Effect of epidural tramadol and lignocaine on physiological and behavioural changes in goats subjected to castration with a high tension band.

AIM: To compare the effect of a single epidural injection of either lignocaine or tramadol on behavioural changes, anaesthetic indices, leucocyte parameters, erythrocyte sedimentation rates and concentration of cortisol in plasma in goats subjected to castration by high tension band. METHODS: Ten male goats weighing 14.4 (SD 0.7) kg were randomly allocated to anaesthesia with epidural injections of tramadol (3 mg/kg), or lignocaine (4 mg/kg). Following anaesthesia, a rubber ring was applied and tensioned to the scrotal neck of each goat. Behavioural changes were noted as they occurred, and the onset of drug action (time between epidural injection and loss of pedal reflex) and duration of antinociception (time interval between disappearance and reappearance of pedal withdrawal reflex) were determined. Hearts rates, respiratory rates and rectal temperatures were determined every 15 minutes for a 90-minute period, while blood was obtained for determination of white cell counts, erythrocyte sedimentation rates and concentrations of cortisol. Anaesthetic indices were compared using Student's t-test, while physiological parameters were compared using an ANOVA for repeated measurements. RESULTS: Goats treated with epidural tramadol were not recumbent and continued rumination while goats treated with epidural lignocaine were recumbent and did not continue rumination. The onset of analgesia was longer (p=0.01) in goats treated with epidural tramadol (5.0 minutes; SD 1.2) than goats treated with epidural lignocaine (3.0 minutes; SD 1.1), while duration of analgesia was shorter (p=0.003) in goats treated with epidural tramadol (47.2 minutes; SD 13.1) than goats treated with epidural lignocaine (89.8 minutes; SD 23.1). There was no significant difference in heart rates, respiratory rates and erythrocyte sedimentation rates, while the concentration of cortisol in plasma differed (p<0.05) between goats treated with epidural tramadol and lignocaine. CONCLUSIONS: Epidural lignocaine injection produced longer duration of antinociception with lower frequency of pain-associated behavioural changes; while treatment with epidural tramadol injection allowed the goats to continue grazing once the rubber ring has been applied. CLINICAL RELEVANCE: Epidural tramadol produced partial pain relief, while epidural lignocaine injection provided the most effective pain control. However, epidural tramadol has an advantage over epidural lignocaine in conditions such as perineal surgery and caesarian section in cattle and where the ability of the animal to maintain standing is desired.

Physiological regulation of maternal behavior in heifers: roles of genital stimulation, intracerebral oxytocin release, and ovarian steroids.

We tested the hypotheses that 1) epidural anesthesia at parturition would block both peripheral and central release of oxytocin and eliminate the development of maternal behavior in primiparous heifers and 2) estradiol priming, genital stimulation, and appropriate neonatal stimuli would induce maternal behavior in nulliparous heifers. In experiment 1, primiparous crossbred heifers (n = 13) with cannulas in the third cerebroventricle (IIIV) were assigned randomly to receive epidural treatments of saline (SAL; n = 6) or lidocaine HCl (EPI; n = 7) at the onset of labor induced between Days 270 and 280 of gestation. Epidural anesthesia blocked (P < 0.001) both central and peripheral release of oxytocin and markedly reduced (P < 0.05) or eliminated licking behaviors during a 3-h period following parturition as compared with SAL. Following approximately 1 wk of controlled daily suckling, during which calves were permitted access only to the inguinal region of their dams (three times daily for 10 min each time), a second maternal behavior test was performed. Although licking behavior remained markedly reduced (P < 0.001) in the EPI compared with the SAL groups, all heifers accepted their calf at the udder. In experiments 2-4, neither estradiol priming in ovariectomized heifers nor estradiol plus progesterone in intact heifers resulted in an induction of maternal behaviors following genital stimulation and presentation of a neonate wetted with amniotic fluid. Pelvic sensory deficits apparently block oxytocin release and disturb both short-latency and long-term maternal behaviors but do not result ultimately in rejection of the calf. Combinations of hormonal, sensory, olfactory, and visual cues observed previously to induce maternal behavior in nulliparous ewes do not appear adequate for induction of maternal behavior in nulliparous heifers.

Transportation of goats: effects on physiological stress responses and live weight loss.

