND) viral infection in particular, a study was carried out in broiler chicks. At 7 days of age, chicks were assigned to groups that would undergo varying vaccination, challenge, and/or As exposures; Group 1 was a control; Group 2 was to receive Newcastle disease virus (NDV) only; two groups (Groups 3, 4) were to be given As daily (50?mg/kg, by gavage) from Days 7–35 of the experiment. All groups underwent normal vaccination on Days 5, 23, and 32 against live NDV (B1 type, LaSota strain); two groups (Groups 2, 4) were challenged with field-isolated NDV at Day 24. At Days 14, 21, 28, and 35 of age, subsets of chicks in each group were evaluated. The results showed feed intake and weight gain were lower in As-treated and NDV-challenged chicks. In As-treated chicks, absolute and relative spleen weights were significantly greater, whereas those of the thymus significantly lower, over the entire 35-day period. Effects on bursa weights (absolute, relative) were only significantly reduced through Day 21. Antibody titers against ND were significantly reduced (vs. control) over the whole 35 days in birds that received As alone, but only significantly depressed through the first 21 days in birds that received As?+?NDV; thereafter, titers were significantly greater (in parallel with effects in birds that received NDV alone). In contrast, antibody responses to T-dependent antigen (Sheep red blood cells [SRBC]) were significantly lower in As only- and As?+?NDV-treated chicks throughout the study period. Among birds exposed to As (alone or with NDV), in situ phagocytic activity was elevated and cutaneous sensitivity responses decreased during the period from Day 28 to Day 35. NDV alone had spurious effects on phagocytic activity but did cause significant reductions in cutaneous sensitivity responses. It was concluded that arsenic decreased immunity in broiler chicks, thereby making them prone to ND.     

Comparisons of insulin related parameters in commercial-type chicks: Evidence for insulin resistance in broiler chicks

The aim of this study is to elucidate whether insulin acts differentially within the central nervous system (CNS) of two types of commercial chicks to control ingestive behavior. Male layer and broiler chicks (4-day-old) were intracerebroventricularly (ICV) injected with saline or insulin under satiated and starved conditions. Feed intake was measured at 30, 60 and 120 min after treatment. Secondly, blood and hypothalamus were collected from both chick types under ad libitum feeding and fasting for 24 h. Plasma insulin concentration was measured by time-resolved fluoro-immunoassay. Hypothalamic insulin receptor mRNA expression levels were measured by quantitative RT-PCR. The ICV injection of insulin significantly inhibited feed consumption in layer chicks when compared with saline (P < 0.05), but not broiler chicks (P > 0.1). Plasma insulin concentration of both chick types significantly decreased following 24 h of fasting, while insulin concentrations in the broiler chicks were significantly higher compared to the layers fed under ad libitum conditions. Hypothalamic insulin receptor mRNA expression levels were significantly lower (P < 0.05) in broiler chicks than in layer ones under ad libitum feeding. Feed deprivation significantly decreased insulin receptor mRNA levels in layer chicks (P < 0.01), but not in broiler chicks (P > 0.1). Moreover, plasma insulin concentrations correlated negatively with hypothalamic insulin receptor protein expression in the two types of chicks fed ad libitum (P < 0.05). These results suggest that insulin resistance exists in the CNS of broiler chicks, possibly due to persistent hyperinsulinemia, which results in a down-regulation of CNS insulin receptor expression compared to that in layer chicks.     

Immuno-pathologic effects of oral administration of chlorpyrifos in broiler chicks

Abstract

This study sought to assess if chlorpyrifos (CPF) induced immunotoxic effects in orally-treated day-old broiler chicks. Groups of chicks received per os CPF diluted in xylene at 5, 10, and 20?mg/kg body weight (CPF-5, CPF-10, and CPF-20) orally daily for 15 days. Xylene and control groups received xylene alone (1?ml/kg BW) and physiological saline, respectively. At various times during/after the exposure regimens, different immune end-points were analyzed in the birds. Humoral immunity was examined by assessing antibody responses to sheep red blood cells. Cell-mediated immunity was measured via lymphoproliferative responses to avian tuberculin. Leukocyte phagocytic ability was measured using a carbon clearance assay. Results showed that CPF administered to broiler chicks caused a dose-dependent decrease in humoral immunity, cell-mediated immunity, and phagocytic activity. Dose- and time-related pathological changes were observed in bursa of Fabricius, spleen, and thymus in treated birds. These changes were mild, moderate, and severe, respectively, in the 5, 10, and 20?mg/kg CPF groups. The Bursa of Fabricius in treated birds showed increased inter-follicular connective tissue proliferation, severe moderate cytoplasmic vacuolation, edema, and degenerative changes such as pyknosis and fragmentation of nuclei that depleted the follicles of lymphoid cells. In the spleen, disorganization of follicular patterns, severe congestion, cytoplasmic vacuolation, degenerative changes, and hyperplasia of reticular cells were noted. The thymus in treated birds exhibited congestion, hyper-cellularity, and a presence of immature monocytes in the medullary region, as well as myoid cell necrosis. Taken together, these studies clearly demonstrated that chlorpyrifos could induce immunotoxicities in broiler birds.     

