Tibial Dyschondroplasia Lesions Research Articles

Immunolocalization of osteonectin in avian tibial dyschondroplastic cartilage.

Osteonectin is an acidic calcium-binding protein found in cartilage, bone matrix, vascular endothelium, and areas of tissue repair. Using immunocytochemistry, osteonectin has been localized in all zones of the normal avian epiphyseal growth plate with notably high amounts in the hypertrophic zone. In the proximal portion of this zone the staining was intracellular, while in the distal calcifying portion of the hypertrophic zone staining was both intracellular and extracellular. Osteonectin was also detected in the growth plate associated with lesions of chickens with tibial dyschondroplasia (TD). Intense intracellular staining was observed in hypertrophic chondrocytes proximal to the lesion; staining was markedly diminished in the TD lesion; extracellular matrix was devoid of staining. Staining intensity was high along the peripheral edges of the lesion that were undergoing vascularization and resorption. This was the only area in the dysplastic cartilage where staining was observed in the extracellular matrix as well as intracellularly. Similar patterns were viewed in all TD lesions examined, whether they were spontaneous or induced by dietary treatments or genetic selection.

Growth plate chondrocyte vitamin D receptor number and affinity are reduced in avian tibial dyschondroplastic lesions.

Tibial dyschondroplasia (TD) is a condition of rapidly growing poultry in which a mass of unmineralized cartilage extends distally from the tibiotarsal growth plate, leading to deformity and lameness. The lesion is characterized by the accumulation of prehypertrophic chondrocytes, probably because the maturing chondrocytes are unable to differentiate fully. The condition can be prevented by feeding 1,25-(OH)2D3. We have investigated the possibility that vitamin D receptors (VDR), through which 1,25-(OH)2D3 exerts its differentiating effects on chondrocytes, may be defective in TD birds. Chondrocytes were isolated from the proliferating and hypertrophic zones of normal tibiotarsi and from the proliferating zone and lesion of affected birds and receptors were characterized by Scatchard analysis. Results showed that, while cells from the proliferating zone in TD birds had normal receptors, those from the TD lesion had significantly lower numbers and affinity for 1,25-(OH)2D3 compared to all other zones. Lesion VDR had low affinity; Kd 83.9 +/- 20.6 pM compared to 30.0 +/- 2.8, 37.8 +/- 3.1, and 33.0 +/- 4.0 pM (p < 0.001), and low receptor number per cell, 920 +/- 74, compared to 1329 +/- 151, 1664 +/- 167, and 1360 +/- 104 (p < 0.01) in the normal proliferating, normal hypertrophic, and TD proliferating cells, respectively. These findings were confirmed by immunohistochemical localization of VDR in sections of normal and TD growth plates using monoclonal antibody 9A7 gamma. In normal growth plate, most cells were VDR positive with intense staining in the mature hypertrophic chondrocytes; in TD growth plates, proliferating zone cells stained well but signal was largely absent from chondrocytes in the lesion. Image analysis showed integrated nuclear staining density per cell of 168.2 +/- 36.9 arbitrary units in normal hypertrophic cartilage compared to 98.8 +/- 60.2 units in the top of the lesion and 2.2 +/- 2.0 units in the midlesion. We conclude that both numbers and affinity of VDR are reduced in TD and this may explain the failure of chondrocytes to differentiate to the mature form. The adverse consequences of defective receptors may be partly overcome by treatment with 1,25-(OH)2D3.

Expression and distribution of cartilage matrix macromolecules in Avian tibial dyschondroplasia

