Tibial Dyschondroplasia Lesions Research Articles

HIF-1α upregulation exerts the antagonistic effect against angiogenesis inhibition in manganese deficiency-induced tibial dyschondroplasia of broiler chicks.

Manganese (Mn) is an essential microelement for broiler breeding and its deficiency causes tibial dyschondroplasia (TD). Tibial growth plate (TGP) development and metaphyseal vascularization are crucial for tibia growth in fast-growing broiler chickens, but their roles in Mn deficiency-induced TD in chicks remain unclear. This study was designed to clarify this issue. A total of 36 one-day-old broilers were divided into the control group and Mn-deficiency (Mn-D) group, which were fed with a standard diet (60mg Mn/kg) and Mn deficiency diet (22mg Mn/kg) for 42 days, respectively. TGP and proximal tibial metaphysis were collected to perform the related assays. This study found that Mn deficiency decreased the tibia length and TGP thickness in the TD model. Also, Mn deficiency increased the irregular and white tibial dyschondroplasia lesions (TDL) region under the TGP, and reduced the expression levels of vascular endothelial growth factor (VEGF) and macrophage migration inhibitory factor (MIF). Combined with histological assessment, it was suggested that Manganese deficiency inhibited angiogenesis in the proximal tibial metaphysis. Meanwhile, Mn deficiency enhanced the expression levels of hypoxia-inducible factor-1 α (HIF-1α), autophagy-related protein 5 (ATG5), and microtubule-associated protein 1 light chain 3 β (LC3-II) in TGP, but decreased the expression level of SQSTM1 (P62), which suggested that autophagy was activated during this process. Collectively, these data indicate that HIF-1α up-regulation and concurrent autophagy activation exert a protective effect against Mn deficiency-induced angiogenesis inhibition, which may provide useful guidance to prevent TD in broilers.

Methodology for the quantification of tibial dyschondroplasia in gallus gallus domesticus (aves : Phasianidae).

Objective: To compare the efficacy of the score technique of the tibial dyschondroplasia lesions with a quantification technique in broiler chickens, in search of a better objectivity and reliability of the diagnosis. Materials and methods: 384 male one-day-old chickens were raised until day 36. A total of 192 chickens were sampled, 96 at day 21 and 96 at day 36; the tibial dyschondroplasia disorder was evaluated by comparing two techniques: 1. Qualitative evaluation of the score of tibial dyschondroplasia and, 2. Quantitative measurement of the percentage of area with tibial dyschondroplasia as an alternative test. Results: the Score test of TD lesions had a sensitivity of 83% and 100% with a specificity of 55% and 54% for day 21 and day 36 respectively, and a positive predictive value of 60% for day 21 and of 66% for day 36, while the negative predictive value was 80% and 100% for days 21 and 36. Conclusions: The evaluated alternative test proved to be an effective and efficient method of quantification of tibial dyschondroplasia in broiler chickens, offering more objectivity than the traditional macroscopic test.

Plastrum Testudinis Extract Mitigates Thiram Toxicity in Broilers via Regulating PI3K/AKT Signaling.

Tibial dyschondroplasia (TD) negatively affects broilers all over the world, in which the accretion of the growth plate (GP) develops into tibial proximal metaphysis. Plastrum testudinis extract (PTE) is renowned as a powerful antioxidant, anti-inflammatory, and bone healing agent. The current study was conducted to evaluate the efficacy of PTE for the treatment of thiram-induced TD chickens. Broilers (day old; n = 300) were raised for 3 days with normal feed. On the 4th day, three groups (n = 100 each) were sorted, namely, the control (normal diet), TD, and PTE groups (normal diet+ thiram 50 mg/kg). On the 7th day, thiram was stopped in the TD and PTE group, and the PTE group received a normal diet and PTE (30 mg/kg/day). Plastrum testudinis extract significantly restored (p < 0.05) the liver antioxidant enzymes, inflammatory cytokines, serum biochemicals, GP width, and tibia weight as compared to the TD group. The PTE administration significantly increased (p < 0.05) growth performance, vascularization, AKT (serine/threonine-protein kinase), and PI3K expressions and the number of hepatocytes and chondrocytes with intact nuclei were enhanced. In conclusion, PTE has the potential to heal TD lesions and act as an antioxidant and anti-inflammatory drug in chickens exposed to thiram via the upregulation of AKT and PI3K expressions.

