Effects of ovine corticotropin-releasing factor and vasopressin on plasma beta-endorphin, cortisol and behavior after minor surgery in sheep

The evidence for an analgesic effect arising from increased peripheral concentrations of beta-endorphin (beta-EP) in various animal species is controversial, and has not been fully evaluated in the sheep. To stimulate beta-EP release, ovine corticotropin-releasing factor (oCRF) and arginine vasopressin (AVP) were injected intravenously (iv) into a group of 12 out of 24 sheep, 15 min prior to minor surgery on all sheep. This brought about significant increases (P less than 0.01) in plasma beta-endorphin (beta-EP) and cortisol concentrations, relative to the non-injected control sheep, 15-30 min after injection. Ultrafiltration indicated that less than 30% of the released beta-EP immunoreactivity was present as higher molecular weight forms (mol. wt greater than 10,000) and that the majority (about 75%) of the beta-EP was probably bound to plasma proteins. By 75 min after injection there was no significant difference in plasma beta-EP or cortisol concentrations between the two groups of sheep. Consistent with previous observations the sheep showed a characteristic aversive behavior to the human handler following surgery, lasting several days. This behavior appeared to be unaffected by a pre-operative increase in peripheral plasma beta-EP, and may indicate that this increase in beta-EP was not sufficiently analgesic to block the cognitive response to the operation, or long-lasting enough to prevent the perception of post-operative soreness.     

Use of local anaesthesia for pain management during husbandry procedures in Australian sheep flocks

Mulesing (removal of breech skin for blowfly strike control), castration, tail-docking and ear-knotching are routine husbandry procedures conducted on many millions of lambs annually in Australia, causing considerable pain and suffering. However, establishing an effective alternative to mulesing is proving to be a difficult and prolonged process. This is particularly so for producers of high-quality fine wool from Merino sheep that have been selected over many generations for skin wrinkle to increase yields, increasing their susceptibility to flystrike by Lucilia cuprina. In late 2005, a spray-on product formulation containing two topical analgesia agents (lignocaine and bupivacaine) for pain relief at mulesing has become commercially available. Increasingly, fine-wool growers have been choosing to continue surgical mulesing, but adopting pain alleviation at surgical mulesing to reduce suffering. This product has led to the development of the “Better Choices” program, in an effort to meet international concerns that mulesing without pain relief was cruel. Studies have been conducted on the use of these products for decrease of pain induced by surgical mulesing, castration and tail-docking. A technique has been developed to measure pain through assessment of wound sensitivity using Von-Frey Hair stimulation, measuring local involuntary reflexes and central cognition. These responses were graded using a numerical rating scale. Behavioural responses to pain were analysed by video. A novel technique was developed to assess the rate of wound healing by digital photography and computerized surface area measurement. Also, a method of application was developed at castration, which enabled analgesia of the remaining scrotal contents, with impressive results compared to other methods of castration such as the use of rubber rings. Findings from a series of field and pen trials indicate that the immediate application of spray-on topical anaesthesia to mulesing, castration and tail-docking wounds, significantly reduced the pain experienced post-procedure and improved the rate of wound healing. Increasing adoption by producers of pain relief for lambs during surgical routine husbandry procedures offers a new welfare-conscious paradigm for the Australian wool industry. This development has potential application to several species undergoing many livestock procedures throughout the world and offers a simple part solution to address the increasingly important and emerging global issue of welfare conscious agriculture.     

Hypothalamic-pituitary-adrenal responses to short-duration high-intensity cycle exercise

beta-Endorphin (beta-EP), adrenocorticotropin (ACTH), and cortisol plasma concentrations were examined before and after maximal exercise at four intensities [36, 55, 73, and 100% of maximal leg power (MLP)] by means of a computerized cycle ergometer. All intensities were greater than those eliciting peak O2 uptake for the individual subjects. Blood samples were collected at rest, immediately after exercise, and at 5 and 15 min postexercise. Significant (P less than 0.05) increases were observed at 36% MLP for beta-EP and ACTH immediately after exercise and at 5 and 15 min postexercise. Plasma cortisol increased at 36% MLP at 15 min postexercise. Blood lactate significantly increased at all postexercise collection points for exercise intensities of 36, 55, and 73% MLP and at 5 min postexercise for 100% MLP. beta-EP concentrations at 36% MLP were significantly correlated (r = 0.75) with capillary density (mm-2), and cortisol concentrations at 36% MLP were significantly correlated (r = 0.89) with percentage of type II muscle fibers. No other significant relationships were observed. These data show that brief, high-intensity exercise up to maximal power production results in a nonlinear response pattern in peripheral blood hormone concentrations. Furthermore, blood lactate levels do not appear to be related to hypothalamic-pituitary-adrenal hormone plasma concentrations at high exercise intensities.     

