Comparison Between a Live,Attenuated Anticoccidial Vaccine and an Anticoccidial Ionophore,on Performance of Broilers Raised with or without a Growth Promoter,in an Initially Eimeria-Free Environment

An experiment was carried out to study the effects of vaccination with Paracox®, a live, attenuated vaccine against avian coccidiosis, on broilers isolated from extraneous Eimeria parasites. The study involved 3200 broiler chickens raised in floor pens similar to commercial conditions, but in an initially Eimeria-free environment. Forty percent of the chickens were vaccinated at 3 days of age and given either a basal unmedicated feed or a feed supplemented with the feed antibiotic virginiamycin. Unvaccinated birds were given either the basal feed or feed supplemented either with virginiamycin or the anticoccidial ionophore narasin. At slaughter at 36 days of age vaccinated birds had a lower live weight than non-vaccinated birds. The difference was 4.6% in unmedicated, and 6.0% in virginiamycin medicated chickens. Feed conversion ratio at slaughter was 2.5% higher for unmedicated vaccinated birds, and 1.3% higher for virginiamycin medicated vaccinated birds, compared to respective non-vaccinated groups. There was no significant difference in overall performance of unvaccinated birds given narasin as compared to virginiamycin. At 10 days post vaccination vaccinated birds had a higher number of Clostridium perfringens in the caeca, but there was no difference thereafter. Throughout the experiment, caecal clostridial counts were considerably higher in vaccinated unmedicated birds than in unvaccinated birds given narasin. The number of oocysts shed in the vaccinated groups was very low, but during a subsequent challenge with E. maxima and E. tenella the birds’ immunity was found to be satisfactory.     

Effects of various energy and protein levels during sequential feeding on feed preferences in meat-type chickens

Short-term feed preferences were studied in individually caged chickens fed sequentially in order to understand a previously described imbalance in the intake of diets offered. Sequential feeding (SF) was carried out for four 48 h cycles in male broiler chickens. The diets varied in energy (2800 (E−) and 3200 kcal/kg (E+)) and protein (230 (P+) and 150 g/kg (P−)) contents. SF was compared to standard feeding (C) (3000 kcal/kg ME and CP = 190 g/kg). In experiment 1, three treatments were used: C, S_E (E− followed by E+) and S_E′ (E+ followed by E−). Four treatments were used in experiment 2: C, S_P (P+ followed by P−), S_E and S_EP (P+E− followed by P−E+). Total feed intake was measured during the SF period. After this, short-term preferences were evaluated with a choice test on chickens previously fed with the same feeds during the SF period (experienced birds) and in C chickens (naïve birds). In both experiments, total feed intake was similar among treatments and the percentage of each feed consumed was not significantly different from controls (50%). In experiment 1, S_E and S_E′ chickens over-consumed E+ and under-consumed E− diets only during the first 15 min of the fourth cycle. The choice test indicated that experienced chickens preferred E+, while naïve chickens preferred E−. Similarly, in experiment 2, chickens over-consumed E+ and E+P− during the first 15 min of the fourth cycle, but the intake of diets varying in protein content was not different from controls. During the choice test, as in experiment 1, experienced chickens preferred E+, while naïve chickens preferred E−. There was a slight preference for the protein-poor diet in naïve birds and there was no preference in the diet varying in both protein and energy contents. Experience modified choice between feeds varying in energy content but not in protein. When feeds were known, preference for energy affected the feed intake immediately after switching from one diet to the other, although lower with the diet also varying in protein, it did not influence the total intake of each diet. Interactions between the nutritional properties and sensorial cues of feed could explain these results.     

Comparison Between Effects of Standard Feed and Whole Wheat Supplemented Diet on Experimental Eimeria tenella and Eimeria maxima Infections in Broiler Chickens

