Biomedical subjects

D G Satterlee

Publications and source records attributed to D G Satterlee.

At least 19 recordsLinked to original sources

PubMed2006

Stressor-induced changes in open-field behavior of Japanese quail selected for contrasting adrenocortical responsiveness to immobilization.

The effect of no treatment (undisturbed controls; CON) or 5 min exposure to immobilization stress (STR) before assessment of open-field behavior in Japanese quail lines selected for high (high stress; HS) or low (low stress; LS) plasma corticosterone (B) response to a similar immobilization stress was examined. During a 5-min test period in an open field, the following behavioral measurements were made: the latency to ambulate (LAMB), the number of open-field floor sectors entered (SECTORS), and freezing behavior (total time spent in complete silence and inactivity, apart from slight movements associated with respiration; FREEZE). A further measure of ambulation across time (ambulation rate; ARATE) was calculated using the formula: ARATE = (SECTORS/[(300 s test ceiling)--LAMB)]. The LS-quail showed higher (P < 0.04) ARATE and lower (P < 0.05) FREEZE behavior than did their HS counterparts. When compared with the CON, quail exposed to STR showed decreased ARATE (P < 0.02) and numbers of open-field SECTORS entered (P < 0.04). More importantly, the LS-CON exhibited a higher (P < 0.05) mean ARATE, less FREEZE behavior, and increased numbers of SECTORS entered than did the other 3 treatment groups (LS-STR, HS-CON, and HS-STR), all of which showed similar responses for these variables. The LS-CON vs. HS-CON findings support our contention that selection for reduced adrenocortical responsiveness has been accompanied by a concomitant decrease in underlying fearfulness (exemplified herein by heightened activity in the open field in LS-CON). We further show here that this relationship was eliminated by application of an acute stressor before open-field testing of LS quail, wherein a reduction in activity similar to that found in both HS quail treatment groups was evident in comparison to the LS-CON.

Animals↗

PubMed2006

Cloacal gland and gonadal photoresponsiveness in male Japanese quail selected for divergent plasma corticosterone response to brief restraint.

Corticosterone is linked to testicular depression, and in Coturnix, a relatively photorefractory species, day length and androgen dependency in cloacal gland development and foam production are evident. Furthermore, male quail selected for reduced (low stress, LS) rather than exaggerated (high stress, HS) plasma corticosterone stress response show more photo-induced reproductive development, greater resistance to reproductive declines induced by exposure to very short days, and a quicker recovery to a higher reproductive level upon return to long days. To determine whether a milder reduction in day length would also influence stress line reproductive photoresponsiveness, and perhaps photorefractoriness, males grown on 16 h of light were given 13 h of light for 4 wk followed by a return to long days for 12 wk. Cloacal gland measurements were made following the initial stimulatory photoperiod and weekly thereafter during the 2 light treatments. Plasma testosterone was determined initially, after 4 wk of light reduction, and at the end of the study, along with BW, testes weight (TWT), and TWT relative to BW. Cloacal gland volume (CVOL) was greater in LS than HS males grown on long days. Whereas exposure to 13 h of light reduced CVOL in both lines, line differences (LS > HS) persisted during the first 3 wk of light reduction. Moreover, by 2 wk of rephotostimulation, and weekly thereafter, line differences (LS > HS) in CVOL reemerged. Cloacal gland foam production and the proportion of individuals that produced cloacal gland foam responses reflected changes in CVOL. The BW did not differ by line, yet LS males had a higher TWT and TWT relative to BW than HS ones. All individuals, however, exhibited relative photorefractory responses. Whereas none of the LS males completely resisted reproductive regression induced by a 3 h light reduction, LS males showed other reproductive benefits upon mild photocastration and subsequent rephotostimulation (e.g., greater resistance to CVOL and cloacal gland foam production losses during a mild light crash and quicker restoration to full reproductive potential upon relighting).

Animals↗

PubMed2006

Active immunization of broiler breeder cockerels against chicken inhibin accelerates puberty and prevents age-induced testicular involution.