Tibial dyschondroplasia (TD) is a disorder of endochondral ossification characterized by the presence of an avascular, non-mineralized cartilage lesion extending from the growth plate into the metaphysis. Cells within the TD growth plate fail to differentiate to full hypertrophy, and instead appear to maintain a 'pre-hypertrophic' or 'transitional' status. The synthesis and distribution of aggrecan, biglycan, decorin, and collagen types II and X in the growth plates of normal and tibial dyschondroplastic chickens have been investigated using in situ hybridization and immunolocalization. Marked reductions in the amount of aggrecan and biglycan core protein mRNAs were observed in the tibial dyschondroplastic lesion by in situ hybridization. Reduction in mRNA production seemed to be specific to the extracellular matrix components since total mRNA expression showed no significant difference between normal and dyschondroplastic cartilage. In addition, expression of collagen type II and decorin did not differ significantly between normal and TD cartilage. Distribution of aggrecan biglycan, decorin, type II and X collagens were examined using immunohistochemistry. Normal hypertrophic cartilage showed a strong matrix labelling for aggrecan and biglycan. Type X collagen in the normal hypertrophic cartilage showed strong pericellular and matrix distribution, whereas in TD cartilage labelling for aggrecan, biglycan and collagen X was located intracellularly with a very low level of signal in the matrix. In contrast, collagen type II was found to be present throughout the extracellular matrix of both the normal growth plate and the TD lesion, suggesting that the differences observed in aggrecan, biglycan and type X collagen distribution are specific to these proteins and not a general disturbance of matrix macromolecular metabolism. The reduced deposition of these macromolecules may have implications in normal and pathological bone development.

Promoter and Transcription of Type X Collagen Gene in Broiler Chickens with Tibial Dyschondroplasia

Type × collagen is produced exclusively in hypertrophic chondrocytes of the growth plate of the proximal tibiotarsus and is believed to play an important role during normal development from chondrogenesis to osteogenesis. Chondrocytes of chickens with tibial dyschondroplasia (TD) fail to attain full hypertrophy and the amount of type × collagen, being a marker of hypertrophy, is likely to be reduced. It is not clear whether transcriptional regulation is functional for expression of the type × collagen gene in TD birds. Nucleotide sequence of the type × collagen gene promoter was determined by sequencing PCR-based DNA clones. Nucleotide identity of this fragment between the normal and TD carriers was 97.6%. Both normal and TD birds were similar in a putative transcription start site, the site of TATAA box, and neither had a CCAAT box. However, there were two gaps in TD carriers, four gaps in normals, and five nucleotide substitution sites. By rapid amplification of cDNA ends by PCR (RACE-PCR), transcription of the gene was assessed using total RNA and mRNA from both normal chondrocytes and TD lesions at 3 and 4 wk of age. The RACE-PCR product for type × collagen mRNA was detectable in both normal and TD birds at two stages. No difference was found between them. This result does not support the hypothesis that transcriptional regulation of type × collagen gene is important in TD development of chickens. Variations in the promoter region did not affect transcription of type × collagen gene in TD carrier chickens.

Immunolocalization of Basic Fibroblastic Growth Factor in Avian Tibial Dyschondroplastic Cartilage

Recent research in our laboratory has demonstrated that basic fibroblast growth factor (bFGF) is a permissive mitogen for epiphyseal growth plate chondrocytes. Immunocytochemistry demonstrated the presence of bFGF in the proliferative and hypertrophic zones of normal epiphyseal growth plates of 4-wk-old broiler chickens. The purpose of this investigation was to extend this research to include examination of the status of bFGF in the cartilage lesion associated with tibial dyschondroplasia (TD). Immunocytochemistry revealed that the distribution of bFGF in the growth plate proximal to the TD lesion was similar to that observed with normal growth plate. However, the intensity of immunofluorescence was greatly diminished in the TD lesion. The number of chondrocytes staining positive for bFGF was also reduced. In the peripheral edges of the lesion where cartilage was being actively resorbed, the staining intensity was greatly increased when compared to the rest of the TD lesion. Similar patterns were observed in all TD tissues examined whether the lesions were spontaneous or induced by dietary treatments or genetic selection. It is hypothesized that the decrease in bFGF, a potent angiogenic factor, may be responsible for the poor vascularization of the TD lesion.

Effect of Dietary 1,25-Dihydroxycholecalciferol Level on Broiler Performance

Studies were conducted to evaluate the level of dietary 1,25-dihydroxycholecalciferol [1,25-(OH)2D3] required to decrease the incidence of tibial dyschondroplasia (TD) in male broilers at 3 and 5 wk of age. The birds were reared in floor pens with wood shavings and fed a corn-soybean meal diet supplemented with 0, 3, 6, or 9 μg/kg l,25-(OH)2D3. The diet contained, by averaged analyses, 0.73% calcium, 0.74% total phosphorus, and 0.22% phytate phosphorus. There was no treatment effect on body weight or gain:feed at either age. The incidence and severity of TD and the percentage of severe lesions were decreased and bone ash was increased by 6 μg/kg l,25-(OH)2D3 at 3 wk of age. At 5 wk of age, the incidences of TD and severe lesions were decreased when 6 μg/kg l,25-(OH)2D3 was fed. Bone ash was increased by this level in one of the two experiments. Plasma calcium was increased at 5 wk when 9 μg/kg l,25-(OH)2D3 was fed, but there was no treatment effect on plasma dialyzable phosphorus or l,25-(OH)2D3. The results indicate that 6 μg/kg l,25-(OH)2D3 is effective for decreasing TD under practical rearing conditions.

