Use of nitrovin in feed and its effect on the development of Marek's disease in chickens

The effect of the Czechoslovak product Nitrovin, administered at a rate of 15 mg per kg of feed mixture, was studied as exerted on the growth activity, meat quality, and the development and intensity of occurrence of patho-morphological changes ascribable to Marek's disease. An increase of weight gains and dressing percentage was recorded in the group of birds given Nitrovin, as well as in those which had Nitrovin in their feed and were infected with a highly virulent virus of Marek's disease. No significant changes occurred in the contents of dry matter and protein, but there was a much lower fat content in breast muscle in the groups of chickens infected with the Marek disease virus. Internal organs were subjected to biometrical measurements. The birds treated with Nitrovin and infected with the highly virulent virus of Marek's disease had significantly lighter hearts and heavier spleens. Liver, nervus ischiadicus, gonads and spleen were affected most intensively by the changes testifying to Marek's disease. The results are just preliminary and the investigation continues.     

A comparison of the efficacy against Marek's disease of cell-free and cell-associated turkey herpesvirus vaccine.

One-day-old White Leghorn and broiler chicks with maternal antibody to turkey herpesvirus (HVT) were vaccinated with 300 or 1,000 plaque-forming units (PFU) of cell-free or cell-associated HVT vaccine and challenged with virulent Marek's disease virus (MDV) by contact exposure. Broiler chicks receiving 300 PFU of cell-associated HVT had a 3.3% incidence of MD lesions, whereas only 2.0% of those receiving 1,000 PFU had macroscopic lesions. Broiler chicks vaccinated with 300 PFU of cell-free vaccine had 6.8% gross lesions, and 0.67% of the birds receiving 1,000 PFU had MD lesions. Unvaccinated broiler chickens had a 28.3% incidence of MD lesions. Unvaccinated White Leghorn chickens had a 48.9% incidence of macroscopic lesions, whereas 5.4% of the birds receiving 300 PFU of cell-associated HVT had gross lesions, and 8.3% of the birds vaccinated with 1,000 PFU had lesions. In contrast, 6.7% of the chicks vaccinated with 300 PFU of cell-free HVT had MD lesions, and only 4.0% of those receiving 1,000 PFU of cell-free HVT had macroscopic lesions.     

Efficacy of a bivalent vaccine against Marek's disease

A bivalent vaccine was prepared by combining inactivated Marek's disease virus and turkey herpesvirus. The efficacy of this vaccine, compared to turkey herpesvirus and inactivated Marek's disease virus separately, was studied in unsexed White Leghorn chicks which were vaccinated at one day old and then challenged at 21 days old with fowl blood infected with virulent Marek's disease virus. The bivalent vaccine appreciably delayed mortality resulting from Marek's disease and elicited the highest protective efficacy as judged on the basis of Marek's disease-specific mortality and percentage occurrence of lesions. The occurrence, extent and severity of gross lymphomas and microscopic lymphoproliferative lesions in various organs of the bivalent vaccinated birds were less than in the other challenged groups. In addition, the level of viraemia remained consistently and significantly lower in the bivalent vaccinated birds.     

Influence of a 12.5 per cent rapeseed diet and an avian reovirus on the production of leg abnormalities in male broiler chickens

The incidence of different forms of leg abnormality were recorded in reovirus (S1133) infected and control male broiler chickens fed on a normal commercial diet or one of similar nutritive value containing 12.5 per cent rapeseed meal. Regular serological examination showed that birds remained free from Mycoplasma gallisepticum and M synoviae infection throughout the 10 week period of investigation. Precipitating antibodies to the reovirus were detected in 90 per cent of the infected birds between the third and 10th week after infection. Carotene levels in rapeseed fed groups showed no significant differences between reovirus infected and control birds or between birds with or without clinical signs of leg abnormality. The most frequent and severe leg abnormalities were present in the infected birds fed on the rapeseed diet, followed by those fed on the normal commercial diet. There was a highly significant difference (P less than 0.01) between the number of birds with leg abnormalities in each of these groups and their corresponding control groups. The lesions which were mainly responsible for these differences were tenosynovitis and enlarged hocks. Oral infection with reovirus did not appear to make the birds more susceptible to other types of leg abnormality, although the severest lesions of dyschondroplasia were seen in birds which had been exposed to the dual effects of reovirus and rapeseed diet.     

