Tibial dyschondroplasia in the fowl

Waddle and shuffle: gait alterations associated with domestication in turkeys

Domestication has altered turkey morphology by artificially selecting for increased muscle mass and breast meat. Artificial selection has resulted in birds that weigh up to 3 times more than their wild counterparts, with relatively little change in the length of their bones and limbs. Considering these structural changes, it seems probable that domestic turkey locomotor kinematics and kinetics would also be altered. To examine the locomotor dynamics of wild and domestic turkeys, we had both strains walk down a runway with a force plate at the center to measure their ground reaction forces and gait parameters. The location of their center of mass was also quantified using a force plate and bi-planar x-ray and found to be further anterior in the domestic strain. The domestic turkeys locomoted across a lower range of speeds (0.25-1.64 ms^-1) than the wild turkeys (0.26-3.26 ms^-1) and increased their stride frequency at a higher rate. They also displayed large lateral oscillations, i.e. waddling, during walking that translated into relatively high medio-lateral ground reaction forces and lateral kinetic energy (3.5 times higher than that of wild turkeys). The results indicate that domestic turkey locomotion is not simply a slowed down version of wild turkey locomotion. The changes in gait observed are similar to the shuffling gait present in some human populations, such as Parkinson's patients, which serves to increase stability. The domestic turkey's increased body mass and more anterior center of mass position may require these kinematic and kinetic gait differences.

Unexpected consequences of genetic selection in broilers and turkeys: problems and solutions

1. Genetic theory leads to the expectation that unexpected consequences of genetic selection for production traits will inevitably occur and that these changes are likely to be undesirable. 2. Both artificial selection for production efficiency and "natural" selection for adaptation to the production environment result in selection sweeps that increase the frequencies of rare recessive alleles that have a negative effect on fitness. 3. Fitness is broadly defined as any trait that affects the ability to survive, reproduce and contribute to the next generation, such as musculoskeletal disease in growing broiler chickens and multiple ovulation in adult broiler parents. 4. Welfare concerns about the negative effects of genetic selection on bird welfare are sometimes exaggerated but are nevertheless real. Breeders have paid increasing attention to these traits over several decades and have demonstrated improvement in pedigree flocks. There is an urgent need to monitor changes in commercial flocks to ensure that genetic change is accompanied by improvements in that target population. 5. New technologies for trait measurement, whole genome selection and targeted genetic modification hold out the promise of efficient and rapid improvement of welfare traits in future breeding of broiler chickens and turkeys. The potential of targeted genetic modification for enhancing welfare traits is considerable, but the goal of achieving public acceptability for the progeny of transgenic poultry will be politically challenging.

Anatomical and biomechanical traits of broiler chickens across ontogeny. Part II. Body segment inertial properties and muscle architecture of the pelvic limb

In broiler chickens, genetic success for desired production traits is often shadowed by welfare concerns related to musculoskeletal health. Whilst these concerns are clear, a viable solution is still elusive. Part of the solution lies in knowing how anatomical changes in afflicted body systems that occur across ontogeny influence standing and moving. Here, to demonstrate these changes we quantify the segment inertial properties of the whole body, trunk (legs removed) and the right pelvic limb segments of five broilers at three different age groups across development. We also consider how muscle architecture (mass, fascicle length and other properties related to mechanics) changes for selected muscles of the pelvic limb. All broilers used had no observed lameness, but we document the limb pathologies identified post mortem, since these two factors do not always correlate, as shown here. The most common leg disorders, including bacterial chondronecrosis with osteomyelitis and rotational and angular deformities of the lower limb, were observed in chickens at all developmental stages. Whole limb morphology is not uniform relative to body size, with broilers obtaining large thighs and feet between four and six weeks of age. This implies that the energetic cost of swinging the limbs is markedly increased across this growth period, perhaps contributing to reduced activity levels. Hindlimb bone length does not change during this period, which may be advantageous for increased stability despite the increased energetic costs. Increased pectoral muscle growth appears to move the centre of mass cranio-dorsally in the last two weeks of growth. This has direct consequences for locomotion (potentially greater limb muscle stresses during standing and moving). Our study is the first to measure these changes in the musculoskeletal system across growth in chickens, and reveals how artificially selected changes of the morphology of the pectoral apparatus may cause deficits in locomotion.