Ultrastructural Changes of Chondrocytes of Growth Plates of Young Broiler Chickens Predisposed to Tibial Dyschondroplasia

Growth plates from the proximal tibiotarsal bones of growing broiler chickens from lines exhibiting high and low incidences of tibial dyschondroplasia (TD) were compared for ultrastructural differences. Samples of growth plates were collected from five chickens of each line at 2, 7, 14, and 21 d of age. Each sample was prepared for ultrastructural evaluation after initial fixation in 2.5% glutaraldehyde and secondary fixation in 1% osmium tetroxide, each containing .7% ruthenium hexamine trichloride. No gross TD lesions were observed. The ultrastructure of growth plates of birds at 2, 7, and 14 d of age was similar between the groups. However, at 21 d of age, chondrocytes in the prehypertrophic zone of the high incidence group contained large lipid inclusions and vesiculated and disarranged stacks of rough endoplasmic reticulum with greatly dilated cisternae. Apoptotic and necrotic chondrocytes were present in the hypertrophic zone. Nuclei of apoptotic chondrocytes contained crescentic caps of condensed chromatin. The cytoplasm contained short segments of dilated granular endoplasmic reticulum, lipid droplets, and vacuoles. Necrotic chondrocytes appeared as amorphous masses with pyknotic and karyorrhectic nuclei. These changes were not observed in chondrocytes of the low TD incidence group and have not been previously reported in nonthickened growth plate cartilage.

The Role of Environment and Management on Leg Abnormalities in Meat-Type Fowl

Continuous light with 1 h of darkness at midnight is a common photoperiod for raising meat-type fowl. The logic behind the 1 h of darkness, usually provided between midnight and 0100 h, is to acclimate the birds to darkness in the event of a power failure. Increasing evidence from several research laboratories indicates that lighting regimens other than continuous light, such as intermittent or step-up lighting, can lower the incidence of leg abnormalities in meat-type fowl. Some evidence suggests that increased exercise contributes in part to the reduction in lameness due to lighting.Management can influence the incidence of leg and foot problems via effects on rate of gain, flooring systems, and litter moisture. Rapid weight gains have been correlated with tibial dyschondroplasia (TD), although more evidence is needed to determine whether other types of leg deformities, such as long bone distortion, are related to rapid growth rates. Using low intensity X-ray imaging (hand-held lixiscope), live breeders with TD lesions can be identified and the incidence of TD can be reduced in breeder flocks through genetic selection. In addition, turkeys can be selected for wider shanks to improve walking ability. Slippery surfaces should be avoided to prevent spraddled legs. With the exception of TD, broilers reared in cages have more leg deformities than floor-reared birds. Dry litter conditions can help prevent foot pad dermatitis caused by Staphylococcus aureus and other bacteria.

Effect of Genetic Strain, Calcium, and Feed Withdrawal on Growth, Tibial Dyschondroplasia, Plasma 1,25-Dihydroxycholecalciferol, and Plasma 25-Hydroxycholecalciferol in Sixteen-Day-Old Chickens

