High dietary concentrations of biotin did not prevent foot pad dermatitis in growing turkeys and external scores were poor indicators of histopathological lesions

1. A randomised block experiment was conducted to determine the effects of increasing dietary biotin supplementation (0, 200, 800 and 1600 microg/kg) on macroscopic and histological changes associated with the development of foot pad dermatitis (FPD) in growing turkeys. 2. Each treatment was replicated in 4 pens containing 36 birds at the start of the experiment. The birds were weighed and external foot pads were scored at 2-week intervals from 2 to 14 weeks of age. A blood sample was obtained at the same ages from two birds in each pen and tissue from one foot pad was processed for histological examination. Liver samples were obtained for determination of fat content. 3. Increasing dietary biotin supplementation was associated with higher initial plasma concentrations of biotin but there was no effect on external scores or histopathology of foot pad lesions. FPD increased rapidly from 2 to 6 weeks and remained similar thereafter. There was no effect of dietary biotin on liver fat content. 4. The correlations between external foot pad scores at different ages were all less than 0.4. The correlation between external and histopathological scores was 0.56 and the respective correlations with body weight were 0.52 and 0.65. There were no differences between the body weights of birds with different external scores but high histopathological scores were associated with lower body weights. 5. It was concluded that current recommendations for biotin in wheat-soy rations for growing turkeys are adequate for normal growth and development and that higher supplements of biotin in these experimental conditions did not prevent the occurrence of FPD.     

Influences of increased levels of biotin, zinc or mannan-oligosaccharides in the diet on foot pad dermatitis in growing turkeys housed on dry and wet litter

Foot pad dermatitis (FPD) is very common in turkeys and it is an animal health and welfare issue affecting not only performance and walking ability but also the carcass quality. Thus, there is a great need to find out the preventive measures against this problem. The potential roles of extra dietary biotin, Zn and mannan-oligosaccharides (MOS) in preventing the development of FPD were assessed in this study which was conducted on 2-week-old female turkeys over a period of 4 weeks. The birds were allotted to four groups, with 29 each, and housed on dry wood shavings in floor pens. The turkeys were fed a control (300 μg biotin and 50 mg Zn/kg), high biotin (2000 μg/kg), high Zn (150 mg/kg) or MOS (1%) diet. Half of the turkeys in each group were additionally exposed to wet litter (27% DM) for 8 h daily in adjacent separate boxes. Foot pads of the birds were examined on days 0, 7, 14, 21 and 28 and assessed macroscopically and histopathologically for foot pad lesions. High dietary levels of biotin or Zn significantly reduced the severity of FPD on dry litter (score 1 vs. 2 in control) but not on wet litter. However, MOS did not affect the severity of foot pad lesions either on dry or wet litter. In addition, the severity was overall substantially higher on wet (approximately three times) than on dry litter. The present results suggest that adding high levels of biotin or Zn to the diet could reduce the development and severity of FPD on dry litter but without having any preventive effects on wet litter. Finally, the high litter moisture appears to be the major factor resulting in FPD. Therefore, the litter should be maintained dry to minimize the prevalence and severity of FPD in turkeys.     

Effects of litter quality (moisture, ammonia, uric acid) on development and severity of foot pad dermatitis in growing turkeys

High dietary protein is thought to increase the incidence of foot pad dermatitis (FPD) as a result of increased uric acid and secondary ammonia production in the excreta or litter. This study was conducted on female turkeys over a period of 3 wk to test the effects of water alone, and also of these end products of protein metabolism, independent of the presence of excreta, on the development and severity of FPD. The animals were allocated into four groups, with 20 birds in each, and housed in floor pens on dry, clean wood shavings (changed daily) throughout the experiment. The control group was housed continuously in its pen, whereas the other groups were additionally exposed daily (for 8 hr) to experimentally treated wood shavings, in adjacent separate boxes, enriched with water alone or water with NH4Cl or uric acid. NH4Cl and uric acid were added via water to the litter to achieve the concentrations of ammonia and uric acid in the litter as found in the excreta of turkeys (about 0.50 g ammonia and 20 g uric acid/kg). The wet litter was kept clean by removing the excreta twice daily and by changing the litter twice a week. The foot pads of all birds were examined on days 0, 7, 14, and 21 and scored externally (macroscopically). Three birds were selected from each group on days 0, 7, and 14, while the remaining 11 birds/group were sacrificed on day 21 for histopathologic assessment of foot pads. The severity of FPD was found to be markedly higher (about 3 times) on wet than on dry litter. There were no negative effects of ammonia and uric acid on foot pad lesions. The results indicate that high litter moisture is the most likely factor causing FPD in turkeys. A focus on nitrogenous irritants in the litter was not substantiated. Exposure of birds to wet litter (in the absence of excreta) for only 8 hr/day was sufficient to develop foot pad lesions. The present results suggest that a focus on the protein content of the diet as a cause of FPD may be misplaced, but all dietary factors which increase excreta or litter moisture, or both, should be considered. The prevalence and severity of FPD can be reduced by maintaining dry litter.     