Avian tibial dyschondroplasia in 19th-century turkey (Meleagris gallopavo L. 1758) remains from the Royal London Hospital

In this paper we call attention to the first recorded archaeological examples of avian tibial dyschondroplasia. This condition is identified in three turkey (Meleagris gallopavo L. 1758) tibiotarsi from the Royal London Hospital site in London, UK. The lesions are described, radiographed and differentially diagnosed. Recognition of this condition testifies to the pace of breed development in the 19th-century and the unintended health consequences of 'improvement'.

Role of dietary calcium and available phosphorus in the aetiology of tibial dyschondroplasia in growing turkeys

1. Large White male turkeys from a heavy commercial male-line were fed 16 diets containing 4 concentrations of calcium (6, 10, 14 and 18 g/kg) and available phosphorus (3, 5, 7 and 9 g/kg) in a 4 x 4 factorial experiment. There were three replicates (pens) of each treatment and the skeletal health, morphology and mineral status of 4 turkeys from each pen were assessed at 7, 10 and 13 weeks of age. 2. The prevalence of tibial dyschondroplasia increased after 7 weeks of age and was present in 50 and 71% of turkeys respectively at 10 and 13 weeks. The lesion was localised in the caudal aspect of the proximal tibiae. Dietary calcium and available phosphorus did not affect the prevalence of the lesion except in turkeys on the diet containing 6 g calcium/kg, where body weight and the incidence of tibial dyschondroplasia were low. 3. Histological investigation showed no evidence of rachitic changes. 4. Low dietary calcium was associated with lower tibial plateau angles at 10 and 13 weeks of age. Tibial torsion and the angle of rotation were not affected by dietary treatments or age. Tibial torsion and the angle of rotation were not affected by dietary treatments or age. 5. Increasing dietary calcium increased tibial radiodensity, cortical density and the widths of the cortex and proximal tibiotarsus. Radiodensities increased to 10 weeks and were significantly lower at 13 weeks of age. 6. Bone ash, calcium and phosphorus declined with age, particularly between 10 and 13 weeks, whereas bone calcium: phosphorus ratios were not affected by dietary treatment or age. 7. Dietary calcium was positively associated with blood calcium and calcium ion concentrations and was without effect on blood phosphorus. Available phosphorus was associated positively with increased blood phosphorus and lower calcium ion concentrations but had no effect on total calcium. Alkaline phosphatase activity was low at high concentrations of dietary calcium with low available phosphorus and there was higher activity on diets containing low calcium and high available phosphorus.

Study of leg weakness in two commercial broiler flocks

The major causes of leg weakness/lameness were investigated in two male commercial broiler flocks. The numbers of dead and lame birds culled from the flocks each day were recorded by the flock managers. Forty-four lame birds and 22 sound birds were examined postmortem during a period of six weeks and the proximal and distal end of each femur, tibiotarsus and tarsometatarsus were examined histologically. Attempts were made to isolate bacteria and viruses from the proximal end of each femur. Blood samples were examined for antibodies to chicken anaemia virus (CAV), infectious bursal disease virus (IBDV) and Mycoplasma species. Bacterial chondronecrosis with osteomyelitis was identified in the proximal end of the femur of eight of the 44 lame birds, and in the proximal end of the tibiotarsus of a further bird (20.4 per cent). Gram-positive bacteria were present in all the lesions. Staphylococcus aureus was recovered from 62.5 per cent of the lesions confirmed by histology. Bacterial chondronecrosis associated with S aureus has thus been identified as an important cause of leg weakness in these commercial broilers. Lesions suggestive of the condition were visible macroscopically in only 11.1 per cent of the cases subsequently diagnosed by histology and bone histology is therefore required before a diagnosis can be excluded. Angular limb deformities (13.6 per cent) and spondylolisthesis (11.4 per cent) were the most common macroscopic lesions identified as causes of lameness. The overall incidence of tibial dyschondroplasia was similar in both the lame and sound broilers, but severe lesions were found only in lame birds (4.5 per cent).

