A randomized cross-over trial assessing salivary and urinary cortisol concentrations after alfaxalone and propofol administration in healthy cats.

The aim of this study was to assess the effects of commonly used anaesthetics alfaxalone and propofol on salivary and urinary cortisol in healthy cats. Fifteen male castrated research-purposed cats received randomly intravenous continuous rate infusions of 8 mg/kg/h of alfaxalone, 12 mg/kg/h of propofol and 2 ml/kg/h of Lactated Ringer's solution for 30 min, with intervals of 6 days between treatments. Saliva samples were collected for 24 h before each infusion and for 24 h from the start of each infusion. Urine was collected as single pooled samples over each 24 h period. Mean integrated saliva cortisol responses in cats treated with alfaxalone were greater than responses of cats treated with propofol (P = 0.034) and controls (P = 0.017). Integrated responses in cats treated with propofol did not differ from controls. The mean urinary cortisol/creatinine ratio (UCCR) was higher on the day of treatment than the day before treatment in cats treated with alfaxalone (P < 0.0001) and in cats treated with propofol (P = 0.0168) and did not differ between days in cats treated with lactated Ringer's solution. The mean UCCR was higher in cats treated with alfaxalone than in cats treated with lactated Ringer's solution (P = 0.0020) on the day of treatment. Mean total urinary cortisol over 24 h was greater in cats treated with alfaxalone than controls (P = 0.0267). In conclusion, alfaxalone increased short-term salivary and urinary cortisol concentrations in healthy cats as compared to propofol and a control group of non-anesthetised cats.

Effects of GnRH, a progesterone-releasing device, and energy balance on an oestrus synchronisation program in anoestrous dairy cows.

OBJECTIVE: The aim of this research was to study the roles of the day 0 energy balance and gonadotrophin-releasing hormone (GnRH) and progesterone levels on dominant follicle (DF) and corpus luteum (CL) development during the first 7 days of a gonadotrophin-prostaglandin-gonadotrophin (GPG) + progesterone (P4) program in anoestrous dairy cows. METHODS: Cows (n = 81) were allocated to one of the three treatments: (1) GPG + P4 (days 0 and 9, 100 µg GnRH; day 0-7, intravaginal P4 device; day 7, 500 µg PGF2α ); (2) GPG (as for treatment 1 but excluding the P4 device) and (3) prostaglandin + GnRH + P4 (as for treatment 1, but excluding day 0 GnRH). DF and CL size, plasma concentrations of insulin, insulin-like growth factor-I (IGF-I) and non-esterified fatty acid (NEFA) were measured on days 0 and 7. RESULTS: The proportion of cows with a CL on day 7 was significantly different between groups (GPG: 78%, GPG+P4: 69%, PGF2α + GnRH + P4: 42%, P = 0.02). The CL volume on day 7 was significantly associated with treatment, treatment by time postpartum and plasma concentrations of insulin, IGF-I and NEFA. CONCLUSION: In cows without a CL present on day 0 of an oestrus synchronisation program, removal of the day 0 GnRH treatment led to reduced CL development; however, no effect of adding progesterone was found. In contrast, in cows with a CL present on day 0 inclusion of a progesterone device led to a higher CL volume, but removal of the first GnRH injection had no effect. Response to the treatment was affected by plasma concentrations of insulin, IGF-I and NEFA.

Corticosterone stress hormone responses in oil rehabilitated and non-rehabilitated little penguins.

Whether oiled wildlife should be rehabilitated during an oil spill is internationally debated. Research on little penguins (LP, Eudyptula minor) rehabilitated and released back into a cleaned environment after the New Zealand C/V Rena grounding oil spill in 2011 found the rehabilitation process was effective at treating and reversing the negative effects of oil-contamination on penguin post-release survival, productivity and diving behaviour. Here we investigated the acute corticosterone stress response of LPs to determine if responses of rehabilitated birds differed from those of "control" birds. Corticosterone responses of LPs two years after an oil spill did not differ between rehabilitated and non-rehabilitated penguins. These results show that the rehabilitation process for LP did not affect their long-term physiological responses to humans. This indicates that wildlife can be rehabilitated and returned to the wild with similar human tolerance levels to non-rehabilitated birds and an absence of habituation.