Biological suppression of aflatoxicosis in Japanese quail (Coturnix coturnix japonica) by dietary addition of yeast (Saccharomyces cerevisiae).

The amelioration of aflatoxicosis in Japanese quails was examined by the dietary addition of live yeast (Saccharomyces cerevisiae; SCE). Yeast incorporated into the diet at 1 g kg(-1) was evaluated for its ability to reduce the deleterious effects of 2.5 mg total aflatoxin (AF; 82.30 per cent AFB1, 2.06 per cent AFB2, 7.68 per cent AFG1 and 7.96 per cent AFG2) kg(-1)diet on growing Japanese quail chicks from 10 days to 45 days of age. Forty 10-day-old Japanese quail chicks were assigned to 2x2 factorial arrangement of treatments (control, AF, SCE, AF plus SCE) each consisting of 10 quails. The performances of birds were evaluated. The AF treatment significantly and dramatically decreased food consumption and body-weight gain from the first week onwards. The significant adverse effect of AF on the food conversion ratio was also determined from week 1 to the end of the experiments. The addition of SCE to the AF -containing diet significantly reduced these deleterious effects of AF on food consumption, body-weight gain and food conversion ratio. Compared to controls, the cumulative body weight gain was reduced by 37 per cent among the quails consuming AF without SCE, but increased 15 per cent for the birds fed AF plus SCE. Interestingly, the single inclusion of SCE to the AF-free diet provided significant improvements in all the investigated growth performances of birds (approximately 40 per cent) compared to controls.     

Effects of aflatoxin B1 and fumonisin B1 on body weight, antibody titres and histology of broiler chicks

1. Our objective was to evaluate the toxic effects of aflatoxin B1 (AFB1) and fumonisin B1 (FB1), administered singly or in combination to broilers. 2. Feeds were prepared with concentrations equal to 0, 50 and 200 microg AFB1/kg, and/or 0, 50 and 200 mg FB1/kg, and offered to broiler chicks from 8 to 41 d of age. The experimental design was totally randomised, in a 3 x 3 factorial arrangement with 9 treatments and 12 birds per treatment. Animals were vaccinated against Newcastle disease on d 14 of life and killed at 41 d. 3. Compared with controls, all mycotoxin-treated groups at 41 d had lower body weight and weight gain, and higher relative heart weight. The relative weight of the liver increased only in birds fed diets containing 200 mg FB1, singly or in combination with AFB1. 4. At 35 d, all groups receiving mycotoxin-treated rations had reduced geometrical mean antibody titres, with birds from groups fed combinations of AFB1 and FB1/kg having even lower values, when compared to the other groups. 5. Histological changes were observed only in liver from birds fed mycotoxin-contaminated rations, and in kidneys of birds fed the diet containing 200 microg AFB1 and 200 mg FB1/kg. Main alterations included vacuolar degeneration and cell proliferation of bile ducts in the liver, and hydropic degeneration in renal tubules in the kidneys. 6. We concluded that AFB1 and FB1 in combination have primarily additive effects on body weight, liver structure and immunological response of broilers at the concentrations used.     