Four experiments were conducted to study the effects of genetic strain, dietary Ca level, and feed withdrawal on growth, feed efficiency, tibia bone ash, tibial dyschondroplasia (TD), and plasma 1,25-dihydroxycholecalciferol [l,25(OH)2 D3] and 25-hydroxycholecalciferol [25(OH)D3]. Experiment 1 used five strains and Experiments 2 to 4 used three broiler strains. A TD-inducing basal diet was used in each experiment. In Experiment 3, the birds were fed .60 or .95% dietary Ca, and in Experiment 4 the birds were fed the basal diet and were fed or deprived of feed for 8 h daily. In Experiment 1, Athens-Canadian Randombred and Single Comb White Leghorn chicks did not develop TD. In birds fed the basal diet alone, Peterson × Hubbard chicks had a significantly higher incidence of the most severe TD lesion than two other broiler strains in each experiment and were significantly lighter in BW in two of the four experiments. Of the three broiler strains, the incidence and average lesion score of TD was significantly higher in Peterson × Hubbard birds in Experiment 2 and was numerically highest in the other three experiments. In birds fed the basal diet, Peterson × Hubbard birds had significantly higher plasma l,25(OH)2 D3 in two of the four experiments. Both feed deprivation and .95% Ca increased bone ash and decreased the incidence and severity of TD. There were no significant differences in plasma l,25(OH)2 D3 among strains of birds deprived of feed or fed .95% Ca. In three of the four experiments, high plasma l,25(OH)2 D3 in Peterson × Hubbard birds was associated with an increase in the incidence and severity of TD.

Recent findings on tibial dyschondroplasia in broilers and osteoporosis in caged layers

The skeletal disorders causing the most severe welfare problems in different classes of poultry are bone growth disorders in young birds and bone fragility in older laying hens.Angular and rotational deformities of leg bones are widespread in young birds, especially in broilers but also in turkeys. Dyschondroplasia is a widely observed defect in the growth plates of leg bones. It occurs most noticeably in the growth plate of the proximal tibia, the fastest growing bone in the young broiler, and is frequently referred to as tibial dyschondroplasia (TD). Resulting from a failure of growth plate chondrocytes to differentiate fully, it leads to a build up of a mass of prehypertrophic chondrocytes. The lesions develop between the ages of 2 and 5 weeks and can regress thereafter.The importance of TD in causing bone deformity was assessed by carrying out sequential radiography of the proximal tibias of a group of 20 broilers growing up to 16 weeks of age. At this time the tibias were dissected and the angulation of the proximal end (tibial plateau angle, TP°) was measured. The severities and durations of the TD lesions, assessed by radiography, were found to be highly correlated with the TP°. Birds with abnormally large TP° were obviously lame. These observations confirm that TD can lead to distortion of bone growth and that this can contribute to lameness in broilers (Lynch et al., 1992).

Effect of Diet on Growth and the Incidence of Tibial Dyschondroplasia in Broilers

Two experiments were conducted to study dietary factors affecting growth rate and the incidence of tibial dyschondroplasia (TD) in broiler cockerels grown to 3 wk of age. Chicks were fed corn-soy-bean meal-based diets containing one of the following: 3,145kcal ME/kg, 24% protein, and .50% available phosphorus (aP) (Diet 1); 2,900kcal ME/kg, 20% protein, and .35% aP (Diet 2); or 2,900 kcal ME/kg, 24% protein, and .50 aP (Diet 3). In experiment 1 chicks were fed Diets 1, 2, and 3ad libitum. During weeks 1 and 2, chicks fed Diet 1 were heavier and had better feed efficiency (g feed/g gain) than those fed Diets 2 and 3. Chicks fed Diets 2 and 3 had a lower incidence of TD (P<.05) than those fed Diet 1.In experiment 2 feed intake of Diet 1 was on an ad libitum and restricted basis (Diet 1-R) and Diet 2 was on an ad libitum basis. Beginning on day 2, chicks fed Diet 1-R were offered 90% of the amount of feed consumed the previous day by chicks fed Diet 1 free choice. Chicks fed Diet 1 were heavier than those fed Diet 1-R at 1 wk, and Diets 1-R and 2 at 2 and 3 wk. Chicks fed Diet 1 had higher incidence (P<.05) of TD lesions at 3 wk than those fed Diets 1-R and 2. No differences occurred (P>.05) in the incidence of TD lesions between chicks fed Diets 1-R and 2. The incidence of leg problems appeared to be related to rate of growth, rather than being a direct effect of dietary aP or calcium:aP ratio.

