Employing Nanostructured Scaffolds to Investigate the Mechanical Properties of Adult Mammalian Retinae Under Tension.

Numerous eye diseases are linked to biomechanical dysfunction of the retina. However, the underlying forces are almost impossible to quantify experimentally. Here, we show how biomechanical properties of adult neuronal tissues such as porcine retinae can be investigated under tension in a home-built tissue stretcher composed of nanostructured TiO2 scaffolds coupled to a self-designed force sensor. The employed TiO2 nanotube scaffolds allow for organotypic long-term preservation of adult tissues ex vivo and support strong tissue adhesion without the application of glues, a prerequisite for tissue investigations under tension. In combination with finite element calculations we found that the deformation behavior is highly dependent on the displacement rate which results in Young's moduli of (760-1270) Pa. Image analysis revealed that the elastic regime is characterized by a reversible shear deformation of retinal layers. For larger deformations, tissue destruction and sliding of retinal layers occurred with an equilibration between slip and stick at the interface of ruptured layers, resulting in a constant force during stretching. Since our study demonstrates how porcine eyes collected from slaughterhouses can be employed for ex vivo experiments, our study also offers new perspectives to investigate tissue biomechanics without excessive animal experiments.

Slaughter of pregnant cattle in German abattoirs--current situation and prevalence: a cross-sectional study.

BACKGROUND: The slaughter of pregnant cattle and the fate of the foetuses are relatively new subjects in the field of animal welfare. The Scientific Committee on Veterinary Measures relating to Public Health (SCVPH), however, does not believe this topic to be a critical issue because of the hitherto supposed rare occurrence of this practice. Some previous studies though, contradict this assessment, emphasising its relevance to animal welfare. With regard to the heterogeneous study design of previous investigations, the objective of this study is to evaluate the current situation concerning the slaughter of pregnant cattle in different German abattoirs. Additionally, the prevalence was assessed semi-quantitatively on the basis of a cross-sectional, voluntary and anonymous survey that was conducted amongst senior veterinary students of the University of Leipzig from 2010 until 2013. RESULTS: Of 255 evaluable questionnaires, 157 (63.6%) mention the slaughter of pregnant cattle, corresponding to 76.9% of all visited abattoirs. Slaughter of pregnant cattle is reported often (>10% of females) in 6 (3.8%), frequently (1-10% of females) in 56 (35.7%), and rarely (<1% of females) in 95 (60.5%) of all cases (n = 157) respectively. About 50% of these animals were reported to be in the second or third stage of gestation. 15 (10.6%) of 142 questionnaires providing information about the foetus, state that the foetus showed visible vital signs after the death of the mother, but in one case the foetus was euthanized subsequently. CONCLUSIONS: The results show that the slaughter of pregnant cattle is a common and widespread practice in German abattoirs. The SCVPH's assumption that pregnant cattle are only slaughtered in rare exceptional cases can no longer be maintained. The high proportion of foetuses in the second and third gestational stage must also be considered. In this context the implementation of suitable studies and detailed analysis of the current situation is indispensable to ensure the high standards in animal welfare in Germany and Europe.

A European survey on post-mortem inspection of finishing pigs: Total condemnation criteria to declare meat unfit for human consumption.

Meat inspection (MI) is essential to verify compliance with legal requirements related to human and animal health and animal welfare protections. Judgement criteria applied during MI, resulting in condemnation data of importance, among other things, for livestock producers and for benchmarking reasons. However, although the Meat Inspection Regulation sets out judgement criteria, most are generic, favouring flexibility, but also subjectivity. To address the degree of variation on total condemnation (TC) criteria applied during post-mortem inspection (PMI) of finishing pigs, an online survey was prepared aiming to collect this information from several European countries. The focus was on TC criteria regarding the following PMI findings: abscesses, arthritis, cachexia, erysipelas, icterus, Mycobacterium-like lesions, osteomyelitis, peritonitis, pleuritis and pneumonia. From September to November 2020, a total of 44 completed questionnaires were obtained from 26 European countries. The results showed a substantial variation in the TC criteria in place in the participating countries. One of the main reasons for the variability seen in the respondents' reported answers was related to the indicators used to define a generalised condition related to the 10 PMI findings addressed, making harmonisation a challenge and avoiding to draw conclusions when comparing condemnation causes between abattoirs. This implies that it would make sense to look into how a generalised condition can be identified/described and how it should be judged. The results should be used as inspiration towards possible harmonisation, improving decision-making, and permitting comparative analysis between different reports to allow trend analyses and benchmarking.