Comparative Pathomorphologic Studies on the Incidence of Fractures Associated with Leg Skeletal Pathology in Commercial Broiler Chickens.

The aim of the present investigation is to report the prevalence of spontaneous fractures associated with leg skeletal pathology and compromised welfare in commercial broiler chickens. Our studies focused on fractures of different leg segments (femur, tibiotarsus, tarsometatarsus) detected as incidental findings during pathoanatomic examinations in cases of rickets, tibial dyschondroplasia (TD), and femoral head necrosis (FHN). The morphogenetic and etiopathogenetic aspects of the findings were further investigated through histopathologic, bacteriologic, and bone mineral analyses. The gross anatomy study showed that in about 10% of bones affected by rickets-specific lesions, fractures of the proximal tibiotarsus were present. A relatively low percentage (6.5%) of fractures of the same anatomic location could be attributed to TD lesions. The highest prevalence of fractures (68.5%), mainly of the proximal femur, was associated with FHN and osteomyelites. The results from the large-scale field surveys allowed us to confirm that the prevalence of spontaneous bone fractures of the legs in broiler chickens was largely associated with FHN, rickets, and TD. The poor vascularization of the grown prehypertrophic cartilage in cases of rickets and TD, as well as the osteolytic lesions in FHN, resulted in degenerative, necrobiotic processes which may entail bone fractures.

The Investigation of the Relationship Between HSP-27 Release and Oxidative DNA Damage in Broiler Chickens with Tibial Dyschondroplasia by Using Histopathological and Immunohistochemical Methods

ABSTRACT Tibial dyschondroplasia (TD) is a skeletal disorder that occurs in the proximal metaphyses of tibiotarsus and sometimes tarsometatarsus, resulting in the development of avascularized and non-mineralized abnormal cartilage and causing significant economic loss. In this study, we aimed to show the histopathological changes and the relationship between the release of Heat-Shock Protein 27 (HSP-27) and oxidative DNA damage in broiler chickens with tibial dyschondroplasia, using histopathologic and immunohistochemical methods. Our study material consisted of totally 20 animals out of 42 days old 205 Ross 308 broiler chickens, 10 with TD lesions and 10 healthy control subjects. Tissue samples taken from animals performed necropsy was exposed to routine tissue follow-up. Macroscopically, unilateral and bilateral thickening and swelling were observed in the growth plates of tibiotarsal joints of the broiler chickens diagnosed with tibial dyscondroplasia. Histopathologic examination of the tibiotarsal joints of broiler chickens affected by TD revealed an increase in the number of immature chondrocytes, as well as deficiencies in vascularization and calcification. In the immunohistochemical study; HSP-27 and 8-OHDG release was positive in the chondrocytes located on the Proliferative Zone, Maturation Zone and Hypertrophic Zone. However, the positivity was the most profound in the PZ and MZ, while less in the HZ chondrocytes. As a result; we demonstrated by immunohistochemical methods that the increase in the HSP-27 release is parallel to the increase in 8-OHDG release in TD lesioned areas and this may be related to oxidative stress.

Effect of Icariin on Tibial Dyschondroplasia Incidence and Tibial Characteristics by Regulating P2RX7 in Chickens.

Tibial dyschondroplasia (TD) is a disease of rapid growing chickens that occurs in many avian species; it is characterized by nonvascular and nonmineralized growth plates, along with tibia bone deformation and lameness. Icariin is widely used to treat bone diseases in humans, but no report is available regarding the effectiveness of icariin against avian TD. Therefore, this study was designed to determine its effect against TD. For this purpose, a total of 180 broiler chicks were distributed into three groups including control, TD, and icariin group. Control group was given a standard normal diet, while TD and icariin groups received normal standard diet containing 50 mg/kg thiram to induce TD from days 3 to 7 after hatch. After the induction of TD, the chicks of icariin group were fed with standard normal diet by adding 10 mg/kg icariin in water. Then morphological and production parameters analysis of tibial bone indicators, physiological index changes, and gene expression were examined. The results showed that icariin administration not only decreased the mortality but also mitigated the lameness and promoted the angiogenesis, which diminished the TD lesion and significantly increased the expression of P2RX7 (P < 0.05) in TD affected thiram induced chicks. In conclusion, present findings suggest that icariin has a significant role in promoting the recovery of chicken growth plates affected by TD via regulating the P2RX7. Our findings reveal a new target for clinical treatment and prevention of TD in broiler chickens.