Injection of quail and breeder hens with a recombinant protein antigen (MBP-cINA521)--a fusion of the bacterical maltose-binding protein (MBP) and a fragment of the alpha-subunit of chicken inhibin (cINA521)--accelerates puberty and enhances lay. Herein, the effects of this immunogen on reproductive responses in broiler breeder males were assessed. Cockerels were subcutaneously injected with 0 (vehicular controls), 1, 3, or 5 mg of MBP-cINA521 at 13 wk of age and with one-half of these dosages (boosters) at 18 wk. Bird subsamples were weighed, blood sampled, and killed at 24, 28, and 39 wk of age to assess age and vaccination effects on BW, testes weight (TWT), TWT relative to BW (RTWT), TWT > or = 20 g (TWT20; theoretical threshold TWT for maximum fertility), and plasma testosterone. Breeder males are sexually developing, reach peak sexual activity, and show age-related reproductive decline at these ages. Because vaccine gonadal effects at 24 wk appeared to be dramatic, the size of the left testis was also scored to see if size differences could be detected by mere visual inspection. Male fighting increasingly reduced sample sizes beyond 24 wk. Because mortality was unrelated to the treatments and to insure meaningful statistical comparisons, MBP-cINA521 data were pooled. Body weight (P < 0.04), testis score (P < 0.02), TWT (P < 0.03), RTWT (P = 0.06), and plasma testosterone (P = 0.08) were elevated in immunogen-treated males at 24 wk of age, and more (P < 0.05) MBP-cINA521-treated birds than controls achieved a TWT20 at this time. These variables did not differ by treatment at 28 wk. However, by 39 wk, treatment effects reemerged as follows: TWT (P < 0.04), RTWT (P = 0.06), and TWT20 (P < 0.01) were increased in vaccinated males who also showed nearly 3-fold higher levels of plasma testosterone. We conclude that immunoneutralization of inhibin accelerates puberty and retards age-related sexual senescence that typically occurs in broiler breeder males.

Aging↗

PubMed2005

Adrenocortical responses of Japanese quail to a routine weighing procedure and to tonic immobility induction.

Tonic immobility (TI) is induced by brief manual restraint, and it is a commonly used test of fearfulness, particularly in poultry. However, in view of increasing ethical concerns about experimentation on living animals, there is a need to ensure that the tests used do not elicit unacceptable distress. In the United Kingdom, there is some debate as to whether TI should be classified as a regulated experimental procedure that requires a Home Office license to experiment on living animals under the Animals (Scientific Procedures) Act of 1986. The present study compared plasma corticosterone (PC) concentrations in undisturbed Japanese quail (controls) with those exposed to the induction of TI or those exposed to a routine weighing procedure. Circulating PC concentrations were higher following TI induction or weighing than in the controls, but the 2 treatments elicited similar adrenocortical responses. Further, the PC levels found here were lower than those reported elsewhere when quail were exposed to crating, transport, or mechanical immobilization stressors. We therefore concluded that the induction of TI might be best regarded as a mild stressor. Furthermore, studies using this technique can identify ways of alleviating fear and thereby improving well-being. Collectively, we believe that the use of TI is justified, and it does not require classification as a regulated procedure in the United Kingdom or elsewhere.

Animal Welfare↗

PubMed2004

Photoperiod-induced changes in cloacal gland physiology and testes weight in male Japanese quail selected for divergent adrenocortical responsiveness.

