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Item Influence of pre-slaughter holding time, growth path and castration on meat quality characteristics of beef M. Longissimus Thoracis : a thesis presented in partial fulfilment of the requirements for the degree of Master of Applied Science in Animal Science at Massey University(Massey University, 1999) Peachey, Bridget MThe New Zealand Beef Industry has included among its research goals the need to enhance product consistency and consumer satisfaction. Identifying on-farm and post-slaughter techniques for producing quality meat will permit the delivery of a more consistent product. The objectives of this study were to examine the influence of castration, pre-slaughter holding time, and growth path on meat quality characteristics with emphasis on meat tenderness. Sixty male Hereford x Angus cattle were used, half of which were castrated at weaning. They were then ranked within their castration groups on their growth performance during a 100-day pretrial period. Of the 40 faster-growing animals, 20 were randomly selected to be slaughtered at 16-18 months of age at approximately 550 kg liveweight (the fast group; F) and the remaining 20 were managed in such a way that they reached the same liveweight as the slower-growing 20 animals (S) at 25 months of age (restricted group; R). Once at the abattoir half the animals were randomly selected within castration and growth path groups to be held for either 4 or 28 hours pre-slaughter. Measures of meat quality characteristics were made on a sample of the M. longissimus thoracis, of each animal that was removed soon after slaughter. The bulls produced meat with higher ultimate pH values (5.64 vs 5.46, P<0.001) and meat that was significantly tougher than steers as evaluated by MIRINZ peak force (6.6 vs 4.6 kg, P<0.001), and sensory toughness (6.10 vs 4.50, P<0.001), both before and after adjustment for differences in pH. Animals held for 4h pre-slaughter had tougher meat as measured by Instron compression maximum load (92.8 vs 82.0, P<0.05). Cattle in Group F produced meat that had a higher ultimate pH (P<0.001), however, meat from animals in Group F was significantly more tender as measured by sensory analysis (P<0.001). There were few differences between cattle in Groups R and S suggesting that differences in tenderness in this and other studies between animals on fast and slow growth rates were a result of differences in animal age rather than in inherent growth potential of the animals. Results suggest that holding cattle under appropriate welfare standards and allowing them enough time to recover from trucking and environmental stress should result in acceptable meat. Results from this trial have practical implications for producers and processors, and for the production of beef for the New Zealand Quality Mark. In this trial beef was tougher when it was from bulls or from older groups of cattle, with these two effects appearing to be additive. It is therefore suggested that cattle age and gender criteria should be considered for inclusion in the Quality Mark system.Item The effect of early post-natal castration on subsequent electroencephalogram response to tail docking in lambs : a thesis presented in fulfilment of the requirements of the degree of Master of Veterinary Science at Massey University, Palmerston North, New Zealand(Massey University, 2015) Impey, StevenThe objective of this study was to investigate the effect of early age painful stimulation on the cortical response to subsequent painful stimulation in lambs. Using the electroencephalogram (EEG), the current study measured the effect of early age castration at one day of age on the cortical pain response to tail docking at 23 days of age in lambs. Lambs were randomly assigned to rubber ring castration (n=12) or handling (n=12) at one day of age. At 23 days of age lambs were tail docked under a minimal plane of anaesthesia maintained using halothane in oxygen (PEHal = 1%). EEG data was recorded for two minutes pre-docking, and for eight minutes following tail docking. EEG median frequency, spectral edge frequency and total power were derived using fast Fourier transform. Data were analysed for group (castrated versus handled), time and group by time effects using mixed model analysis, as well as for the effect of group on pre-docking EEG. Castrated lambs showed an increased cortical response to pain, demonstrated by a greater increase in EEG median frequency (Mixed model analysis; F = 5.45, P = 0.03) and greater reduction in total power (F = 5.15, P = 0.03) in response to subsequent tail docking. These findings indicate that early age noxious stimulation results in an increased cortical response to subsequent noxious stimulation at approximately three weeks of age in lambs. The greater cortical response in the castrated lambs would likely correspond to an increased perception of pain, and therefore the potential for a greater degree of suffering and welfare compromise in response to subsequent painful injuries, for example lambing, injury and footrot. There was