Effects of progesterone inclusion in a gonadotropin-prostaglandin-gonadotropin programme on follicular dynamics and ovulation synchronisation of pasture-based dairy cows with anoestrous.

The aim of this study was to evaluate how the addition of a progesterone device to a gonadotropin-prostaglandin-gonadotropin (GPG) programme in dairy cows with postpartum anovulatory anoestrus affected ovarian follicular dynamics and the synchronisation of ovulation. Twenty-two dairy cows were randomly assigned to either GPG (Day 0: 100 µg GnRH, Day 7: 500 µg PGF2α, Day 9: 100 µg GnRH, Day 0-7: Day 10) or GPG with a progesterone device from Day 0 to 7 (GPG+P4). Ovarian follicular dynamics and ovulation synchronisation were studied using transrectal ultrasonography. Compared to the GPG+P4, GPG alone resulted in a relatively larger mean dominant follicle size and a higher mean peripheral oestradiol concentration (74.9 pg ∗ day vs. 60.6 pg ∗ day; P=0.002); however, there was much greater variation in follicle diameter in the group treated with GPG (7.8-22 mm vs. 10.8-17.5mm in GPG+P4) and this may, at least partly explain why only 7/11 cows in this group ovulated within 48 h of the Day 9 GnRH injection compared to 10/10 of the cows in the GPG+P4 group. These results suggest that differences in follicular dynamics between GPG and GPG+P4 programmes are not a key driver of the difference in conception rate, but further studies are required to better assess the role of ovulation synchronisation.

The effects of exclusion of progesterone or Day 0 GnRH from a GnRH, prostaglandin, GnRH + progesterone program on synchronization of ovulation in pasture-based dairy heifers.

This study evaluated the effect of removing the GnRH injection on Day 0 or the progesterone (P4) device from a GnRH, PGF2α, GnRH (GPG) + P4 program on follicular dynamics and synchronization of ovulation in dairy heifers. Friesian and Friesian × Jersey heifers, in autumn 2009 (n = 35) and spring 2010 (n = 38), were randomly allocated to one of three estrus synchronization programs. The first group (GPG + P4) received 100 µg GnRH on Day 0, a P4-releasing intravaginal device from Days 0 to 7, 500 µg PGF2α on Day 7, and 100 µg GnRH on Day 9, followed by fixed-time artificial insemination 16 to 20 hours later. The program for group 2 (GPG) was the same as group 1 with the exclusion of the P4 device. Group 3 (P + G + P4) was treated the same as group 1, except for the absence of the GnRH treatment on Day 0. Ultrasonography was performed on Days 0, 1, 2, 3, and 7 and then at 12 hourly intervals on Days 9 to 11. Dominant follicle size was affected by both treatment and day, and there was also a significant interaction (P < 0.02) between treatment and day. Mean dominant follicle size was larger in the heifers treated with P + G + P4 on Days 1 to 3 than those treated with GPG + P4 (P < 0.02) and, on Day 2, than those treated with GPG (P = 0.005). However, on Day 7, mean dominant follicle size was larger in heifers treated with GPG than heifers treated with P + G + P4 (P = 0.03). The emergence of a new follicular wave was later in heifers treated with P + G + P4 than heifers, which received a GnRH injection on Day 0 (4.3 ± 0.7 days, compared with combined GPG + P4 and GPG 3.0 ± 0.3 days; P = 0.03). The proportion of heifers that ovulated within the first 48 hours after the Day 9 injection of GnRH was not affected by treatment (GPG, 81%; GPG + P4, 84%; and P + G + P4, 100% [including early ovulation]; P = 0.11). The timing of the ovulation was not different between treatments (P = 0.97).

Voluntary exercise in pregnant rats improves post-lactation maternal bone parameters but does not affect offspring outcomes in early life.