In quail, activation of the hypothalamic-pituitary-adrenal axis has been linked to depression in the hypothalamic-pituitary-testicular axis, and cloacal gland development and foam production are known to be androgen dependent. Therefore, photoperiod manipulations that induce gonadal growth (long day) and involution (short day) were used to examine changes in cloacal gland physiology in male quail from lines selected for a reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone response to brief restraint. Line differences in cloacal gland area (CAREA) and volume (CVOL), the proportion of individuals that produced cloacal gland foam (PICF), and the intensity of cloacal gland foam production (CFP) were initially assessed in adult males maintained on stimulatory, long photoperiods of 14L:10D. Thereafter, these variables were re-examined weekly in the same males during their subsequent exposure to 3 wk of short days (6L:18D) followed by return to long d for 3 more wk. Line differences in testes weight relative to body weight (RTW) were also measured at the end of the study. CAREA and CVOL were markedly greater in LS than HS males grown under long days. As expected, these indices of cloacal gland size were greatly reduced upon exposure to short days in both lines. However, line differences (LS > HS) in CAREA and CVOL were maintained during the first 2 wk of exposure to short days. Line differences in the depressed cloacal gland size measures were no longer evident by the third week on short days as well as after the first week of relighting wherein there were no further depressions in gland size of either line. However, by the end of 2 wk of rephotostimulation and thereafter, marked line differences (LS > HS) in CAREA and CVOL re-emerged. Photoperiod-induced line effects on CFP generally mimicked those of CAREA and CVOL. The PICF was marginally different (P < 0.07) between the lines (LS > HS) only after 1 wk of light reduction. After 3 wk of rephotostimulation, RTW was nearly 25% greater in LS quail. The results suggest that selection for reduced adrenocortical responsiveness in Coturnix has resulted in certain reproductive advantages in middle-aged, adult males maintained on stimulatory photoperiods as well as in such adults subjected to photocastration and subsequent rephotostimulation.

Adrenal Cortex↗

PubMed2004

Cloacal gland and testes development in male Japanese quail selected for divergent adrenocortical responsiveness.

The time course of sexual development in male quail from lines selected for either a reduced (low stress, LS) or an exaggerated (high stress, HS) plasma corticosterone response to brief restraint was determined. Sexual development was assessed by examination of cloacal gland area (CAREA) and volume (CVOL), proportion of individuals that produced cloacal gland foam, and the intensity of cloacal gland foam production (CFP) at 4, 5, 6, 8, 10, 14, and 16 wk of age. These intervals encompass ages during which growing, photostimulated quail would be expected to evolve from being totally prepubescent to well into adulthood. Testes weight (TW) and the proportion of individuals that had achieved a combined TW of 500 mg (PI500) were also measured at 6 and 16 wk of age. Mean CAREA and CVOL were similar in LS and HS quail at 4 wk of age. Beginning at 5 wk of age and thereafter, CAREA was greater (P < 0.05) in LS than in HS quail. Similarly, beginning at 6 wk of age and thereafter, CVOL was greater (P < 0.05) in LS than in HS quail. More LS than HS birds also expressed foam at 4 (P < 0.05), 5 (P = 0.15), and 6 wk (P < 0.05) of age. From 8 wk on, all birds were in foam production. CFP results mimicked those found for CAREA and CVOL in that LS quail tended toward higher CFP values than HS quail at all intervals of measurement. TW were higher (P < 0.02) in LS than HS quail when data from the 2 ages at which testes were harvested were combined. At 6 wk of age, the LS and HS birds showed a PI500 line difference (P < 0.08) of 1.0 and 0.91, respectively; by 16 wk, all birds exhibited a maximum PI500. The results suggest that 1) selection for reduced adrenocortical responsiveness in Coturnix is accompanied by an accelerated onset of puberty in males, and 2) enhanced reproductive development in LS males remains extant throughout early to middle-age adulthood.

Adrenal Cortex↗

PubMed2003

Genetic characterization of stress responsiveness in Japanese quail. 1. Analyses of line effects and combining abilities by diallel crosses.

The inheritance of stress responsiveness (line effects and combining abilities) was phenotypically studied in progeny from diallel crosses of randombred (RB) quail and quail selected for exaggerated (high stress, HS) or reduced (low stress, LS) plasma corticosterone (CS) response to brief immobilization. The three genotypes were crossed in a 3 x 3 factorial arrangement of treatments that allowed all possible crosses between RB, LS, and HS males with RB, LS, and HS females. The nine crosses produced 479 progeny. At 28 d of age, quail of each cross were stressed by immobilization, and blood was sampled. Plasma CS was used to estimate stress responsiveness in the progeny of each cross. Estimates of the following genetic effects were made: average post-immobilization plasma CS response within each cross, general combining ability (GCA), and specific combining ability (SCA). Differences (P < 0.05) in plasma CS response to immobilization between crosses involving the LS and HS lines (HS crosses > LS crosses) were commonly observed. There were no significant differences in the means of plasma CS responses between males and females within each of the crosses except for the marginal (P = 0.07) sex difference (male > female) found within the LL cross (LS male with LS female). The GCA estimates were -1.23, -2.89, and 5.08 for the RB, LS, and HS quail, respectively. The SCA was not significant for any diallel mating except HH (P < 0.007). Line effects on plasma CS response were different from zero for the LS and HS lines.