Excess dietary cystine intensifies the adverse effect of a methionine deficiency in the cat

Foot pad dermatitis has been observed in turkeys, puppies and kittens fed diets deficient in methionine. Excess cystine aggravated the lesions and decreased body weight gain in puppies and turkeys. The objective of this study was to determine whether methionine deficiency induced perioral and foot pad lesions in kittens and whether excess cystine exacerbated the lesions. Eighteen kittens were divided into three groups and offered one of three diets: diet 1, low-methionine, low-cystine (LMLC; 1.6 g methionine and 1.6 g cystine/kg diet); diet 2, low-methionine, high-cystine (HMHC; 1.6 methionine and 15 g cystine/kg diet); diet 3, high-methionine, high-cystine (HMHC; 15 g methionine and 15 g cystine/kg diet). Kittens in the LMLC group lost body weight, whereas those in the LMHC group maintained their body weight and those in the HMHC group gained weight. Plasma methionine concentrations were significantly higher (p < 0.001) for the HMHC group than for the LMLC and LMHC groups. Plasma cyst(e)ine (sum of cysteine and cystine) concentrations were different (p < 0.001) among all the three groups. Two kittens given the LMLC diet developed mild perioral lesions. All kittens receiving the LMHC diet developed foot pad lesions and severe perioral lesions. Histopathological changes observed in perioral biopsy specimens were similar to those described in protein deficiency. In conclusion, the results showed that a diet severely deficient in methionine causes perioral lesions in kittens, and that addition of excess cystine to the diet aggravates the perioral lesions and also causes foot pad lesions.     

Effects of floor heating and litter quality on the development and severity of foot pad dermatitis in young turkeys

Actions concerning animal health in turkey production are coming more and more to the fore. Litter quality has a great impact on the bird's health and welfare. This study aimed at evaluating the effects of using floor heating, different litter materials, and exposure to litter with a "critical moisture content" of 35% for 16 or 24 hr/day on the severity of foot pad dermatitis (FPD), a widespread disease in fattening turkeys. Four groups of 2-wk-old female turkeys, with 20 birds in each, were reared during 3 wk. All turkeys were fed a commercial pellet diet ad libitum. The first two groups were kept on wood shavings (35% moisture) without and with floor heating. The other two groups were housed on lignocellulose (Soft Cell) of 35% moisture without and with floor heating. In each group, half of the birds were housed for 8 hr/day in adjacent separate boxes where the litter was kept clean and dry throughout the experimental period. Foot pads were assessed weekly for external and at day 35 for histopathologic scoring (scores: 0 = healthy; 7 = ulcer). At day 14 each bird had normal and healthy foot pads. The results indicate that using floor heating resulted in significantly lower FPD scores (0.8 +/- 0.2) compared to groups without floor heating (2.0 +/- 0.8). Using lignocellulose as a litter material resulted in significantly lower histopathologic FPD scores (1.4 +/- 0.7) compared with wood shavings (1.7 +/- 0.8). In all birds housed on dry litter for 8 hr/day, significantly lower FPD scores were found compared to birds housed on wet litter for 24 hr. In conclusion, using floor heating, even with wet litter (35% moisture), independent of the litter type, resulted in reduced severity of FPD compared to those birds housed in pens without using floor heating. Additionally, using lignocellulose as a litter material resulted in lower FPD compared with wood shavings. Keeping litter dry and "warm" could be achieved by using floor heating, which is considered a practical step to enhance animal health and welfare.     