OBJECTIVES: The objectives of this study were to examine the effects of voluntary exercise during pregnancy on maternal post-lactation bone parameters and offspring growth. METHODS: Pregnant Wistar rats were housed in conventional cages (control), or were housed in raised cages requiring them to rise to an erect, bipedal stance to obtain food/water, throughout pregnancy. Dual energy X-ray absorptiometry and peripheral quantitative computed tomography scans were performed pre-mating and post-weaning. Maternal stress was assessed by fecal corticosterone measurement. Offspring weights were assessed at postnatal days 1 and 25 (weaning). RESULTS: Changes in bone mineral over the pregnancy/lactation period were site-specific. Exercise did not affect loss of bone mineral from the lumbar spine, but did attenuate the loss of trabecular bone mineral from the tibial metaphysis and enhance the strength strain index and cross-sectional moment of inertia at the tibial diaphysis (P≤0.05) in dams in the exercised group. Fecal corticosterone did not differ between dam groups. There were no significant differences in offspring weight between the exercised and control group at either time point. CONCLUSIONS: Voluntary exercise in the pregnant rat can improve some post-lactation bone parameters and does not adversely affect early postnatal outcomes of the offspring.

Changes in plasma gonadotrophins, 17ß-oestradiol, progesterone, prolactin, thyroxine and triiodothyronine concentrations in female Japanese quail (Coturnix coturnix japonica) of a heavy body weight line during photo-induced ovarian growth and regression.

1. Simultaneous changes of the width of the cloacal opening and plasma luteinising hormone (LH), follicle stimulating hormone (FSH), 17ß-oestradiol, progesterone, prolactin, thyroxine (T(4)) and triiodothyronine (T(3)) during photo-induced ovarian growth and regression were measured in commercially bred Japanese quail from a heavy body weight line. 2. Somatically mature female Japanese quail were transferred from short days (light:dark 8L:16D) at 10°C to long days (16L:8D) at 20°C, and sexually mature female Japanese quail were transferred from long to short days. All variables were measured at transfer and every five days thereafter (except for a measurement at 12 instead of 10 d) for 35 d. 3. Transfer from short to long days caused significant increases in LH, FSH, 17ß-oestradiol, ovary weights and oviduct weights after five days, and in the cloacal opening after 12 d. T(3) decreased after five days, whereas no significant changes were observed in T(4) concentrations. Progesterone and prolactin both decreased after 25 long days. 4. The transfer of quail from long to short days caused significant decreases in LH, FSH, 17ß-oestradiol, progesterone, prolactin, ovary and oviduct weights after 12 d and an increase in T(3). There was no significant change in T(4) concentrations. The cloacal opening decreased after 25 short days. 5. These results are the first to show simultaneous changes in gonadotrophins, sex steroids, thyroid hormones and prolactin during photo-induced gonadal growth and regression in female Japanese quail.

Fecal corticosterone metabolites and plasma corticosterone in Japanese quail selected for low or high plasma corticosterone responses to brief restraint.

Fecal corticosterone metabolites and plasma corticosterone in Japanese quail selected for low- or high-plasma corticosterone responses to brief mechanical restraint (low- and high-stress lines), and in a line of unselected quail, were measured in this study. No line differences were observed in baseline plasma corticosterone concentrations, but fecal corticosterone metabolite concentrations and daily fecal corticosterone metabolite production were 20% higher in quail of the high-stress line than in unselected or low-stress quail for males and females living together in group cages (P < 0.05). No differences were observed between lines in corticosterone metabolite concentrations and production for male birds in individual cages. Baseline plasma corticosterone concentrations, fecal corticosterone metabolite concentrations, and production appeared to be higher for males and females in group cages compared with males in individual cages. This difference might have been because of greater corticosterone secretion by male quail living in mixed sex groups than living individually. Correlations between baseline plasma corticosterone concentrations and fecal corticosterone metabolite concentrations in low-stress and high-stress quail, and for all birds combined, were r = 0.521 (P = 0.038), r = 0.604 (P = 0.013), and r = 0.431 (P = 0.002), respectively. The low- and high-stress lines that have been selected for low- and high-corticosterone responses differ in other characteristics, including growth and reproductive performance, and the current results are consistent with the assumption that these other differences are a consequence of greater daily corticosterone secretion in quail of the high-stress line.