Alleles↗

PubMed2003

Genetic characterization of stress responsiveness in Japanese quail. 2. Analyses of maternal effects, additive sex linkage effects, heterosis, and heritability by diallel crosses.

Diallel crosses were used to investigate the genetic inheritance of stress responsiveness through examination of population effects in progeny of randombred (RB) quail and quail selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone (CS) response to brief immobilization. The three genotypes were crossed in a 3 x 3 factorial arrangement of treatments that allowed all possible crosses between RB, LS, and HS males with RB, LS, and HS females. The nine crosses produced 479 progeny that were, at 28 d of age, stressed by immobilization, and a sample of blood was collected. The following quantitative genetic parameters were estimated for plasma CS: heritability, heterosis, maternal effects, sex-linkage effects, and heterosis due to the sex chromosomes. Genotypic-phenotypic correlations within RB quail and quail of the two selected lines were also obtained. Maternal effects were different (P < 0.05) from zero for the plasma CS responses of all three genotypes. Additive sex linkage effects on plasma CS responses were variable and of much less importance than maternal effects. The correlations between plasma CS response and genotype were: 0.22 for RB quail and 0.37 and 0.55 for quail of the LS and HS lines, respectively. Heterosis effects were low and most likely due to either an increase in homozygozity of genes on the sex chromosomes or an increase of maternal effects within reciprocal crosses. Heritability, estimated for the post-immobilization plasma CS response, was 0.05 for RB quail and 0.14 and 0.30 for quail of the LS and HS lines, respectively.

Alleles↗

PubMed2003

Early T-maze behavior and broiler growth.

In the laboratory and at a commercial farm in Argentina, chicks that showed a short latency to exit a T-maze (LEX) (HP, high performance) gained more weight than those with a longer LEX (LP, low performance). The present study re-examined this relationship and evaluated additional T-maze measures using broilers reared in quasi-intensive, environmentally controlled conditions. In the T-maze, a mirror strategically placed at the end of a corridor stimulates the test chick to leave the isolation chamber (start box) and to move toward its reflection. Having done so, it can then see other birds and thereby be further stimulated to completely exit the maze. However, when a test bird hesitates or stops at the mirror, its performance categorization may be confounded. Herein, the T-maze performance of 3-d-old broiler chicks was assessed using three different measurements: 1) the latency to exit the start box (LEB), 2) the latency to reach the mirror section of the maze (LRM), and 3) LEX. The fastest (top 25%) and slowest (bottom 25%) of the birds within a sex and within each of the three T-maze criteria were classified as HP and LP chicks, respectively. The relationships between these measures and body weight were examined in 4-, 42-, and 56-d-old males and females. Irrespective of the T-maze classification criteria used, HP and LP chicks had similar body weights at 4 d of age. However, chicks classified as HP according to LEB or LRM measures were heavier at 42 and 56 d of age than LP ones (P < 0.02 for all comparisons). These differences were apparent in both sexes. On the other hand, there were no detectable differences in body weight at the latter ages between chicks categorized as HP or LP according to their LEX scores. The present results indicate that 1) broiler chicks that exit the T-maze start box and reach the mirror quickly subsequently grow faster than their slower LP counterparts and 2) LEB and LRM are better predictors of growth than the LEX value used in previous studies.

Aging↗

PubMed2002

Sex differences in central benzodiazepine receptor densities and circulating corticosterone release after acute stress in broiler chicks.