Effect of a topical anaesthetic formulation on the cortisol response to surgical castration of unweaned beef calves

Impracticality and cost of existing pain management strategies during surgical castration of beef cattle have limited their widespread implementation on-farm. A farmer-applied topical anaesthetic formulation, originally developed and used commercially to mitigate the pain of mulesing in lambs, was investigated for its potential use for managing pain in surgically castrated calves. This formulation contained lidocaine, bupivacaine, adrenalin and cetrimide. In this study, 24 Angus bull calves were randomly allocated to (1) surgical castration (C, n=8), (2) surgical castration with the post-operative application of topical anaesthetic (CTA, n=8) and (3) sham castration/control (CON, n=8). The experiment was conducted over 2 days, with treatment groups evenly represented across each day. Calves were habituated to handling before the experiment and blood samples were collected for plasma cortisol measurement at defined time periods before, at and post treatment, (at −0.5, 0 h, then +0.5, 1, 1.5, 2, 4 and 6 h). There was a significant effect of time on cortisol concentrations across all treatment groups (P<0.01), with lowest concentrations at −0.5 and 6 h and peak concentration at 0.5 h being significantly higher than the cortisol response at 0 h. The effect of treatment was not significant (P=0.077), however, there was a trend for CON calves to display lower cortisol concentrations than C and CTA calves and CTA calves to display lower cortisol concentrations than C calves. The mean area under the curve (AUC) of CON calves was significantly lower than those of C and CTA calves (P=0.04), however, there was no significant difference between the AUCs of CTA and C calves. Immediate application of topical anaesthetic after surgical castration did not significantly reduce plasma cortisol concentrations. However, the trend for CTA calves to display lower cortisol concentrations than C calves warrants further investigation into the use of TA for pain relief of surgically castrated beef calves.     

Behavioural measures reflect pain-mitigating effects of meloxicam in combination with Tri-Solfen® in mulesed Merino lambs

Flystrike costs the Australian industry $173 to 280 M per annum and 70% to 80% of Merino lambs are currently mulesed to reduce the risk of flystrike. To alleviate welfare concerns there has been widespread adoption of analgesics to mitigate the pain associated with mulesing. The objective of this experiment was to determine the effectiveness of Tri-Solfen® and meloxicam (Metacam® 20) at reducing pain-related behavioural responses to mulesing in Merino lambs. One hundred and forty Merino lambs were allocated to one of seven treatment groups: (1) non-mulesed (Control); (2) mulesed with no pain relief; (3) subcutaneous (s.c.) meloxicam administered 15 min before mulesing; (4) Tri-Solfen® administered at time of mulesing; (5) Tri-Solfen® and saline injection (s.c.) 15 min before mulesing; (6) Tri-Solfen® and meloxicam (s.c.) 15 min before mulesing; and (7) meloxicam (s.c.) at time the of mulesing. Behavioural responses such as standing, walking and lying were measured every 15 min for 6 h on the day of marking and for up to 2 h for 4 days thereafter. Standing (hunched v. normal) and walking (stiff v. normal) behaviours were then categorised into pain- and normal-related behaviours while lying remained in its own category. Mulesed lambs with no pain relief displayed significantly more pain-related behaviours than Control lambs during the 6 h post-mulesing (1.22 v. 0.22 out of a total score of 3; RSD=1.15). Lambs that received a combination of pain relief displayed significantly less pain-related behaviour than mulesed lambs with no pain relief on the day of mulesing (0.85 v. 1.22 out of a total score of 3; RSD=1.15). Administration of meloxicam or Tri-Solfen® on their own had minimal if any significant effect on pain-related behaviours on the day of mulesing. The results of this experiment support the use of pain-related behaviours to measure the efficacy of analgesics and the use of multimodal analgesia during mulesing of lambs.     