Uterine environment as a regulator of birth weight and body dimensions of newborn lambs.

Pure-bred embryos were transferred within and reciprocally between large (Suffolk) and small (Cheviot) breeds of sheep to establish 4 treatment groups: SinS (Suffolk embryos in Suffolk dams), SinC (Suffolk embryos in Cheviot dams), CinS (Cheviot embryos in Suffolk dams), and CinC (Cheviot embryos in Cheviot dams). The recipient ewes carried single fetuses to term. The maternal plasma concentrations of ovine placental lactogen (oPL), progesterone, IGF-1, FFA, and glucose were measured on d 50, 90, 120, and 140 of pregnancy. Birth weight, body dimensions, and placental characteristics of lambs were recorded at birth. There was a recipient ewe breed × lamb breed × time interaction for the concentration of oPL (P = 0.03), but no such interaction was observed for progesterone (P = 0.42), IGF-1 (P = 0.57), glucose (P = 0.36), or FFA (P = 0.72). There were no differences in oPL (P = 0.28) and progesterone (P = 0.34) concentrations between SinC and SinS ewes. The concentrations of FFA on d 140 (P = 0.008), and those of glucose on d 50 (P = 0.02) and 120 (P = 0.01), were greater in SinC ewes than in SinS ewes. The ewes in CinS had less FFA concentration (P = 0.002) at all time points than CinC ewes. The concentrations of IGF-1 on d 90 were greater (P = 0.004) in CinS ewes than CinC ewes, but did not differ (P = 0.16) on d 50, 120, and 140. The concentrations of glucose on d 50 (P = 0.001), 90 (P = 0.03), and 140 (P = 0.03) were less in CinS ewes compared with CinC ewes. The birth weight of SinC lambs (5.04 ± 0.20 kg) was lighter (P = 0.001) than SinS lambs (5.94 ± 0.19 kg), and body dimensions of SinC lambs were smaller (P = 0.01) than SinS lambs. Neither birth weight nor the body dimensions of CinS lambs differed (P = 0.24) from CinC lambs. Cotyledon number was reduced (P = 0.04) in the CinS (57.5 ± 6.3) compared with the SinS group (74.2 ± 5.9), whereas mean cotyledon weight in CinS (2.42 ± 0.20 g) was greater (P = 0.02) than SinS (1.74 ± 0.21 g). It was concluded that the large genotype lambs were lighter and smaller when born to small genotype dams; however, the birth weight or body dimensions of small genotype lambs did not differ when born to large genotype dams. This study suggests that plasma oPL, progesterone, IGF-1, FFA, and glucose concentrations at different times throughout pregnancy reflect the regulatory effect of the uterine environment on the development of the fetus.

Normal vitamin D receptor function with increased expression of 25-hydroxyvitamin D(3)-24-hydroxylase in Corriedale sheep with inherited rickets.

A likely inherited disease with gross and microscopic features of rickets has been recognised in Corriedale sheep in New Zealand, and a defect in end-organ responsiveness to vitamin D has been proposed as a likely mechanism. The aim of the present study was to characterize the mode of inheritance and determine the disease mechanism. Breeding trials showed that the mode of inheritance was autosomal recessive. Serum chemistry testing using different methodology and studies in cultured skin fibroblasts did not support our previous hypothesis of a defect in end-organ responsiveness. The studies revealed normal serum 1,25-dihydroxyvitamin D concentrations, normal vitamin D receptor function, and the presence of 24-hydroxylase mRNA in cells from affected sheep, even without induction by 1,25-dihydroxyvitamin D(3). In addition, osteocalcin mRNA expression was similar in both affected and control sheep. It was concluded that increased expression of 25-hydroxyvitamin D(3)-24-hydroxylase, the enzyme that breaks down vitamin D, may be involved in the pathogenesis of inherited rickets in Corriedale sheep, but its role requires further clarification.

