Monensin toxicity in turkey breeder hens

High mortality in two flocks of 1900 turkey breeder hens accidentally fed 280 g monensin/ton of complete feed is described. Mortality attributed to the poisoning was 76% in flock 1 and 18% in flock 2. Clinically, turkeys were found dead, exhibited respiratory distress with wings extended laterally, had fine tremors, or showed posterior paresis and inability to rise. The most striking finding at necropsy was the almost complete absence of gross lesions. Some turkeys had severely congested lungs; however, many did not. A few birds had pale streaks within the adductor muscles of the legs. Microscopic lesions included myofiber degeneration and necrosis of skeletal and myocardial muscle. Serum phosphorus, lactate dehydrogenase, and creatine phosphokinase were markedly elevated, whereas potassium, chloride, and calcium values were lowered.     

Alterations in levels of various host antioxidant factors in turkey knockdown syndrome

Five components (selenium, glutathione peroxidase, copper, superoxide dismutase, and vitamin E) of the antioxidant system of turkey poults were examined to determine if they play any role in the knockdown (KD) syndrome. All flocks were provided with feed formulated to contain monensin at 54-60 g/ton. Flock data were analyzed as a case-control study with three treatment groups (KD-affected and unaffected turkey poults from a KD flock and poults from an unaffected flock [control]). Affected turkey poults had lower (P < 0.001) serum vitamin E levels compared with unaffected poults from KD flocks or poults from unaffected flocks. No significant differences were observed for the other parameters evaluated but there was a trend towards lower copper and superoxide dismutase values in affected birds. It appears that serum vitamin E concentrations in turkey poults may play a significant role in susceptibility to or protection against KD syndrome. Other components of the antioxidant system may also be involved, and complex interactions among several body systems may be critical.     

Interaction of ionophore and vitamin E in knockdown syndrome of turkeys

Monensin and vitamin E concentrations, as well as histopathology of skeletal muscles and myocardium, were evaluated in broad-breasted white turkeys kept in commercial facilities. Turkeys with knockdown syndrome had myopathy of skeletal muscles, but no lesions in the myocardium. Generally, concentration of monensin in serum was highest in turkeys diagnosed with knockdown syndrome given more than 90 mg/kg of monensin in the diet, followed by turkeys diagnosed with knockdown syndrome given <90 mg/kg of monensin in the diet, healthy turkeys fed a diet that contained <90 mg/kg of monensin, and finally healthy turkeys fed a diet free of monensin (not detectable). However, the concentration of monensin was highly variable within each group, and the median was lower than the average. Vitamin E concentrations in the livers varied from low-normal to below normal and were statistically higher in healthy turkeys fed a diet free of monensin than in the livers of birds from the 3 groups exposed to monensin. This suggests that the concentration of monensin in serum positively correlates to the severity of clinical signs and pathology and to the amount of monensin in the feed. Although the methodology developed to detect serum monensin concentrations is beneficial and accurate for case investigations, it is recommended that several samples from each flock be evaluated because of variation within a flock. The current study also suggests that monensin in the feed could induce lower concentrations of vitamin E in the liver of turkeys and can predispose the turkeys to knockdown syndrome.     

Neoplasms in the oviducts of turkeys

The reproductive tracts of turkey breeder hens from five flocks were examined grossly and histologically. Hens from one flock had a normal reproductive history, but hens from the four other flocks had poor records in both egg production and hatchability. Nodular growths occurred in the oviducts of birds in all five flocks. The incidence of lesions varied from flock to flock and from bird to bird. In four flocks, lesions were small and consisted of areas of dysplasia with adenomatous change. Histologically, the lesions in some birds in the fifth flock were adenocarcinomas. No metastases were observed.     

Skeletal muscle lesions in turkeys associated with the feeding of monensin

The feeding of monensin as a coccidiostat in three separate flocks of turkeys was associated with increased mortality, posterior paresis, and a skeletal muscle myopathy. Mortality attributed to the disease was 1.65%, 1.86%, and 4.80% in the three flocks. Samples of monensin-supplemented feed fed to the flocks when showing clinical signs contained 88, 85, and 106 g/ton of complete feed, respectively. Clinically, the turkeys showed posterior paresis, inability to rise, incoordination, reluctance to move, and leg trembling and weakness. Necropsy findings included consistent lesions of pallor within the type I muscles of the legs, wings, and backs. Microscopic lesions included myofiber degeneration and necrosis with massive cellular proliferation interpreted as sarcolemmal nuclei proliferation. Occasional axonal degeneration with loss of axons was present in peripheral nerves embedded in the damaged musculature. In the youngest flock, multifocal areas of acute coagulation necrosis of the myocardium were also present. These outbreaks occurred following intake of monensin in the complete feed at levels considered therapeutic; however, no associated predisposing clinical condition, drug/toxin interaction, or excessive monensin levels in the feed could be demonstrated.     