Renal lesions in baby chicks due to sodium chloride poisoning

The pathogenesis is described of renal lesions which developed in 1-day-old chicks fed a ration containing 10% sodium chloride for 25 successive days. The gross lesions are described. Microscopically the kidneys showed that nephrosis and glomerular changes were very prominent. These included glomerular hypertrophy, formation of epithelial crescents, fibrous adhesions, lobularity, shrinkage and collapse of the glomerular tuft and thickening of the basement membrane of the capillary tuft. Segmental hyalinosis of the tuft was also sometimes observed.     

Kinetics of serum antibody responses in broiler chicks against Cryptosporidium baileyi

The kinetics of serum antibody responses in broiler chickens against Cryptosporidium baileyi were studied. Broilers were inoculated intratracheally with 250,000 C. baileyi oocysts at 1, 7, or 14 days of age. Antibody was quantified by an enzyme linked immunosorbent assay. Anti-cryptosporidial serum immunoglobulins (IgM and IgG) were detected 9 days post-inoculation (DPI) in birds inoculated at 1 or 7 days of age with oocysts and 4 DPI when 14-day-old birds were inoculated. Results also reaffirmed age related susceptibility, with day-old birds being more susceptible than 7-day, and 14-day-old birds were not susceptible to clinical disease. The susceptibility to infection correlated with the amount and duration of the IgM response. Day-old inoculated birds developed a higher, longer-lasting response than 7 or 14-day-old infected birds.     

Isolation and characterisation of cytopathic avian enteroviruses from broiler chicks

Cytopathic viruses were isolated from the faeces, pancreas and caecal contents of broiler chicks in two cases of a stunting syndrome. Two representative strains, designated AAF7 and M-8, were identified as enteroviruses on the basis of their size (25 nm in diameter), RNA in the viral core, virus growth in the cytoplasm, resistance to chloroform, trypsin and acid, and partial heat-stabilisation to molar magnesium chloride. They formed irregular plaques in chick kidney cell cultures. Numerous granula eosinophilic inclusions were induced in the cytoplasm of chicken kidney cell cultures infected with the viruses. Both isolates reacted partially with the G4260 strain of avian nephritis virus but not with the VR strain of avian encephalomyelitis virus.     

Effect of thyroid hormone on concentrations of plasma calcitonin in broiler chicks

The purpose of these studies was to determine the effect of thyroidectomy (Tx), and thyroid hormone (T3/T4) treatment on concentrations of plasma CT in chicks. In addition, the turnover of CT in Tx- and T3/T4-treated chicks was estimated using a novel nonradioactive salmon CT preparation. One-week-old broiler chicks (Gallus domesticus) (n = 75) were divided into three groups. Group I was sham-injected daily (i.m. saline), Group II was injected with 50 micrograms/day of T3/T4 while Group III was injected with the goitrogen, methimazole, (150 mg/kg BW per day) for 8 weeks. Chicks (8-9 weeks old) were implanted with catheters in the brachial wing vein and administered ruthenium-labeled salmon CT. Blood samples were collected at 30 s, 1, 2, 4, 8, 20 min, and 3 h after injection. Results showed that concentrations of plasma CT were decreased in T3/T4-injected birds. There was no significant effect of methimazole on circulating concentrations of plasma CT. The half-life of CT was significantly increased (P < 0.05) in both T3/T4-injected (n = 6; 1.34 +/- 0.16 min) and goitrogen-treated birds (n = 2; 5.81 +/- 2.83 min) compared to controls (n = 7; 54 +/- 3 s) The results demonstrate that changes in concentrations of plasma thyroid hormones can significantly affect concentrations of plasma CT.     

