Analysis of bovine postmortem condemnation data in France: Contributions from a comprehensive and standardised information system at the slaughterhouse.

BACKGROUND: The condemnation of carcases and offal unfit for human consumption is a regulatory requirement at the slaughterhouse. Condemnation data, if comprehensive and standardised, can be a valuable source of information for risk-based inspection and decision making. METHODS: The aim of this study was to analyse postmortem condemnation data that were recorded in all bovine slaughterhouses in mainland France from 1 January 2016 to 31 December 2020 in a comprehensive and standardised information system. The rates of and reasons for condemnation, as well as factors influencing rate variation, were investigated through descriptive analysis and multivariable logistic regression models. RESULTS: The global, total and partial condemnation rates were 4.5%, 0.7% and 3.8% for adult cattle and 1.4%, 0.3% and 1.1% for calves, respectively. Reasons for condemnation varied with the animal category; for example, the three main reasons for total condemnation in adult cattle were serous infiltration of connective tissue (49% of condemned animals), congestive peritonitis (12.2%) and fibrinous peritonitis (10.9%), whereas the top three reasons for partial condemnation were unique abscess (21.9%), haemorrhagic infiltration (20.6%) and muscular sclerosis (17.4%). Condemnation rates were influenced by animal-related factors (sex, age, type of breed) and slaughterhouse-related factors (status, type, slaughter volume). CONCLUSION: Our findings could usefully contribute to the continuous improvement of the harmonisation of inspection decisions and support the risk manager's strategy in the modernisation of official controls at the slaughterhouse.

Dlx5 drives Runx2 expression and osteogenic differentiation in developing cranial suture mesenchyme.

Craniofacial bones derive from cephalic neural crest, by endochondral or intramembranous ossification. Here, we address the role of the homeobox transcription factor Dlx5 during the initial steps of calvaria membranous differentiation and we show that Dlx5 elicits Runx2 induction and full osteoblast differentiation in embryonic suture mesenchyme grown "in vitro". First, we compare Dlx5 expression to bone-related gene expression in the developing skull and mandibular bones. We classify genes into three groups related to consecutive steps of ossification. Secondly, we study Dlx5 activity in osteoblast precursors, by transfecting Dlx5 into skull mesenchyme dissected prior to the onset of either Dlx5 and Runx2 expression or osteogenesis. We find that Dlx5 does not modify the proliferation rate or the expression of suture markers in the immature calvaria cells. Rather, Dlx5 initiates a complete osteogenic differentiation in these early primary cells, by triggering Runx2, osteopontin, alkaline phosphatase, and other gene expression according to the sequential temporal sequence observed during skull osteogenesis "in vivo". Thirdly, we show that BMP signaling activates Dlx5, Runx2, and alkaline phosphatase in those primary cultures and that a dominant-negative Dlx factor interferes with the ability of the BMP pathway to activate Runx2 expression. Together, these data suggest a pivotal role of Dlx5 and related Dlx factors in the onset of differentiation of chick calvaria osteoblasts.

BMP signals regulate Dlx5 during early avian skull development.

The vertebrate skull vault forms almost entirely by the direct mineralisation of mesenchyme, without the formation of a cartilaginous template, a mechanism called membranous ossification. Dlx5 gene mutation leads to cranial dismorphogenesis which differs from the previously studied craniosynostosis syndromes [Development 126 (1999), 3795; Development 126 (1999), 3831]. In avians, little is known about the genetic regulation of cranial vault development. In this study, we analyze Dlx5 expression and regulation during skull formation in the chick embryo. We compare Dlx5 expression pattern with that of several genes involved in mouse cranial suture regulation. This provides an initial description of the expression in the developing skull of the genes encoding the secreted molecules BMP 2, BMP 4, BMP 7, the transmembrane FGF receptors FGFR 1, FGFR 2, FGFR 4, the transcription factors Msx1, Msx2, and Twist, as well as Goosecoid and the early membranous bone differentiation marker osteopontin. We show that Dlx5 is activated in proliferating osteoblast precursors, before osteoblast differentiation. High levels of Dlx5 transcripts are observed at the osteogenic fronts (OFs) and at the edges of the suture mesenchyme, but not in the suture itself. Dlx5 expression is initiated in areas where Bmp4 and Bmp7 genes become coexpressed. In a calvarial explant culture system, Dlx5 transcription is upregulated by BMPs and inhibited by the BMP-antagonist Noggin. In addition, FGF4 activates Bmp4 but not Bmp7 gene transcription and is not sufficient to induce ectopic Dlx5 expression in the immature calvarial mesenchyme. From these data, we propose a model for the regulatory network implicated in early steps of chick calvarial development.