Changes in plasma gonadotrophins, testosterone, prolactin, thyroxine and triiodothyronine concentrations in male Japanese quail (Coturnix coturnix japonica) of a heavy body weight line during photo-induced testicular growth and regression.

1. Simultaneous changes of cloacal gland area (CGA) and plasma luteinising hormone (LH), follicle stimulating hormone (FSH), testosterone (T), prolactin (PRL), thyroxine (T(4)) and triiodothyronine (T(3)) during photo-induced testicular growth and regression were measured in commercially bred Japanese quail from a heavy body weight line. 2. Somatically mature male Japanese quail were transferred from short days (light:dark 8L:16D) at 10°C, to long days (16L:8D) at 20°C; and sexually mature male Japanese quail were transferred from long to short days. All variables were measured at transfer and every 5 d thereafter for 35 d. 3. Transfer from short to long days caused significant increases in LH, FSH, T and testis weight (TW) after 5 d, and in CGA after 10 d. T(3) decreased after 5 d, whereas T(4) increased significantly after 25 long days and PRL did not undergo any consistent change. The testicular growth rate was k = 0·1146. 4. Transferring quail from long to short days caused significant decreases in LH and FSH after 5 d, and decreases in T, TW and CGA after 10 d. T(4) decreased after 5 d whilst T(3) increased significantly by day 15. PRL decreased significantly after 10 d then rose before declining again. The testicular regression rate was k = 0·0582. 5. The rates of photo-induced testicular development and regression in a strain of large Japanese quail did not differ from rates reported for other strains of quail. CGA was a better indicator of TW than plasma T concentrations during growth and regression. The role of PRL in photo-induced reproductive cycles in male Japanese quail remains to be determined. 6. The photoperiod-induced changes in gonad size and hormone concentrations, together provide valuable information that can be used in future studies of the endocrinology and neuroendocrinology of photoperiodism in birds.

Plasma corticosterone responses to handling in Japanese quail selected for low or high plasma corticosterone responses to brief restraint.

1. Plasma corticosterone responses to handling in Japanese quail selected for low or high corticosterone responses to brief mechanical restraint (low and high stress lines) were measured in this study. 2. Initial corticosterone concentrations did not differ between the two lines. Corticosterone concentrations increased 15 min after handling began in quail handled for 5 or 15 min, with greater increases in quail from the high stress than the low stress line. Integrated corticosterone responses were higher in high stress than low stress quail, although the difference between the lines was not significant in quail handled for 5 min. 3. Patterns of plasma corticosterone after 15 min differed between quail handled for 5 or 15 min. Corticosterone increased further or did not change from 15 to 30 min then decreased from 30 to 60 min in quail handled for 5 min, whereas corticosterone decreased from 15 to 30 min then did not change in quail handled for 15 min. Corticosterone concentrations at 60 min remained elevated above initial concentrations, and were similar in quail handled for 5 or 15 min. Corticosterone concentrations at 15 min were more than twice as high in quail handled for 15 min compared with quail handled for 5 min. 4. Although the lines of quail have been selected on the magnitude of corticosterone responses, there was still marked variation in responses between birds within each line. Some quail in the high stress line showed little or no corticosterone response to handling, whilst large responses were seen in some birds of the low stress line. The lines of quail differ in characteristics other than corticosterone responses, including fear behaviour and reproductive development, so the lines provide valuable opportunities to investigate the potential significance of differences between individual birds in their corticosterone responses.

Effects of corticosterone treatment in laying Japanese quail.

