Presence and recovery of Ascaridia dissimilis ova on the external shell surface of turkey eggs.

Ascaridia dissimilis, a roundworm in turkeys, has been noted with increased frequency in commercial turkeys. Because infected turkeys can shed A. dissimilis ova in their feces, the potential exists for the external surface of turkey eggshells to be contaminated with A. dissimilis ova. The objectives of this study were to determine the presence of and recover A. dissimilis ova on the external surface of the turkey egg. In Experiment 1, turkey eggs were collected from naturally infected flocks, and eggs were processed by a sodium hydroxide procedure to recover any A. dissimilis ova on the external egg surface. In Experiment 2, the external surface of the turkey eggs was inoculated with 116 A. dissimilis ova/g feces, and eggshells were sampled every 3 days until 28 days of incubation to assess the recovery of A. dissimilis ova from the eggshell. In Experiment 1, of the 36 eggs examined from a flock naturally infected with A. dissimilis, one egg had an A. dissimilis ovum on its external eggshell surface. Experiment 2 demonstrated that A. dissimilis ova can be recovered from the external egg surface after a 28-day incubation period in the incubator. Ova recovery declined from an average of 62 A. dissimilis ova/turkey egg at day 2 of incubation to an average of 3 A. dissimilis ova/turkey egg at day 28 of incubation.     

Effect of oral Escherichia coli inoculation on performance of young turkeys

A strain of Escherichia coli isolated from the yolk sac of stunted turkey poults was administered orally to day-old large white poults. Poults were inoculated with either 0.1 ml of sterile broth or 0.1 ml of a 10(-2) dilution of a 24-hr E. coli culture containing 3.4 x 10(8) viable bacteria per ml. Two levels of dietary protein (28 or 22%) were fed from 1 day to 3 weeks of age. Following E. coli inoculation of 3.4 x 10(5) viable bacteria at day one, body weight gain and feed consumption from 0 to 3 weeks of age were numerically increased 4.5 and 2.1%, respectively, and feed efficiency was significantly increased 2.4%. E. coli had a greater effect on performance of poults fed the 28% protein diet than on poults fed the 22% protein diet. Metabolism studies, conducted from 7 to 10 and from 17 to 20 days postinoculation, showed no significant changes in the measurements of nutrient utilization due to E. coli other than a 17% increase in nitrogen retention from 17 to 20 days by those poults fed the 28% protein diet.     

Ascarid-associated hepatic foci in turkeys

Hepatic foci are a serious economic problem for most turkey-producing areas in the United States. Current estimates indicate that as much as 43% of the flocks sent to slaughter may experience condemnations because of hepatic foci. The present experiments were designed to duplicate naturally occurring lesions with Ascaridia dissimilis. Newly hatched poults were placed on fresh litter and given feed containing either 500 embryonated A. dissimilis ova/bird/day (from day of hatch) or no ova, in three experiments. Hepatic foci were reproduced in exposed poults in all three experiments, indicating that A. dissimilis is directly involved in the etiology of hepatic foci.     

Immune response of poults following intranasal inoculation with Artvax vaccine and a formalin-inactivated Bordetella avium bacterin

Poults 3 weeks and older developed temporary tracheal resistance to intranasal challenge following inoculation of either Artvax vaccine or formalin-inactivated Bordetella avium bacterin by the intranasal and eyedrop routes. Resistance usually persisted for 3-4 weeks after B. avium challenge. However, with constant exposure to infected controls, the vaccinated birds eventually developed tracheal infection. Day-old poults did not respond to either the Artvax or the bacterin and were completely susceptible to challenge. Two-week-old poults responded to some degree, but poults 3 weeks old and older responded best. Poults inoculated with bacterin by aerosol or by drinking water did not respond as well as those inoculated by the intranasal and eyedrop routes. When poults were given a single subcutaneous injection at 3 weeks of age and challenged 2 weeks later, three of five resisted infection for 18 days.     