Tail docking in pigs: acute physiological and behavioural responses

Tail docking of piglets is a routine procedure on farms to control tail-biting behaviour; however, docking can cause an acute stress response. The objectives of this research were to determine the stress responses to tail docking in piglets and to compare two methods of tail docking; cautery iron (CAUT) and the more commonly used blunt trauma cutters (BT). At approximately 6 days of age, piglets were tail docked using CAUT (n = 20), BT (n = 20) or sham tail docked with their tails remaining intact (CON; n = 40). Blood samples were taken prior to tail docking and at 30, 60 and 90 min after tail docking to evaluate the effect of tail docking on white blood cell (WBC) measures and cortisol concentrations. The above experiment was repeated to observe behaviour without the periodic blood sampling, so as not to confound the effects of blood sampling on piglet behaviour. Piglet behaviour was recorded in the farrowing crate using 1 min scan-samples via live observations for 60 min prior to and 90 min after tail docking. Total WBC counts were reduced (P > 0.05) among BT and CAUT compared with CON piglets 30 min after tail docking. Cortisol concentrations were higher (P < 0.01) among BT compared with CON and CAUT piglets 60 min after tail docking. Cautery and BT-docked piglets spent more (P < 0.05) time posterior scooting compared with CON piglets between 0 and 15 min, and 31 and 45 min after tail docking. Piglets tail docked using CAUT and BT tended to spend more (P < 0.07) time sitting than CON piglets between 0 and 15 min post tail docking. Elevated blood cortisol can be reduced by the use of the CAUT rather than the BT method of tail docking. Although the tail docking-induced rise in cortisol was prevented by using CAUT, the behavioural response to BT and CAUT docking methods was similar.     

Ear tagging in piglets: the cortisol response with and without analgesia in comparison with castration and tail docking

The objectives of the present study were to compare the cortisol response caused by ear tagging piglets with the distress caused by other known painful husbandry procedures (e.g. castration and tail docking) and to evaluate the effectiveness of analgesia with meloxicam to reduce the cortisol response caused by these procedures. In total, 210 male piglets were randomised to equal numbers (n=30) into one of seven groups: a control group which was only handled (H), an ear tagged group that received no analgesia (ET), an ear tagged group with analgesia (ETM), a castration group with no analgesia (C), a castration group with analgesia (CM), a tail-docked group with no analgesia (TD) and a tail-docked group with analgesia (TDM). The procedures were carried out on day 3 or 4 after farrowing. Five blood samples were taken from each piglet: 30 min before the respective procedure (baseline value), and 30, 60 min, 4 and 7 h after processing, to assess cortisol concentrations. Means as well as the area under the curve (AUC) value were analysed and the effective sizes of the procedures were established. At 7 h after the experimental treatment, cortisol concentrations had returned to base values in all groups. ET evoked a greater cortisol response than H piglets at 30 min (P<0.001) and 60 min (P=0.001). The cortisol response to ET was lower than C at 30 min (P=0.001) but did not differ significantly at the other sample times. The mean cortisol response was similar between ET and TD piglets over all sample times. Taking both intensity and duration of the cortisol response into account (AUC), ET evoked a greater response than TD. Analgesia (ETM) resulted in significantly lower cortisol levels than ET at 30 and 60 min post-procedure. Castration (C) provoked the highest cortisol response of all procedures; a significant analgesic effect (CM) was shown only at 4 h post-procedure. TD resulted in significantly higher cortisol levels than H piglets only at 30 min; analgesia (TDM) significantly reduced the cortisol response at 30 min. We conclude that ear tagging causes a dramatic increase in cortisol levels compared with handling alone in piglets, which suggests that this procedure causes substantial distress. However, further research is needed to confirm these results.     