La Sota vaccination may not protect against virus shedding and the lesions of velogenic Newcastle disease in commercial turkeys

The aim of this project is to study the clinical signs and lesion of velogenic Newcastle disease (vND) in commercial turkeys, and also to find out if La Sota vaccination offered protection against these signs and lesions. The cockerels were included as positive controls. One hundred and twenty turkey poults and cockerels were divided into eight groups as follows: unvaccinated unchallenged turkeys (UUT), unvaccinated challenged turkeys (UCT), vaccinated unchallenged turkeys (VUT), vaccinated challenged turkeys (VCT), and along the same lines, the cockerel groups were UUC, UCC, VUC and vaccinated challenged cockerels (VCC). Vaccination was at 3 weeks of age while challenge was at 6 weeks of age. The unvaccinated turkeys and cockerels (UCT and UCC) showed different degrees of depression, diarrhoea and later paralysis at challenge. Total mortality was 100% in cockerels within 6 days, but 60% in turkeys. Similar but milder clinical signs were found in the VCC with a total mortality of 13.3%. The VCT showed mild drop in feed and water consumption, and no mortality. All the challenged groups had significant (p < 0.05) loss of weight when compared with their controls. Necropsy showed that while the UCC had severe proventricular haemorrhages, intestinal and caecal tonsil ulcers, the UCT had no digestive tract lesion. There was severe atrophy of the lymphoid organs in all the challenged groups. Histopathological sections of the bursa, spleen and thymus in all the challenged groups with special emphasis on the vaccinated and unvaccinated turkeys with mortalities of 0 and 60%, respectively, had very severe necrosis and depletion of the lymphoid tissue. Virus was isolated from the cloacal swabs. The haemagglutination inhibition antibodies were significantly higher (p < 0.05) in the challenged groups than the unchallenged. The above observations in the intestinal tracts of UCT are of diagnostic significance while the gross and microscopic lesions in the UCT and VCT show that La Sota vaccination may not protect turkeys against the destruction of the lymphoid organs by vND as earlier reported in chickens. This may lead to immunosuppression and production problems in areas where vND is enzootic.     

Development and Fine Structure of the Reticulate Scales of the Turkey Foetuses with Regard to Occurrence of the Food Pad Lesions in Turkey Poults

Introduction: Most of the morphological studies on the skin of birds refer to chickens. Little can be found about the specific fine structure of the foot‐pad epidermis of turkeys and almost nothing is known about the developing reticulate scales in turkey foetuses. This study deals with the question as to whether the development and morphology of the reticulate scales of turkeys are similar to those of chickens. Since the first signs of food‐pad dermatitis can be observed in turkey poults at the age of four days, it was additionally examined if these alterations can be found in turkey foetuses already. Methods: Foot pad samples of heavy strain BUT Big 6 turkeys were collected at different developmental stages (day 20, 23, and 28 of incubation). The specimens were compared by light‐ and electron‐microscopic methods. Results: On the 20th day of incubation, the reticulate scales cover the food pads as small knob‐like structures. Between the embryonic epidermal cells wide inter‐cellular spaces are visible, and in the intermediate cells multigranular bodies (MGBs) are detectable. Peridermal cells cover the reticulate scales. They are characterized by peridermal granules and protuberances of the outer cell membrane. On the 23rd day of incubation, many lipid droplets are scattered within the intermediate cells. Because a thin stratum corneum has formed, the periderm is almost completely sloughing off. On the 28th day of incubation, the turkey poults hatch. The epidermis has almost reached maturity and a broad stratum corneum is detectable. Conclusions: The development and morphology of the reticulate scale epidermis of turkey is comparable to that of chicken, although little differences were found. Besides former investigations, which described the peridermal protuberances as microvilli, scanning‐electron microscopy proved that they also show a fingerprint‐like surface structure that has not been observed for birds previously. Up to the hatching day, no signs of food pad alterations are seen in developing turkeys.     