The effects of &amp;lt;i&amp;gt;Saccharomyces cerevisiae&amp;lt;/i&amp;gt; on the morphological and biomechanical characteristics of the tibiotarsus in broiler chickens

Abstract. The aim of this study is to examine the effects of different levels of the feed supplement Saccharomyces cerevisiae, a yeast metabolite, on broiler tibiotarsus traits and to reduce leg problems by identifying the pathological changes in leg skeletal system. Thus, reducing leg disorders due to the skeletal system, the cause of significant economic losses in our country (Turkey), was investigated by the supplementation of Saccharomyces cerevisiae in broiler feed. In the study, 300 male day-old, Ross 308 broiler chicks were used. Experiment groups were designed as follows: control; 0.1 % Saccharomyces cerevisiae; 0.2 % Saccharomyces cerevisiae; 0.4 % Saccharomyces cerevisiae. The experimental diets were chemically analyzed according to the methods of the Association of Official Analytical Chemists. Twelve groups were obtained, including three replicates for each experimental group. Each replicated group was comprised of 25 chicks, and thus 75 chicks were placed in each experimental group. After 42 days, broiler chickens were slaughtered. Tibiotarsi were weighed with a digital scale, and the lengths were measured with a digital caliper after the drying process. Cortical areas were measured with the ImageJ Image Processing and Analysis Program. A UTEST Model-7014 tension and compression machine and a Maxtest software were used to determine the bone strength of the tibiotarsus. The severity of the tibial dyschondroplasia lesion was evaluated as 0, +1, +2 and +3. Crude ash, calcium and phosphorus analyses were performed to determine the inorganic matter of tibiotarsi. For radiographic evaluations of epiphyseal growth plates, tibiotarsi from the right legs were photographed in lateral and craniocaudal positions and examined. Statistical analyses were performed with the SPSS statistics program. It was observed that the use of Saccharomyces cerevisiae as a feed supplement led to an increase in the bone traits of broiler chickens. Optimum results for bone mineral content, biomechanical traits and strength were provided by the addition of 0.2 % Saccharomyces cerevisiae in broiler feed. As a result, the use of yeast as feed supplements in broilers is considered to be an economic and convenient way of providing animal welfare and preventing commercial losses due to leg problems.

Earlier hatching time predisposes Cobb broiler chickens to tibial dyschondroplasia

Fertile eggs from Cobb 500 broiler breeder hens were incubated to provide low starting egg shell temperatures (EST; 36.9°C to 37.3°C) which were gradually increased to 37.8°C during the first 7 to 15 days of incubation compared with eggs incubated with a constant EST of 37.8°C (standard conditions) over the first 18 days of incubation. Time of individual chick hatching (measured at 6 h intervals from 468 h of incubation), chick weight, chick length and yolk weight were measured at take-off and BW was measured at 7, 14, 28, 34 and 42 days of age. Male birds at 34 and 42 days of age were assessed for their ability to remain standing in a latency-to-lie test. At 34 and 42 days, male birds were examined for leg symmetry, foot pad dermatitis, hock bruising and scored (scale 0 to 4, where 0=no lesion and 4=lesions extending completely across the tibial growth plate) for tibial dyschondroplasia (TD) lesions. The lower EST profiles caused chicks to hatch later than those incubated under the standard EST profile. Chicks which hatched at ⩽498 h incubation grew faster over the first 7 days than those that hatched later. There were significantly more birds (only males were studied) that hatched from the lower EST profiles with TD scores of 0 and 1 and fewer with score 4 at 34 days than those hatched under the standard profile. Male birds at 34 days with TD lesions ⩾3 stood for significantly shorter times than males with TD scores ⩽2. Moreover, male birds at 34 and 42 days with TD lesion scores of ⩾3 hatched significantly earlier and grew significantly faster over the first 2 weeks of age than did male birds with TD scores ⩽2. It appears possible to decrease the severity and prevalence of TD in the Cobb 500 broiler by ensuring that the birds do not hatch before 498 h of incubation.