Relationships between the bone pathologies, ash and mineral content of long bones in 35-day-old broiler chickens

Histological examinations and estimations of the contents of ash, phosphorus and calcium were used to investigate the femora and tibiotarsi from lame and normal 35-day-old broilers from Holland, Northern Ireland and Scotland. The prevalence of different pathologies varied with the source of the broilers and there were correlations between histological and bone ash values. The most common condition causing lameness was bacterial infection within the physis and cartilaginous epiphysis (bacterial chondronecrosis) of the proximal tibiotarsus, and there was a possible link between rickets attributable to a relative phosphorus deficiency and this condition. There were wide variations between birds in the cortical bone quality as assessed histologically and by estimates of the bone ash content and phosphorus to calcium ratios. Theses variations may be related to different probabilities of bone fracture.

Expression of the gene for transforming growth factor-beta in avian dyschondroplasia

Previous immunolocalisation studies of dyschondroplasia have indicated that there is a reduction in the number of growth plate chondrocytes containing the protein transforming growth factor beta 3 (TGF-beta 3). The reduction in TGF-beta 3 in dyschondroplasia is likely to be a direct result of a reduction in the expression of the TGF-beta 3 gene. mRNA was extracted from small (0.09 g) samples of growth cartilage from the proximal tibiotarsus of three-week-old broiler chicks. The cartilage samples contained cells from all three zones of the growth plate (proliferative, transitional and upper hypertrophic) and were collected from normal and dyschondroplastic growth plates. The dyschondroplastic growth plates were identified by an accumulation of transitional chondrocytes which were considered to be a result of a failure to differentiate to the hypertrophic phenotype. A semi-quantitative polymerase chain reaction (PCR) was used to estimate the quantity of mRNA specific for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and for each of the three isoforms of TGF beta (TGF-beta 1, TGF-beta 2 and TGF-beta 3) in each of the cartilage samples. The levels of expression of mRNA for GAPDH, TGF-beta 1 and TGF-beta 2 were similar in the two groups, but the expression of TGF-beta 3 mRNA was significantly reduced in the samples from the dyschondroplastic growth plates. The reduction in TGF-beta 3 levels is thought to be associated with the failure of chondrocyte hypertrophy in dyschondroplasia, and provides in vivo evidence that TGF-beta 3 is part of the cascade of events associated with the differentiation of chondrocytes during endochondral ossification in the chick.

Sequential studies of endochondral ossification and serum 1,25-dihydroxycholecalciferol in broiler chickens between one and 21 days of age

Two commercial broiler flocks of two distinct strains (A and B) were studied at weekly intervals from day old to 21 days, to assess the progressive endochondral ossification of the proximal tibiotarsus and the serum concentration of 1,25-dihydroxycholecalciferol (1,25(OH)2D3). The incidence of defects of endochondral ossification was different in the two strains, strain B having an incidence of tibial dyschondroplasia (TD) of 10 to 70 per cent and strain A an incidence of 10 to 20 per cent. In strain B, 40 per cent of the bone samples collected at 14 days of age also had lesions of calcium deficiency rickets. The concentration of 1,25(OH)2D3 in the two flocks was similar in the day-old chicks, but was 40 to 50 per cent lower at seven, 14 and 21 days of age in strain B, during the development of the rachitic and dyschondroplastic lesions. These results suggest that TD in some broiler strains is related to an inherent predisposition to rickets and to lower serum concentrations of 1,25(OH)2D3.