The effects of experimental infections with Eimeria tenella (Experiment 1, n = 144) or E. maxima (Experiment 2, n = 216) in broiler chickens fed whole wheat, with or without access to grit, as compared to a standard pelleted feed were studied. Inclusion of whole wheat was gradually increased up to 30% at 3 weeks of age. Grit was given separately. The chickens were kept on litter in a parasite-free environment with free access to water and feed. At 3 weeks of age half the number of chickens were individually inoculated with 500 sporulated oocysts of E. tenella (Experiment 1) or 3 000 sporulated oocysts of Eimeria maxima (Experiment 2), and the remaining birds were kept separate as uninfected controls. Neither coccidiostats nor growth enhancers were used. Oocyst concentration was determined from each group separately. Intestinal lesions were scored on 6 birds per feed regime 7 d postinoculation, and on the remaining birds at slaughter. Diet had no significant effect on bird performance during infection. However, there was an indication that the E. maxima infection had more negative effect on weight gain in birds given standard feed than in those given whole wheat supplement, but the difference was not significant (p<0.09). The number of oocysts shed or mean intestinal lesion scores did not differ between diets in either experiment. In both experiments, the number of Clostridium perfringens was higher in the caeca of inoculated birds, but there were no differences between diets.     

Histological alterations of intestinal villi in chickens fed dried Bacillus subtilis var. natto

Two experiments were conducted. In experiment 1, chickens were fed dried Bacillus subtilis var. natto for 3 or 28 days. Growth performance and internal organs were not different from controls, but feed efficiency tended to be improved in the 28-day feeding. In these birds, blood ammonia concentration was decreased (P<0.05). Blood glucose concentration, and amylase and lipase activity in the intestinal content were not significantly different among dietary groups. These results suggest that the B. subtilis natto depressed ammonia concentration. In experiment 2, chickens were fed dietary B. subtilis natto for 28 days. These birds had a tendency to display greater growth performance and intestinal histologies, such as villus height, cell area and cell mitosis, than the controls. Flat cell outline on the duodenal villus surface in controls developed large, protruded cell clusters and cell protuberances after feeding of dietary B. subtilis natto. These results indicate that intestinal function was activated by the depressed blood ammonia concentration in the body of the chicken. The present results may suggest that the B. subtilis natto has the potential to be a beneficial microorganism in chickens.     

Effect of Campylobacter-specific maternal antibodies on Campylobacter jejuni colonization in young chickens

Using laboratory challenge experiments, we examined whether Campylobacter-specific maternal antibody (MAB) plays a protective role in young chickens, which are usually free of Campylobacter under natural production conditions. Kinetics of C. jejuni colonization were compared by infecting 3-day-old broiler chicks, which were naturally positive for Campylobacter-specific MAB, and 21-day-old broilers, which were negative for Campylobacter-specific MAB. The onset of colonization occurred much sooner in birds challenged at the age of 21 days than it did in the birds inoculated at 3 days of age, which suggested a possible involvement of specific MAB in the delay of colonization. To further examine this possibility, specific-pathogen-free layer chickens were raised under laboratory conditions with or without Campylobacter infection, and their 3-day-old progenies with (MAB(+)) or without (MAB(-)) Campylobacter-specific MAB were orally challenged with C. jejuni. Significant decreases in the percentage of colonized chickens were observed in the MAB(+) group during the first week compared with the MAB(-) group. These results indicate that Campylobacter-specific MAB plays a partial role in protecting young chickens against colonization by C. jejuni. Presence of MAB in young chickens did not seem to affect the development of systemic immune response following infection with C. jejuni. However, active immune responses to Campylobacter occurred earlier and more strongly in birds infected at 21 days of age than those infected at 3 days of age. Clearance of Campylobacter infection was also observed in chickens infected at 21 days of age. Taken together, these findings (i) indicate that anti-Campylobacter MAB contributes to the lack of Campylobacter infection in young broiler chickens in natural environments and (ii) provide further evidence supporting the feasibility of development of immunization-based approaches for control of Campylobacter infection in poultry.     

In Ovo Olfactory Experience Influences Post‐hatch Feeding Behaviour in Young Chickens

In several mammalian species, prenatal exposure to odours can elicit later positive consummatory behaviour in response to substrates bearing that odorant. In birds, the sense of smell has been considerably underestimated, and very little is known about the effects of early sensory experience on the regulation of feeding behaviour. We tested the hypothesis that the feeding behaviour of the domestic chicken could be regulated by olfactory learning during the embryonic life. To that end, chicken embryos were exposed to an olfactory stimulus (blend of essential oil of orange and nature identical vanillin) from embryonic day (ED) 12 to ED20, and chicks were tested between 4 and 9 d of age. In short‐term choice tests, at day 4 and 5, chickens previously exposed to a low concentration (LC) of the olfactory stimulus spent a higher proportion of time eating a familiar or an unfamiliar food bearing the olfactory stimulus compared to non‐exposed control chickens. Conversely, chickens previously exposed to a high concentration (HC) of the olfactory stimulus were found to avoid all foods bearing the olfactory stimulus. On a 24‐ h time scale at day 7–8, LC and HC birds, but not controls, ingest significantly less familiar food containing the olfactory stimulus. This result indicated a long‐term effect of the early olfactory experience on feeding preferences. We demonstrated that chickens can utilize information from their pre‐hatch chemosensory environment to guide their later feeding behaviour. A pre‐hatch effect of the intensity of odour signals in the regulation of feeding behaviour is reported here for the first time.     