1. The effects of exogenous corticosterone on plasma corticosterone concentrations, body weight, food intake, the percentage of birds that laid an egg each day and egg weight were measured in laying Japanese quail. Data were collected from birds in the week before corticosterone treatment began, during a 21-d treatment period, and in the 22 d after treatment ended. 2. Groups of quail were treated with corticosterone at three different concentrations in their drinking water. Corticosterone intakes were calculated for each bird and birds were then assigned to 4 intake groups. The groups were 0 (control group), 0.31-0.60, 0.61-0.90, 0.91-1.50 or >1.51 mg corticosterone/bird/d. 3. Plasma corticosterone concentrations in the 4 intake groups increased from around 1 ng/ml on the day before corticosterone treatment began to maximum mean concentrations of 13-18 ng/ml on day 14 of treatment. Mean corticosterone concentrations did not change between day 14 of treatment and the day after treatment ended, and had decreased in only one of 4 intake groups one week later. 4. Mean body weight in the highest intake group remained significantly lower than in controls 22 d after corticosterone treatment ended. Whilst there was no clear effect of corticosterone on food intake during treatment, mean food intake in the three highest corticosterone intake groups was significantly lower than in controls in the week after treatment ended. The percentage of birds that laid an egg each day and egg weight were both decreased by corticosterone, and the percentage of birds that laid an egg each day remained significantly lower in the highest corticosterone intake group compared with controls in the third week after treatment ended. 5. It is suggested that elevated plasma corticosterone concentrations in quail after treatment ended were maintained by a hyperactive hypothalamo-pituitary-adrenal axis for at least one week. Although none of the negative effects of corticosterone were evident in the group of quail with the lowest corticosterone intakes, the findings of the present study show that corticosterone treatment can affect birds for up to several weeks after corticosterone intake ends.

Rams genetically superior for IGF-I do not exhibit improved male reproductive traits.

Insulin-like growth factors (IGFs) play an important role in regulating normal physiology, and may be involved in the control of reproduction. The aim of this study was to define the relationship between IGF-I concentrations and reproductive performance over the breeding and non-breeding seasons in lines of New Zealand Romney rams that had been selected for low and high blood serum IGF-I concentration. Yearling rams from two selection lines (13 from the high line and 19 from the low line) were examined in July (winter), September (autumn) and November (summer) 2006 and March (spring) 2007. Scrotal circumference including the inguinal skin was recorded. Semen was collected by electroejaculation on 4 occasions over a 12-month period. Semen was evaluated according to standard procedures (volume, motility, density and morphology). Samples were collected from four animals from each group for measurements of mRNA for IGF-I and the IGF type 1 receptor (IGF 1R) in the testis, and IGF-I, IGF 1R and the insulin receptor (IR) in the liver. Blood samples were collected via jugular venipuncture for the measurement of IGF-I, insulin and testosterone. The incidences of morphologically abnormal sperm cells, the scrotal circumference and sperm motility were higher in the breeding than in non-breeding season. Seasonal changes were found in the percentage of abnormal sperm, scrotal circumference, sperm motility and sperm density, but there were no differences between lines in any reproductive parameters. IGF-I mRNA levels were higher in the high than the low line in the liver but not in the testis, whereas the opposite was found for levels of IGF 1R mRNA. mRNA levels for the insulin receptor in the liver were higher in the high line. Plasma testosterone concentrations did not differ between lines, whereas the concentrations of IGF-I and insulin were higher in the high line. The results suggest that IGF-I may be locally produced in the liver and the testis, and that selection for high IGF-I may not be associated with improved reproductive performance in rams.

Non-precocial grey-faced petrel chicks (Pterodroma macroptera gouldi) show no age-related variation in corticosterone responses to capture and handling.

Development patterns in birds range from precocial species, which hatch chicks largely capable of independent existence, to altricial species, chicks of which are highly dependent on their parents for extended periods. Previous work indicates precocial chicks have a robust corticosterone response from hatching whereas non-precocial and altricial chicks have a small response that increases through development. Grey-faced petrels are characteristic of most burrowing procellariiform seabirds with non-precocial chicks that are unable to locomote and are dependent on adults for food, although chicks have well developed downy plumage and can thermoregulate at or soon after hatching. Initial plasma corticosterone concentrations and corticosterone responses to handling were measured during development in semi-precocial grey-faced petrel (Pterodroma macroptera gouldi) chicks to determine whether they showed a precocial or altricial corticosterone response pattern. Chicks were sampled at six intervals through development from shortly after hatching until close to fledging. Mean corticosterone responses to handling after 30 min were high (115.9+/-10.7 ng/ml) from 2 to 4d after hatching and remained high throughout development (70-110 ng/ml). Contrary to expectations for non-precocial chicks, this pattern of corticosterone responses to handling indicates that grey-faced petrel chicks are able to perceive and respond to potential stressors from hatching, a response previously only demonstrated for precocial birds.