Differential expression of extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) in avian tibial dyschondroplasia

Tibial dyschondroplasia (TD) is an avian bone disorder of different aetiologies that may be associated with lameness. The disorder is characterized by focal disruption of endochondral bone formation, with a lack of matrix proteolysis and an accumulation of non-mineralized avascular cartilage. The aim of this study was to determine the expression of extracellular matrix metalloproteinase inducer (EMMPRIN/CD147) in normal, thiram-induced TD lesions and in the process of recovery from TD in broiler chickens. An extracellular matrix (ECM) degrading enzyme, matrix metalloproteinase-9 (MMP-9), was selected to investigate the effects of CD147 in the degradation of ECM. Gene expression was analysed by quantitative real-time polymerase chain reaction and protein levels by immunohistochemistry and western blotting. The birds were divided into three groups: thiram fed; recovery; and controls. Genes encoding CD147 and MMP-9 were down-regulated during the development of the disease, and were up-regulated during recovery. Western blotting also showed lower protein levels of CD147 in TD, which increased during the recovery phase associated with ECM degradation and growth plate repair. The findings of this study suggest that ECM has a crucial role in the occurrence of TD and that CD147 appears to play a pivotal role in matrix proteolysis in the chicken, similar to that in other species.

Comparative clinical and morphological studies on the incidence of tibial dyschondroplasia as a cause of lameness in three commercial lines of broiler chickens

SUMMARY Tibial dyschondroplasia (TD) is the most common skeletal anomaly associated with fast growth in broiler and turkey lines and often results in the occurrence of bone deformation and lameness. It is a fairly common cartilage defect associated with the prehypertrophic cartilage of the growth plate being retained in the metaphysis. The objective of this investigation was to determine, through the use of pathomorphological methods, the prevalence of TD lesions that lead to lameness in 3 commercial broiler lines grown in Bulgaria. The study involved 20 broiler flocks with approximately 17,000 birds per flock and included flocks of Ross 308, Cobb 500, and Pureline broiler chickens. The initial age-related occurrence of TD-associated lesions averaged 23.7 d for Ross 308 flocks from 18 to 34 d of age, 19.6 d for Cobb 500 flocks from 16 to 23 d of age, and 28.8 d for Pureline flocks from 22 to 34 d of age. The number of observed macroscopic TD lesions in the Ross 308 broilers was 355 (24.22%), of which 203 (13.74%) were found in males and 152 (10.28%) were found in females; the number of lesions for Cobb 500 broilers was 185 (24.22%), of which 73 (10.48%) were found in males and 112 (16.09%) were found in females; and the number for Pureline was 313 (27.7%), of which 187 (16.54%) were found in males and 126 (11.16%) were found in females. A comparatively high prevalence of TD lesion-associated deformities was found in the proximal tibial metaphysis. There was a relatively low prevalence of TD lesion-associated proximal tibiotarsal fractures. We suggest, based on the results of our field investigation, that macroscopic TD lesions are developing at younger ages than reported previously. In the commercial broilers involved in the study, the prevalence of TD lesion-associated proximal tibiotarsal deformities was relatively high, and this condition involving TD lesion development potentially has severe consequences leading to lameness in broiler chickens.

Evaluation of a radiographic method to detect tibial dyschondroplasia lesions in broilers

This study aimed at developing radiographic techniques for the early detection of dyschondroplastic lesions in the tibia of broilers. The experiment was carried out at the facilities of UNIFOR/MG and Formiga and UNIFENAS/ Alfenas with 420 one-day-old male Cobb broilers. At 20 days of age, all birds were radiographed and identified with an alpha-numeric metal ring in the right leg. At 40 days of age, 42 broilers previously selected as a function of bone mineral density and lesion thickness scores were again radiographed and scored, and then sacrificed. Their right tibia was removed for gross and histological examination of the growth plate. The results showed that radiographic techniques are correlated with gross and histological examination and that there was no significant differences among techniques (P>0.05). it was concluded that the use of radiographic examination to identify tibial dyschondroplasia in broilers precludes the use of bone mineral density to diagnose this condition. The non-parametric statistical Chi-square test at 5% significance level was used to analyze the results.