An Epidemic of Salmonella Infantis Infection in Finnish Broiler Chickens in 1975–76

A large S. infantis infection epidemic in broiler chickens was studied during a period of one year. The outbreak affected three broiler producing companies in Finland. The infection spread to breeding farms according to available data during the summer of 1975. The epidemic still prevailed at the end of the studies on the farms of certain companies. The origin of the infection and the means of its spreading could not be ascertained. Some epidemiological evidence suggesting that a hatchery might have spread the infection was found. Contaminated feed may also have been involved, although the findings do not support feed as the principal vehicle in the epidemic. A complex pattern of transmission is most probable. A microbiological preventive method based on the feeding of a culture of intestinal flora of adult chickens to newly hatched broiler chickens was used on many farms in the study. The feeding of the culture lowered the proportion of infected flocks on the farms and significantly lowered the number of infected birds in those flocks, where the prevention was not complete. kw|Keywords|k]Salmonella infantis; k]infection; k]epidemic; k]broiler chicken     

Sources of Salmonella on broiler carcasses during transportation and processing: modes of contamination and methods of control

AIMS: The prevalence and types of salmonella in broiler chickens during transportation and during slaughter and dressing were studied. This was part of a comprehensive investigation of salmonellas in two UK poultry companies, which aimed to find the origins and mechanisms of salmonella contamination. METHODS AND RESULTS: Salmonellas were isolated using cultural methods. Serovars of Salmonella detected during rearing were usually also found in a small proportion of birds on the day of slaughter and on the carcasses at various points during processing. There was little evidence of salmonellas spreading to large numbers of carcasses during processing. Many serovars found in the feedmills or hatcheries were also detected in the birds during rearing and/or slaughter. Transport crates were contaminated with salmonellas after washing and disinfection. CONCLUSIONS: Prevalence of salmonellas fell in the two companies during this survey. A small number of serovars predominated in the processing plants of each company. These serovars originated from the feed mills. Reasons for transport crate contamination were: (1) inadequate cleaning, resulting in residual faecal soiling; (2) disinfectant concentration and temperature of disinfectant too low; (3) contaminated recycled flume water used to soak the crates. SIGNIFICANCE AND IMPACT OF THE STUDY: Efforts to control salmonella infection in broilers need to concentrate on crate cleaning and disinfection and hygiene in the feed mills.     

Secondary phytohaemagglutinin (PHA) swelling response is a good indicator of T‐cell‐mediated immunity in free‐living birds

The validity of using the phytohaemagglutinin (PHA) test to measure acquired immunity, one of the most widely used methods, is currently being debated due to new knowledge on the complex physiology of the process. As a greater secondary response to repeated challenges linked to increases of circulating lymphocyte levels would be indicative of a T‐cell‐mediated immune response, we performed for the first time an experiment under natural conditions with repeated PHA challenges in free‐living adult birds and chicks to shed light on this topic. We found significantly stronger secondary response to PHA injection independent of sex or age, while controlling for body condition, the second response being on average 90% larger than the first. Likewise, lymphocyte counts were significantly higher in the second PHA challenge, whereas no significant differences were found among untreated birds. Significant positive correlations between the PHA response and both lymphocyte counts and plasma protein levels (mainly albumin, globulin precursor) were recovered, whereas no significant differences were recovered in plasma protein levels between challenges. Our results are consistent with those from captive birds, supporting the validity of the PHA skin‐swelling test as an accurate gauge of acquired T‐cell‐mediated immunity in birds.     