Effects of vitamin A and D supplementation on tibial dyschondroplasia in broilers

A 2 × 2 factorial experiment was conducted to assess the effects of vitamin A and/of vitamin D 3 and their interaction on performance, the incidence and severity of tibial dyschondroplasia (TD), and serum mineral levels in broilers. The results showed that there were no significant effects with a high-chloride basal diet of supplementation with vitamin A (45 000 IU kg −1) on growth pe: ormance and TD lesions. Supplementation with vitamin D 3 (1000 IU kg −1) improved chick growate and lowered the incidence of TD significantly ( P < 0.01). The effects of dietary vitamin A and vitamin D 3 on serum calcium, molybdenum and sodium contents were interdependent. Dietary vitamin D 3 plays an anti-rachitic role by affecting the metabolism of calcium and magnesium. This study indicates that supplementation of vitamin D 3 can prevent TD in broilers.

Relationships Among Mineral Balance in the Diet, Early Growth Manipulation, and Incidence of Tibial Dyschondroplasia in Different Strains of Meat Type Chickens

In two experiments, a high dietary level of available phosphorus (.65%) in the presence of high chloride concentrations (.36%) was associated with a significant increase in the incidence of tibial dyschondroplasia (TD) in male broiler chickens. The level of dietary calcium and the interaction between Ca and available P had no effect on TD.Heterozygous normal (DW/DW) male broilers had a significantly lower incidence of TD than homozygous normal (Dw/Dw) chicks (Experiments 1 and 2). In Experiments 3 and 4, there were no significant differences between BW at 14 days for roaster-broiler cross and broiler chicks. At 21 and 28 days, however, the roaster-broiler cross chicks weighed significantly less than the broilers and had a significantly lower incidence of TD.Decreasing growth rates in broiler chicks after 14 days of age resulted in a significant decrease in the incidence of TD (Experiments 4 and 5), but did not decrease the severity of TD lesions at 28 days (Experiment 5). Depressed growth from 0 to 14 days decreased, but did not eliminate, TD lesions (45%) at 28 days, but it did significantly decrease the severity of the lesions compared with that in the 14 to 28-day manipulation treatments (Experiment 5).In Experiment 5, chicks were growth restricted from 0 to 14 or 14 to 21 days and then ad libitum fed the control diet until 28 days of age. The serum growth hormone concentrations at 28 days were inversely related to the rate of BW gain from 21 to 28 days of age, independent of BW at 21 or 28 days or feed consumption from 21 to 28 days. There were no differences in serum concentration of thyroxine or triiodothyronine at 28 days.

Effect of Intermittent Lighting and Time of Hatch on Large Broad-Breasted White Turkeys

To determine if intermittent lighting would reduce leg abnormalities in turkeys, males reared in intermittent lighting of 2 h light:4 h dark were compared to toms subjected to a low intensity, step-down lighting program (15-h photoperiod). Also, to determine if housing poults as soon as possible following hatch would affect later production characteristics, effects of four hatching treatments were assessed.Toms in intermittent as compared with low intensity, step-down lighting programs showed a significant reduction in the incidence of leg abnormalities. There were no significant differences in body weight, feed efficiency, mortality, tibial dyschondroplasia lesions, growth plate closure, and tarsometatarsal length and width for the two lighting programs. Toms exposed to intermittent lighting had heavier testes.It is concluded that intermittent lighting can be used in light-tight, environmentally enclosed turkey houses to reduce leg anomalies without affecting other production traits. Under the experimental conditions employed in the present study, there was no advantage to removing poults from incubator trays as they hatched, as hatching treatments had no effect on production traits of either turkey toms or hens.

Evaluation of Tibial Dyschondroplasia During Aflatoxicosis and Feed Restriction in Young Broiler Chickens

Graded levels of aflatoxin (0, .625, 1.25, 2.5, 5.0, and 10.0 μg of toxin per gram of feed) were incorporated into a broiler starter ration that was fed from day-old to 3 weeks of age. Both tibias were removed from the birds, tibial dyschondroplasia lesions were scored, and the incidence of lesions reported. Both the incidence and severity of tibial dyschondroplasia decreased significantly (P<.05) at the aflatoxin levels of 2.5, 5.0, and 10.0 ppm. In a second experiment, birds received a broiler starter ration either ad libitum or feed restricted by 23% of the feed consumed by the controls. The feed-restricted birds’ body weights and the severity and the incidence of tibial dyschondroplasia decreased to values comparable with those of birds receiving 5.0 ppm aflatoxin. These data suggest that either feed consumption or growth rate, or both, plays a major role in the initiation of tibial dyschondroplasia and tibial dyschondroplasia is not a result of direct intervention of aflatoxin in bone development.