An Outbreak of Marek's Disease in Chickens in Central Ethiopia

A study was conducted on an outbreak of Marek's disease in a commercial poultry farm containing 8500 chickens in central Ethiopia. On repeated visits, farm and flock history was collected, sick birds were examined and clinical signs and daily mortality were recorded. A total of 80 (27 sick and 53 dead) birds 12-22 weeks old, were collected, autopsied and examined. The mortality rate was 46% for the first 14 weeks of the outbreak. Acute and chronic (classical) forms of the disease, the respective occurrence of which varied significantly (p<0.01) in young (14.6% vs 85.4%) and adults (48.7% vs 51.31%) were manifested. All the autopsied birds had gross and microscopic lesions indicative of Marek's disease in the peripheral nerve(s) and/or visceral organs. Lesions involving peripheral nerves and visceral lymphomas were recorded mainly in adults (28/35, 80%) and young birds (34/45, 75%), respectively. These differences in the two age groups were statistically significant (p<0.01). Young birds seem to be highly susceptible to the acute disease. Poor management, overstocking and lack of vaccination might have favoured the outbreak. Marek's disease causes considerable economic loss and is a major threat to poultry production in Ethiopia. This report emphasizes that Marek's disease should be considered as a disease of economic significance in chicken production in Ethiopia and warrants due attention.     

Elevated bile acids in the plasma of laying hens fed rapeseed meal

A simple procedure was developed for the estimation of bile acid taurine conjugates in fowl plasma. Laying hens fed a diet containing rapeseed meal (RSM) (400 g kg-1) for 12 weeks had higher bile acid levels (154 mumol litre-1) than hens fed a control soyabean diet (116 mumol litre-1) (P less than 0.01). The incidence of liver haemorrhages was higher (34.8 per cent) in RSM-fed hens than in controls (21 per cent), but the severity of the lesions did not correlate with the bile acid concentration in affected birds. Histological examination of sections from livers of RSM-fed birds did not reveal significant hepatocyte degeneration outside the immediate vicinity of the haemorrhage. Canalicular bile plugs were never seen. The incidence of liver haemorrhages (13 per cent) and plasma bile acids (85 mumol litre-1) were lower in hens fed a diet containing beta-aminopropionitrile (0.5 g kg-1), a known lathyrogen. Acute treatment of hens with the hepatotoxin alpha-naphthyl isothiocyanate over four days induced necrosis of hepatocytes and resulted in elevated bile acid concentrations (262 mumol litre-1) compared with controls (73 mumol litre-1) given arachis oil. It was concluded that laying hens fed high levels of RSM develop cholestasis but the toxic principle is not known.     

Effect of dietary resveratrol in ameliorating aflatoxin B1‐induced changes in broiler birds

Consumption of aflatoxin B1 (AFB1) contaminated feed by poultry affects the health of broiler birds causing severe economic losses. The use of phytochemicals is a safe, effective, alternative and practical approach to combat the toxic effect of AF in broilers. Resveratrol, a polyphenol derived from red grapes, berries and peanuts, exerts anti‐inflammatory, antioxidant and immunomodulatory effects. Our study was aimed at evaluating the possible protective effects of resveratrol against the adverse effects of AFB1 in broiler birds. A feeding trial of 42 days of duration was undertaken in a completely randomized design with five dietary treatments: G1‐AFB1(1.0 ppm); G2‐CTR (basal diet alone); G3‐AFB1(1.0 ppm)+Resv 0.5%; G4‐AFB1(1.0 ppm)+Resv 1%; and G5‐Resv 1%. Gain in body weight (BWG) and feed intake (FI) was observed to be highest (p < 0.05) in the AFB1 birds followed by the control group. Feed conversion ratio was lowest in G2‐CTR birds and failed to record any significant variation (p > 0.05) between groups as well as within groups. Birds fed resveratrol at both 0.5% and 1.0% levels in combination with AFB1 as well as alone along with basal diet had lower BWG and FI between the fourth and fifth week and also at the fifth week (p < 0.05). No variation (p > 0.05) was obtained in the FCR of AFB1 and resveratrol group of broiler birds. AFB1 feeding significantly increased the activities of aspartate‐(AST) and alanine‐(ALT) amino transferase, superoxide dismutase (SOD) and catalase (CAT) activities (p < 0.05) but lowered glucose, cholesterol and triglyceride levels in serum. Supplementation of resveratrol helped in increasing the activities of the oxidative enzymes and in improving the plasma total antioxidant capacity (TAOC) and total protein (TP) significantly (p < 0.05) and protein values. The livers of AFB1 group showed degeneration of hepatocytes, bile duct hyperplasia and microgranuloma formation. In resveratrol supplemented birds, the severity and degree of the liver lesions was far less. Apoptotic proteins failed to show any variation in expression between AFB1, control and resveratrol group of birds. The inclusion of resveratrol in broiler diets enhanced antioxidant status of birds indicating the protective effect of resveratrol against AFB1‐induced toxicity. So, we advice use of resveratrol as a feed additive to control aflatoxicosis in poultry farms.     