Avian tibial dyschondroplasia: a morphological and biochemical review of the growth plate lesion and its causes

Avian tibial dyschondroplasia is a disease found in fast growing strains of chickens, ducks, and turkeys worldwide in which growth plate cartilage accumulates in the metaphyseal region of the tibiotarsus; it is similar to mammalian osteochondrosis. Several biochemical and pathologic studies have shown that the growth plate chondrocytes do not reach their expected size in the hypertrophic zone and necroses prematurely. The chondrocytes also produce decreased amounts of extracellular proteins, such as collagen X and fibroblast growth factor-beta, that are necessary for cartilage maturation. This immature cartilage becomes highly cross-linked in the collagen molecules and apparently resistant to resorption and vascularization by the metaphyseal vessels. The dyschondroplastic cartilage remains in the metaphysis for several weeks. Not until the growth rate of the birds slows down is the cartilage able to be resorbed and replaced by trabecular bone. Many conditions have been found to induce tibial dyschondroplasia, including copper deficiency; fusarochromanone, thiram, and antabuse intoxication; excessive dietary levels of cysteine and homocysteine; metabolic acidosis; and bird rearing environment. However, the mechanism(s) by which these various methods induce tibial dyschondroplasia is presently not known. Current research is focusing on understanding the development of the disease and whether or not all these methods work by the same physiological chain of events. Recent biochemical evidence suggests that a copper deficiency might be caused by a different mechanism than genetically and thiram-induced tibial dyschondroplasia.

Plasma concentrations of growth hormone and insulin-like growth factor-I in chickens developing tibial dyschondroplasia

The concentrations of plasma growth hormone (GH) and insulin-like growth factor-I (IGF-I) were measured in broilers during the initial development of tibial dyschondroplasia. Chicks were fed a standard starter ration, or a diet imbalanced in calcium and phosphorus to increase the incidence of dyschondroplasia. At 14 days of age four blood samples were collected and assayed for GH and IGF-I. The chicks were killed at three weeks of age and sections of bone were assessed histologically for evidence of dyschondroplasia. All the chicks displayed a pulsatile pattern of GH secretion. Eight of the group fed the imbalanced diet developed dyschondroplasia which was accompanied by a significant increase in the mean and peak GH concentrations compared with the control group but no increase in basal concentrations. The chicks fed the imbalanced diet which did not develop dyschondroplasia were not different from the control birds. There were no differences in IGF-I concentrations between the groups.

Factors influencing growth plate cartilage turnover

A number of nutrients and chemicals have now been identified as consistent inducers of tibia dyschondroplasia (TD). Thiram, Antabuse, and fusarochromanone induce TD when fed at 30 to 75 ppm. Cysteine, cystine, homocysteine, and histidine induced TD when fed at .5 to 3% of the diet. Cation: anion imbalances resulting in acidotic diets also induced TD. Even though prevention of TD induced by these chemicals and nutrients has been established, reversal of the spontaneous TD lesion has not been clearly demonstrated. Thus, the etiology of the spontaneous lesion awaits elucidation. These model systems all suggest that TD is the result of decreased growth plate cartilage degradation. Recent work has shown that increased collagen cross-links in the accumulated cartilage, which makes collagen less susceptible to degradation. Cysteine-induced TD seems to decrease growth plate collagenase activity and production. A role of growth plate macrophages in paracrine signaling of collagenase production by chondrocytes has been presented.