Evidence for bursal involvement in the pathogenesis of hemorrhagic enteritis of turkeys

The pathogenesis of hemorrhagic enteritis in turkey poults infected with hemorrhagic enteritis virus (HEV) at 3 days or at 2 or 5 weeks of age was compared with pathogenesis in poults that had been chemically bursectomized neonatally and exposed to cell-culture-propagated virus at 2 or 5 weeks of age. Conventional poults exposed to HEV at 2 or 5 weeks developed clinical disease, and mortality ranged from 38% to 100%. In addition to the splenic and intestinal lesions usually seen with HEV infection, the pancreas, bursa of Fabricius, and thymus were also affected. In contrast, although they were free from detectable maternal antibody, poults infected with HEV at 3 days of age failed to develop clinical disease or mortality; however, virus was demonstrated by histological and electron microscopic examinations in spleens of these poults. Neonatal chemical bursectomy completely prevented the clinical signs, gross lesions, and mortality induced by HEV in poults at 2 or 5 weeks of age. These findings strongly suggest that an intact bursa is necessary for HEV to induce disease in turkeys.     

生长前期北京鸭生物素需要量及脚裂症的初步探究

本文旨在研究不同生物素水平对生长前期北京鸭生长性能的影响,并对生物素缺乏症———脚裂症进行初步探究。试验选用体重相近的1日龄雄性北京鸭480只,随机分成10组,每组6个重复,每个重复8只鸭。各组分别添加0、0.03、0.06、0.09、0.12、0.15、0.18、0.21、1.50 mg/kg生物素及3 g/kg蛋清粉。试验期4周。结果表明,不同生物素水平对1～21日龄北京鸭平均日采食量和平均日增重有显著影响(P<0.05),但对料重比没有显著影响(P>0.05)。统计发现,各组表现出不同程度的脚裂症,其中3 g/kg蛋清粉组最为严重;生物素添加水平高于0.15 mg/kg时,脚裂症得到有效缓解。不同生物素水平对28日龄北京鸭肝脏磷脂含量和血清谷丙转氨酶(ALT)和天冬氨酸氨基转移酶(AST)活性有显著影响(P<0.05)。通过数据分析得出,以平均日增重为衡量指标,采用直线折线和二次曲线模型估测生物素适宜需要量分别为0.180和0.202 mg/kg,并初步判断脚裂症与脱水存在一定的关系。     

Soya bean meal increases litter moisture and foot pad dermatitis in maize and wheat based diets for turkeys but maize and non-soya diets lower body weight

1. A 2 × 2 factorial experiment was conducted to compare the effects of wheat or maize based diets differing in dietary electrolyte balance (DEB) on litter moisture and foot pad dermatitis (FPD) at 4, 8 and 12 weeks of age in heavy-medium turkeys. A second objective was to investigate the effects on foot pad dermatitis of the interaction between dietary composition and artificially increasing litter moisture by adding water to the litter.

2. High DEB diets contained soya as the main protein source whereas low DEB diets did not contain soya bean meal. Diets were formulated to be iso-caloric and iso-nitrogenous in each of 3 successive 4-week phases following recommended dietary compositions. DEB concentrations were 330, 290 and 250 mEq/kg in high DEB diets and 230, 200 and 180 mEq/kg in low DEB diets.

3. Litter moisture and mean FPD score were higher in turkeys fed on high DEB diets compared with low DEB diets whereas there was no difference between maize and wheat.

4. Food intake was similar and body weight was lower after litter moisture was artificially raised in the wet compared with the dry litter treatment and there was no interaction with dietary composition.

5. Mean body weight and feed intake were higher in turkeys fed on wheat compared with maize and in high DEB compared with low DEB diets at 12 weeks of age.

6. Lowering dietary DEB for turkeys may improve litter moisture and lower the prevalence of FPD in commercial turkey flocks.     

Effect of crude protein concentration and dietary electrolyte balance on litter quality,foot pad dermatitis,growth performance and processing yields in two medium heavy turkey hybrids

1. An experiment was conducted to investigate the effect of crude protein (CP) concentration and dietary electrolyte balance (DEB) on growth performance, processing yields, litter quality and foot pad dermatitis (FPD) in male turkeys from two commercial hybrids. Soya bean meal was replaced by vegetable protein sources selected for lower K concentrations to lower DEB in order to improve litter quality and subsequent quality of foot pads.