Pathogenicity for Chickens of a Paramyxovirus Type 1, Isolated from Racing Pigeons in Sweden

Strains of paramyxovirus type 1 (PMV-1) have been isolated from diseased racing pigeons in Sweden. One of these isolates was selected for studies of the pathogenicity and contagiousness in chickens. The same isolate was previously found to have a high intravenous pathogenicity index (IVPI) in 6 weeks old chickens. In three experiments it was found that the PMV-1 isolate was very pathogenic for 1 week old chickens but not pathogenic for 120 day old pullets inoculated intranasally and ocularly. Symptoms in the young chickens were similar to those seen in the neurotropic form of Newcastle disease. The mortality was high and the incubation period 5–11 days. The disease easily spread to young chickens kept in contact with diseased birds. The microscopic examination revealed an interstitial nonpurulent pneumonia and a nonpurulent encephalitis in the young chickens. In the pullets the only finding was a mild encephalitis. PMV-1 was recovered from all young chickens but not from the pullets. Both the chickens and the inoculated pullets developed antibodies to PMV-1.     

Dietary protein regulates in vitro lipogenesis and lipogenic gene expression in broilers

The purpose of this experiment was to determine the possible relationship between certain indices of lipid metabolism and specific gene expression in chickens fed graded levels of dietary crude protein. Male, broiler chickens growing from 7 to 28 days of age were fed diets containing 12, 21 or 30% protein ad libitum. In addition, another group of birds was fed on a regimen consisting of a daily change in the dietary protein level (12 or 30%). This latter group was further subdivided such that one-half of the birds received each level of protein on alternating days. Birds were sampled from 28 to 30 days of age. Measurements taken included in vitro lipogenesis, malic enzyme activity the expression of the genes for malic enzyme, fatty acid synthase and acetyl coenzyme carboxylase. In vitro lipogenesis and malic enzyme activity were inversely related to dietary protein levels (12-30%) and to acute changes from 12 to 30%. In contrast, expression of malic enzyme, fatty acid synthase and acetyl CoA carboxylase genes were constant over a dietary protein range of 12-21%, but decreased by feeding a 30% protein diet (acute or chronic feeding). Results of the present study demonstrate a continued role for protein in the regulation of broiler metabolism. It should be pointed out, however, that metabolic regulation at the gene level only occurs when feeding very high levels of dietary protein.     

Effect of dodecanoic acid on the colonisation of sugar beet by aphids and the secondary spread of virus yellows

The effect of dodecanoic acid, a behaviour-controlling chemical which alters aphid feeding behaviour and virus transmission efficiency, was studied under field conditions. In a first experiment, dodecanoic acid reduced the level of natural colonisation of sugar beet by Aphis fabae. A second experiment revealed no significant influence of dodecanoic acid on the secondary spread of the semi-persistent beet yellows virus and the persistent beet mild yellowing virus.     

Incidence of Salmonellae in Dressed Broiler-Fryer Chickens

Salmonellae were isolated from 72 of 264 broiler-fryer type chickens that had been purchased in retail stores in the Lafayette, Ind., area in 1963. Meat from the tail area and giblet portions were used in sampling. Equal numbers of dressed whole and cut-up birds were positive for salmonellae. Thirteen different serotypes were identified, the more common being Salmonella infantis, S. reading, and S. blockley. Incubation at 43 C of the blended sample in Selenite-F Enrichment broth containing cystine gave a larger number of recoveries than did incubation at 37 C. There was no significant difference between the means for the birds that yielded salmonellae and those that did not in the locally processed group, when compared for numbers of aerobic microorganisms at 37 C, coliforms, or most probable number of enterococci. In a comparison of poultry processed in-state by the five processors included in the study with that processed out-of-state, there was a general trend for a larger number of positive specimens in the locally produced group. The fall season was an exception.     

The feeding strategy of the dunlin (Calidris alpina L.) in artificial and non-artificial habitats at Ria de Aveiro,Portugal