also a tendency toward a higher pre-docking total power of the EEG in the castrated lambs when compared with handled lambs (Satterthwaite’s t-test; T = 1.86, P = 0.08). The higher pre-docking total power may indicate a greater background activity in the nociceptive centres of the castrated lambs. However, the significance of this finding is not clear at this stage, and further work is necessary to better define the basis and clinical importance of this observation.Item Pain assessment and alleviation in the domestic cat (Felis catus) : a thesis presented in fulfilment of the requirements for the degree of Doctor of Philosophy in Veterinary Science at Massey University, Manawatu, New Zealand(Massey University, 2014) Farnworth, Mark JamesThis thesis begins by exploring current knowledge around the domestic cat population and gonadectomy as well as pain assessment tools and pain alleviation for cats. It identifies a number of areas where knowledge is either absent or in need of updating and limitations in tools for the assessment of pain in cats. It therefore proposes the undertaking of the projects which can be found in the subsequent chapters. Chapters two and three compared the attitudes and practices of veterinarians in New Zealand, Australia and the United Kingdom (UK) around pre-pubertal gonadectomy and provision of analgesia for cats. This used an electronic questionnaire which received 717 responses. Most respondents believed pre-pubertal gonadectomy was either entirely or ‘sometimes’ desirable (556/621). Age of patient at gonadectomy was significantly affected by country surveyed and respondents’ provision or nonprovision of services for pounds. Post hoc Tukey HSD analysis indicated the mean age of both spaying and castration (both 4.3 months) in the UK was significantly different from both Australia (spaying: 3.4 months, castration: 3.2 months) and New Zealand (spaying: 3.4 months, castration: 3.2 months) (all p < 0.001). Mean ages at spaying and castration were also significantly different (p=0.008; p=0.019 respectively) for non-providers (spaying: 3.9 months, castration: 3.8 months) of services to pounds when compared to providers (spaying and castration: both 3.6 months). With respect to the use of analgesics there has been a substantial increase in provision of analgesia to cats undergoing gonadectomy when compared to the early literature. There were significant differences in prevalence of analgesia provision prior to and following spaying and castration (both p < 0.001). There were also significant postoperative and post-discharge differences in provision of analgesia for castration, as compared to spaying (both p < 0.001), and a similar effect was seen pre/intraoperatively (p = 0.002). Significant effects amongst countries and between genders relative to the desirability of pre-pubertal gonadectomy were identified. Respondents from the UK were more likely to answer ‘no’ (p=0.004) or ‘sometimes’ (p=0.05) as compared to those from New Zealand or Australia. Females were more likely to respond with ‘sometimes’ as opposed to ‘yes’ than males. Reasons for considering pre-pubertal gonadectomy desirable or sometimes desirable focussed on reducing unwanted pregnancies and improving population control, as well as improving rates of adoption, owner compliance and cat behaviour and health. Post-operative provision of analgesia following both castration (p < 0.001) and spaying (p < 0.001) also differed amongst countries of practice. Veterinarians in Australia and New Zealand were more likely to provide post-operative analgesia than those from the UK. Veterinarians from the UK more commonly used non-steroidal anti-inflammatory drugs (NSAID) in the pre/intraoperative phase (P < 0.001) than veterinarians from either New Zealand or Australia. Differences in attitudes towards pre-pubertal gonadectomy amongst countries may relate to the specific Veterinary Association’s guidelines or possibly differences in social discourse which affect perception of cats. There is substantial overlap between the reported minimum age of gonadectomy and the age at which cats can enter early puberty, allowing a window for unintentional pregnancy when pre-pubertal gonadectomy does not occur. The differences in use of analgesics amongst the UK, Australia and New Zealand may reflect differing professional considerations of the risks associated with the use of NSAID. In the interests of animal welfare, pain relief should perhaps be provided or offered more frequently for owner administration. Chapters four through six explored the value of a thermal carbon dioxide (CO2) laser for the assessment of nociceptive thresholds in cats. To begin repeatabilites were established based on individual responses to three thermal tests on the same day and across 4 consecutive days. A total of 12 thermal tests were conducted on 16 adult cats (50% male). A non-thermal helium aiming laser was used as a control to ensure the animals were responding to the thermal component of the device. All thermal tests elicited a behavioural response 97% of which were a skin twitch