2. Effects of CP on litter friability and wetness were not consistent during the production period. FPD in turkeys fed on diets with low CP was significantly lower than FPD in turkeys fed on diets with high CP until 84 d. Growth performance was adversely affected at low CP. Processing yields were not affected by CP.

3. Litter was significantly dryer in pens of turkeys fed on diets with low DEB than in pens of turkeys fed on diets with high DEB. FPD in turkeys fed on diets with low DEB was significantly lower than in turkeys fed on diets with high DEB. Growth performance and processing yields were adversely affected at low DEB.

4. FPD in turkey hybrid A was higher than in turkey hybrid B at 28 d of age. Thereafter, no differences in FPD between turkey hybrids were observed. Growth performance and processing yields were not affected by turkey hybrid.

5. Overall, a significant interaction effect of CP × DEB was observed for FCR: in turkeys fed on the high DEB treatment, FCR of turkeys fed on the high CP diets was lower than FCR of turkeys fed on the low CP (LCP) diets whereas on the low DEB treatment, FCR was not affected by CP treatment.

6. It was concluded that litter quality can be improved and FPD may be decreased in turkeys fed on diets containing lower CP and DEB levels.     

Poor serologic response to upper respiratory infection with Mycoplasma synoviae in turkeys

Mycoplasma synoviae (MS) was isolated from a flock of commercial tom turkeys in which a small percentage of the birds exhibited clinical signs and lesions typical of MS synovitis. However, serologic testing of such flocks revealed poor to inconsistent reactivity by agglutination, enzyme-linked immunosorbent assay (ELISA) or hemagglutination inhibition; isolation of MS from such flocks proved to be very difficult. Turkeys were challenged with one of the isolates (K4463B) either by aerosol or systemically by a combination of intravenous, foot pad, and eyedrop routes. Turkeys challenged by the systemic route responded normally to all serologic tests, whereas those challenged by aerosol either responded very poorly on all serologic tests or were seronegative up to 6 wk postchallenge even though they were positive for MS by tracheal culture. These results suggest that turkeys may harbor an upper respiratory infection with MS while remaining serologically negative.     

The nutrition of poultry as a factor affecting litter quality and foot pad dermatitis – an updated review

Foot pad dermatitis (FPD), a condition of inflammation and necrotic lesions on the plantar surface of the footpads, is commonly observed in fast‐growing broiler chickens and turkeys. FPD negatively affects the welfare of birds, performance indices and the economic profit of poultry meat production. Nutrition is an important factor affecting water intake, excreta moisture and litter quality and, in this way, the occurrence and intensity of FPD in birds. This article reviews and discusses the recent results published in the literature on the effects of nutritional factors on litter quality and FPD severity in broiler chickens and turkeys. Literature data on the efficacy of nutritional methods on the litter quality and FPD occurrence are not consistent. However, the results of several experiments indicate that the optimal level of crude protein, biotin and electrolytes (Na, K) in the diet, as well as feed additives such as feed enzymes hydrolysating non‐starch polysaccharides and organic sources of microelements (zinc), may reduce the litter moisture as well as FPD incidence and severity in broiler chickens and turkey.     

Experimental and serologic observations on avian pneumovirus (APV/turkey/Colorado/97) infection in turkeys

An avian pneumovirus (APV) was isolated from commercial turkeys in Colorado (APV/Colorado) showing clinical signs of a respiratory disease. The results of virus neutralization and indirect fluorescent antibody tests showed that the APV/Colorado was partially related to APV subgroup A but was unrelated to APV subgroup B. Turkeys experimentally inoculated with the APV/Colorado were observed for signs, lesions, seroconversion, and virus shedding. Thirty-six 7-wk-old turkeys were distributed into three groups. Eighteen turkeys were inoculated oculonasally with APV/Colorado, six were placed in contact at 1 day postinoculation (DPI), and 12 served as noninoculated controls. Tracheal swabs and blood samples were collected at 3, 5, 7, 10, 14, and 21 DPI. Tissues were collected from three inoculated and two control turkeys on aforementioned days for pathologic examination and APV isolation. Inoculated turkeys developed respiratory disease, yielded APV at 3, 5, and 7 DPI, and seroconverted at 10 DPI. Contact turkeys yielded APV at 7 and 10 DPI. No gross lesions were observed in the turbinates, infraorbital sinuses, and trachea. However, microscopic examination revealed acute rhinitis, sinusitis, and tracheitis manifested by congestion, edema, lymphocytic and heterophilic infiltration, and loss of ciliated epithelia. The inflammatory lesions were seen at 3 DPI and became extensive at 5 and 7 DPI. Active regenerative changes in the epithelia were seen at 10 and 14 DPI. Serologic survey for the presence of antibodies in commercial turkeys (24,504 sera from 18 states) and chickens (3,517 sera from 12 states) to APV/Colorado showed seropositive turkeys in Minnesota, North Dakota, and South Dakota and no seropositive chickens. This report is the first on the isolation of an APV and APV infection in the United States.     

