Biomarkers and biosensors for the diagnosis of noncompliant pH, dark cutting beef predisposition, and welfare in cattle.

Meat quality can be affected by stress, exhaustion, feed composition, and other physical and environmental conditions. These stressors can alter the pH in postmortem muscle, leading to high pH and low-quality dark cutting (DC) beef, resulting in considerable economic loss. Moreover, the dark cutting prediction may equally provide a measure for animal welfare since it is directly related to animal stress. There are two needs to advance on-site detection of dark cutters: (1) a clear indication that biomarker (signature compounds) levels in cattle correlate with stress and DC outcome; and (2) measuring these biomarkers rapidly and accurately on-farm or the abattoir, depending on the objectives. This critical review assesses which small molecules and proteins have been identified as potential biomarkers of stress and dark cutting in cattle. We discuss the potential of promising small molecule biomarkers, including catecholamine/cortisol metabolites, lactate, succinate, inosine, glucose, and ß-hydroxybutyrate, and we identify a clear research gap for proteomic biomarker discovery in live cattle. We also explore the potential of chemical-sensing and biosensing technologies, including direct electrochemical detection improved through nanotechnology (e.g., carbon and gold nanostructures), surface-enhanced Raman spectroscopy in combination with chemometrics, and commercial hand-held devices for small molecule detection. No current strategy exists to rapidly detect predictive meat quality biomarkers due to the need to further validate biomarkers and the fact that different biosensor types are needed to optimally detect different molecules. Nonetheless, several biomarker/biosensor combinations reported herein show excellent potential to enable the measurement of DC potential in live cattle.

Claudin-8 expression in Sertoli cells and putative spermatogonial stem cells in the bovine testis.

Adhesion molecules are expressed by both adult and embryonic stem cells, with different classes of adhesion molecules involved in cell-membrane and intercellular contacts. In this study the expression of the adhesion molecule claudin-8 (CLDN8), a tight-junction protein, was investigated as a potential marker for undifferentiated spermatogonia in the bovine testis. We found that CLDN8 was expressed by both spermatogonia and a subset of Sertoli cells in the bovine testis. We also showed co-expression of GFRα1 in testis cells with CLDN8 and with Dolichos biflorus agglutinin-fluorescein isothiocyanate (DBA-FITC) staining. We observed co-enrichment of spermatogonia and CLDN8-expressing Sertoli cells in DBA-FITC-assisted magnetic-activated cell sorting (MACS), an observation supported by results from fluorescence-activated cell sorting analysis, which showed CLDN8-expressing cells were over-represented in the MACS-positive cell fraction, leading to the hypothesis that CLDN8 may play a role in the spermatogonial stem-cell niche.

Postnatal maternal behaviour expression depends on lambing difficulty in Merino ewes.

Dystocia, a prolonged or non-progressive birth event, is the main contributor to lamb mortality in Australia and across the world. Dystocia can cause neonatal hypoxia, central nervous system (CNS) damage leading to increased risk of starvation, exposure and mismothering, and death. These prolonged birth events can also cause fatigue, injury and death in the ewe. Dystocia may interrupt the expression of maternal behaviour and the strength of the ewe-lamb bond, and consequently lamb survival. This study focused on the effect of dystocia on ewe behaviour in the 2 h post-lambing. A total of 18 ewes were chosen for continuous behaviour annotation and analysis (dystocic (n = 9) and eutocic (n = 9)) based on the quality of video recordings, length of stage 2 parturition and classification by a single experienced observer. Dystocic ewes showed significantly lower expression of maternal behaviours and a significantly greater expression of avoidance behaviours compared to eutocic ewes. Additionally, dystocic ewes performed fewer behaviours in total compared to eutocic ewes. Dystocia can significantly affect the quality and quantity of ewe maternal behaviour expression, leading to increased avoidance of the lamb, increased risk of maternal disinterest, and increased risk of death for the lamb. If dystocic events can be identified quickly and accurately, measures can be taken to ensure the ewe and lamb recover successfully.

Using Pen-Side Measurable Blood Parameters to Predict or Identify Dystocic Lambing Events.

Dystocia is the greatest contributor to neonatal lamb mortality in Australia and poses significant welfare and economic concerns worldwide. In this study, we set out to investigate whether pen-side analysis technology could be employed to detect blood parameters predictive of dystocic labour events in sheep. In a pilot trial, we collected and analysed blood samples in pen-side assays for glucose, lactate, pH, pCO2, pO2, base excess, HCO3, TCO2, sO2, lactate, sodium, potassium, chloride, calcium, urea nitrogen, creatinine, haematocrit, haemoglobin and anion gap. From the pilot data, we identified creatinine, TCO2, chloride and calcium as potentially useful markers. To develop a time course and to establish variability of the selected blood parameters, a time series of samples was collected from 12 ewes, from mid-gestation to 48 h after birth. For the main trial, blood samples were collected at mid- and late gestation for glucose determination and for the full set of blood parameters at three time points before, at and after birth. Possible predictors of lambing difficulty were chloride, haematocrit and haemoglobin, sampled one week before birth; creatinine, sampled at birth; and blood pH and base excess after birth. In conclusion, we found that pen-side analysis of blood markers showed promise in identifying dystocic lambing events.

Depletion of testis cell populations in pre-pubertal Bos indicus cattle by irradiation.

Recovery of spermatogenesis following a single dose of irradiation was evaluated in pre-pubertal Brahman bulls, after receiving a single dose of 3, 6, 9 or 12Gray (Gy) irradiation. Biopsy samples of testis tissue were collected and processed for immunohistology at various times following irradiation. Spermatogenic recovery was defined by the changes in tubule diameter, and absolute numbers of undifferentiated spermatogonia (PLZF positive cells) and Sertoli cells (GATA-4 positive cells) per tubule cross section. The effect of irradiation on the depletion of testicular cells was dose-dependent. Immunohistological results from both the 9 and 12Gy group showed degeneration of seminiferous tubules, compared with other doses and controls. From 2 weeks after the treatment, irradiation resulted in a significant and dramatic reduction in tubule diameter (up to 40%), number of undifferentiated spermatogonia (up to 90%) and Sertoli cells (up to 70%), which was sustained for up to 16 weeks post-irradiation in 9 and 12Gy groups (P<0.0001). However, a moderate depletion effect was observed in the 6Gy treatment groups, compared with 9 and 12Gy doses. The 6Gy treatment had significant effects on spermatogonia (up to 79% reduction) and Sertoli cell (30% reduction) numbers following irradiation (P<0.0001). In contrast, the 3Gy dose had no significant effect at either 3 or 5 weeks post-irradiation on tubule diameter, spermatogonia or Sertoli cells. In conclusion, the results from the current study suggest that treatment of recipient testes with a single dose of 6Gy irradiation can temporarily deplete spermatogonial cells in pre-pubertal Brahman bulls, whilst minimising the impact on Sertoli cells and tubule morphology.