Physiological studies of turkey tibial dyschondroplasia

Comparative differences between tibial dyschondroplastic (TD) and age-matched control turkey epiphyseal cartilages were studied using cellular, metabolic, and extracellular matrix characteristics. Alkaline phosphatase and aryl sulfatase activities were measured as variables of calcification and cartilage degradation, respectively. There was a decrease in the activities of both enzymes in TD tissues. An increase in tissue phosphate concentrations was noted in the TD tissue whereas neither tissue calcium nor serum calcium and phosphorous concentrations were affected. Profiles of noncollagenous and collagenous proteins from normal and TD-affected tissues were compared following in vitro biotinylation of epiphyseal cartilage followed by a sequential extraction using 4 M guanidine HCl and pepsin digestion, respectively. Electrophoretically separated proteins from both extracts were analyzed on Western blots and compared for any prominent differences between normal and TD cartilages. Biotinylation enhanced the detectability of extracted proteins. There were, however, no major differences in the patterns of noncollagenous or collagenous proteins between the two groups of tissues. Tibial dyschondroplastic lesions further exhibited a large number of dead chondrocytes, which increased with severity of lesion. There appears to be no significant difference in the pattern of extracellular-matrix-associated proteins. However, enzyme and metabolic activities of TD-affected cartilages were significantly reduced, and this may be due to premature death of chondrocytes in the process of development.

Effects of selected minerals on acid-base balance and tibial dyschondroplasia in broiler chickens

Experiments were conducted to determine the relative acidogenicities of several anions, including chloride, sulfate, and mono-, di-, and tribasic phosphate in commercial broiler chickens. Graded levels (80 and 160 meq/kg of diet in two experiments; 50, 100, and 150 meq/kg in a third experiment) of all anions were substituted as calcium salts on a molar equivalent basis for calcium carbonate in a semipurified diet. All diets contained equivalent amounts of calcium. The occurrence of tibial dyschondroplasia was determined by visual scoring of the epiphyseal growth plate in the distal end of the tibiotarsus. None of the anions added to the diet at levels of 160 meq/kg or less affected body weight or feed consumption. A higher level of chloride (240 meq/kg) that was utilized in some experiments decreased weight gain by 16 to 22%. All anions except tribasic phosphate resulted in reduced blood pH or bicarbonate concentrations or both. Monobasic phosphate was more acidogenic than dibasic phosphate and sulfate and chloride was the most acidogenic of all mineral anions. All anions including tribasic phosphate increased the severity of tibial dyschondroplasia. There was no consistent relationship between blood pH, bicarbonate concentration, or partial pressure of CO2 and the severity of tibial dyschondroplasia.

Effects of photoschedule and strain cross on broiler performance and carcass yield

The purpose of the present experiment was to examine possible interactions of strain cross and age with photoschedule for broiler performance and carcass yield. Day-old male broiler chicks from strain crosses of either Peterson x Arbor Acres (PA) or Ross x Arbor Acres (RA) were placed in light-controlled chambers (5.6 lx) with either 23 h light (L):1 h dark (D) from 1 to 56 days (Treatment E) or 6L:18D from 1 to 14 days and 1L:3D repeated from 15 to 56 days of age (Treatment BI). There were age by light treatment and age by strain cross interactions for BW; Treatment E had greater BW than Treatment BI from 7 to 42 days, and the PA cross BW was greater than the RA cross BW from 1 to 42 days of age. Cumulative feed efficiency was improved by Treatment BI compared with Treatment E up to 49 days. There were no differences among main effects for mortality, and the incidence of leg problems increased with age. Fillet and tender yields (per lean carcass weight) were higher for Treatment E than BI and opposite responses were seen for drumstick and thigh yields. The RA cross showed higher fillet and tender yields than the PA cross and the opposite relationship was found for drumstick and wing yields.

Live performance and carcass yield of broiler strain crosses provided either sixteen or twenty-three hours of light per day