Behavioural assessment of pain in commercial turkeys (Meleagris gallopavo) with foot pad dermatitis

1. Two experiments were conducted to investigate the differences in susceptibility to foot pad dermatitis (FPD) of two medium-heavy lines of turkeys, and whether FPD is painful, by detailed analysis of behaviour in birds with and without analgesic treatment (betamethasone).

2. Turkeys housed on dry litter in the first experiment generally had more frequent bouts of different behaviours that were of shorter duration than birds on wet litter. T-patterns (behavioural sequences) were more frequent, varied and complex on dry than on wet litter. Betamethasone-injected birds of line B, but not breed A, had shorter resting and longer standing durations on wet litter than saline-injected birds.

3. In the second experiment, turkeys on wet litter given saline stood less and rested more than all other treatment groups, suggesting that they experienced pain that was alleviated in birds receiving betamethasone. Turkeys on dry litter had more frequent, varied and complex patterns of behaviour than turkeys on wet litter and birds kept on intermediate litter wetness. Betamethasone provision increased pattern variety regardless of litter treatment.

4. Turkeys with low FPD scores transferred to wet litter and given saline injections had a longer total duration of resting and shorter duration of standing compared to betamethasone-treated birds. Low FPD birds transferred to wet litter had a similar number of patterns and total pattern occurrence as high FPD birds transferred to dry litter. Betamethasone increased pattern variety and frequency compared to saline injections whereas overall pattern complexity was similar.

5. It was concluded that wet litter affects the behaviour of turkey poults independently of FPD and that betamethasone may also change the behaviour of turkeys. There was some evidence from analgesic treatment and T-pattern analyses that FPD was painful. However, there was no evidence of differences in susceptibility to FPD of the two commercial hybrids.

     

Effects of photostimulation at 18, 24 and 30 weeks of age on the productivity of female turkeys fed ad libitum or restricted until point of lay.

1. Turkey females were fed ad libitum or restricted from 6 weeks of age to achieve mean body weights of 0.6 of ad libitum fed birds on photostimulation at 18, 24 or 30 weeks of age. Body weight, food intake, egg production and hatchability were recorded to 54 weeks of age. 2. Restricted turkeys were fed ad libitum after first egg or 36 weeks of age. Food intake after 30 weeks of age averaged 170 g/bird/d and was similar for all treatments. At 54 weeks of age, restricted turkeys photostimulated at 24 and 30 weeks were not as heavy as turkeys photostimulated at 18 weeks and ad libitum fed turkeys. 3. A large proportion of restricted turkeys photostimulated at 18 weeks of age did not commence lay until 30 to 40 weeks and a significant number of restricted birds photostimulated at 24 weeks had short laying cycles. Restricted birds photostimulated at 30 weeks came into lay and showed similar persistency of lay to ad libitum fed turkeys. 4. Ad libitum fed turkeys laid 115.0, 122.0 and 101.0 and restricted turkeys 92.4, 99.5 and 103.4 eggs when photostimulated at 18, 24 and 30 weeks, respectively. The number of non-settable eggs was lower in restricted compared with ad libitum fed turkeys and declined with age at photostimulation. 5. Egg size at the end of the experiment was similar for ad libitum fed turkeys and restricted birds photostimulated at 18 weeks but was 2.3 g lower for restricted birds photostimulated at 24 and 30 weeks of age. 6. Hatchability was higher, and the proportion of second quality poults was lower with eggs from restricted turkeys. The mean numbers of poults hatched were 59.9, 75.1 and 66.0 for ad libitum fed and 71.7, 65.7 and 79.4 for restricted turkeys photostimulated at 18, 24 and 30 weeks of age.     