Effects on maternal and fetal steroid concentrations of induction of parturition in the sheep by inhibition of 3 beta-hydroxysteroid dehydrogenase

Changes in circulating steroid hormones, the incidence of myometrial contractions, and the onset of labour were all monitored after administration of the 3 beta-hydroxysteroid dehydrogenase inhibitor, epostane, to chronically catheterized ewes and fetuses near term. In all animals the drug induced delivery 33-36 h after injection or infusion into the ewe with the birth of live healthy lambs which showed normal subsequent development. Epostane induced immediate, permanent falls in both maternal and fetal plasma progesterone concentrations, accompanied by increased PGF metabolite concentrations in the uterine vein beginning 15 min after treatment. Of the other hormonal changes observed, the most striking was the pronounced drop in both maternal and fetal plasma cortisol. In the fetus this fall was followed by increasing concentrations of circulating ACTH which eventually restored the cortisol levels. By 12-24 h after epostane a substantial overshoot had occurred and at 27-30 h the fetal plasma cortisol concentrations were as high as those seen during normal parturition at term. No significant changes in maternal plasma oestradiol-17 beta could be detected after epostane treatment or during labour. The incidence of slow myometrial contractions increased significantly during the second 3-h period after epostane, although their duration did not change. Contraction patterns typical of first stage labour were seen from 20 to 24 h. These results show that epostane may be used as a safe, predictable inducing agent in sheep if given 6-10 days before term; the lambs showed no signs of prematurity despite their lowered plasma cortisol concentrations which persisted for some hours before labour was induced.     

Effect of beta-endorphin on fetal breathing movements in sheep

It has been suggested that endogenous opioids, such as beta-endorphin (beta-EP), act to depress respiration in the fetus and newborn. We have investigated the effect of infusing beta-EP either intravenously or into a lateral cerebral ventricle on breathing movements and electrocortical activity in eight fetal lambs between 116 and 133 days gestation. Intravenous infusion of beta-EP (200 or 500 micrograms over 1 h) increased plasma beta-EP concentrations 2- to 230-fold and was associated with a small decrease in the percent time spent breathing, from 57.8 +/- 9.1 to 51.3 +/- 8.2%/h (n = 6 exp). There was no change in the amount of high- or low-voltage electrocortical activity. Intracerebroventricular beta-EP infusion (1 or 2 micrograms beta-EP/min for 120 min) was not associated with any change of breathing movements (n = 5 exp) during the period of the infusion. However, in four experiments, in the 6-h period after the end of the beta-EP infusion there were episodes of 2-4 h when the percent time per hour spent breathing exceeded 70%. Electrocortical activity increased in amplitude and distinct episodes of high- and low-voltage activity were sometimes lost in these experiments. We conclude that high concentrations of beta-EP in plasma or cerebrospinal fluid do not totally suppress fetal breathing directly in the fetal lamb.     

Effect of myiasis and acute restraint stress on plasma levels of immunoreactive beta-endorphin, adrenocorticotrophin (ACTH) and cortisol in the sheep

Cutaneous myiasis in sheep arising from the activity of Lucilia cuprina larvae can result in significant physiological changes in susceptible animals. The stress imposed on the pituitary-adrenal axis of the sheep in response to myiasis and acute restraint is the subject of this investigation. Merino wethers were exposed to handling restraint, and blood sampling, during examination for blowfly strike; where necessary, they were treated for cutaneous myiasis. Significant changes in the plasma concentrations of immunoreactive beta-endorphin (beta-EP), ACTH and cortisol were found in sheep with extensive myiasis, as compared with unstruck sheep or those with only localized myiasis. In five susceptible sheep with extensive cutaneous myiasis, mean plasma levels of beta-EP, ACTH and cortisol were 307 +/- 71 pg ml-1, 953 +/- 58 pg ml-1 and 232 +/- 46 nmol l-1 respectively, compared with 818 +/- 89 pg ml-1, 641 +/- 41 pg ml-1 and 107 +/- 17 nmol l-1 in six unstruck sheep handled similarly. Whereas significant increases in plasma ACTH and cortisol can result from pituitary-adrenal responses to acute emotional or surgical stress, and are usually accompanied by a concomitant release of beta-EP from the pituitary, the present findings indicate a marked reduction in beta-EP levels and a significant increase in ACTH and cortisol in sheep following blowfly strike and acute handling restraint. This result suggests that cutaneous myiasis in susceptible sheep can alter the pituitary-adrenal response to acute restraint stress, and this could occur either by an alteration of precursor processing in the pituitary or by the selective release of ACTH.     

