Evaluation of Electroencephalography, Behaviour and Eye Temperature in Response to Surgical Castration in Sheep

Castration has been demonstrated to cause pain in sheep. However, it is routinely performed for management purposes. Electroencephalography (EEG) has been used successfully to measure pain in lambs in response to castration and other husbandry procedures in livestock. The aim of this study was to evaluate the use of EEG as a measure of pain and analgesia in conscious lambs undergoing castration on farm over a 24 h period. EEG responses were compared to behavioural observations and changes in ocular temperature via infrared thermography. Twenty-four merino ram lambs (18.63 ± 2.06 kg) were used in this study. Lambs were randomly allocated to one of the following treatment groups: (1) castration with pre-surgical administration of meloxicam (0.5 mg/kg Metacam 20 mg/mL injected subcutaneously into the skin of the neck 15 min prior to recording) and lignocaine (applied via intra-testicular injection five minutes prior to castration, 2 mL lignocaine hydrochloride 20 mg/mL, Troy/Ilium) (CML, n = 8); (2) castration only (C, n = 8); (3) sham castration, handling only (SC, n = 8). EEG was recorded for 5 mins pre-procedure (prior to any intervention), and for 5 mins post-procedure at 0, 1, 4 and 24 h. Behavioural reactions to the procedure were scored, and behaviours were scan sampled at 5 min intervals at the above time points, by blinded observers. Eye temperature was measured for five-minute intervals at each time point. EEG decreased from baseline to 0 h for CML and C groups (p < 0.001), C group values returned similar to baseline at 24 h. Eye temperature increased post-castration at 0 h for C group, no initial change was seen for CML or SC groups. CML and C groups were more likely to have higher reaction scores and showed more abnormal behaviours (p = 0.017). CML and C groups had similar results, indicating minimal effect of analgesic intervention. Lambs in SC group showed significant EEG changes, suggesting that stress from handling also impacted EEG results.

Salivary Cortisol and Infrared Thermographic Ocular Temperature Use as Biomarkers during Endurance Competitions

Objective quantification of effort and distress during endurance rides through biomarkers could help manage competitions more effectively and monitor horse welfare through an evidence-based approach. This study aimed to determine if salivary cortisol (SC) and ocular temperature measured by infrared thermography (IRTOT) are related to the outcome in endurance competitions. Saliva was collected and IRTOT measured from 61 and 14 horses, respectively, competing at qualifier 40km and 80km rides at Pre-Inspection (PI) and Vet Gates (VG). The variation of the baseline SC at the PI (median±IQR=0.27ng/dl±0.36) into VG1 was abrupt (93-256% rise) and in the next VGs either decreased or rose at a very modest level. Less experienced horses in the 40km ride showed a significantly (p<0.05) higher IRTOT (median±IQR=35.7ºC±1.4) at the PI, than their counterparts in the 80Km ride (median±IQR=35. ºC ±1.5). Horses classifying in the Top5, in the 40 km ride category had significantly (p=0.05) higher SC levels (median±IQR=0.90ng/ml ±0.61) at the PI, than horses positioned from 10th position on (median±IQR = 0.16ng/ml ±0.40). A lower IRTOT in the PI was correlated with a better placement (p>0.05) and those in the Top5 (median±IQR = 33.9ºC ±0.0) had a higher variation (+10.65%) into the last VG. A 62% predictive value for elimination (80% sensibility and 82% specificity) where SC is higher than 0.23ng/ml is advanced. SC and IRTOT can be potentially used in association to characterise physical effort and emotional stress in endurance competitions, but its significance to performance has to be put in context with the competition level.

Short communication: Using infrared ocular thermography as a tool to predict meat quality from lean cattle breeds prior to slaughter: Exploratory trial

Aim of study: To assess the potential of using infrared ocular thermography (IROT) as a tool to predict beef quality at the slaughterhouse.Area of study: The study was carried out in the Salteras’s slaughterhouse (Seville, Spain).Material and methods: Ocular temperature images were captured from 175 lean young bulls prior to slaughter. Carcasses were classified into three groups according to weight: ˂250 kg, 250-310 kg and ˃310 kg. IROT was measured just before slaughter and pH was measured 24 h later. Colour parameters (CIELAB space) were evaluated 48 h post-slaughter. Water holding capacity was evaluated at seven days after slaughter.Main results: IROT mean values were higher in heavier bulls (p<0.05), probably due to these animals appeared to movilize a greater blood flow, thus increasing ocular temperature. Furthermore, IROT showed a statistically significant correlation with both pH from light carcasses (r=0.66; p<0.001), and mean Hue value from all carcass weights (r=-0.22; p<0.05). A quadratic regression analysis accounting carcass weight as a continuous variable, found medium to strong fit values for pH (R2=0.52; RMSE=0.032; p<0.01) and medium fit values for H* (R2=0.41; RMSE=3.793; p<0.001), changing their relation with IROT depending on carcass weight.Research highlights: IROT showed potential to become a useful tool to assess pH in light carcasses and to assess H* in all carcasses of young bulls prior to slaughter, regardless their weight. However, further studies would be recommended under more variable pre-slaughter stress conditions.

Effect of Lignocaine and a Topical Vapocoolant Spray on Pain Response during Surgical Castration of Beef Calves

This study assessed the efficacy of pre-operative injected lignocaine and peri-operative topical vapocoolant spray, administered as most practical for incorporation into routine calf castration procedures. Calves were randomly allocated to: (1) sham castration (SHAM); (2) surgical castration (CAST); (3) surgical castration with lignocaine (LIG); and (4) surgical castration with vapocoolant spray (VAPO). Calf behavioural responses were scored at different stages of the sham castration or castration procedure. Maximum ocular temperatures were measured at three time-points relative to restraint and treatment. There were significant effects of treatment (p < 0.001) and stage of procedure (p < 0.001) on calf behavioural response. SHAM calves were more likely to display less severe responses compared to all other calves and LIG calves were more likely to display less severe responses compared to VAPO calves. Calves were more likely to display more severe responses to extrusion of the first spermatic cord compared to all other stages of castration, and to extrusion of the second spermatic cord compared to severing of the second spermatic cord. There was a significant effect of time (p < 0.001) on ocular temperature, with ocular temperature being greater following sham castration or castration. In this study, there was no evidence of pain reduction during castration of calves by either lignocaine or vapocoolant spray.