Pathophysiological effects of chronic toxicity with synthetic pyrethroid, organophosphate and chlorinated pesticides on bone health of broiler chicks

This experiment evaluated effects following chronic toxicity with 20 ppm fenvalerate (synthetic pyrethroid), 2 ppm monocrotophos (organophosphate) and 2 ppm endosulfan (chlorinated hydrocarbon) on bone health of broiler chicks. A total of 120 chicks were divided equally into 4 groups and were fed poultry mash without (control) or mixed with different pesticides for 8 weeks. Body mass, serum calcium and phosphorus levels were unaffected due to pesticides treatment. However, increase an (p < 0.01) in serum alkaline phosphatase activity was noted and serum total protein decreased (p < 0.01) in all treated groups. Roentogenography revealed destructive changes in the upper part of the femur in the monocrotophos group. Endosulfan intoxicated chicks had increased numbers of trabeculae in the medullary cavity. Microscopic alterations of the costochondral junction in intoxicated chicks were similar. The zones of proliferating, maturing and degenerating, and calcifying cartilage cells were reduced in width and the metaphysis in treated birds showed a reduced number of cartilage cells and thinner trabeculae. Due to toxicity, the capillary scaffolding of the degenerating cartilage cells was reduced and a larger number of transverse trabeculae could be seen in the metaphysis. Appositional bone growth studied by the tetracyclicline labeling technique indicated decreased active osteons.     

Death in broiler breeders due to salpeingitis: Possible role of zearalenone

High mortality occurred in a flock of 24,000 broiler breeders. During the 40 weeks of the laying period the mortality was approximately 40% in two houses and 20% in two other houses. Peak egg production in the severely affected houses reached 51% and 56% while the two other houses achieved 66% and 76%. Fertility was not affected and the progeny appeared normal in all respects. In the affected birds ascitic fluid was found in the abdomen while cysts and a large amount of fibrinous material were present in the oviduct. The histopatho-logical examination showed caseous cysts in the epithelium with chronic inflammation of the genital tract (salpingitis and peritonitis). Examination of feed extracts with a radioreceptor assay indicated a high degree of oestrogenic activity. Examination by thin layer and high pressure liquid chromatography indicated that zearalenone - a naturally occurring oestrogenic mycotoxin produced by Fusarium spp -was present in concentrations of up to 5mug/g of feed.     

High stocking density as a predisposing factor for necrotic enteritis in broiler chicks

Stocking density is a management factor which has critical implications for the poultry industry. The aim of the present study was to investigate the effect of high stocking density as a predisposing factor in an experimental model of necrotic enteritis in broiler chicks. The experimental challenge model included an oral inoculation with 10-fold dose of attenuated anticoccidial vaccine and multiple oral inoculations with a specific strain of Clostridium perfringens. Two hundred and forty as hatched day-old broiler chicks were randomly allocated to four treatment groups according to the following experimental design: group N, with normal stocking density (15 birds/m²) and no challenge; group D, with high stocking density (30 birds/m²) and no challenge; group P, with normal stocking density and positive challenge; and group DP, with high stocking density and positive challenge. From each bird, the intestine, gizzard and liver were collected and scored for gross lesions. The intestinal digesta was collected for pH and viscosity determination. One caecum from each bird was taken for microbiological analysis. The statistical analysis and evaluation of the experimental data revealed significant interaction effects between “stocking density” and “challenge”, regarding gross lesion scores in intestine and liver, pH values in jejunum, ileum and caeca as well as C. perfringens counts in the caeca (P ≤ 0.05). High stocking density in challenged birds increased the gross lesion score in the intestine (P ≤ 0.05), contrary to unchallenged birds. It can be concluded that high stocking density affects unfavourably the welfare and gut health of broiler chicks, predisposes to necrotic enteritis in a subclinical experimental model and increases further its importance as a management factor for the poultry industry.     