Perceptions of the importance of different welfare issues in livestock production

The opinions of seven respondent groups about the relative importance of different practices pertaining to the welfare of Australian beef cattle, sheep and goats were surveyed. Respondent groups comprised farmers, livestock transportation representatives, veterinarians, meat processors, animal welfare advocates, animal welfare scientists and government officers. The survey consisted of a web-based adaptive conjoint analysis questionnaire, which was administered to a sample population that was selected randomly for large respondent groups and comprehensively for small groups. The hierarchy of opinion concerning the importance of the different beef cattle practices was: stockmanship > ground (road and rail) transport > spaying > food supply > dehorning > stunning > shelter > identification > pretransport food and water deprivation > castration > sea transport > mustering > confinement. For sheep/goat practices the hierarchy was: parasite control > mulesing > shelter > stockmanship > tail docking > ground transport > feeding > predation > stunning > castration > pretransport food and water deprivation > sea transport > mustering. The method of performing invasive procedures was perceived as less important than the provision of pain relief. Differences in opinion were evident between respondent groups, with animal welfare advocates tending to focus on painful procedures more than those with direct involvement in the industry.     

Effects of a local anaesthetic and NSAID in castration of piglets,on the acute pain responses,growth and mortality

The present study addresses the questions whether on-farm use of local anaesthesia with lidocaine leads to a reduction in pain responses during castration, and whether the non-steroidal anti-inflammatory drug meloxicam improves technical performance after castration of piglets. Five treatments were included in the study: (1) castration without anaesthesia or analgesia (CAST), (2) castration after local anaesthesia with lidocaine (LIDO), (3) castration after administration of meloxicam (MELO), (4) castration after lidocaine and meloxicam (L + M) and (5) sham castration (SHAM). To reduce litter influences, each treatment was present in each of the 32 litters (n = 32 per treatment). During castration, vocalizations were recorded continuously. Blood samples were collected 15 min before and 20 min after castration for determination of plasma levels of total cortisol, glucose, lactate and creatine kinase (CK). Mortality was registered and piglets were weighed several times to calculate growth. Several aspects of vocalizations during castration showed consistent and significantly different levels in CAST compared with LIDO, L + M and SHAM. CAST piglets squealed longer, louder and higher. Vocalizations of MELO piglets most resembled those of CAST. An increase in cortisol was seen in all treatments. However, in SHAM piglets this increase was significantly lower than in the other treatments. LIDO piglets showed a significantly smaller increase in plasma cortisol levels compared with CAST and MELO. L + M piglets differed significantly only from the SHAM group. Lactate levels differed significantly between LIDO and MELO, the level in LIDO being decreased after castration. In the other treatments an increase was measured. No treatment effects were found in plasma glucose and CK levels, nor in growth and mortality of the piglets. In conclusion, on the basis of vocalizations and plasma cortisol, local anaesthesia with lidocaine reduces pain responses in piglets during castration. A positive effect of meloxicam on technical performance was not found.     

Plasma beta-endorphin during fasting in man

To identify the effects of acute starvation on endogenous opioids in man, plasma beta-endorphin (beta-EP) was measured in 17 patients before, during and after fasting. Patients were assigned a posteriori into two groups: group A, comprised of 11 patients able to tolerate 5-7 days of fasting, and group B, comprised of 6 patients able to tolerate 10 days of fasting. Changes in plasma beta-EP, serum cortisol, circulating nutritional markers, and their relative levels were assessed on the 5th and 10th days of fasting, and on the 5th and 10th days of the refeeding period. Beta-EP had increased by the 5th day (group A: 4.74 +/- 0.42 to 6.91 +/- 0.65 pmol/l, p less than 0.01; group B: 3.60 +/- 0.48 to 5.14 +/- 0.22 pmol/l, p less than 0.05, and remained at 5.05 +/- 0.65 pmol/l on the 10th day (group B: 0.05 less than p less than 0.1) during fasting. Group B had lower levels of plasma beta-EP on the 5th day of fasting than group A (p less than 0.05). However, serum cortisol levels changed similarly in both groups. Plasma beta-EP showed no significant correlation with either the percentage of body weight lost or the body mass index (kg/m2) over this study period. These findings indicate that plasma beta-EP is elevated in the early phase of fasting, while not directly being associated with body weight changes. Plasma beta-EP is lower and less activated in subjects who are able to tolerate fasting for longer periods.     