Changes in Serum Protein Profiles of Chickens with Tibial Dyschondroplasia

Differences in serum protein profiles were analyzed to identify possible biomarkers associated with a poultry leg problem named tibial dyschondroplasia (TD) that can lead to lameness. A bead-based affinity matrix (ProteoMiner TM ) containing a combinatorial library of hexapeptides was used to deplete high abundant proteins and enrich the less abundant ones to compare between the sera of six-week old normal and TD affected chickens. Equal amounts of proteins in ProteoMiner depleted serum from control and TD-affected birds were subject to 2D gel electrophoresis, image analysis, and compared to identify the differentially expressed protein spots. The protein spots were characterized using in-gel trypsin digestion followed by mass spectrometry (MS). Of 46 matched protein spots in the gels, 33 were identified by peptide mass finger printing (PMF) and tandem mass spectrometry (MS/MS). Eight spots corresponding to immunoglobulins (Ig) were up-regulated in birds with TD and two spots down regulated. The up-regulated Ig proteins belonged to IgM and IgY(IgG) classes indicated by the identification of 'mu' chain and Fc fragment associated peptides respectively. Enzyme linked immunosorbent assay corroborated an increase in serum IgM levels but not IgG. Although the significance of the increase in IgM proteins in the serum of TD-affected chickens is not understood, it is likely that IgM plays some role in the removal of apoptotic chondrocytes which abound within TD lesions.

The Role of Matrix Gla Protein in Ossification and Recovery of the Avian Growth Plate

Extracellular matrix mineralization is an essential physiologic process in bone, teeth, and hypertrophic cartilage. Matrix Gla protein (MGP), an inhibitor of mineralization, is expressed by chondrocytes and vascular smooth muscle cells to inhibit calcification of those soft tissues. Tibial dyschondroplasia (TD), a skeletal abnormality apparent as a plug of non-vascularized, non-mineralized, white opaque cartilage in the tibial growth plate of avian species can serve as a good model for studying process and genes involved in matrix mineralization and calcification. In this work, we studied the involvement of MGP in the development of TD, as well as in the processes of spontaneous and induced recovery from this syndrome. First, we found that during normal bone development, MGP is expressed in specific time and locations, starting from wide-spread expression in the yet un-ossified diaphysis during embryonic development, to specific expression in hypertrophic chondrocytes adjacent to the chondro-osseous junction and the secondary ossification center just prior to calcification. In addition, we show that MGP is not expressed in the impaired TD lesion, however when the lesion begins to heal, it strongly express MGP prior to its calcification. Moreover, we show that when calcification is inhibited, a gap is formed between the expression zones of MGP and BMP2 and that this gap is closed during the healing process. To conclude, we suggest that MGP, directly or through interaction with BMP2, plays a role as ossification regulator that acts prior to ossification, rather then simple inhibitor.

Expressão da caderina na discondroplasia tibial

ABSTRACT By immunohistochemistry the expression of a pan-cadherin antibody that recognizes a wide variety of cadherins in chondrocytes from normal and tibial dyschondroplasia (TD) growth plates was compared. Surprisingly, an upregulated expression that was not expected in TD lesion chondrocytes was observed. The reason for this apparent upregulation is not clear. The increased expression may simply be due to the particular phenotype of lesion chondrocytes, and cadherin may be involved in apoptosis of chondrocytes of TD lesion. Another possibility, is that a low level of calcium in the lesion may be responsible for the observed upregulation. The results of the present study suggest that the formation of the dyschondroplastic lesion is not merely due to the impaired terminal differentiation of lesion chondrocytes and that other mechanisms are probably involved in TD etiology. Further studies will be necessary to provide insight into the precise nature of the condition. Keywords: tibial dyschondroplasia, cadherin, immunohistochemistry

Expression of matrix metalloproteinases during impairment and recovery of the avian growth plate1

Tibial dyschondroplasia (TD) is a prevalent skeletal abnormality associated with rapid growth rate in many avian species. It is characterized by the presence of a nonvascularized, nonmineralized lesion that extends from the epiphyseal growth plate into the metaphysis of the proximal tibiotarsal bones. In this study, we examined the expression of 4 members of the matrix metalloproteinase (MMP) family (MMP-2, -3, -9, and -13) in thiram-induced TD lesions and in the process of recovery from TD, by in situ hybridization analysis and quantitative real-time PCR. A model for the induction and recovery of TD was established, consisting of 3 groups of broilers: (1) thiram group, chicks fed a thiram-enriched diet to induce TD; (2) recovery group, chicks fed a thiram-enriched diet during the first week of the experiment and a normal diet from the second week on; and (3) control group, chicks fed a normal diet throughout the experimental period. In agreement with our previous data, the 4 MMP were diminished in the TD lesion (P < 0.05); however, in the current study we show that the growth plate was able to repair itself and that the MMP reappeared during the process of recovery from TD. Our results strengthen the link between MMP expression and growth-plate impairment, and we suggest that gelatinase activity (MMP-2 and 9) facilitates this process.