The purpose of the study was to determine the effect of sex on central benzodiazepine receptor (CBR) and serum corticosterone (CS) responses to an acute stressor in broiler chicks. Birds were housed in ten mixed-sex groups of eight chicks per cage. At 15 d of age, chicks were taken from a randomly selected cage and blood was immediately sampled (undisturbed controls), or they were taken from the same cage and immersed up to their necks in warm water (partial water immersion, PWI) for 15 min before blood was sampled. After blood sampling, forebrains were dissected for preparation of membranes, and bird sex was determined by gonadal inspection. Serum CS levels were determined by a competitive protein-binding assay. CBR densities were determined by radiolabeled receptor binding assay. There were no sex differences in serum CS levels or benzodiazepine receptor densities in controls. Exposure to PWI significantly increased (P < 0.01) circulating CS levels in both sexes, and this elevation was more pronounced (P < 0.01) in males than in females. Male, but not female, chicks also showed a significant stressor-induced increase (P < 0.01) in CBR densities. These findings showed sexual differences in acute, stressor-induced benzodiazepine and adrenocortical responses that suggest broiler males are more stress-susceptible than females.

Animals↗

PubMed2002

Active immunization of broiler breeder hens with a recombinant chicken inhibin fusion protein enhances egg lay.

We have demonstrated that inoculation of female Coturnix with an inhibin-based immunogen (MBP-cINA521) accelerated puberty and enhanced hen-day egg production (HDEP). Herein, MBP-cINA521, a fusion protein, which consists of the bacterial maltose binding protein (MBP) and a fragment of the infinity-subunit of chicken inhibin (cINA521), was tested for its ability to enhance production performance in broiler breeders. Pullets (Arbor Acres Classic Females; n = 60 birds/treatment group) were given (subcutaneously) 0, 1, 3, or 5 mg of MBP-cINA521 in Freund's complete adjuvant at 20 wk and 4 d of age. Booster immunizations (one-half of the primary dosages) were given at 23 wk of age. The vehicle for controls (CON; no booster) and MBP-cINA521-boosted birds was Freund's incomplete adjuvant. Blood samples were obtained at the end of the trial to assess immunological response to the antigen with a titer ELISA. The onset of puberty was assessed by calculation of the average ages at first lay (FIRST) and at 50% egg production (FIFTY). Cumulative percentage HDEP was determined weekly throughout the laying period (40 wk). Egg weight (EWT) and specific gravity (SG) assessments were made periodically during the trial. Body weight gain (BWG) and mortality (MORT) data were also collected. Significant injection treatment differences (P < 0.01) in inhibin antibody titers were detected according to the following order: low dose = intermediate dose > high dose > CON. A dose of MBP-cINA521 capable of accelerating puberty and increasing overall egg lay was identified. FIRST and FIFTY responses were decreased (P < 0.05) in birds given the intermediate dose (3.0 mg) of MBP-cINA521 when compared to the CON. FIFTY responses were also lower (P < 0.05) than CON responses in those birds given the highest dose (5.0 mg) of the inhibin antigen. Cumulative HDEP was also higher (P < 0.05), beginning at 3 wk of lay and weekly thereafter (P < 0.05, for the remaining 40 wk), in birds given the intermediate immunogen dosage when compared to the CON. By Week 40, an average increase of 9.5% HDEP was realized in birds given 3.0 mg of MBP-cINA521. MORT rates were similar in the CON and in the two lowest MBP-cINA521 treatment groups but were higher (P < 0.05) in those birds given 5.0 mg of the antigen. EWT, SG, and BWG measurements were unaffected by treatment with the inhibin vaccine. In agreement with our findings in quail, immunoneutralization of inhibin enhanced production performance in breeder hens.

Animals↗

PubMed2002

Selection of Japanese quail for reduced adrenocortical responsiveness accelerates puberty in males.