Egg production drops in breeder turkeys associated with western equine encephalitis virus infection

Egg production drops associated with western equine encephalitis (WEE) virus infection occurred in three turkey breeder flocks in California during summer 1993 and again in one flock the following year. Egg production losses totaled 8.76%, 9.57%, 9.71%, and 10.12% and were accompanied by an increase in small white-shelled and shell-less eggs. The outbreaks coincided with peak WEE virus activity in the state on the basis of statistics compiled by the California Department of Health Services on seroconversion rates in sentinel chicken flocks. Paired serum samples taken 2-3 wk apart showed increased titers to WEE between acute and convalescent sera in turkeys from three affected flocks. Convalescent sera were not available for testing from the fourth flock. WEE virus was isolated from one breeder hen submitted to the diagnostic laboratory during the early stages of the outbreak.     

Clinical outbreak of Bordetella avium infection in two turkey breeder flocks

An acute upper respiratory disease was observed in two broad-breasted white (BBW) turkey primary breeder flocks. Associated clinical signs included sneezing, depression, and a deep dry cough originating from large conducting airways. Morbidity reached approximately 15-20% of the hens in an affected house. None of the turkeys died, and total feed consumption was not affected. A minimal effect upon egg production was noticed. Sera from an acutely affected flock exhibited a marked rise in titer to Bordetella avium compared with preinfection sera samples. In Case 1, B. avium was isolated in pure culture from affected birds. In Case 2, B. avium was diagnosed by serological results and clinical signs; bacteriological examination was not attempted. The findings presented here are consistent with an acute clinical outbreak of B. avium-induced turkey rhinotracheitis (turkey coryza) in BBW turkey breeder hens.     

Characteristics of fowl cholera outbreaks in turkeys in Georgia in 1986

Information was gathered from 64 cases of fowl cholera (FC) in turkey flocks through diagnostic case records, flock records, and telephone and mail surveys. Forty-five cases came from flocks of commercial turkeys, of which 15 were presented twice, and four came from mature breeder flocks. The prevalence of FC was 18.0% of commercial flocks and 14.7% of breeder flocks at risk. The average age at first diagnosis of FC was 90 days in commercial turkey flocks and 32 weeks 5 days in breeder flocks. Acute mortality was the most common presenting complaint, with a 0.37% average mortality in commercial flocks on the day of first presentation, 0.80% in commercial flocks presented a second time, and 0.43% in breeder flocks. Pasteurella multocida was cultured from 69.8% of the 361 tissue samples submitted from these cases. Novobiocin, penicillin, and chlortetracycline (CTC) had the greatest in vitro activity against isolates. Serotype 3-cross-4 was found in all 18 commercial flocks from which isolates were typed. All breeder flocks and 88.6% of commercial flocks were vaccinated before disease onset. Flocks were treated for an average of 14.3 days, most commonly with high levels of sulfadimethoxine and/or CTC. Body weights of affected birds were comparable to those of birds in unaffected flocks, but mortality and feed efficiency were worse.     

Isolation of Salmonella Organisms from Commercial Layer Houses Where the Flocks Were Molted with a Wheat Bran Diet

To develop an alternative method to feed withdrawal for molting layers, 2 flocks consisting of approximately 26,000 commercial laying hens each at 478 (68 wk, flock 1) and 466 (67 wk, flock 2) d of age were reared in an environmentally controlled windowless house and were fed wheat bran (WB) diet. Flock 1 hens were fed WB for 25 d, and flock 2 hens were fed WB for 21 d and then fed a mixture of WB and layer feed (1:1, wt:wt) for the last 4 d of the treatment. After that, the birds in both flocks were fed a normal layer feed. The photoperiod was reduced from 16 to 9 h in both flocks. Most of the birds in both flocks ceased egg production by 10 to 15 d of feeding the WB diets. Egg production in flock 1 gradually increased to 11.4% by 31 to 40 d and 71.4% by 41 to 50 d of the treatment, whereas the egg production in flock 2 hens lagged behind by almost 10 d. The mean egg production from 61 to 140 d exceeded 86% in both flocks. The houses in the farm were naturally contaminated with several serovars of Salmonella, not Enteriditis or Typhimurium. In both flocks with the WB treatment, no marked increase in Salmonella isolation from environmental samples was observed postmolt relative to premolt levels. The study demonstrated that feeding hens WB could be successfully used as an alternative to feed withdrawal to force-rest aging hens while not exacerbating a Salmonella problem in a commercial egg-production setting.     