The management of food animals prior to slaughter influences both profitability and animal well-being. This experiment was conducted as a split-unit design to determine live weight shrink and stress responses in goats due to differences in stocking density during transportation and holding. A total of 150 Spanish does were transported on two different days (replicate) and held overnight (18 h) without feed in low- (LD) or high-density (HD) groups. On each day, 75 does were transported 2.5 h with floor spaces of .18 m2 and .37 m2/animal in LD (25 does) and HD (50 does) groups, respectively. The average temperatures in the trailer during transportation were 34.6 and 35 degrees C, respectively, on d 1 and 2. All animals were blood-sampled before loading (PRELOAD) and four does from each treatment were sampled immediately after loading (POSTLOAD). Animals were blood-sampled in holding pens either at 0, 1, 2, 3, 4, or 18 h after transportation (time) to assess the time course (n = 8 does per time per replicate) of stress responses. Individual animals were weighed just before loading onto a trailer and after overnight holding to assess shrinkage. Treatment or treatment x time did not have a significant effect on any of the dependent variables studied. There were significant effects of time (P < .01) on plasma cortisol, glucose, and urea nitrogen (PUN) concentrations. Time also had significant effects (P < .01) on plasma creatine kinase (CK) activity, differential leukocyte counts (neutrophils, lymphocytes, monocytes, and eosinophils), and ratio of neutrophils to lymphocytes (N:L). However, plasma leptin concentrations were not influenced by time. Cortisol concentrations increased at POSTLOAD sampling, peaked at 0 h, and decreased thereafter before spiking again at 18 h of holding. The PUN was higher at 18 h than at other time periods studied. Plasma glucose concentrations increased and remained at higher levels at 0, 1, and 2 h and began decreasing at 3 h, reaching PRELOAD levels at 18 h. Plasma CK kinase activity peaked at approximately 2 h after transportation. The N:L ratio was higher at all time periods after transportation than prior to starting the journey, indicating a prolonged effect of transportation stress on the immune system. The mean (+/- SE) shrinkage losses were 10.2 +/- .68 and 9.8 +/- .68 in HD and LD treatment groups, respectively. The results indicate that the stress responses of goats due to transportation begin decreasing within 3 h after transportation. However, prolonged holding periods without feed may increase stress responses and bring about metabolic changes.

Injection of neuropeptide Y into the third cerebroventricle differentially influences pituitary secretion of luteinizing hormone and growth hormone in ovariectomized cows.

Hypothalamic neurons that control the luteinizing hormone (LH) and growth hormone (GH) axes are localized in regions that also express neuropeptide Y (NPY). Increased hypothalamic expression of NPY due to diet restriction has been associated with suppressed secretion of LH and enhanced secretion of GH in numerous species. However, these physiological relationships have not been described in cattle. Thus, two studies were conducted to characterize these relationships using ovariectomized (Experiment 1) or ovariectomized estrogen-implanted (Experiment 2) cows. In Experiment 1, four well-nourished, ovariectomized cows received third cerebroventricular (TCV) injections of 50 and 500 micrograms of NPY in a split-plot design. Venous blood was collected at 10-min intervals from -4 hr (pre-injection control period) to +4 hr (postinjection treatment period) relative to TCV injection. NPY suppressed (P < or = 0.04) tonic secretion of LH irrespective of dose and tended to stimulate (P < or = 0.10) an increase in tonic secretion of GH. In Experiment 2, six ovariectomized cows that were well nourished and implanted with estradiol received TCV injections of 0, 50, or 500 micrograms of NPY in a replicated 3 x 3 Latin Square. Both doses of NPY suppressed (P < 0.06) mean concentration of LH relative to the 0-microgram dose. The 50-microgram dose of NPY tended (P < 0.10) to increase the amplitude of GH pulses. In conclusion, TCV injection of NPY suppressed pituitary secretion of LH and simultaneously tended to increase pituitary secretion of GH.

Effects of time of suckling during the solar day on duration of the postpartum anovulatory interval in Brahman x Hereford (F1) cows.

Previously published reports have indicated that postpartum anovulatory intervals can be markedly reduced and rebreeding performance enhanced in Bos taurus cows by eliminating nighttime suckling. We sought to confirm this hypothesis by examining the effects of day, nighttime, and ad libitum suckling on suckling behavior of calves, duration of the postpartum anovulatory interval, and pregnancy rates in 45 fall-calving Brahman x Hereford (F1) cows. Beginning on d 9 to 12 postpartum, calves were removed from lactating cows from 0700 to 1900 (Night-Suckled, n = 15) or from 1900 to 0700 (Day-Suckled, n = 15), or remained with their dams continuously (Ad Libitum-Suckled, n = 15). Cows in each group were maintained with fertile Angus bulls from d 10 postpartum until the first normal luteal phase or 100 d postpartum, whichever occurred first. Cows were observed for estrous behavior twice daily, and jugular blood samples were collected twice weekly for the determination of serum progesterone concentration. Mean number of suckling episodes per 24 h was greater (P < .0001) for the Ad Libitum-Suckled group than either Night- or Day-Suckled groups (5.9+/-.42 vs 3.8+/-.14, and 3.9+/-.32, respectively). Hourly analysis of suckling episodes in the Ad Libitum group indicated that they were not skewed toward a particular period, with suckling occurring at a periodicity of 4 to 6 h. Intervals to the first rise in progesterone > or = 1 ng/mL (32+/-2.5, 32+/-4.5, and 31+/-1.7 d, respectively), first normal luteal phase (38+/-3.1, 38+/-3.8, and 37+/-2.5 d, respectively), and first estrus (43+/-3.5, 40+/-3.9, and 36+/-1.1 d, respectively) did not differ (P > .05) among the three groups. Similarly, cumulative pregnancy rates within 100 d after calving did not differ (P > .05). These results in Bos indicus x Bos taurus (F1) cattle do not support the previous conclusions in Bos taurus that eliminating nighttime suckling reduces the postpartum anovulatory interval.