known as the panniculus reflex. No control tests resulted in this reflex behaviour. There was no evidence that cats became sensitised or habituated to the low power thermal stimulus on any given day (p=0.426) or across days (p=0.115). There was also no difference in latency to respond between males and females (p=0.094), although there was a significant day of testing and sex interation (p=0.042). Significant intra-class correlations (ICC) demonstrated that individual responses were repeatable over days 1 to 3 (all p<0.05) but not over day 4 (p=0.096). A significant intra-class correlation was also evident across all days when data were combined (p<0.0001). Significant repeatabilities in the first laser-based experiment were low ranging from 0.241 to 0.414 therefore a larger sample was used (n=113) to establish any other factors, including age or sex effects, that impacted upon thermal sensitivity. In this next phase cats were exposed to a more powerful (500mW) CO2 thermal laser three times during a 45-60 min test period with a minimum of 15 min elapsed between consecutive tests on any one individual. Again time to display a behavioural response was repeatable across tests for any given cat (ICC=0.482; p<0.001). Analyses of covariance established that the body weight of females significantly affected response threshold (p=0.013) but for males this effect was marginal (p=0.058). All other factors included in the analyses were non-significant. A post hoc t-test for males and females with overlapping body weights found no significant differences between the sexes (p=0.721). The precise reason for the effect of body weight on latency to respond is unknown and further exploration is needed. Finally the CO2 laser’s ability to assess analgesia in pain-free cats was explored. Sixty healthy adult female cats were used and randomly allocated to one of six treatments 1) saline 0.2 ml/cat; 2) morphine 0.5 mg/kg; 3) buprenorphine 20μg/kg; 4) medetomidine 2 μg/kg; 5) tramadol 2mg/kg; 6) ketoprofen 2mg/kg. Latency to respond to thermal stimulation was assessed prior to intramuscular injection and at 6 time periods following injection (15-30; 30-45; 45-60; 60-75; 90-105; 120-135 min). Thermal thresholds were again assessed using time to respond behaviourally to stimulation with a 500mW CO2 laser. Maximum latency to respond was set at 60 sec but given that this technique was found to cause minor skin blistering in individuals that reached the 60s exposure limit, a cut off time of <45s is recommended.. Differences in response latency for each treatment across the duration of the experiment were assessed using a Friedman’s test. Differences between treatments at any given time were assessed using an independent Kruskal-Wallis test. Where significant effects were identified, pair-wise comparisons were conducted to further explain the direction of the effect. Cats treated with morphine (p=0.045) and tramadol (p=0.002) showed significant increases in latency to respond over the duration of the test period. Treatment with buprenorphine also resulted in increases in latency to respond although only at the level of a statistical trend (p=0.091). Injection of saline, ketoprofen or medetomidine showed no significant effect on latency to respond. The longest latency to respond after injection of morphine was achieved at 60-75 min whilst that of buprenorphine occurred at 90-105 min. These projects validated the CO2 laser technique for use in cats and demonstrate that it can be used for assessment of analgesia and may be useful for differentiating amongst analgesic treatments. This technique may provide a simpler alternative to existing systems although further exploration is required both in terms of its sensitivity and comparative utility (i.e. relative to other thermal threshold systems). Future possible experiments using this technique are to be found in the discussion chapter.Item Assessment and alleviation of castration distress in lambs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science at Massey University(Massey University, 1995) Dinniss, Andrew SelwynThere is increasing pressure on the farming community to assess and minimise the distress caused by husbandry procedures. This is due to an increase in awareness of animal welfare throughout New Zealand, and economic pressures from overseas. This study involved an investigations into the acute pain-induced distress of lambs caused by castration, the effectiveness of different anaesthetic methods to alleviate that distress, characterisation and validation of behavioural responses as indices of pain-induced distress, and the assessment of the use of the burdizzo to reduce the acute pain-induced distress caused by ring castration. The castration techniques examined were ring, burdizzo, and ring + burdizzo. Short scrotum creation was also assessed. The alleviation techniques were injections of local anaesthetic into the scrotum, spermatic cords, testes or the scrotum + spermatic cords, 15 minutes prior to castration. This study assessed the effectiveness of using a burdizzo before application