Measurements of footpad dermatitis in broiler chickens at processing plants

A four-point photographic scale was developed to score the severity of lesions of footpad dermatitis (FPD) in broiler chickens. There was a linear relationship between the square root of the relative area of the lesions and their scores, and good agreement between different assessors using the scale. The scale was used to assess samples of 100 birds from each of 190 flocks slaughtered at two uk processing plants in 2002 and 2003; 12 of the flocks (6.3 per cent) had no lesions, but the others had lesions of different prevalences and severity. The maximum proportion of affected birds in a flock was 92 per cent. In the 178 affected flocks, 84.0 per cent of the birds had no lesions and 16.0 per cent had some evidence of FPD. The overall unweighted prevalence of birds with FPD in all 190 flocks sampled was 18.1 per cent; 10.2 per cent had only small lesions, on average equivalent in area to 2.1 per cent of the total area of the foot, 6.2 per cent had lesions on average equivalent to 6.6 per cent of the area of the foot, and 1.7 per cent had lesions on average equivalent to 21.5 per cent of the area of the foot. There were differences between the two plants in the overall prevalence and severity of FPD, but this may have been due to the fact that the plants were sampled at different times of the year.     

Trials with Marek's disease vaccines prepared from a turkey herpes virus and an attenuated Marek's disease virus.

In field trials involving over 224,000 fowls in 11 different commercial flocks, three vaccines were used, namely a freeze-dried vaccine prepared from a turkey herpes virus, a cell-associated virus vaccine prepared from the same isolate and a cell-associated vaccine prepared from a strain of Marek's disease virus isolated from a fowl. The mortality from Marek's disease was reduced by 80 per cent to 95 per cent in birds vaccinated with the freeze-dried vaccine. Cell associated vaccines gave slightly less protection.     

Pathogenesis of a Marek's disease virus mutant lacking vIL-8 in resistant and susceptible chickens

A homologue of interleukin-8, viral interleukin-8 (vIL-8) has been identified in the genome of Marek's disease virus (MDV). This protein attracts peripheral blood mononuclear cells in vitro although its role in the pathogenesis of Marek's disease (MD) is not known. P chickens, genetically susceptible to MD, and N chickens, genetically resistant to the disease, were inoculated with either RB1B MDVor RB1BvIL-8smGFP, a vIL8 knockout RB1B MDV, to assess the role of vIL8 in the pathogenesis of MD. The tumor incidence was highest in the P birds given the RBIB virus, where the incidence was 100%. Tumor incidence in N birds given RB1B was 41.5%. Thirty-one percent of the P birds given RB1BvIL-8smGFP developed tumors, and no N bird given RB1BvIL-8smGFP developed tumors. Histologically, the tumors from RB1B-inoculated birds were larger and more invasive and had a more homogeneous cellular composition than those from RB1BvIL-8smGFP-inoculated birds, which were best described as microtumors. These microtumors did not obliterate the normal architecture of the tissues, and in contrast to the RBIB tumors, moderate numbers of heterophils were admixed with the proliferating lymphocytes. Susceptible birds receiving RB1B had the highest viral titers throughout the study, followed by the resistant birds inoculated with RB1B. P and N birds receiving RB1BvIL-8smGFP virus had consistently lower levels of viremia than their RB1B-inoculated counterparts although virus could be recovered from the birds during all stages of MD. In addition, the RB1BvIL-8smGFP virus was detected in birds held in contact with the inoculated group, although no tumors developed in contact control birds. This result indicates that RB1BvIL-8smGFP replicates in vivo but not as well as RB1B and that vIL8 is not essential for the completion of the pathogenesis of MD.     