Simultaneous circadian variations of plasma ACTH, beta-lipotropin, beta-endorphin and cortisol

The major objective of this study was to investigate the analogy existing between the typical circadian periodicity of ACTH and that recently described of beta-lipotropin (beta-LPH) and beta-endorphin (beta-EP) plasma levels. The determination of their concentrations, plus cortisol, has been performed on the same plasma samples of 6 healthy volunteers. All hormones were measured by radioimmunoassay. Those of beta-LPH and beta-EP were preceded by a purification of plasma through silicic acid extraction and Sephadex G-75 gel filtration. The highest values (mean +/- SEM) were found in the morning (ACTH: 10.3 +/- 0.9; beta-LPH; 6.3 +/- 0.7; beta-EP: 6.5 +/- 0.5 fmol/ml; cortisol: 378 +/- 30 pmol/ml) and the lowest values in the evening (ACTH: 6:1 +/- 0.7; beta-LPH: 3.3 +/- 0.4; beta-EP: 3.7 +/- 0.6 fmol/ml; cortisol: 130 +/- 23 pmol/ml). Statistical analysis using the Fourier method led to the evidence of a concomitant circadian secretory pattern of the three proopiocortin-related peptides. These results strongly suggest that the phasic secretion of ACTH, beta-LPH and beta-EP underlies a common central control.     

Social transmission of physiological and behavioural responses to castration in suckling Merino lambs

In social species like sheep, social context can modify both physiological and behavioural responses to stressors and normal behavioural patterns. Presence of conspecifics can ameliorate responses to noxious stimuli, an effect termed social buffering, whereas the presence of a distressed conspecific can invoke a distress response in an observer animal not receiving a noxious organic insult, an effect termed social contagion. Furthermore, synchrony of normal behaviours can occur within a group. Here a range of social contexts were created by grouping suckling lambs undergoing knife, ring or sham castration treatments either homogeneously or heterogeneously by castration treatment in pens within an animal house. The impact of social grouping on cortisol, rectal temperature, pain avoidance behaviours, postural behaviours and synchrony of behaviour in the first 12 h following castration treatment was examined. Irrespective of castration treatment, lambs grouped homogeneously by castration treatment had higher cortisol concentrations across the four time points measured than lambs grouped heterogeneously. They also spent 1.9% more of the time in restless behaviour in the first 1 h following castration, and in the 12 h following castration spent 6.7% more of their time lying ventrally, 4.9% less time standing normally, 1.6% more time walking normally, and 4.9% less time in total standing postures. Interactions between social grouping and castration treatment were not significant for physiological variables, pain related behaviours or postures with the exception of lateral lying which was decreased in knife castrated lambs grouped heterogeneously with other castration treatments from 1.9% (homogeneous grouping) to 0.4% (heterogeneous group). Synchronisation of behaviour was seen for walking in lambs grouped heterogeneously by castration treatment and for feeding at the trough in lambs grouped homogenously by ring and sham castration treatments. Lying and standing respectively, were negatively synchronised (occurred less frequently than predicted by chance alone) in ring and knife castrated lambs grouped homogeneously. The results indicate that mixing lambs that received the three castration treatments within a pen modified the activity profile of the lambs but did not substantially modify the behavioural or physiological changes that are stigmatic of responses to the specific castration treatments. The social contexts contrasted in the study did not result in marked contagion or social buffering between lambs of the measured responses and did not confound comparison of castration treatments. None-the-less, the comparability of responses observed in castration treatment groups penned homogenously or heterogeneously might not necessarily occur in other classes of sheep or in other social contexts. The absence of social transmission of behavioural and physiological responses indicates that grouping non-castrated lambs with castrated lambs did not compromise the welfare of the non-castrated lambs when their mothers were present.     