Hemorrhagic enteritis of turkeys: influence of maternal antibody and age at exposure

The effect of maternal antibody (MAB) to hemorrhagic enteritis (HE) on the response of turkeys to infection with virulent and avirulent strains of HE virus (HEV) was examined. The influence of age at exposure and treatment with HEV antibody on development of clinical HE also was studied. MAB protected poults from clinical HE for up to 6 weeks of age. MAB also interfered with vaccination against the disease for at least 5 weeks after hatching, as indicated by absence of HEV antigen in spleens and by poor seroconversion at 6 days and at 3 weeks post-vaccination, respectively. The incidence of clinical HE in MAB-negative poults was significantly higher in poults inoculated with virus at 15 days of age or older than in poults inoculated at 1-13 days of age. Further, MAB-negative poults embryonally inoculated with virulent or avirulent strains of HEV did not develop disease; these poults developed antibody and resisted challenge with virulent virus at 6 weeks of age. Poults treated with HE antibody within 1 hour of challenge or at 1, 3, or 5 weeks before challenge with virulent virus were protected against lesions and mortality induced by HEV. These results suggest that MAB may influence susceptibility of turkeys to infection with HEV for at least 5 to 6 weeks after hatching, unlike the case with most other viral infections of poultry. The results confirm that early age resistance to clinical HE is independent of MAB and suggest that such resistance persists for up to 13 days of age. The data also suggest that turkeys lacking MAB can be immunized against HE by embryo vaccination.     

Pathogenicity of turkey coronavirus in turkeys and chickens

We designed this study to compare the replication potential of turkey coronavirus (TCV) and its effect in chickens and turkeys and to study the effect of singleand combined infection of turkey poults with TCV and astrovirus. We studied the pathogenicity of TCV in experimentally inoculated turkey poults and chickens by observing the dinical signs and gross lesions. Two trials were conducted with 1-day-old and 4-wk-old specific-pathogen-free turkey poults and chickens. One-day-old turkey poults developed diarrhea at 48 hr postinoculation. Poults euthanatized at 3, 5, and 7 days postinoculation had flaccid, pale, and thin-walled intestines with watery contents. The 4-wk-old turkeys had no clinical signs or gross lesions. One-day-old and 4-wk-old chicks developed no clinical signs or gross lesions although the TCV was detected in gut contents of the birds throughout the experimental period (14 days). In another experiment, mean plasma D-xylose concentrations in 3-day-old turkey poults inoculated with TCV, turkey astrovirus, or a combination of both viruses were significantly lower than in the uninoculated controls.     

Enteric disease in specific-pathogen-free turkey poults inoculated with a small round turkey-origin enteric virus

Four- and 5-day-old specific-pathogen-free turkey poults were inoculated orally or by contact exposure to a small round turkey-origin enteric virus. At days 4 and 8 postinoculation (PI), the orally inoculated poults had significantly lower body weight gains than control poults. Poults at day 4 (orally inoculated) and 5 (contact-exposed) PI had watery droppings, dilated thin-walled ceca filled with yellow foamy fluid, catarrhal small intestinal secretions, pale intestinal serosa, and mild lymphocytic enteritis. In addition, at day 4 PI, poults were lymphopenic, had intracytoplasmic crystalline arrays of 17.1 +/- 1.1 nm viral particles in the jejunal villar enterocytes, and had an 18-to-24-nm virus in intestinal contents. Analysis of morphometric data revealed mild shortening of villi in the duodenum and elongation of crypts in the duodenum and ileum during the late stage of the syndrome (day 8 PI). These findings suggest that the 18-to-24-nm virus can produce an enteric disease syndrome and that the acute clinical manifestation of this syndrome is not the result of morphologic change such as intestinal villus atrophy. The definitive identity of this 18-to-24-nm virus is not known; however, based on size and intracytoplasmic arrays of virus, it is most probably an enterovirus.     