Histopathology and immunohistochemistry of renal lesions due to infectious bronchitis virus in chicks

Two-day-old specific-pathogen-free chicks were inoculated intranasally with the MA-87 strain of infectious bronchitis virus, and trachea and kidney lesions studied histologically and immunohistochemically. Lesions and viral antigen were first detected in the trachea; severe damage was then observed in the kidney. Viral antigen appeared prior to the development of renal lesions and was detected in the cytoplasm of epithelial cells by 4 days post-inoculation (p.i.). The epithelial cells of the collecting ducts, collecting tubules and distal convoluted tubules were first affected, followed by involvement of Henle's loops, whereas the proximal convoluted tubules were only minimally affected. Antigen-positive cells of ducts and tubules were degenerated and desquamated. The severe epithelial cell damage resulted in infiltration of heterophils and macrophages in the interstitium, ducts and tubules. The detection of viral antigen was consistent with the distribution of histological lesions at 6 to 8 days p.i. At a later stage, antigen-positive cells disappeared and repair of epithelial cells was seen, accompanied by interstitial lymphoplasmacytic infiltration and lymphoid nodular formation.     

The pathological and biochemical effects of feeding fermented leaves of cassia obtusifolia 'Kawal' to broiler chicks

Fermented leaves of Cassia obtusifolia 'Kawal' were mixed in the food of broiler chicks at concentrations of 25, 50 and 100 g/Kg and then fed to chicks from 1 day to 8 weeks of age. Growth rate was depressed in relation to the concentration of Kawal. Lesions of an inflammatory-degenerative type were seen in the proventriculus, intestine, liver, heart, lungs and kidneys, their severity increasing with the amount of Kawal eaten. These were accompanied by similar increases in the activities of lactate dehydrogenase, alkaline phosphatase, glutamate oxaloacetate and glutamate pyruvate transaminases and in the concentrations of bilirubin, potassium, phosphorus, total lipids and carotenes in the blood and dose-related decreases in total protein, albumin, cholesterol, globulin, sodium, calcium and alkaline phosphatase in the blood. Birds fed on Kawal tended to become anaemic but white blood cell counts increased. It is concluded that Kawal even at an inclusion rate of 25 g/Kg is unacceptable as a protein supplement.     

Evaluation of Salmonella enteritidis-immune lymphokines on host resistance to Salmonella enterica ser. gallinarum infection in broiler chicks

The prophylactic treatment of neonatal broiler chicks with lymphokines derived from S. enteritidis-immurazed chickens (SE-ILK) was evaluated for its effect on the birds' resistance to an experimental infection S. enterica ser. gallinarum (SG). On the day of hatch, chicks were injected intraperitoneally with either SE-ILK, control non-immune lymphokines (NILK), or were left untreated. Thirty minutes later, all chicks were orally gavaged with either 10(4) colony forming units (CFU) or 10(6) CFU SG. The chicks were observed twice daily for 10 days for morbidity and mortality. Chicks that died during the experiment had their livers cultured for SG. The survivors were killed and their livers, spleens and caecal tonsils cultured for SG. The prophylactic treatment of chickens with SE-ILK induced significant protection against extraintestinal SG infection when compared to the NILK-treated or non-treated controls as evidenced by: (1) a significant reduction (P< 0.005) in the mortality of chicks challenged with either 10(4) and 10(6) CFU SG; (2) an increased average weight gains of chicks challenged with either 10(4) and 10(6) CFU SG; and (3) a significant (P< 0.001) reduction in the number of chicks with organs culture-positive for SG. The results suggest that the prophylactic administration of SE-ILK can confer non-specific protection to chicks against a pathogenic species of Salmonella resulting in reduced morbidity, mortality, and organ infectivity caused by SG infections of broiler chicks, while enhancing performance during the first 10 days of Ufe.     

Infection of broiler chicks (Gallus domesticus) with human intestinal spirochaetes

One-day-old broiler chicks were infected orally with spirochaetes isolated from cases of intestinal disorder in humans. Three different isolates were studied in an experiment of 22 days duration. No signs of clinical disease were observed; the infection did not cause changes in the concentration of carotenoids or in the activity of alkaline phosphatase in the serum. Spirochaetes were shed in the caecal faeces. At autopsy, no lesions were seen in the intestinal tracts of the birds. Large numbers of spirochaetes were present in the caecum of 30 to 100% of the infected birds; in a few birds small numbers of spirochaetes were observed in scrapings from the mucosa of the small intestine. On histological examination massive colonisation of the caecal mucosa was observed. Spirochaetes of two isolates had invaded the caecal mucosa and for one of these, they were found between enterocytes, but not below the basement membrane. The other isolate had produced gap-like lesions, subepithelial accumulations of spirochaetes and focal erosion. No signs of an inflammatory reaction were observed.