Effects of an oral dose of acetyl salicylate at tail docking on the behaviour of lambs aged three to six weeks

To investigate a practical method of providing analgesia for docking of lambs' tails, the effectiveness of an oral dose of aspirin (acetyl salicylate) in reducing discomfort behaviour immediately following application of elastrator rings, was evaluated. The study involved a pilot trial and an experiment, both using Romney crossbred lambs aged 3-6 weeks accompanied by their mothers in a group pen, with behaviour recorded on videotape. In the pilot trial, lambs were manually restrained, an elastrator ring was applied, then lambs were given either an oral dose (26mg/kg) of aspirin dissolved in water (Treatment RA, n=5 lambs) or an oral dose of water (Treatment R, n=4 lambs), and released. RA lambs changed posture between sternal recumbency and standing less frequently than R lambs, significantly so from 10 to 20min post-treatment (11 times for RA, compared with 28% (S.E.D. 6.6%) for R lambs). In the experiment, 56 lambs were given one of two docking treatments (either RA: application of an elastrator ring plus the same aspirin treatment as in the pilot trial, or R: application of the ring plus water), or one of two control treatments (CA: restraint plus aspirin; or C: restraint plus water). During the hour after treatment, docking was associated with differences in over three quarters of 52 postures and activities used to describe behaviour (P<0.05), and marked changes over time in the postures/activities affected were observed. Differences were evident within 5min and some were still apparent at 60min post-treatment. When postures and activities were designated as 'normal' or 'abnormal' (typical of docked lambs), over the total hours of observation the mean frequency of abnormal postures was 3.5% for control lambs and 22.6% (S.E.D. 1.64%) for docked lambs, and the mean frequency of abnormal activities was 5.2% for control lambs and 19.3% (S.E.D. 1.40%) for docked lambs. Provision of aspirin to docked lambs was associated with similar levels to those seen in control lambs for two activities but was also associated with increased levels of some activities/postures (P<0.05). These effects were minor compared with the effects of docking and there was no indication of effective analgesia. Thus, when elastrator tail docking rings were applied, behavioural effects indicative of pain were observed immediately and did not subside fully within 1h. Despite indications in the pilot trial of an analgesic effect of aspirin, further experimentation did not substantiate this effect.     

Plasma cortisol stress response in fingerling rainbow trout, Salmo gairdneri Richardson, to various transport conditions, anaesthesia, and cold shock

Plasma cortisol levels of fingerling rainbow trout were measured as an index of the stress resulting from various procedures used for transport of the fish for stocking. When transported under 'normal' conditions, which included water at the hatchery acclimation temperature (10–11°C), O₂ saturation or supersaturation, and neutral pH, there was a marked increase in plasma cortisol levels within 0.5 h, which was maintained over the next 4 h of transport; there was a significant decrease in plasma cortisol by 8 h of transport. It was found that the plasma cortisol levels at 4 and 8 h were not appreciably altered by transport under partial O₂ desaturation, O₂ saturation, O₂ supersaturation, or 0.5% NaCl, or by anaesthesia with tricaine methanesulfonate (MS 222) prior to capture and transport in MS 222-free water or 0.5% NaCl. A 15 min exposure to an immobilizing dose of buffered or unbuffered MS 222, or 2-phenoxyethanol, caused an increase in plasma cortisol of about 2 h duration, indicating that anaesthetics are themselves stressful. Exposure to chilled water (1° C) caused a large increase in plasma cortisol levels by 4 h after initiation of exposure; plasma cortisol had decreased at 1 day, and by 2 days a constant level was reached which was above the level in fingerling trout under 'normal' hatchery conditions. Trout acclimated to chilled water for 24 h and transported in chilled water had an increase in plasma cortisol during transport. Anaesthesia prior to transport or addition of salt did not reduce the stress of transport as judged by plasma cortisol levels. The results indicate that stress from capture and transport during stocking cannot be avoided using present methods.     