AUS in the prevention of Marek's disease

Aminoureidosulfone (AUS) was used as a feed additive to prevent mortality in Marek's disease (MD)-infected chickens in the laboratory. Chicks infected with MD virus (5000 plaque-forming units) at 1 day of age were given AUS in the feed from 1 day of age until the experiment was terminated. AUS, at all concentrations tested, reduced mortality due to Marek's disease. Chickens receiving AUS at the 0.002% level had a 4% mortality rate, those receiving 0.005% had 9% mortality, and those receiving 0.01% had 2% mortality; mortality rates in the respective controls were 44%, 49%, and 50%. However, lesion reduction in surviving chicks was minimal. When AUS was withdrawn from the feed, MD-induced mortality increased within two weeks; average body weight decreased also.     

Toxicity in utility pigeons caused by the coccidiostat dinitolmide

Utility pigeons on 3 farms were affected by a severe neurological disturbance manifested by fine tremors, rolling gait and incoordination. Affected birds had necrosis of the Purkinje cells of the cerebellar cortex. The birds from the 3 farms had been fed a pelleted diet obtained from a single mix of feed prepared by a stockfeed manufacturer. When feed obtained from the farms was given to utility pigeons under controlled conditions at the laboratory, they suffered the same clinical signs and lesions as seen in birds from the farms. Cross-bred cockerels were not affected when given this feed from day-old to 6 weeks of age. Samples of the feed contained 185 to 226 ppm of the coccidiostat dinitolmide. Utility pigeons given a prepared diet containing a similar level (234 ppm) of dinitolmide developed an identical condition after 3 to 4 weeks feeding. Laying hens were not affected by this feed. Dimetridazole, which was also present in some of the original feed samples, did not exacerbate the condition when included in the diet at a rate of 233 ppm. Production of squabs from the affected farms was dramatically reduced, and many of the breeder had to be culled because of the long-standing neurological disease.     

Herpes virus of turkey vaccine: viraemias in field flocks and in experimental chickens

In a field survey of viraemias due to vaccination of chickens with herpes virus of turkey, variation was encountered in titres and percentages of birds viraemic. The incidence of viraemias was much lower in sick than in healthy birds in flocks undergoing mortality from Marek's disease. In a concurrent experiment the same strain of chicken and the same commercial vaccine were used as in the field flocks affected with Marek's disease. A high incidence of viraemia and 84.6 per cent protection against Marek's disease were obtained with single vaccination at one day of age. Revaccination at 21 days of age produced no measurable benefits in the same experiment.     

Low-dose immunization of northern bobwhites (Colinus virginianus) with Eimeria lettyae provides protection against a high-dose challenge

To determine whether northern bobwhite quail (Colinus virginianus) could be immunized against Eimeria lettyae by a low-dose inoculation of oocysts, we inoculated 30 birds each with either 100 or 1000 oocysts at 2 days of age (given orally by pipette). Four weeks after immunization, the immunized birds and unimmunized controls were challenged with 1 x 10(6) E. lettyae oocysts. Eight days after challenge, birds were killed and weighed, and their intestines examined for gross lesions. Effectiveness of the immunization was measured by analyzing weight gain, intestinal lesions, severity of diarrhea, feed conversion ratio, and oocyst production. After challenge, birds immunized with 100 or 1000 oocysts gained an average of 33.3 g and 28.9 g, respectively, whereas unimmunized challenged birds gained an average of 11.5 g. Immunized quail produced approximately 99.7% fewer oocysts, had minimal gross intestinal and cecal lesions, had minimal diarrhea, and had a 50% lower feed conversion ratio compared to unimmunized challenged controls. These findings indicate that vaccination is a viable option for controlling coccidiosis in quail and that further research into vaccination is warranted.     