The purpose of the present study was to compare a restricted (R) lighting program [16 h light (L):8 h dark (D)] with a standard extended (E) lighting schedule (23L:1D) for broilers. Experiment 1 was carried out during March and April (mean temperature of 23.3 C). Light treatments were 1) E; 2) R; 3) 16L:8D Days 1 to 21 and 23L:1D thereafter to 49 days (R3E); and 4) 16L:8D Days 1 to 14 and 23L:1D thereafter to 49 days (R2E). Treatments were factorially arranged with two strain crosses [Indian River x Arbor Acres (IA) and Peterson x Arbor Acres (PA)]. Experiment 2 was carried out during the summer (mean temperature of 27.0 C). Light Treatments E and R were factorially arranged with two strain crosses [Cobb x Arbor Acres (CA) and PA]. In Experiment 1, BW of Cross PA was greater than BW of Cross IA at 1, 14, 35, and 49 days of age. The percentage of birds with breast blisters was greater in Cross PA than IA. The incidence of broken clavicles was lower in Treatments R and R3E than in Treatments E or R2E. In Experiment 2, Treatment E had greater BW than R from 7 to 42 days of age, and BW of Cross CA was greater than that of PA from 1 to 48 days. Yield (percentage of lean carcass weight) of breast meat at 49 days of age was higher for Treatment E than R, and the percentage of birds with breast blisters was greater in Treatment R than E.(ABSTRACT TRUNCATED AT 250 WORDS)

Live performance and yields of broilers provided various lighting schedules

The purpose of the present study was to measure performance and carcass yield from broilers maintained on photoschedules that may influence incidence of leg disorders. Day-old male broilers were placed on litter floors of light-controlled chambers. Four chambers were randomly assigned to each of four light treatments: 1) 23 h light (L): 1 h dark (D) from 1 to 56 days of age (designated extended, E); 2) 1L:3D from 1 to 56 days (intermittent, I); 3) 6L:18D from 1 to 14 days and 1L:3D from 15 to 56 days (brief-I, BI); and 4) 6L:18D from 1 to 14 days and 23L:1D from 15 to 56 days (brief-E, BE). Mean (+/- SEM) light intensity was 5.4 +/- .26 lx for all light treatments. At 13, 21, and 42 days of age, Treatments BI and BE had lower BW than Treatment E. The percentage of birds with leg abnormalities among treatments was greater at 56 days than at 42 days. The BI birds had significantly fewer leg abnormalities than E birds. There was an age by treatment interaction for the frequency of tibial dyschondroplasia (TD), with BI showing better recovery from TD at 56 days than other treatments. At 42 days of age, split breast yield (percentage of BW) was greater in E than I, and breast yield (percentage of lean carcass) was greater in E and BI compared with I. At 56 days of age, yield (percentage of BW) of tenders was lower in I and BI compared with E and BE.(ABSTRACT TRUNCATED AT 250 WORDS)

Avian tibial dyschondroplasia: a comparison of the incidence and severity as assessed by gross examination and histopathology

The assessment of avian tibial dyschondroplasia (TD) in many recent studies is based on examination of slices of the proximal tibiotarsus with the naked eye. This study examines the incidence and severity of TD in broilers under four different dietary regimes and compares the efficacy of naked eye assessment with histopathological examination. The diets contained reduced levels of calcium relative to phosphorus with adequate (diet 1) and high (diet 2) levels of vitamin D3 supplementation; a very low calcium diet (diet 3) and a standard diet (diet 4) were also included. Gross examination suggested that TD was present in 80 per cent, 79 per cent and 27 per cent of tibiotarsi from birds on diets 1, 2 and 4, respectively. However, histological examination indicated TD, correspondingly, to be present in 18 per cent, 39 per cent and 6 per cent of tibiotarsi. Some birds on diet 1 exhibited physeal changes consistent with mild hypocalcaemic rickets. Many of the bone extremities which, grossly, were considered dyschondroplastic (diets 1, 2 and 4), histologically were shown to have an extensive hypertrophied zone with poor metaphyseal vessel penetration, but no cellular or matrix changes consistent with TD. This cast doubt on the validity of earlier studies of TD which relied solely on naked eye examination. The birds on diet 3 all demonstrated histopathology considered consistent with severe hypocalcaemic rickets and the present study suggests that in three-week-old broilers a moderately hypocalcaemic diet with a high level of vitamin D3 will not cause rickets but will increase the incidence and severity of TD.(ABSTRACT TRUNCATED AT 250 WORDS)

Natural occurrence of the mycotoxin fusarochromanone, a metabolite of Fusarium equiseti, in cereal feed associated with tibial dyschondroplasia