Astrovirus: a cause of an enteric disease in turkey poults

Virus particles of 30 nm diameter and star-shaped morphology were detected in intestinal contents of turkey poults and were identified as astroviruses. Seventy-six intestinal samples from 65 commercial turkey flocks between 6 and 35 days of age were evaluated for the presence of astroviruses by immune electron microscopy. Astroviruses were frequently detected in intestinal samples from poults that had enteritis and diarrhea of undetermined etiology. Astroviruses were geographically widespread and were present in poults from all six operations evaluated. Astroviruses were inoculated into specific-pathogen-free poults. Changes observed in the gastrointestinal tract were: dilatated ceca containing yellowish frothy contents, gaseous fluid in the intestinal tract, and loss of tone of the intestinal tract (gut thinness). Poults experimentally inoculated with astrovirus gained significantly less body weight and absorbed significantly less D-xylose than uninoculated controls.     

Protection of turkey poults from Bordetella avium infection and disease by pili and bacterins

The role of pili in protection against Bordetella avium infection in turkey poults was studied. An isolate that produced the largest number of pili under growth conditions developed in our laboratory was used for preparation of pili and bacterin and for challenge. The pili were isolated, purified, examined by electron microscopy, and tested for purity by gel electrophoresis. Poults were vaccinated with oil-adjuvant pili, formaldehyde- or merthiolate-inactivated bacterins, or a commercial bacterin. Poults were vaccinated once or twice subcutaneously at different ages and challenged intranasally with a pathogenic B. avium isolate 5 days following the last vaccination. A few vaccinated birds had very mild clinical signs. B. avium was isolated from the sinuses of a few vaccinated birds, and growth was scanty. The mean colony counts from tracheal sections was significantly higher (P less than 0.1) in unvaccinated challenged poults than in vaccinated challenged poults. It is postulated that B. avium pili are important immunogens in turkey poults.     

Passively administered antibodies alleviate stunting syndrome in turkey poults

Stunting syndrome is an enteric disease of young turkeys that results in reduced growth (stunting) of poults and impaired feed efficiency. A virus, which has been termed the stunting syndrome agent (SSA), causes stunting syndrome. In this study passive immunity was evaluated as a method of protecting poults from stunting syndrome. One-day-old poults were injected with either tryptose phosphate broth, an anti-SSA antibody preparation, or an anti-Newcastle disease virus antibody preparation before challenge by placing them into SSA-contaminated isolators or control (nonchallenge) isolators. Poults that received anti-SSA antibodies were significantly heavier (P < 0.05) and did not display as severe clinical disease compared to birds that did not receive the anti-SSA antibodies. However, the birds that received anti-SSA antibodies and were challenged were significantly lighter (P < 0.05) than birds that were not challenged. The results of this trial demonstrate that the injection of anti-SSA antibodies benefited poults undergoing stunting syndrome. The role of passive immunity, either through breeder hen vaccination or through supplying antibodies to poults artificially (i.e., at the hatchery), may have future applications in alleviating stunting syndrome.     

Delayed T-cell maturation and suppression of mitogen-induced blastogenesis in turkey poults fed cortisone acetate and furazolidone

The effect of cortisone acetate (CA) on the immune response of control and furazolidone (FZ)-fed turkey poults was investigated. CA, fed at a dose of 500 mg/kg of ration beginning at 1 week of age, decreased mortality but had little effect on the development of FZ-induced cardiomyopathy. When poults were 2 weeks of age, the in vitro stimulation of lymphocytes by phytohemagglutinin (PHA) and concanavalin A (Con A) was significantly depressed (P less than or equal to 0.001 and P less than or equal to 0.05, respectively) in cortisone-treated poults. The time of the peak response of lymphocytes from poults 2-5 weeks of age to in vitro stimulation by PHA was significantly delayed (P less than or equal to 0.01) and the magnitude of the response was significantly depressed (P less than or equal to 0.001) in cortisone-treated poults compared with control poults. Cortisone treatment had no effect on time of peak response to Con A stimulation but significantly depressed (P less than or equal to 0.05) the magnitude of the response. Poults receiving FZ administered by gastric tube showed a peak response to PHA stimulation significantly (P less than or equal to 0.05) earlier and significantly (P less than or equal to 0.05) greater than did control poults.     