of a rubber ring to reduce the distress, as indicated by cortisol and behaviour responses, caused by ring application. The concept of using a burdizzo to reduce the distress caused by ring castration was based on the hypothesis that 'disabling the afferent nerves from the testes would prevent nociception caused by ring application from being transmitted' (Kent et al. 1993,1995). It was found that the burdizzo used in the conventional manner (one application to each spermatic cord and the surrounding scrotal tissue with no overlap of 'cuts') together with ring application did not reduce the cortisol or behavioural responses to ring castration. Hence it is unlikely that pain will have been reduced. This study characterised the cortisol and behavioural response to burdizzo castration. The cortisol response was found to have a duration of 180 minutes with a magnitude similar to that exhibited by ring lambs. However, the values remained elevated for longer than ring in lambs. Although the cortisol response is likely to indicate noxious sensory input caused by burdizzo application, it cannot be proved, using the results of this study, that sensory-independent stimulation of the hypothalamic pituitary adrenal axis is not responsible for this cortisol response to burdizzo castration. Local anaesthetic administrated into the scrotum, spermatic cords plus scrotum, or testes was found to abolish the cortisol response and either reduce or abolish different behaviours after ring castration suggesting that pain-induced distress caused by application of a rubber ring was prevented. The cortisol response and some behaviours caused by burdizzo plus ring castration were also prevented by injecting local anaesthetic into the scrotum prior to treatment indicating that pain-induced distress was also prevented. Local anaesthetic injected into the spermatic cords reduced numerically (although not significantly), but did not abolish the cortisol response to ring or burdizzo plus ring castration. This suggested that the scrotum, which was presumed to be unanaesthetised, was a significant source of nociception after these two treatments. Local anaesthetic injected into the scrotum or spermatic cords did not reduce the cortisol or behavioural responses to burdizzo castration. This can lead to two conclusions; either local anaesthetic did not anaesthetise all the tissue effected by the burdizzo, or something other than sensory input stimulated the hypothalamic-pituitary-adrenal axis after burdizzo castration. Intuitively, the former seems most likely. Some behaviour parameters were found to be useful when comparing the pain-induced distress caused by similar treatments that elicited similar behaviours, but not when comparing between treatments that caused different types of tissue damage and elicited different behavioural responses. Burdizzo castration did not cause any obvious abnormal behaviours, suggesting that either no significant sensory input was caused by burdizzo application or that our behaviour observation methodology was not sensitive enough to pick up nuances of behaviour. Hence it was not possible to use behaviour to compare intensities of pain-induced distress caused by ring or burdizzo castration. Practically the use of the burdizzo in the conventional manner to reduce the pain-induced distress caused by ring application cannot be advised. Further work needs to be done to assess practical aspects of the modified use of the burdizzo (across the whole width of the scrotum suggested by Kent et al. 1993,1995) before it can be recommended as an alternative method of castration. The use of local anaesthetic in the field needs to be investigated further before it can be recommended. It seems that simple methods of local analgesia may be possible, however the danger of possible complications such as sepsis must be evaluated.Item Effects of cranial cervical ganglionectomy and castration on endocrine and morphological characteristics of male lambs : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University(Massey University, 1978) Fisher, Mark WarrenIn a study of the effects of the pineal gland on reproductive development and hormone secretion, male lambs were incorporated into an overall 2 x 2 factorial design in which the experimental factors were: (1) cranial cervical ganglionectomized or non-ganglionectomized, and (2) castrated or entire. The first experiment described was a longitudinal study of endocrine and morphological parameters recorded from these animals between 7 and 37 weeks of age. Plasma LH levels in entire lambs usually were very low throughout the experiment, although non-ganglionectomized entires did display a small elevation in levels between 8 and 13 weeks of age, which was not evident in ganglionectomized entires. At all ages plasma LH levels were elevated significantly in castrated animals. Neither ganglionectomy nor its interaction with castration had any significant effect on LH levels. In entire lambs plasma testosterone concentrations increased from 7 weeks to highest concentrations between 31 and 37 weeks of