Microsequencing of bovine cerebrospinal fluid apolipoproteins: identification of bovine apolipoprotein E.

In studies of bovine plasma lipoproteins, apolipoprotein E (apoE) was not found associated with alpha-lipoproteins isolated over a broad range of densities. However, studies of cerebrospinal fluid (CSF) lipoproteins from other mammals have shown that apoE is a major apolipoprotein associated with high density lipoprotein, a fact that prompted us to determine if this were also the case in bovine CSF. CSF samples were obtained from animals with a surgically implanted catheter. Most analyzed samples were obtained from cows at various stages of the postpartum period; however, a few samples also were obtained at term or during pregnancy. Analyses of isolated ultracentrifugal fractions by polyacrylamide gel electrophoresis revealed the presence of two apo, with the expected molecular weights for apoE and apoA-I. By using both matrix-assisted laser desorption mass spectrometry and microsequencing techniques, we demonstrated that these apo are indeed apoE and apoA-I.

Gonadotropin-releasing hormone secretion into third-ventricle cerebrospinal fluid of cattle: correspondence with the tonic and surge release of luteinizing hormone and its tonic inhibition by suckling and neuropeptide Y.

Objectives of the current studies were to characterize the pattern of GnRH secretion in the cerebrospinal fluid of the bovine third ventricle, determine its correspondence with the tonic and surge release of LH in ovariectomized cows, and examine the dynamics of GnRH pulse generator activity in response to known modulators of LH release (suckling; neuropeptide Y [NPY]). In ovariectomized cows, both tonic release patterns and estradiol-induced surges of GnRH and LH were highly correlated (0.95; p < 0.01). Collectively, LH pulses at the baseline began coincident with (84%) or within one sampling point after (100%) the onset of a GnRH pulse, and all estradiol-induced LH surges were accompanied by corresponding surges of GnRH. A 500- microg dose of NPY caused immediate cessation of LH pulses and lowered (p < 0.001) plasma concentrations of LH for at least 4 h. This corresponded with declines (p < 0.05) in both GnRH pulse amplitude and frequency, but GnRH pulses were completely inhibited for only 1.5-3 h. In intact, anestrous cows, GnRH pulse frequency did not differ before and 48-54 h after weaning on Day 18 postpartum, but concentrations of GnRH (p < 0.05) and amplitudes of GnRH pulses (4 of 7 cows) increased in association with weaning and heightened secretion of LH. We conclude that the study of GnRH secretory dynamics in third-ventricle CSF provides a reasonable approach for examining the activity and regulation of the hypothalamic pulse generator in adult cattle. However, data generated using this approach must be interpreted in their broadest context. Although strong neurally mediated inhibitors of LH pulsatility (suckling; NPY) had robust effects on one or more GnRH secretory characteristics in CSF, only high doses of NPY briefly abolished GnRH pulses. This implies that the GnRH signal received at the hypophyseal portal vessels under these conditions may differ quantitatively or qualitatively from those in CSF, and theoretically would be undetectable or below a biologically effective threshold when LH pulses are absent.

Opioids modulate progesterone production in prepubertal Bunaji heifers.