The effect of a direct-fed microbial (Primalac) on turkey live performance

Two pen trials and 2 field trials were conducted to determine whether a direct-fed microbial (DFM; Primalac) was effective in improving turkey productive performance. In the pen trials, typical turkey diets were formulated with and without Primalac. All feed was provided by a commercial feed mill. In trial 1, Large White male turkey poults were placed in 48 pens (18 birds/pen, 24 pens/treatment) on the day of hatch and were reared to 20 wk. In trial 2, Large White female turkey poults were placed in 48 pens (30 birds/pen, 24 pens/treatment) on the day of hatch and were reared to 18 wk. Cumulative FCR was significantly improved for birds fed DFM feed compared with birds fed control feed at 20 wk in trial 1 and at 8 wk in trial 2. Body weight was significantly greater for birds fed DFM feed compared with birds fed the control feed through 12 wk in both trials. In 2 field trials, 2 brooder houses and 4 grow-out houses were paired on each farm (4 brooder houses and 8 grow-out houses total). All birds received the same feed provided by the integrator. The DFM was provided in the water from placement to market in 1 brooder house and in the 2 matching grow-out houses. Breeder flocks were equally represented in both brooder houses within each trial. Approximately 12,000 male poults were placed in each brooder house and were transferred to 2 grow-out houses at 5 wk. Although no statistical analyses were computed for the field trials, there was a nominal improvement in performance associated with the DFM: mean livability was increased by 3.5%, mean BW was increased by 0.9 kg (2 lb), mean total weight removed from the farms was increased by 13,706 kg (30,153 lb), mean FCR was improved by 0.165, and cost of production was reduced by $0.0195/kg ($0.043/lb) of BW by the DFM. In conclusion, the DFM product (Primalac) used in these studies was effective in improving turkey live performance.     

Clinical signs and mortality caused by Ornithobacterium rhinotracheale in turkey flocks

Upper respiratory tract disease (manifesting itself in rhinitis, tracheitis and conjunctivitis) and mortality associated with Ornithobacterium rhinotracheale infection were observed in four flocks of 2- to 3-week-old turkeys. In a 15- to 16-week-old turkey flock bilateral catarrhal-croupous pneumonia was found in the dead birds. In a further 5-week-old flock and in three 16- to 20-week-old turkey flocks mortality was preceded by nervous signs (motor disturbances, recumbency, abnormal carriage of the head) and was found to be associated with fibrinopurulent inflammation of the cranial bones and meningitis. The bacterium O. rhinotracheale was isolated from the affected organs in the different disease conditions. The isolated strains did not differ markedly in cultural, morphological and biochemical properties. This is the first report of a turkey disease manifesting itself in nervous signs associated with O. rhinotracheale infection.     

Monitoring the Immune Status of Broilers Against Reoviruses Using Challenge and Serologic Data

Reoviruses are an important cause of suboptimum performance in commercial broilers worldwide. Integrators use the enzyme-linked immunosorbent assay against the S1133 antigen for monitoring serum of breeders for indicating pullet vaccine success. However, without correlating serology to reovirus challenge, it is difficult to determine whether titers reflect protective immunity. We developed a broiler challenge test against 2 common reovirus isolates (2408 and S1133) to evaluate the efficacy of reovirus pullet vaccine programs. Two reovirus serologic and challenge studies were undertaken using chicks from broiler integrators from the southeastern United States. Breeder flocks, from which the chicks were obtained, received at least 1 live and 2 inactivated reovirus vaccines during their pullet phase. One-day-old progeny were collected from 6 breeder flocks. At 1 d of age, 20 chicks from each broiler flock were bled, and serum was analyzed for antibodies. At 3 to 4 d of age, 20 progeny per flock were challenged with the 2408 reovirus by intratracheal route. At 10 to 14 d of age, another 20 birds per flock were challenged with the S1133 reovirus by footpad. Twenty birds per flock were used as nonchallenged controls. At 3 wk of age, all birds were killed and weighed. Percentage of protection was calculated for each flock based on the absence of gross lesions. Flocks with at least 50% protection were considered well protected. Most flocks were well protected against both viruses. The percentage of protection correlated with day-old enzyme-linked immunosorbent assay titers. Chicks from younger hens had higher titers and the best protection against challenge. Producers, whose hen flocks were monitored herein, were doing a good job of immunizing pullets against reovirus. They are now using reovirus progeny challenge studies along with breeder antibody titers to determine vaccination success of their pullets.     