The mycotoxin fusarochromanone, a metabolite of Fusarium fungi, is able to induce tibial dyschondroplasia (TD) in chickens under experimental conditions. On the basis of health surveillance data on TD, two broiler farms with TD prevalence rates of up to 56% were identified. In the corresponding pelleted feed samples, fusarochromanone was detected in all 12 samples analyzed by column purification and TLC, with concentrations 4 to 59 micrograms/kg. No Fusarium fungi were available from the feed because of the pelleting process, but seven Fusarium equiseti strains previously isolated from Danish cereals were checked for fusarochromanone production, and all produced fusarochromanone at 57 to 1,435 mg/kg. Thus, the potential for fusarochromanone production by F. equiseti is considerable. The identification of fusarochromanone from feed and F. equiseti was confirmed by mass, infrared, and nuclear magnetic resonance spectral analyses. This is the first report of fusarochromanone as a naturally occurring contaminant.

Development of a quantitative method for the evaluation of varus-angular bone deformity in chickens

A quantitative technique was developed to measure the degree of flexion (twisting) and torsion (angulation) of the tibiotarsus bone from chickens affected with varus-angular bone deformity (varus-ABD). A plexiglass device was constructed consisting of X, Y, and Z-axis planes. The Y-axis plane was used to position the tibia in a constant reference position. The distance in millimeters from the (0, 0, 0) coordinate to the (X', 0, 0) coordinate was used to measure medial tibial flexion (TF), and the distance from the (0, 0, 5 cm) coordinate to the (X', 0, 5 cm) coordinate was used to measure lateral TF. The X-axis plane was fitted with a protractor to measure the angle of the proximal head of the tibia as a measure of tibial torsion (TT). The Z-axis plane was used to measure tibial length. Tibias with mild varus-ABD had TF values of greater than 0 but less than or equal to 5 mm, whereas severe varus-ABD tibias had TF values of greater than 5 mm. The TT values ranged from 10 to 60 degrees, with the lower values associated with severe varus-ABD.

Histology and histomorphometry of the tibia growth in two turkey strains

Qualitative and quantitative histological methods on decalcified and undecalcified specimens were used for comparing the linear and radial growth of the tibia in two turkey strains: a light strain, Betina, without leg problems and a heavy strain, Maxiboul, with leg problems. Groups of 10 clinically healthy male turkeys of each strain were studied at 2, 6, 8, 16, and 20 weeks of age. Three histomorphometric parameters of longitudinal growth were quantitated in the proximal growth plate and metaphysis. These were: height of the proliferative zone, density of ossification buds (metaphyseal sprouts), and volume of metaphyseal trabecular bone. Four histomorphometric parameters of radial growth were quantitated in the diaphysis. These were cortical thickness, active zone/total surface, density of maturing osteons in the active zone, and bone apposition rate at the maturing primary osteons level. The results showed some evidence for factors predisposing to leg problems in the Maxiboul strain. At 8 weeks, the Maxiboul strain had a lower ossification bud density (13.1/mm2 vs. 20.7/mm2; P less than .05) and a lower metaphyseal trabecular bone volume (16.4% vs. 22.0%; P less than .05) when compared to the Betina strain. No difference was detected in the cortical thickness of the diaphysis in the two strains except at 2 weeks of age (799 microns vs. 387 microns; P less than .001), despite the heavier weight of the Maxiboul strain.

Ultrastructure of Fusarium-induced tibial dyschondroplasia in chickens: a sequential study

Female broiler chicks were randomly placed into two groups; one was treated twice daily with TDP-1 (a mycotoxin produced by Fusarium roseum), the other was controls. Chicks were sacrificed after 2, 4, 6, 8, 10, and 14 days of treatment and were evaluated for tibial dyschondroplasia. TDP-1-treated chicks examined after 2, 4, or 6 days of treatment had either no gross lesions (2 days) or mild gross lesions (4 and 6 days); growth plates from these groups did not have ultrastructural changes. TDP-1-treated chicks examined after 8, 10, or 12 days of treatment had moderate to severe gross lesions of tibial dyschondroplasia. These groups also had intracellular lipid accumulation and necrosis of chondrocytes within the retained cartilage. It was concluded that the cellular changes in tibial dyschondroplasia develop only after the cartilage accumulates; the changes are sequelae, possibly due to nutrient depletion from an increased distance between chondrocytes and perforating epiphyseal vessels, their nutrient source.