Hypoxia, Hypoxia-Inducible Factor-1α (HIF-1α), and Heat-Shock Proteins in Tibial Dyschondroplasia

Tibial dyschondroplasia (TD) is one of the most prevalent skeletal abnormalities in avian species; it causes economic losses and is an animal welfare problem. It has been hypothesized that the absence of vasculature in the lesion of the TD growth plates at the ends of the long bones is involved in the etiology of the disease. We evaluated the hypoxia status of normal and thiram-induced TD growth plates by immunostaining the protein adducts after pimonidazole hydrochloride administration. In addition, we evaluated the expression of hypoxia-inducible factor-1α (HIF-1α), the major regulator of the hypoxic response that is essential for chondrogenesis, and that of heat-shock proteins (Hsp) downstream from HIF-1α. We demonstrated that, in contrast to the normal growth plates, those afflicted by TD were hypoxic. A major increase in hypoxia was observed in the proliferative, hypertrophic, and calcified zones. In the normal growth plate, HIF-1α was expressed in chondrocytes of the articular cartilage and of the maturation zone, whereas in cases of TD, HIF-1α was also expressed in chondrocytes below the lesion. The expression level of HIF-1α was related to the severity of the disease, but was independent of its cause; the same pattern of expression was observed in growth plates of chicks selected for a high incidence of TD. No differentiation-dependent expression of HIF-1α was observed in response to hypoxia, as demonstrated by the use of primary cultures of growth plate chondrocytes. In the normal growth plates, Hsp90 and Hsp70 were localized to the maturation zone. More cells expressed both Hsp in the TD lesion. In conclusion, we demonstrated that the TD growth plate, in contrast to the normal one, is hypoxic, probably because of the lack of vascularization. Hypoxia leads to an increase in the transcription factor HIF-1α, causing increases in the levels of Hsp90 and Hsp70.

Performance, Livability, and Carcass Yield of Slow- and Fast-Growing Chicken Genotypes Fed Low-Nutrient or Standard Diets and Raised Indoors or with Outdoor Access

Two experiments were conducted to assess the effect of genotype, production system, and nutrition on performance and livability of meat chickens for niche markets. Slow-growing (SG) and fast-growing genotypes (FG) were raised for 91 and 63 d, respectively, in experiment 1 (females) or 84 and 56 d, respectively, in experiment 2 (males). In each trial, SG were placed before FG to achieve a similar BW at processing. In experiment 1, each genotype was assigned to 8 pens of 20 birds each, with 4 pens within each genotype raised indoors in a conventional research facility or in a small facility with outdoor access. All birds were fed a low-nutrient diet. In experiment 2, genotype assignment to pens was as in experiment 1; however, 4 pens within each genotype were fed a low-nutrient diet or a conventional diet, and birds were raised indoors. Birds were gait-scored and commercially processed; legs were examined for tibial dyschon-droplasia lesions and scanned for bone mineral density. In experiment 1, FG gained more weight than SG (P < 0.05) even though they were placed later. Outdoor access increased feed intake, and feed efficiency was poorer (P< 0.05). Fast-growing genotypes had higher breast meat yield, whereas SG had higher wing and leg yields (P < 0.05). In experiment 2, the low-nutrient diet reduced (P< 0.05) gain of the SG; FG increased feed intake of the low-nutrient diet such that their gain was unaffected (P> 0.05). For FG, the low-nutrient diet resulted in a poorer (P < 0.05) feed efficiency. Although weight gain of the FG was maintained on the low-nutrient diet, breast yield was reduced (P < 0.05). Genotype affected bone health in both experiments, with SG having better gait scores and less tibial dyschondroplasia (P < 0.05). Outdoor access and the low-nutrient diet also resulted in better gait score (P < 0.05). These data indicate differences among genotypes and provide information about the efficiency and potential for alternative poultry systems.