Extending the interval between second vaccination and slaughter: I. Effects on growth,scrotal size and stress responses of immunocastrated ram lambs

Immunocastration provides a less invasive means of castrating lambs. Considering increasing consumer awareness, the efficacy of this technique on commercial slaughter lambs needs to be further investigated and its effects on growth and stress responses need to be established. This study compared the growth rate, testes size and stress responses of immunocastrated lambs with that of lambs physically castrated with a Burdizzo clamp, as well as intact rams. A total of 40 Dohne Merino ram lambs (average live weight = 45.4±3.68 kg) were randomly allocated to the following four treatment groups: control (intact; R), Burdizzo-castrated (on day 2; B), immunocastrated with a 4-week (ICS4), or a 6-week (ICS6) interval between the second immunocastration vaccination and slaughter. Within the immunocastration treatments, the reaction to vaccination was assessed through injection site scoring, recording the local injection site surface temperature and assigning a walking score. The response to Burdizzo castration was assessed by scoring the reaction during the procedure, testes palpation reaction, walking gait and measuring testis temperature. Additional parameters recorded included BW, serum cortisol concentration, scrotal circumference and rectal temperature. Pain behaviours were described for the short-, medium- and long-term effects after the two methods of castration. Predominantly, tissue-hardening and bruising occurred at the injection sites of immunocastrates, but little effect was observed on walking comfort and no effect on injection site temperature or rectal temperatures. After Burdizzo castration, lambs spent more time in abnormal postures, and from day 3 (D3) to D8 of the trial, discomfort was observed during testes palpation and walking in B lambs. Serum cortisol concentrations were elevated in B lambs on D3 and D15, indicating physiological stress. Thus, immunocastration improved the welfare of castrated lambs as assessed by cortisol secretion, scrotal swelling and pain behaviours, without influencing growth rate.     

Effects of cranial cervical ganglionectomy and castration of male lambs. II. 24 hour plasma profiles of luteinizing hormone, testosterone and prolactin

Male lambs were utilized in an experiment designed to evaluate the effects of cranial cervical ganglionectomy (GX), castration and age on hormone secretion profiles. Blood plasma samples were collected at hourly intervals for 24 hours from 24 lambs aged 101 days and 20 lambs aged 277 days, then assayed for concentrations of luteinizing hormone (LH), testosterone and prolactin. At both ages pulsatile secretion of LH and testosterone was confirmed, but no circadian rhythm of LH testosterone or prolactin secretion was detected. Castration elevated LH levels significantly at both ages. GX and its interaction with castration had no effect on LH secretion at 101 days, but at 277 days these factors were significant, largely due to elevated levels being recorded from GX castrates. GX did not affect testosterone levels in entire animals at either age, while plasma from castrates contained no detectable testosterone. GX reduced prolactin concentrations at 101 days of age (summer) but elevated them at 277 days of age (winter). Castration and the interaction of castration with GX had no significant influence on plasma prolactin levels at either age. This study confirmed that the pineal gland of sheep is involved in the regulation of prolactin secretion, and probably influences LH secretion as well.     

Effect of reduced uterine blood flow on fetal and maternal cortisol

We have measured the changes in fetal and maternal plasma concentrations of cortisol in relation to blood gases and percent oxygen saturation during 2- and 4-h episodes of reversibly reduced uterine blood flow in sheep between 120 days gestation and term. During that period of reduced uterine blood flow there was a significant decrease in fetal arterial percent oxygen saturation (SaO2), PO2 and pH. Fetal SaO2 decreased from 59.5 +/- 3.2% to 31.8% +/- 2.8% by 15 min, 32.9 +/- 2.9% by 60 min, and 33.5 +/- 2.9% by 120 min. Fetal PO2 decreased from 3.2 +/- 0.1 KPa to 2.0 +/- 0.2 KPa by 15 min, 2.2 +/- 0.2 KPa by 60 min and 2.3 +/- 0.1 KPa by 120 min. Fetal pH decreased from 7.36 +/- 0.01 to 7.30 +/- 0.03 by 15 min, 7.27 +/- 0.02 by 60 min and 7.25 +/- 0.03 by 120 min. During the period of reduced uterine blood flow, fetal plasma concentrations of cortisol increased from 37.1 +/- 10.8 nmol/l to 53.3 +/- 9.2 nmol/l by 15 min, 49.2 +/- 11.4 nmol/l by 60 min and 43.3 +/- 9.0 nmol/l by 120 min. The greatest percentage increase in fetal plasma concentrations of cortisol occurred in fetuses of 126-139 days gestation. There was no significant change in maternal blood gases, SaO2 or plasma concentrations of cortisol. These experiments demonstrate that there is a significant increase in fetal plasma concentrations of cortisol in response to reductions in uterine blood flow from as early as 120 days gestation.