Effects of poult source on turkey production parameters

Flock records from a commercial turkey company were analyzed to determine if poult source affected flock performance. Comparisons were made between flocks supplied by two hatcheries (X and Y) reared on the same farms and among flocks reared on different farms. Flocks from hatchery X had significantly better livability and feed-conversion ratios than flocks from hatchery Y. Although not statistically significant, flocks from hatchery X tended to grade better at processing (percent grade A) and have lower condemnations than flocks from hatchery Y. Season significantly affected livability and feed conversion of all flocks regardless of hatchery source.     

The use of the drag-swab technique and improved selective plating media in the recovery of Salmonella arizona (7:1,7,8) from turkey breeder hens

The litter of six turkey hen flocks was sampled using the drag-swab technique to determine the effectiveness of this method in detecting Salmonella arizona. Two flocks with the lowest biosecurity standards were found to have S. arizona. Results showed that the drag-swab technique can provide a sensitive and cost-effective measure of S. arizona infection within a flock.     

A national survey to estimate the prevalence of Salmonella species among Canadian registered commercial turkey flocks.

In 1990-1991, a national survey was conducted to estimate the prevalence of Salmonella species among Canadian commercial turkey flocks. Two hundred and seventy flocks were randomly selected across Canada. The proportion sampled from each province was selected according to each province's share of the national turkey market. Samples, consisting of 12 pooled litter and four pooled dust samples, were used to determine the Salmonella status of the environment of each flock. Additionally, a one kilogram sample of feed was taken from each flock premise. Salmonella was recovered from environmental samples in 234/270 (86.7%) of flocks and from feed samples in 26/266 (9.8%) of flocks. Forty-eight different Salmonella serovars were isolated from flock environmental samples. The most prevalent serovars were S. anatum, S. hadar, S. agona, S. heidelberg and S. saintpaul which were isolated from 53/270 (19.6%), 49/270 (18.1%), 49/270 (18.1%), 42/270 (15.6%) and 34/270 (12.6%) flocks, respectively.     

Clinical signs and pathology of accidental monensin poisoning in sheep

The clinical signs and postmortem findings in sheep from two flocks accidentally poisoned with monensin are described. Clinical signs began within 24 hours of exposure to monensin. In the acute stages they consisted of lethargy, stiffness, muscular weakness, a stilted gait and recumbency. Feed refusal was seen in one flock but not in the second. Subacute to chronic clinical signs were decreased muscle volume of the rump and thigh. When forced to run, chronically affected sheep had a stilted, stiff legged, rocking horse gait.

Gross postmortem changes were not always visible. Where visible, they affected skeletal muscles and consisted of pale streaking, with atrophy in the chronic stages. Lesions were most severe in muscles of the rump and hind limbs. Microscopically myofiber swelling and hyalinization were seen with interstitial mononuclear cell reaction and extensive sarcoplasmic mineralization in some cases. Chronic lesions consisted of fibrosis and myofiber atrophy. In lambs less than one month old, diffuse gastrointestinal hemorrhage was the only finding.

     

Vitamin A deficiency in turkey poults.

Vitamin A deficiency was diagnosed in a commercial flock of 13,000 4-6-week-old turkey poults in the summer of 2004. The birds were initially submitted for examination because of a 3% increase in the reported daily mortality of the flock. Clinically, affected birds had stunted growth and ruffled feathers, showed signs of incoordination, and were depressed. At necropsy, pale white pseudomembranous to mucoid material was observed on the mucosal surface of the tongue, oral cavity, portions of the esophagus, and the crop of some birds. Histologically, there was squamous metaplasia of the mucosal epithelium of the oral mucosa, esophagus, sinuses, nasal glands, bronchi, proventriculus, and the bursa of Fabricius. Vitamin A was not detected in the feed sample at a detection limit of 0.5 mg/kg. Serum vitamin A concentrations in 7 birds were very low and ranged from 0.05 to 0.1 mg/L. Vitamin A concentrations in livers were extremely low (0.1 mg/kg wet weight, 1/7 poults) or undetectable (< 0.1 mg/kg wet weight, 6/7 poults). A diagnosis of vitamin A deficiency was made based on gross and microscopic lesions and vitamin A concentrations in serum, liver, and feed. To the authors' knowledge, this is the first documented case of vitamin A deficiency in poults submitted from a commercial meat turkey producer comparatively depicting the gross and microscopic lesions with those found in other species of birds and mammals.     

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 (<150 m³/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.