Differences in the onset of puberty were assessed in male Japanese quail from a random-bred (RB, control) line and two lines that had been genetically selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone response to brief mechanical restraint. At 42 d of age, cloacal gland area (CAREA) and volume (CVOL), proportion of individuals that produced cloacal gland foam (PICF), and intensity of cloacal gland foam production (CFP) were examined in 60 representatives from each of these quail lines. CFP was quantified by subjective scaling of the amount of foam ejected upon manual expression (squeezing) of the foam gland, using a scale of 1 (no foam expressed) to 5 (maximum amount of foam expression). Mean CAREA and CVOL were similar in quail of the RB and HS lines, but these measures were greater (P < 0.01) in the LS quail. In addition, more (P < 0.05) LS than HS birds expressed foam at 42 d, whereas RB quail exhibited an intermediate PICF response that was not different from either selected line. CFP results mimicked those found for PICF (i.e., LS quail produced a greater (P < 0.05) amount of foam than HS birds, whereas RB quail showed intermediate production that was not different from LS or HS levels). In prepubertal and pubertal Japanese quail, cloacal gland hypertrophy is androgen-dependent and highly positively correlated with testes size as well as sexual activity. Cloacal gland foam production is also considered a reliable indicator of testicular size and activity. Thus, we conclude that selection for reduced adrenocortical responsiveness in Coturnix is associated with acceleration in the onset of puberty in males. The potential interaction between adrenocortical and testicular activity as it relates to male reproductive performance is discussed.

Adrenal Cortex↗

PubMed2002

T-maze behavior and early egg production in Japanese quail selected for contrasting adrenocortical responsiveness.

Broiler chicks that traverse a T-maze quickly to reinstate contact with their companions (HP, high performance) are known to grow faster, be more social, and exhibit a reduced plasma corticosterone (B) response to acute stress than slower (LP, low performance) chicks. Genetic lines of Japanese quail selected for reduced (LS, low stress) or exaggerated (HS, high stress) plasma B response to brief restraint also differ in sociality and performance. In the present study, we asked if divergence in early T-maze behavior was associated with differential attainment of puberty and early egg production in these lines. At 3 d of age, LS and HS quail were categorized as HP or LP birds based on running times in a T-maze. Thus, there were four treatment combinations: HP-LS, HP-HS, LP-LS, and LP-HS birds. Daily egg records were kept for 8 wk. The average ages at first egg lay (FIRST), at 25% egg production (A25% EP), and weekly and cumulative hen-day egg production (HDEP) where calculated. Daily egg weight (EWT) data were also collected, and BW measures were made at the end of the trial. Mean FIRST and A25% EP responses were lower (P < 0.02) and cumulative HDEP was greater (P < 0.04) in HP than in LP quail. Despite considerable numerical reductions in FIRST and A25% EP, as well as 5% elevation in cumulative HDEP in LS quail, line differences in these variables were not significant. On the other hand, FIRST and A25% EP were reduced (P < 0.05) in HP-LS quail when compared to LP-HS ones, whereas HP-HS and LP-LS quail showed intermediate and similar responses that did not differ from the other two treatment groups. Mean cumulative HDEP findings for the interactive effect of performance category with line mimicked these puberty findings. EWT and BW measures were not affected by any of the treatments or their interactions. Our results suggest that rapid negotiation of the T-maze by quail chicks is associated with accelerated puberty and increased HDEP in quail of two genetically diverse lines. This effect is particularly evident in quail selected for reduced adrenocortical responsiveness, suggesting possible additive effects.

Adrenal Cortex↗

PubMed2000

Effects of repeated restraint in Japanese quail genetically selected for contrasting adrenocortical responses.

Behavioral and adrenocortical responses to repeated mechanical restraint were compared in 28-day-old to 31-day-old male Japanese quail from two genetic lines divergently selected for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone (C) responses to brief immobilization. Restraint in a metal crush cage for 5 min elicited immobility and silence in all the birds. Circulating C levels were considerably higher in quail of both lines following restraint than in the undisturbed controls of either line. As expected, both the behavioral and physiological effects were more pronounced in HS than in LS birds. Struggling increased with repeated restraint in HS and LS quail, thus suggesting behavioral habituation to the stressor in both lines. On the other hand, a line effect on the pattern of adrenocortical responses was revealed upon subtracting the change in plasma C concentrations from Day 1 to Day 4 in the undisturbed controls from the corresponding change in restrained birds. Thus, unlike LS quail, in which there were no detectable effects of repeated restraint, the adrenocortical responses of HS birds showed evidence of experience-dependent sensitization. Our results demonstrate the importance of the background genome in determining the patterns of the behavioral and adrenocortical responses elicited by repeated exposure to stressful stimulation. The present results and those of previous studies could be explained in one or both of two ways: that underlying fearfulness is lower in LS than HS quail or that they adopt active or passive coping strategies, respectively. Our findings may also have important implications for poultry welfare and productivity. @ 2000 Elsevier Science Inc.