The opioid antagonist naloxone was administered to prepubertal heifers, and its effects on progesterone, cortisol, and LH secretions were studied. Pooled pretreatment values in peripheral plasma for progesterone averaged 0.26 +/- 0.08 ng/ml (+/- SE), and those for cortisol averaged 13 +/- 1.2 ng/ml. Naloxone treatment at either 1.1 (Nal-1) or 2.0 (Nal-2) mg/kg BW significantly increased circulating progesterone within 15 min of i.v. injection, which was sustained for 45 and 75 min, respectively. Maximal progesterone concentrations were 1.8 +/- 0.16 ng/ml and 1.8 +/- 0.19 ng/ml at the low and high naloxone dosages; progesterone values were basal by 120 min. Naloxone caused a dose-dependent increase in plasma cortisol averaging 20 +/- 3.1, 28 +/- 4.2, and 49 +/- 5.7 ng/ml in the immediate 120 min posttreatment in control, Nal-1, and Nal-2 heifers, respectively; but naloxone injection, at either the low or the high dosage, had no effect on plasma LH concentration. The effect of naloxone on progesterone concentration was dependent on the age and body weight of the animal; it was first observed at 28 mo of age and between 130 and 160 kg BW. None of the heifers that showed transient elevations in progesterone exhibited estrous behavior or had a palpable CL throughout the study. These coincident transient increases in circulating progesterone and cortisol demonstrate that an endogenous inhibitory opioidergic system is involved in the control of steroid hormone secretion in prepubertal zebu heifers. Further, an adrenal source of this progesterone is indicated, but whether the progesterone participates in the induction of an LH increase in the prepubertal heifer is not clear.

Attenuation of antepartum relaxin surge and induction of parturition by antiprogesterone RU 486 in sheep.

Pregnant ewes were injected with either the antiprogesterone, RU 486 (4 mg kg-1 body weight, i.m.; n = 5), 3000 iu relaxin (i.m.; n = 9), or diluent (n = 8) at 12:00 h on days 144 and 145, to determine its effect on progesterone and relaxin secretion, and on induction of lambing. RU 486 induced earlier lambing (P < 0.01) compared with diluent treatment, but relaxin treatment did not significantly reduce the interval to parturition. Mean injection-lambing intervals were 31 +/- 2, 109 +/- 23 and 121 +/- 27 h for the RU 486, relaxin and diluent groups, respectively. There was no incidence of difficult birth (dystocia); all lambs were vigorous at birth; and placenta delivery was rapid (within 207 min) with RU 486 and relaxin treatments compared with diluent treated controls. Plasma progesterone concentrations averaged 11 ng ml-1 during the pretreatment period for all animals. RU 486 had a biphasic effect on progesterone concentrations, causing an initial increase (P < 0.05) within 2 h, and then an abrupt drop (P < 0.01) to 6 ng ml-1 by 18:00 h on day 145. Progesterone concentrations remained consistently lower (P < 0.05) in relaxin-treated ewes than in diluent-treated controls from days 144 to 147 and then began a steady decrease to 4 ng ml-1 on the day of parturition (days 149 and 150) in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Antiprogesterone, RU 486, facilitates parturition in cattle.

RU 486, a potent progesterone antagonist with high affinity for progesterone receptor, was used alone or in combination with relaxin in late pregnant cattle to determine its effect on induction of parturition. Cross-bred beef cattle were bred by artificial insemination. An indwelling cannula was inserted into a jugular vein on day 269 (expected term = day 283) for repeated blood sample collection. On day 277, the cattle were assigned randomly to three groups (n = 6 each): group 1 received RU 486 (2 mg/kg BW, im) at 0800 h on days 277 and 278; group 2 received the same RU 486 treatment plus 3000 U relaxin, injected sc at 0800 h on day 278; and group 3 served as controls and received vehicle injection. Parturition occurred 55 h after treatment in group 1 and 53 h after treatment in group 2 compared with 210 h in the controls (P less than 0.01). The calves from treated groups were vigorous at birth, and their birth weights (32 and 33 kg in groups 1 and 2) were less than those of control calves (38 kg; P less than 0.01). There was no incidence of difficult birth (dystocia) with RU 486 treatment compared with that in the controls. Placenta delivery averaged 6.5 h after birth in both RU 486-treated groups and did not differ from the control value (5 h). Plasma progesterone concentrations averaged 8.2 ng/ml during the pretreatment period for all animals. Progesterone started to decrease markedly by 1200 h on day 278, dropped to about 4 ng/ml by 2400 h that same day, and was at basal levels on day 279, the day of calving, in two hormone-treated groups. In sharp contrast, progesterone was maintained at about 6 ng/ml in placebo-treated controls during this period and did not decrease to basal levels until 2 days before parturition on day 286 (P less than 0.01). Peak RU 486 in plasma was 7.2 ng/ml after the first injection and 14.3 ng/ml after the second injection, and averaged 7.9 ng/ml on the day of induced calving (day 279). Peak relaxin was 4.1 ng/ml after hormone injection. The results indicate that RU 486 alone or combined with relaxin precisely controlled the time of parturition in cattle in late pregnancy. Such treatment can be used to facilitate parturition and increase survival rates of neonatal calves without detrimental effects of dystocia, retention of placenta, and delayed postpartum fertility.