Usually waders (Aves, Charadrii) feed in the inter-tidal zone over the low tide period and roost over high tide. But occasionally when their energetic needs increase, due to adverse weather conditions or to a need to store fat to fuel migration, the birds also feed during high tide, sometimes in agricultural land. At the Ria de Aveiro, about 44% (corresponding to 4500 birds) of the wintering dunlin (Calidris alpina) use artificial salt pan habitats throughout the winter whilst the others utilize natural intertidal habitats, mainly mudflats. The dunlin that feed intertidally in natural areas, such as the Canal de Mira, do not feed over high tide. In contrast, the birds that use the salt pan area feed both during low tide, in abandoned salt pans whose walls are breached and thus allow access to the tide, and high tide, in active salt pans, and keep on doing so throughout the winter. The energetic needs of both groups of birds are thought to be similar. However, the benthos of the abandoned salt pans seem to be different, and poorer in energetic terms, from those of the natural mudflats. It is argued that dunlin wintering in the salt pan area must compensate for this by feeding over high tide in active salt pans. Rather than just being a means of obtaining more energy at certain times of high energy demand, it would seem that feeding in active salt pans over high tide should be considered as a normal component of the feeding strategy of these birds, a strategy that is different from those wintering in the natural mudflats. These findings highlight the importance of the salt exploitation industry to waders and also show that artificial habitats can support large numbers of wintering waders.     

Locally stable wintering numbers in the Oystercatcher Haematopus ostralegus where carrying capacity has not been reached

Since 1976, the numbers of Oystercatchers Haematopus ostralegus wintering on the Exeestuary have fluctuated independently of the substantial increase over the same period in the numbers wintering in Britain as a whole. While this might imply that the carrying capacity of the Exe has been reached, closer examination suggests not. Over a sample of the years studied, Oystercatcher numbers on the main Mussel Mytilus edulis feeding areas increased even though the mussel bed quality remained unchanged, food abundance decreased and disturbance on some important beds increased. There was some redistribution of birds between mussel beds, apparently linked to the increased bird numbers and to a relative improvement in the food supply on two preferred mussel beds. The increase in Oystercatcher numbers on the main feeding areas over a period in which the feeding conditions did not improve suggests that carrying capacity was not reached on the mussel beds themselves and, therefore, on the estuary as a whole.     

Weights and measurements of the Manx shearwater, Puffinus puffinus

Large numbers of Manx shearwaters were caught at night at the breeding colony on Skokholm Island, Pembrokeshire, Wales. Most of the birds caught were of known age. In 1973 and 1974 the weight of all age groups was highest in March and then declined to a minimum in June and July. Weight increased slightly in August. It was generally true that the older a bird was, the heavier it was in any particular month, and this effect appeared to hold good until the birds were eight to ten years old. Unlike weight, bill and wing length did not alter with age. It is suggested that, up until an age of about five or six years old, the greater weight of older birds may be due to higher feeding efficiency. This result is therefore related to hypotheses concerning the delayed onset of breeding shown by many seabirds. The seasonal pattern of weight change may reflect the severity of the prevailing feeding conditions.     

A preliminary study on the effects of oyster culturing structures on birds in a sheltered Irish estuary

This study investigated the species composition, numbers and behaviour of birds in an intertidal oyster culture area in Cork Harbour . These data were compared to a nearby area free of aquaculture within the same estuary in March 1999. Species which occurred in the aquaculture free area were also observed in the trestle-area. The most abundant species were oystercatcher Haematopus ostralegus, redshank Tringa totanus, dunlin Calidris alpina, curlew Numenius arquata, black-headed gull Larus ridibundus and common gull Larus canus. Oystercatcher, curlew, black-headed gull and common gull occurred in significantly lower numbers in the trestle area, while for redshank and dunlin the differences were not significant. The percentage of birds feeding did not differ between the two areas. Oystercatcher, redshank, dunlin and curlew mostly fed in both areas. In contrast, black-headed gull and common gull generally did not feed, but surveyed the area. Whether the trestles were covered by oyster bags or not did not have any effect on the number of birds except for the dunlin. Dunlin were significantly more frequent beneath the trestles with bags compared with those without bags. In general, the percentage of birds feeding did not differ between areas. Interspecies differences occurred with regard to the position occupied by birds at the trestles. Oystercatcher, redshank and curlew spent more time underneath the trestles. Dunlin, black-headed gulls and common gulls did not differ in numbers underneath or on top of the trestles. These preliminary observations at a single time period give some insight as to the potential interactions between shellfish aquaculture and intertidal birds.     