A comparative study of energy utilisation by the laying hen from diets containing a high proportion of fat and diets made up mainly from carbohydrate sources

An experiment was carried out in which laying hens were fed diets containing about 30 per cent tallow at three protein levels. Productive performances of hens on these diets were compared with those of hens fed either a diet containing 15 per cent arachis oil, a diet containing 15 per cent sucrose or a conventional cereal‐based control diet.

It was found that the best performance was obtained with hens fed the control diet. Gross energetic efficiency of egg production was slightly lower in the birds fed the diets containing arachis or sucrose. It appeared that the lower efficiency was due to the higher mean body weight of birds on these diets. Egg size was significantly increased by feeding the diet containing arachis oil.

Performance of hens given diets containing tallow was unsatisfactory. For each diet egg production was significantly less than that recorded for the control diet and the gross energetic efficiency of egg production was much lower than that on the control diet.     

Control of salmonella infections in broiler chickens by the acid treatment of their feed

In three experiments a solution of formic acid (Bioadd) was added to feed 'naturally' contaminated with salmonellas. In two of them no salmonella infections were demonstrated in broiler chickens given feed containing 0.6 per cent (w/w) of the formic acid solution for seven weeks and in the third the infection rate was reduced considerably. In four other experiments the feed was contaminated artificially with between 1 and 47 Salmonella kedougou/g and a second product (BPO12), consisting of a mixture of formic acid and propionic acid, was evaluated. When it was added at 0.5 to 0.68 per cent (w/w) only one of 30 groups of 10 to 12 birds became infected with S kedougou by two weeks of age, compared with 22 of 27 control groups. The treatment of the feed with BPO12 one week before the addition of the salmonellas prevented the establishment of infection in chicks given the treated feed, indicating that acid treatment will provide protection against subsequent recontamination of the feed with the organisms. The isolation rate of S kedougou from artificially contaminated feed treated with BPO12 was reduced only slightly but the feed was apparently 'safe' for the birds which consumed it.     

Two-year study of bovine hepatic abscessation in 10 abattoirs in County Cork, Ireland

The livers from 6337, 12- to 16-month-old heifers slaughtered in 10 domestic abattoirs over a period of two years were examined; 368 (5.8 per cent) had gross lesions, of which 120 (1.9 per cent) had abscesses, 74 (1.17 per cent) had only scarring, and 44 (0.7 per cent) had telangiectasis (so-called 'sawdust' liver). Of the 120 livers in which abscesses were detected, 53 (44 per cent) had a single large abscess (>4 cm diameter), 44 (36.6 per cent) had a single small abscess (<4 cm), and 23 (19 per cent) had more than two abscesses; in 20 of them (16.6 per cent) the abscesses were resolving, and in 10 (8.3 per cent) the abscesses were ruptured. Forty-three (35.8 per cent) of the livers with abscesses had adhesions to the diaphragm and diaphragmatic lung lobes, three (2.5 per cent) had adhesions to other abdominal organs, 12 (10 per cent) also had scarring and two (1.7 per cent) also had lesions due to liver fluke. There was no significant association between the liver fluke lesions and the abscesses. In 46 (38.3 per cent) of the livers the abscesses were located in the mid-dorsal diaphragmatic or dorsocranial area of the liver; 28 (23.3 per cent) were adjacent to the posterior vena cava and could as a result have caused thromboembolic disease. Clinical signs attributable to the abscesses were observed in only one animal.     

Abattoir survey of bovine kidney disease

A survey of the prevalence and type of renal disease was carried out at a Dublin abattoir in 1979-80. Of 4166 cattle surveyed, 173 (4.2 per cent) had kidneys rejected for gross abnormalities. The rejection rate was 7.7, 1.7, 2.2 and 28 per cent for cows, bullocks, heifers and bulls, respectively. The most common reason for rejection was focal interstitial nephritis (60.1 per cent of rejected kidneys). Other lesions included cysts (26.0 per cent), pigmentation (6.4 per cent), pyelonephritis (3.5 per cent), amyloidosis (2.9 per cent), glomerulonephritis (0.6 per cent), renal atrophy (0.6 per cent) and agonal haemorrhage.