The influence of age on the response of ring-necked pheasants to infection with marble spleen disease virus.

Ring-necked pheasants that were negative for maternal antibody against type II avian adenoviruses were orally inoculated with 5.0 x 10(2) tissues-culture-infective doses of marble spleen disease (MSD) virus at 1-week intervals through 6 weeks of age, and at 9 and 13 weeks of age. Groups of four virus-inoculated birds and two control birds were necropsied at 4, 6, 8, and 10 days postinoculation, and the spleens were evaluated for gross and microscopic lesions. No lesions consistent with MSD were present in birds inoculated at 1, 2, 3, or 4 weeks of age. A single bird in the group inoculated at 5 weeks of age had gross and microscopic lesions of MSD. Five birds in the group inoculated at 6 weeks of age had lesions of MSD. The patterns of lesion development in the 6-week-old birds were similar to those produced in the 9- and 13-week-old birds inoculated with MSD virus. The reason for the lack of gross or microscopic lesion development during the first 4 weeks of life is unknown.     

Practical assessment and management of foot pad dermatitis in commercial broiler chickens: A Field Study

Foot pad dermatitis (FPD) is a welfare concern in broiler chickens characterized by ulcerated lesions on the pad of the foot, which results from prolonged contact of foot pads with wet litter. During Canadian prairie winters, barn moisture levels tend to increase due to reduced ventilation as a means of conserving heat and minimizing costs. However, there are no published benchmarks regarding the prevalence of foot pad dermatitis in broilers reared in western Canadian provinces such as Alberta, Canada. As such the objectives of the current study were to evaluate practical means of assessing FPD in Alberta broilers as well as on-farm management practices which correlate with higher prevalence of foot pad dermatitis. A management-practices survey and 3 foot pad assessment methods were used to benchmark foot pad dermatitis in 32 broiler flocks throughout the province of Alberta. Four flocks per farm were sampled from a total of 8 commercial broiler farms. Per flock, 200 birds were assessed on-farm, 3 processor-line scores were taken at the processing plant, and 600 foot pad samples were assessed post-processing. The prevalence of foot pad dermatitis by assessment method was benchmarked on a per-flock basis at 28.65% on-farm, 26.17% on the processing line (processor-line), and 31.83% for samples taken off the processing line (processor-sampled). On-farm and processor-sampled assessment results were highly correlated (r = 0.90) compared with processor-line and on-farm (r = 0.77) and processor-line and processor-sampled results (r = 0.72; P < 0.001). Specifically, processor-line assessments were not found to be reliable when repeated (P > 0.10). On farm, wheat straw was used by the majority of Alberta’s producers (62.5%) and was associated with a higher prevalence of foot pad dermatitis per flock (40.6%). In contrast, pine shavings was associated with lower FPD prevalence (6.4%; P < 0.001), but was used by only 21.9% of producers in Alberta. Primary results from this field study support the use of on-farm FPD assessments rather than processor-line-based assessments, and a shift away from wheat straw as a broiler litter substrate.     

High litter moisture alone is sufficient to cause footpad dermatitis in growing turkeys

1. Four randomised block experiments were conducted to determine the role of litter moisture, excreta and alternative bedding materials on the development of footpad dermatitis in growing turkeys. 2. Adding water to the litter increased external and histopathological scores independently of the presence of excreta. Fully developed lesions were induced by the application of water to dry litter in 2 to 4 d. 3. Footpad lesions were associated with discomfort during walking in one experiment and body weight was lower in birds on wet compared with dry litter. 4. Footpad lesions had virtually healed 15 d after transfer of the turkeys from wet to dry litter although histopathology assessment showed some residual tissue repair. 5. Long barley straw was associated with high footpad scores on wet and dry treatments. The footpad scores for turkeys on reprocessed cardboard chips were similarly high whereas scores were similar on paper litter and wood shavings whether dry or wet. 6. It was concluded that high litter moisture alone was sufficient to cause footpad dermatitis in young turkeys and that footpad dermatitis should be minimised by the maintenance of dry litter.     

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.