Efficacy of a commercial turkey coryza vaccine (Art-Vax) in turkey poults

Four laboratory experiments were designed to study the efficacy of the only available commercial vaccine for turkey coryza, Art-Vax. Poults were vaccinated either once or twice at different ages and challenged with pathogenic Alcaligenes faecalis. In another study, commercial turkeys vaccinated at 1 and 12 days of age on a commercial farm were brought to the laboratory for challenge with pathogenic A. faecalis. Both the laboratory- and field-vaccinated poults were given the manufacturer's recommended dosage of the vaccine strain. Regardless of the vaccine schedule or source of poults, the vaccine was not effective in protecting challenged turkeys from infection. Furthermore, the vaccine was not effective in protecting poults less than 3 weeks of age from disease, but it was effective in protecting poults more than 3 weeks of age from disease. These results indicate that although vaccinated turkeys older than 3 weeks of age were not susceptible to disease, they were susceptible to infection and could act as carriers of field strains of A. faecalis, thus perpetuating the risk of infection to flocks subsequently raised in the same buildings.     

Genetic variation in resistance of turkeys to experimental challenge with Pasteurella multocida.

Six hundred fifty-five male and female turkeys representing four genetic lines were challenged in 10 experiments over a 3-year period with a field isolate of Pasteurella multocida. Poults were challenged at 45 days of age with 1 ml of an inoculum containing 1.2 x 10(7) bacteria per ml. The lines of turkeys included two randombred control lines (RBC1 and RBC2), a subline (E) of RBC1 selected for increased egg production, and a subline (F) of RBC2 selected for increased 16-week body weight. The number of days from exposure to severe clinical signs or death for Line F (5.8 days) differed significantly from that of Line E (8.2 days), Line RBC1 (8.0 days), and Line RBC2 (8.2 days). There were no significant differences due to sex of poult for number of days from exposure to severe clinical signs or death. Overall mortality observed was 51.2%. Mortality was highest for Line F (72.1%) and differed significantly from that of the other lines. Mortality among male poults did not differ significantly from mortality among female poults.     

Poult malabsorption syndrome. II. Pathogenesis of skeletal lesions.

One-day-old poults were placed on litter on which poults had previously developed diarrhea, increased mortality, stunting, and malabsorption. Gross, microscopic, and morphometric evaluations of the proximal tibiotarsal growth plate, along with analysis of plasma calcium, phosphorus, and 25-hydroxyvitamin D3 concentrations, were conducted for 3 weeks to determine the development and character of skeletal lesions. Poults developed enteritis with diarrhea and dehydration. Body weights and shank lengths were significantly decreased. Plasma 25-hydroxyvitamin D3 concentrations were significantly decreased. Plasma calcium was significantly decreased on day 8. Plasma phosphorus concentrations were significantly increased on day 8 and were significantly decreased on days 15, 18, and 22. Growth plates narrowed on days 8 and 11 and expanded on days 15, 18, and 22. The proliferating-prehypertrophy zone significantly decreased in length on days 11, 18, and 22, and significantly increased in length on day 15. The unmineralized hypertrophy zone was significantly increased in length on days 15, 18, and 22. The mineralized hypertrophy zone was significantly decreased in length on all days. Skeletal lesions during the poult malabsorption syndrome evolved from an early osteoporotic lesion associated with hypocalcemia to a rachitic lesion associated with depleted vitamin D and hypophosphatemia.     