Expression of matrix metalloproteinases during vascularization and ossification of normal and impaired avian growth plate1

Enzymes of the matrix metalloproteinase (MMP) family regulate angiogenesis and are involved in the endochondral ossification process. Tibial dyschondroplasia (TD) and rickets are 2 disorders associated with impairments in this process, mainly in the vascularization of the avian growth plate. In this paper, we induced TD and rickets and studied the expression patterns of 4 members of the MMP family known to be important for endochondral ossification, MMP-2, 3, 9, and 13, in normal and impaired avian growth plates. The expression of MMP-3, 9, and 13 was reduced in the lesions and lined up parallel to the expulsion of blood vessels, which was extended up to the border of the lesion, but did not penetrate into it. Matrix metallopro-teinase-2 was not expressed in the TD lesion but was overexpressed in the rachitic lesion. We also studied the differentiation stage of the chondrocytes populating the lesions and found that the rachitic lesions were populated with proliferative chondrocytes, whereas the TD lesions were filled with chondrocytes that presented both proliferative and hypertrophic markers. These results suggest that MMP-3, 9, and 13 play a role in the vascularization and ossification processes, whereas MMP-2 is related to chondrocyte differentiation and may be involved in cartilage remodeling in the avian growth plate.

Thiram-Induced Changes in the Expression of Genes Relating to Vascularization and Tibial Dyschondroplasia

Tibial dyschondroplasia (TD), a major metabolic cartilage disease in poultry, is characterized by the distension of proximal growth plates of tibia that fail to form bone, lack blood vessels, and contain nonviable cells. Thiram, a carbamate pesticide, when fed to young broiler chicks induces TD with high regularity and precision. We used this experimental model to understand the cause of the defects associated with TD by determining the expression of selective candidate genes associated with vascularization and cell survival. Week-old broiler chickens were fed 100 ppm thiram for 48 h between d 8 and 10 posthatch and the expression of the genes for vascular endothelial growth factor (VEGF), its receptors (VEGFR1 and VEGFR2), and an antiapoptotic protein (Bcl-2) were determined in the growth plate cartilage at 48 and 166 h after feeding thiram. Reverse transcription PCR and capillary electrophoresis were used to determine the expression of these genes relative to the 18S gene as an internal standard. There was an increase in the expression of the VEGF gene by thiram at 48 h, which remained elevated above the control level at 166 h. A suppression of genes encoding both VEGF receptors and Bcl-2 was evident at 48 h in thiram-fed chickens when there was no visible distension of growth plate indicative of TD. At 166 h, however, there was a significant distension of growth plates in thiram-treated birds, with a high percentage of cells derived from these tissues exhibiting characteristics of dead cells. Although the expressions of VEGF receptors were low at 166 h in thiram-treated birds, they were not statistically different from controls; the Bcl-2 gene expression, however, remained significantly downregulated in those birds. It appears that some of the early effects of thiram on the growth plate may be the failure of genes encoding VEGF receptors and Bcl-2 resulting from endothelial cell death, which compromise vascularization, cartilage remodeling, and the removal of dead chondrocytes leading to TD lesions.

Induction of Tibial Dyschondroplasia in Turkeys by Tetramethylthiuram Disulfide (Thiram)

Tibial dyschondroplasia (TD) is a prevalent skeletal abnormality associated with rapid growth rate in many avian species; it causes enormous economic losses and is an animal welfare problem. Tibial dyschondroplasia is characterized by the presence of a nonvascularized, nonmineralized lesion that extends from the epiphyseal growth plate into the metaphysis of the proximal tibiotarsal bones. The mechanisms underlying TD development are not known, although they have been extensively studied in broilers using different induction models. However, an effective model for TD induction in turkeys has never been described. The objective of this study was to establish such a model by using tetramethylthiuram disulfide (thiram), an agent that is frequently used in broilers to induce TD. We found that dramatically longer exposures to much higher concentrations of thiram were required to induce TD in turkeys vs. broilers. In contrast to broilers, in which 50 mg/kg of thiram induces a high incidence of severe TD within 10 d, in turkeys, an exposure to 400 mg/kg of thiram for 11 wk was necessary for the development of severe TD lesions. These results show different mechanisms for TD induction in these 2 closely related species, suggesting differences in TD etiology between them.