Investigation of the link between avian vacuolar myelinopathy and a novel species of cyanobacteria through laboratory feeding trials

Avian vacuolar myelinopathy (AVM) is a neurologic disease affecting Bald Eagles (Haliaeetus leucocephalus), American Coots (Fulica americana), and other birds in the southeastern United States. The cause of the disease has not yet been determined, although it is generally thought to be a natural toxin. Previous studies have linked AVM to aquatic vegetation, and the current working hypothesis is that a species of cyanobacteria growing epiphytically on that vegetation is producing a toxin that causes AVM. Surveys of epiphytic communities have identified a novel species of cyanobacteria in the order Stigonematales as the most likely suspect. The purpose of this study was to further examine the relationship between the suspect Stigonematales species and induction of AVM, by using animal feeding trials. Adult Mallards and domestic chickens were fed aquatic vegetation from two study sites containing the suspect cyanobacterial epiphyte, as well as a control site that did not contain the Stigonematales species. Two trials were conducted. The first trial used vegetation collected during mid-October 2003, and the second trial used vegetation collected during November and December 2003. Neither treatment nor control birds in the first trial developed AVM lesions. Ten of 12 treatment Mallards in the second trial were diagnosed with AVM, and control birds were not affected. This study provides further evidence that the novel Stigonematales species may be involved with AVM induction, or at the least it is a good predictor of AVM toxin presence in a system. The results also demonstrate the seasonal nature of AVM events.     

The aversion of broiler chickens to concurrent vibrational and thermal stressors

The requirement for assessing the effects of multiple concurrent stressors in improving the welfare of broiler chickens during transport has not been widely recognised. A discrete-choice technique was used to investigate the aversion of broiler chickens to concurrent vibrational and thermal transport stressors. In experiment 1, 12 female broiler chickens, aged 42+/-3 days were studied individually using two choice-chambers. Each chamber had four compartments connected via a central zone and offered four treatments; thermal (T: air temperature; 40 degrees C, 21% RH), vibrational (V: frequency; 2Hz, acceleration; 1ms(-2)), concurrent vibrational and thermal (VT) and no applied stressors (N). Coloured compartment wall panels, allocated at random, assisted chickens' identification of compartments. Birds were fasted overnight and were required to make five consecutive choices on each of four consecutive days. A choice was defined as entering a compartment and feeding (5g pellets), whereupon confinement for 60min was initiated. Choices were totalled over all birds and analysed using a log-linear generalised linear model. The vibration was significantly avoided (V and VT versus N and T; P<0.05) but the thermal stressor was not (T and VT versus N and V; P>0.05) and there was no interaction. In experiment 2, the procedure was repeated with 12 more birds and modifications to increase method sensitivity and maximise bird learning. Choices were more disparate than before with vibration avoided to a greater extent (V and VT versus T and N; P<0.01) but there was still no main effect of the thermal treatment or a significant interaction. Substantial differences between individuals were observed in both experiments. The overall response to vibration supported previous findings for short-term exposure, however, non-avoidance of the thermal treatment was unexpected. Possibly, the birds were unable to associate the delayed heat stress with the compartment. Alternatively, the thermal conditions were not perceived as aversive either initially or throughout the 60min confinement. The preference method provides a useful starting point for assessing combinations of stressors which affect broiler welfare, allowing relative ranking of treatments from an animal-centred perspective.     

The effects of oestrogen and progesterone on re-excretion of infectious bronchitis virus strain G (correction of strainG) in SPF chickens.

The effects of oestrogen and progesterone on the re-excretion of IB virus strain G in chickens infected at day-old was evaluated in this study. Following infection of the chickens at day-old, the birds were swabbed regularly from the trachea and cloaca until no more virus was isolated from either site. Between 10 and 14 weeks of age oestrogen and progesterone were administered by intramuscular injection to infected or control chickens. An infected but non-hormone injected group was maintained. All the birds were monitored for virus re-excretion and/or increase in serum neutralising (SN) antibody levels during this period of treatment. Similar parameters, and the egg production of these birds were evaluated when they reached their natural sexual maturity. At the end of the experiment, the birds were sacrificed and their internal organs especially the reproductive organs were examined for any pathological lesions. The acute phase of the disease following infection at day-old was typical of IB virus infection in terms of clinical signs and virus excretions from trachea and cloaca [1]. The injected hormones failed to induce virus re-excretion as no virus was isolated during this period. There was no change in the level of antibody during this period either. However, when the hens attained their natural sexual maturity, IB virus was re-excreted by all the birds. Isolations was also more frequent from the cloaca than from the trachea. The SN antibody levels of individual showed no definite pattern to correspond with periods of re-excretion in the birds up to the end of the experiment. The control birds remained normal throughout the period of the study.