Effects of corticosterone treatment on growth, development, and the corticosterone response to handling in young Japanese quail (Coturnix coturnix japonica).

Corticosterone, a glucocorticoid secreted during stress responses, has a range of actions that help birds respond to stressors. Although effects of corticosterone treatment have been described in several avian species, the impacts of defined increases in plasma corticosterone on early development and on corticosterone stress responses are little known. These issues were addressed by providing quail with different doses of corticosterone in drinking water from days 8 to 38 post-hatch. The corticosterone dose consumed by each bird during treatment days 15-30 was calculated by measuring water intake. The corticosterone dose was inversely, but weakly, correlated with weights of the bursa, thymus, spleen, liver, testes, oviduct, muscle, and body, and positively correlated with peritoneal fat deposition. When birds were divided into groups based on their corticosterone intake, weights of the spleen, thymus, bursa, muscle, testes, and oviduct were significantly reduced in birds receiving the highest doses; with the exception of muscle, similar reductions were also observed in birds receiving medium doses, and thymic growth was inhibited in birds receiving low doses. The acute corticosterone stress response was measured by handling birds for 15 min. Plasma corticosterone was transiently increased at 15 min in control birds in response to the handling stressor. Some birds consuming low doses of corticosterone had corticosterone responses similar to control birds. Initial corticosterone concentrations were elevated in birds consuming higher doses of corticosterone. Plasma corticosterone in these birds decreased from 0 to 15 min, then increased from 15 to 30 min. The initial decrease could be due to corticosterone clearance, whilst the increase could indicate that the birds had a greater response than control birds to isolation as a stressor. Corticosterone treatment may have reduced the strength of corticosterone negative feedback within the hypothalamo-pituitary-adrenal axis. The results indicate that individuals and organs differ in their sensitivity to corticosterone. Moreover, elevated plasma corticosterone may disrupt the acute corticosterone stress response, and may thus reduce the ability of birds to cope with stressors.

Corticosterone in relation to body mass in Adelie penguins (Pygoscelis adeliae) affected by unusual sea ice conditions at Ross Island, Antarctica.

Penguins naturally fast each year during breeding and again whilst moulting, and may lose more than 40% of body mass during a fast. Fasting in emperor (Aptenodytes forsteri) and king (Aptenodytes patagonicus) penguins has been divided into three phases, with phase III characterised by an increased rate of body mass loss, increased plasma corticosterone concentrations, and a change in behaviour leading to abandonment of the breeding attempt and return to sea to feed. Initial corticosterone concentrations and corticosterone responses to a handling stressor were measured in the current study to determine if they increase during phase III of fasting in Adelie penguins (Pygoscelis adeliae). The study was conducted in 2001 at the northern Cape Bird colony on Ross Island, Antarctica. Penguin breeding on Ross Island was disrupted in the 2001-2002 summer by a large iceberg (B15A) which stopped the normal movement of sea ice in the Ross Sea. Penguins departing from the Cape Bird colony were lighter than returning or incubating birds (3.39+/-0.10cf. 4.16+/-0.06 and 4.07+/-0.08kg). It is likely that the departing birds were males that had been lighter than normal when they arrived at the colony. Initial plasma corticosterone concentrations were higher in departing than returning or incubating penguins (6.89+/-1.69cf. 2.36+/-0.42 and 1.08+/-0.19ng/ml). Corticosterone responses to handling were also greater in departing penguins. Initial plasma corticosterone, concentrations at 30min and total and corrected integrated corticosterone responses were inversely related to body mass in departing penguins, whereas there were no relationships in arriving penguins. beta-hydroxybutyrate and uric acid concentrations were consistent with departing birds having entered phase III of fasting. The results indicate that corticosterone and corticosterone responses are elevated in phase III of fasting in the Adelie penguin.