Fractured fibulae in broiler fowls

Fibular diaphyseal fractures were identified bilaterally or unilaterally in 15 broilers aged between 13 and 105 days. Incomplete cortical defects were also identified on radiographs in a further 8 birds. Fractures and incomplete defects always occurred at the Tuberculum M. iliofibularis of fibulae. The character of bone at this site differed from bone elsewhere in the diaphysis. Following fracture, cartilaginous callus united the diaphyseal segments and pseudarthrosis or fibrous non-union were common sequelae. The concept that fibular fractures in broilers are always a consequence of abnormal proximal tibiotarsal curvature is not supported by this study. It is suggested that differential growth of the paired crural bones is of primary importance.

The influence of ascorbic acid on the occurrence of tibial dyschondroplasia in young broiler chickens

Two distinctly different basal diets were used to test the influence of supplementary ascorbic acid on the occurrence of tibial dyschondroplasia. Addition of either .1 or .25% ascorbic acid to these diets did not alter the occurrence of tibial dyschondroplasia in 25-day-old broiler chickens. However, supplementary ascorbic acid did increase the amounts of ascorbic acid present in blood plasma. Also, individual differences in circulating ascorbic acid were not associated with this disease. Furthermore, two strains of chickens selected for high or low incidence of tibial dyschondroplasia had similar amounts of this vitamin in blood plasma. In contrast to the results reported for the Willow Ptarmigan, ascorbic acid does not appear to be involved in the development of tibial dyschondroplasia in the young broiler chicken.

Some observations on the development of the long bones of ratite birds

Observations were made on the long bones of 16 young ratite birds (10 rheas, 3 emus and 3 ostriches), from 1-day-old to 12 weeks of age. At hatching all long bones contained large cartilaginous cones which were continuous with the growth plates, and an osseous cortex. At one week of age ossification had commenced on the periphery of these embryonic cones and in some bones the cones had become separated from the growth plates. At 3 weeks of age the embryonic cones of cartilage were still present in the proximal and distal tibio-tarsi and narrow cartilaginous bridges connected the cones to the growth plates. Embryonic cones were not present in other long bones of this 3-week-old rhea nor in the long bones of ratites 6, 8 and 12 weeks of age. Other praecocial birds such as turkey poults and chickens have cones of embryonic cartilage in their long bones at hatching and these persist in the tibio-tarsi till one to 2 weeks of age. The presence of large cones of embryonic cartilage in the tibio-tarsal bones of 3-week-old ratite birds is probably a normal phenomenon. Awareness of this feature is necessary for the correct differential diagnosis of the prevalent musculoskeletal disorders of ratite birds.

Tibial dyschondroplasia in growing chickens experimentally intoxicated with tetramethylthiuram disulfide

Graded levels of tetramethylthiuram disulfide (0, 30, 60, 120, and 240 ppm) were incorporated into a broiler starter ration fed to chickens from one day old to 8 weeks of age. Clinical signs of leg abnormalities were observed as early as 5 days after the beginning of the trial. After the 3rd week, the joints were shown to present lesions, especially in the femorotibial articulation, comparable to the ones found in perosis. Tibiotarsus and other organs from the birds were examined for pathological changes at weekly intervals. Histologically, the tibiotarsus has shown an osteochondrodystrophy identical to that of tibial dyschondroplasia (TD), although it varied according to the level of tetramethylthiuram disulfide. The histopathology of the thyroid gland of the chickens involved in the present experiment will be reported in a separate manuscript.