Selection for early (precocious) development of Eimeria meleagridis in the turkey

A precocious line of Eimeria meleagridis was developed by repeated propagation of the parasite in young turkeys and collection of the very first oocysts produced following infection. After 20 generations of selection, the prepatent period was reduced by 4-8 hr. Weight gain of poults given this line, from days 0-3 after infection, was significantly greater than that of poults given the parental strain, indicating that selection resulted in a loss of pathogenicity. Poults immunized with the precocious line produced no oocysts following challenge with the parental strain, indicating that immunogenicity was retained following selection. This is the first published report of the selection of a precocious line of Eimeria in the turkey.     

Induction of functional defects in macrophages by a poult enteritis and mortality syndrome-associated turkey astrovirus.

The interaction of a poult enteritis and mortality syndrome (PEMS)-turkey astrovirus-Ohio State University (TAst-OSU) with the mononuclear phagocytic system cells, namely macrophages, was examined after in vitro and in vivo exposure. In vitro exposures were performed by incubating adherent turkey macrophages with various volumes of 10(6) 50% embryo infective dose (EID50)/ml TAst-OSU stock, whereas for in vivo challenge, poults were given a 200 microl inoculum of 10(6) EID50/ml TAst-OSU stock at 7 days of age. Results show that TAst-OSU in vitro exposure reduced macrophage viability relative to controls (P < 0.05) and decreased phagocytosis (P < 0.05) and intracytoplasmic killing of Escherichia coli (P < 0.05) after a 42-48-hr exposure. Poults challenged with TAst-OSU in vivo recruited almost 50% fewer Sephadex-elicited inflammatory cells in the abdominal cavity (P < 0.05) as compared with the sham controls. Similar to in vitro exposure, macrophages isolated from in vivo TAst-OSU-challenged poults exhibited reduced percentage of phagocytic macrophages (P < 0.05) as well as fewer intracytoplasmic E. coli per phagocytic macrophage (P < 0.05). TAst-OSU-challenged poults had a greater number of viable E. coli in their spleens (P < 0.05) after an intravenous E. coli challenge as compared with the non-TAst-OSU-challenged control poults. Macrophage-mediated cytokines and metabolites were also examined during this study. Both in vitro and in vivo TAst-OSU challenge resulted in reduced interleukin (IL)-1 and IL-6 activity. On the contrary, nitrite levels in macrophage culture supernatant fraction of TAst-OSU-challenged macrophages were significantly higher (P < or = 0.05). The findings of these studies indicated that TAst-OSU challenge induced defects in macrophage effector functions, implying that PEMS-turkey astrovirus can potentially impair the immune response of turkeys, thereby leading to enhanced susceptibility of turkeys to secondary, perhaps even fatal, bacterial infections.     

Pulmonary bacterial deposition and clearance during ascarid larval migration in weanling pigs.

Pulmonary deposition and clearance of bacteria were measured in weanling pigs, half of which had been inoculated at age 31 days with larvated Ascaris suum ova. Seven days later, when breathing signs of larval migration were pronounced, all pigs were exposed to aerosolized Escherichia coli (strain B). Then, either immediately after aerosol exposure (for deposition assessment) or immediately after a 120 minute period in filtered air (for clearance), bacteria in the pigs' lungs were counted. Ascarid ova-inoculated pigs did not differ significantly from control pigs for number of bacteria in the lungs after aerosol exposure, but after the 120 minute clearance period they had 7.2 times more than did the control pigs. Thus, in weanling pigs, the breathing-pattern changes that were evident during ascarid-larval migration did not affect pulmonary deposition of inhaled bacteria significantly, but the presence of ascarid larvae in the lungs was associated with impaired pulmonary bacterial clearance.     