age. Overall, ganglionectomy reduced testosterone secretion, but this probably was due to the lower body and testicular weights recorded from that group. The normal photoperiod-induced seasonal pattern of prolactin secretion in non-ganglionectomized lambs, with high levels during the summer months and low during winter, was markedly disrupted by ganglionectomy. Castration had no effect on prolactin levels and the interaction of castration and ganglionectomy also was non-significant. Bodyweight was reduced significantly by ganglionectomy and this effect was accentuated in the ganglionectomized castrates. At autopsy, testicular weights and epididymal weights as well as epididymal sperm reserves were reduced, but not significantly, by ganglionectomy; these results probably reflected the bodyweight of those animals. Neither ganglionectomy nor castration had any significant effect on pineal weights, however the interaction of these two factors was significant due to the very large pineal of one of the non-ganglionectomized castrates. A second experiment involved measurement of LH, prolactin and testosterone profiles in plasma obtained during hourly blood samplings which were conducted for 24 hours when lambs were both approximately 100 and 300 days of age. At both ages pulsatile secretion of LH and testosterone was confirmed, but no circadian rhythms of LH, testosterone or prolactin secretion were detected. Castration elevated LH levels significantly at both ages. Ganglionectomy and its interaction with castration had no effect on LH secretion at 100 days, but at 300 days these factors were significant largely due to elevated levels being recorded from ganglionectomized castrates. Ganglionectomy did not affect testosterone levels in entire animals at either age while castrates had no detectable testosterone. Ganglionectomy reduced prolactin concentrations at 100 days of age (summer) and prevented the normal winter decline at 300 days of age. Castration and the interaction of castration with ganglionectomy had no significant influence on plasma prolactin levels at either age. Pituitary LH and gonadal testosterone responses to 10 μg synthetic GnRH were tested at 100 days and 300 days of age in a third experiment. In all animals, GnRH elevated LH levels and in entires this in turn resulted in increased testosterone levels. Castration significantly increased basal and peak LH levels together with total LH output. At both ages the LH and testosterone responses to GnRH were not influenced significantly by ganglionectomy, nor did the interaction of castration and ganglionectomy have any significant effect on LH secretory responses. These studies confirm the concept that the pineal gland can influence the secretion of prolactin, and probably also LH and testosterone, and thus may be involved in the regulation of pubertal development in ram lambs.Item The effect of early painful experiences on subsequent pain sensitivity in lambs : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Science in Physiology at Massey University, Manawatu, New Zealand(Massey University, 2011) Pifeliti, SeiniThere is evidence that painful events in early life can alter subsequent pain processing and sensitivity, at least in altricial species. However, it is not known whether similar effects occur in precocial species, such as lambs, which are relatively mature at birth. Lambs in New Zealand are routinely exposed to painful procedures like castration and tail docking at a young age. The possibility that these early procedures result in hypersensitivity to subsequent painful events is a serious welfare issue. The aim of this study was to assess the effect of early castration on the behavioural responses of lambs to subsequent tail docking. The effect of age at first treatment (castration or control handling) and age at docking were also assessed. Lambs were castrated (C) or handled (H) at either 1 (Group 1, N=21; Group 2, N=27; Group 3, N=23; Group 4, N=24) or 21 (Group 5, N=26; Group 6, N=24) days of age and their behavioural responses to docking measured 3-6 weeks later. Differences between C and H lambs were evident before docking had taken place; C lambs walked backwards less frequently and spent less time standing unsteadily than H lambs. After docking, C lambs stamped their feet more frequently and spent less time lying laterally than H lambs. Age at first treatment was not found to have a significant effect on behaviour in response to docking. Interestingly, lambs docked at 42 days of age differed from those docked at 21 days of age in their response. Twenty-one-day old lambs displayed significantly higher frequencies and durations of a number of pain-related behaviours when compared to their 42 day old counterparts. Only one behaviour, unsteady standing, was performed for longer durations by the older lambs. It can be concluded that castration does affect the behavioural response of lambs to subsequent docking and that age at docking is also a significant factor in this response. Further research is required to further clarify the magnitude of these effects.