Corticosterone and fear behaviour in white and brown caged laying hens.

Physiological and behavioural measures of stress in caged hens on a commercial farm were compared between White Leghorn and brown Hyline strains, and between three tiers of cages. Blood and faecal samples were collected from undisturbed birds for corticosterone measurements. Plasma corticosterone responses to a stressor were measured by the collection of blood samples after 15, 30, and 60 min of a handling stressor. Tonic immobility and novel object tests were used to measure fear behaviour. Plasma corticosterone in undisturbed hens and faecal corticosterone did not differ between White Leghorn and brown Hyline hens, whereas the plasma corticosterone response to a handling stressor was greater in White Leghorns. The duration of tonic immobility, latency to first head movement and number of head movements in tonic immobility tests were greater in white than brown birds, whereas the number of inductions was less for tonic immobility tests. There were no differences between the strains in their responses to a novel object. There were no differences between tiers in plasma corticosterone or corticosterone responses or tonic immobility responses, and no consistent differences in responses of birds to a novel object. This is the first study in which plasma and faecal corticosterone concentrations and fear behaviour have been measured together in laying hens, and the first description of plasma corticosterone responses to handling over 60 min for caged laying hens on a commercial farm. The study has shown the value of measuring endocrine and behavioural variables together to provide objective data on characteristics of different strains of hens.

Conservation and behavioral neuroendocrinology.

The total number of threatened species of vertebrates is likely to be more than 10,000, with approximately one quarter of the world's mammal species, one eighth of the birds and one third of the amphibians threatened with extinction. The rate of loss of animal species and hence of biodiversity is increasing and may become even greater as ecosystems become affected by climate change due to global warming. Behavioral neuroendocrinology, which considers interactions between behavior and neuroendocrine function in animals from all vertebrate taxa, can contribute to animal conservation. Research with laboratory animals can address questions in basic biology relevant to conservation and develop methods for use with threatened animals. Field work with free-living animals considers the basic biology of new species and the use of endocrine tools to assess the susceptibility of species to threats. Non-invasive measurements of hormone concentrations, especially fecal steroids, are extensively used to assess reproductive function and the stress status of animals in captive breeding programs and in the wild. Biodiversity and natural selection both depend on individual variation, and conservation programs often work with animals on an individual basis. The consideration of data from individuals is essential in conservation endocrinology. Direct contributions to conservation programs are challenging as study situations are determined by practical conservation concerns. Indirect contributions such as the provision of scientific input to conservation plans and participation in public education programs offer significant benefits for conservation programs. Directly and indirectly, there are many opportunities for behavioral neuroendocrinologists to contribute to conservation.

Corticosterone responses of grey-faced petrels (Pterodroma macroptera gouldi) are higher during incubation than during other breeding stages.

We report the results of the first field study examining seasonal changes in corticosterone responses of typically long-lived birds of the order Procellariiformes. In particular, we examined whether grey-faced petrels Pterodroma macroptera gouldi showed changes in circulating baseline corticosterone concentrations and corticosterone responses to a standardized handling protocol across the breeding season. Such changes have been associated with changes in body condition and variations in energy demands on adult birds through the breeding season. During early incubation, males were in significantly better condition than females that had just completed laying, whereas during late incubation, males were in significantly poorer condition than females. In spite of these differences, there was no significant difference in baseline corticosterone concentrations between sexes or among birds at different reproductive stages. However, we detected significant differences in corticosterone responses associated with a standardized handling protocol at different stages through the breeding season. Responses were significantly greater during incubation compared with the prelay period and late chick rearing. Body condition was weakly and negatively correlated with maximum and total integrated corticosterone level, indicating that some of the individual variability in stress corticosterone responses could be explained by variation in body condition. However, the largest stress response occurred during late incubation and was independent of sex, although males were in relatively poor condition and females in relatively good condition. This period coincided with the breeding stage in which energy constraints on individual adults were higher than at other periods of the reproductive cycle and birds may be physiologically primed for extended fasts.