Efficacy and safety of a cell-culture live virus vaccine for hemorrhagic enteritis of turkeys: laboratory studies

Poults free from hemorrhagic enteritis (HE) antibody were vaccinated by gavage at 1 day or 2 weeks of age with a live HE vaccine virus that had been propagated in a Marek's disease (MD)-induced B-lymphoblastoid cell line of turkey origin. Vaccinated and unvaccinated poults were challenged with a virulent HE virus at various times postvaccination. One hundred tissue-culture-infectious doses of the vaccine virus per poult were sufficient to induce a serological response as well as to protect poults against HE lesions and mortality. Vaccinated poults were protected against the disease as early as 1 week and as late as 8 weeks PV. The vaccine was efficacious by several routes of application. The vaccine virus spread horizontally from vaccinated to contact-exposed poults, as indicated by seroconversion and resistance of contact-exposed poults to challenge. The vaccine had no detectable harmful effects on the humoral immune response to particulate antigens or on weight gain of vaccinated poults. The vaccine proved to be free from MD virus, as indicated by the absence of MD lesions and antibody in 8-week-old chickens inoculated intra-abdominally with the vaccine at hatching. These findings indicate that the cell-culture-propagated HE vaccine is efficacious and safe.     

Intestinal and bursal cryptosporidiosis in turkeys following inoculation with Cryptosporidium sp. isolated from commercial poults

Cryptosporidium meleagridis oocysts, originally isolated from droppings of commercial turkey poults with increased mortality due to viral (reovirus) hepatitis and enteritis, were treated with peracetic acid to kill companion bacteria and viruses and then propagated by passage in young turkeys. Thirty-eight 5-day-old large white turkey poults were inoculated by crop gavage with 500,000 cryptosporidial oocysts and compared with 40 uninoculated poults. Cryptosporidial oocysts shedding began 3 days postinoculation (PI), peaked on day 4 PI, and persisted at a low level for the duration of the 21-day trial. Low to moderate cryptosporidial infections of the ileal mucosa (days 3, 6, and 15 PI), cecal mucosa (days 3, 6, and 21 PI), and bursa of Fabricius (days 6, 12, 15 and 21 PI) were found on histopathological examination. There were no differences in mean body weights between the inoculated and uninoculated groups, and no mortality or clinical signs of disease were seen in either group.     

Evaluation of lasalocid as a coccidiostat in calves: titration, efficacy, and comparison with monensin and decoquinate

Two experiments were conducted to evaluate lasalocid as a coccidiostat in Holstein calves and to compare lasalocid with monensin and decoquinate. In experiment 1, calves in 3 groups (6 calves/group) were each inoculated with 500,000 sporulated oocysts, 88% of which were Eimeria bovis and 12% were E zuernii. Calves in each group were given lasalocid-medicated feed at 0.50 (group 3), 0.75 (group 4), or 1 mg/kg (group 5) of body weight/day for 45 days. Two control groups (6 calves/group) were also evaluated; calves in control group 2 were inoculated and nontreated, and calves in control group 1 were noninoculated and nontreated. At 0.50, 0.75, or 1 mg/kg/day, lasalocid was equally effective in preventing induced coccidiosis (E bovis and E zuernii) in calves. Compared with inoculated nontreated controls, treated calves had significantly (P less than 0.05) fewer oocysts in feces and had fewer clinical signs of coccidiosis from days 16 to 30 after inoculation. Experiment 2 was conducted to compare the effectiveness of monensin, lasalocid, and decoquinate for the prevention of experimentally induced coccidiosis. Calves (n = 48) were allotted into 4 groups (12 calves/group); each was inoculated orally with 275,000 sporulated oocysts, predominantly E bovis and E zuernii, and each was given nonmedicated feed (group 6) or feed medicated with 33 mg of lasalocid (group 7), decoquinate (group 8), or monensin (group 9)/kg of feed for 46 days. Calves given medicated rations had significantly (P less than 0.05) fewer oocysts in their feces and fewer clinical signs of coccidiosis than did calves given nonmedicated rations.(ABSTRACT TRUNCATED AT 250 WORDS)