Adrenal Cortex↗

PubMed2000

Developmental instability in japanese quail genetically selected for contrasting adrenocortical responsiveness.

Differences in developmental instability were assessed with Japanese quail of two lines that had been genetically selected over several generations for reduced (low stress, LS) or exaggerated (high stress, HS) plasma corticosterone response to brief mechanical restraint. At 32 wk of age, three bilateral traits were selected for study in each quail line. The characteristics chosen were length of the metatarsus (shank length, SHL), diameter of the shank (SHD) perpendicular to the spur, and distance between the auditory canal and the nares (face length, FL). Significantly greater bilateral trait size variances were associated with the measurement of SHL (P < 0.0088) and FL (P < 0.0016) in the HS line than in the LS line. SHD variances did not differ (P = 0.22) in quail of the HS and LS lines. These findings suggest that developmental instability (i.e., fluctuating asymmetry, FA) is more pronounced in HS quail than in LS quail. Previous studies have shown that not only do quail of the HS line show greater adrenocortical responsiveness to a wide range of stressors but that they are also more easily frightened than LS birds. Therefore, the line differences in FA found here may reflect the birds' differential responsiveness to chronic social and physical environmental stressors. The present findings also support previous suggestions that measuring asymmetries in bilateral traits could be an additional and valid method of assessing stress and of comparing phenotypic stability in selected populations.

Adrenal Cortex↗

PubMed2000

Struggling behavior in shackled male and female broiler chickens.

Anecdotal evidence suggests that the struggling behavior of shackled broiler chickens may be positively related to compression of the shank and the probable associated discomfort: birds with large shanks tend to struggle more violently than do those with smaller shanks. Males are generally heavier and have thicker shanks than females. Therefore, we tested the hypothesis that, because the leg gaps of shackles are fixed in size, male broilers would struggle more than females. At 42 d of age, 264 floor-reared broilers were cooped in groups of 12 (six males and six females) and were transported from the university farm to the abattoir. Eighty of these served as test birds (n = 40/sex) and were shackled on a moving processing line with a bird of randomly selected sex on either side. Upon shackling, the latencies to struggle, numbers of struggling bouts, and total time spent struggling were recorded during a 1-min test period. Subsequently, the BW and circumference of the right shank (CRS) of each test bird were measured. Male birds were heavier and had thicker shanks than females (both P < 0.0001); they also struggled sooner (P < 0.01) and longer (P < 0.008). When data from males and females were pooled, CRS was negatively correlated with latency to struggle (r = -0.30; P < 0.006) and positively associated with SB (r = 0.23; P < 0.04) and total time spent struggling (r = 0.23; P < 0.04). However, there were no detectable correlations within sex. Body weight was not significantly correlated with any of the struggling behavior measures. Although other gender-related factors may be influential, an interpretation of our findings based on sex differences in CRS seems the most parsimonious. We conclude that use of shackles of fixed leg-gap size may contribute to increased struggling behavior in male broilers.

Abattoirs↗

PubMed1999

Timidity in Japanese quail: effects of vitamin C and divergent selection for adrenocortical response.

Male Japanese quail chicks of two genetic lines selected for low (LS) or high (HS) adrenocortical responses to mechanical restraint were housed in mixed-line groups of 24 in four compartments of a multitier brooder battery at 20 days of age. Quail in two of the four compartments were given vitamin C (ascorbyl-2-polyphosphate, APP, 1 g L-ascorbic acid/L) solution for 48 h, whereas the other birds received untreated tap water as usual before they were tested at 23 days of age. At test, each quail was placed individually in a dark, sheltered compartment of an emergence box and allowed 1 min to acclimatise before a door was raised allowing access to an illuminated and exposed area. Vocalisation and the latencies to head and full emergence were then recorded to measure its fear levels. More LS quail vocalised than did HS ones. They also emerged more rapidly from the sheltered compartment into the illuminated one than HS birds. These findings further support our hypothesis that decreased fearfulness has accompanied genetic selection for reduced adrenocortical responsiveness. Treatment with APP reduced the latency to emerge fully into the exposed compartment, and there were no line x treatment interactions. These results suggest that vitamin C supplementation alleviated fearfulness, regardless of existing line differences in this behavioural trait.

Adrenal Cortex↗

PubMed1999

Concentration-dependent, biphasic effect of prostaglandins on avian corticosteroidogenesis in vitro.

Previous work with mammalian and frog adrenocortical tissue and cells indicates that prostaglandins (PGs) can directly stimulate corticosteroidogenesis. However, work with avian adrenal preparations is absent. Therefore, the present studies with isolated chicken (Gallus gallus domesticus) and turkey (Meleagris gallopavo) adrenal steroidogenic cells were conducted to determine whether PGs can directly influence avian corticosteroidogenesis as well. Cells (1 x 10(5) cells/ml) were incubated with a wide range of concentrations of PGs in the presence of indomethacin (1 microg/ml) (to attenuate endogenous PG production) and 1-methyl-3-isobutylxanthine (0.5 mM) [to preserve cyclic AMP (cAMP)] for 2 h. Corticosterone and cAMP production were measured by highly specific radioimmunoassay. PGI2 was without effect. With the exception of PGF2alpha, which had a slight stimulation in chicken but not in turkey cells, the influence of the other PGs on corticosterone production was biphasic. For the stimulatory phase (up to a concentration of 5 x 10(-5) M), there were prostanoid structural and avian species differences in both potency and efficacy of PGs. Overall, PGs were 11 times more potent in turkey cells than in chicken cells. However, the order of potency for stimulation was similar for both chicken and turkey cells: for chicken cells the order was PGE2 > PGE1 > PGA1 > PGB2 > PGB1 > PGF2alpha and for turkey cells it was PGE2 > PGE1 > PGA1 > PGB2 = PGB1. In contrast, PG efficacy for stimulation was greater for chicken cells. In addition, the orders of efficacy were different from the orders of potency. In chicken cells, the order of efficacy was PGE2 = PGA1 > PGE1 > PGB2 > PGB1 > PGF2alpha and for turkey cells it was PGB2 = PGE2 > PGA1 > PGE1 > PGB1. Because of the greater maximal corticosterone response over basal production of chicken cells to PGs, they were used to assess the interaction of PGs with ACTH and to examine more fully the inhibitory phase of PGs. Cells were incubated with PGs in the presence of threshold (2.5 x 10(-11) M), half-maximal (1 x 10(-10) M), and maximal (1 x 10(-7) M) steroidogenic concentrations of ACTH. With the exception of PGF2alpha, the average efficacy of PGs to elevate corticosterone was increased 55% by a threshold steroidogenic concentration of ACTH. However, with higher concentrations of ACTH, this enhancement of efficacy disappeared as did the stimulatory effect of some PGs. The results suggest that the steroidogenic actions of PGs and ACTH converge on the same pool of steroidogenic enzymes leading to corticosterone. At concentrations greater than 5 x 10(-5) M, several PGs (notably PGA1, PGA2, PGB1, and PGB2) inhibited both ACTH-induced and basal corticosterone production. PGA1 and PGA2 were the most potent inhibitors. Corticosterone and cAMP production were closely associated in the biphasic action of PGs, suggesting that the effect of PGs was mediated by the changing levels of intracellular cAMP. Collectively, these data suggest that PGs may be important modulators of corticosteroidogenesis in the avian adrenal gland.

1-Methyl-3-isobutylxanthine↗