Faecal measurements of oestradiol and testosterone allow the non-invasive estimation of plasma steroid concentrations in the domestic fowl

Validation of enzyme immunoassays for quantifying sex steroid hormones in tropical screech owls (Megascops choliba)

Androgens and estrogens are steroid hormones that regulate reproductive processes in both males and females. Monitoring plasma levels of these steroids or their metabolites present in feces, offers diagnostic support for assessing the reproductive status of animals. Immunoassays are commonly used methods for quantifying these hormones, but their protocols require species-specific validation to ensure reliability. The objective of this study was to perform analytically and biologically validation of enzyme immunoassay (EIA) kits for measuring testosterone (T), estradiol (E2), faecal androgen metabolites (fAM), and faecal estrogenic metabolites (fEM) in the tropical screech owl (Megascops choliba). Serum and fecal samples were collected from six adult females and six males both before and during breeding season, with males' gonadal activity assessed using electroejaculation (EE). The parallelism test confirmed the immunogenic similarity of the antigens in the estradiol and testosterone standards and the antigens in the serum samples and fecal extracts of M. choliba. Additionally, the EIA kits displayed nearly 100% recovery rates, and showed coefficients of variation ranging from 8% to 14% at the intra-assay level and from 10% to 16% at the inter-assay level, underscoring result reliability and consistency. In males, the highest serum T and fAM levels were recorded concurrently with the presence of spermatozoa in samples collected via EE. Although females did not exhibit oviposition events, significantly higher E2 and fEM levels were observed in August compared to May, suggesting potential seasonal variations in estrogenic hormone production. Fecal androgen and estrogen levels were significantly different between sexes in August, with males having higher fAM and females having higher fEM levels. Overall, the immunoassays validated in this study were found to be efficient in diagnosing reproductive activity in owls.

Testosterone levels in hair of free-ranging male northern fur seals (Callorhinus ursinus) in relation to sampling month, age class and spermatogenesis

Information about the reproductive status of free-ranging pinnipeds provides useful insight into their population dynamics, which is essential to their management and conservation. To determine the reproductive status of individual animals, blood sampling is often required despite being impractical to collect in open water. Hair as an endocrine marker has been used to less invasively assess the reproductive status of terrestrial animals. However, it is unknown whether pinniped reproductive status can be assessed from hair samples. Here, we examine testosterone levels in hair obtained from 57 male northern fur seals and used it to compare their age class and spermatogenesis during the non-breeding season off Hokkaido. We isolated testosterone from the samples using gas chromatography and measured testosterone levels using time-resolved fluoroimmunoassay. Testosterone levels in hair increased towards the breeding season. In May, testosterone levels were the highest in seals aged between 4 and 7 years, followed by those over the age of 8 years and under the age of 4 years. Spermatids, the final phase of spermatogenesis, were present in the seals sampled between April and June, even though testosterone levels were low in April. The seals with spermatids in May showed the highest testosterone levels. Our results demonstrate that seals with higher testosterone levels in May are likely to be mature males (≥4 years). Since hair can be collected using biopsy darts in the field, it will be possible to less invasively determine testosterone levels of male seals in the future.

Estrogenicity of agricultural runoff: A rainfall simulation study of worst-case scenarios using fresh layer and roaster litter, and farrowing swine manure

Scientists have correlated land application of animal wastes as fertilizer with the feminization of fish. Two questions were asked. 1) Under a worst case scenario when animal waste (layer and roaster litter, or farrowing swine slurry) is applied and tilled in 24 h prior to a surface-runoff producing rainfall, will estrogenic equivalents exceed the Lowest Observable Effect Concentration (LOEC) for fish (10 ng/L)? 2) Can calcium concentrations in runoff, measured using a rapid meter-based method, be used as a sentinel of elevated estrogenic activity? In a 3-yr study wastes were surface-applied and incorporated and 24 h later, 1.5 by 3 m plots were subjected to simulated rainfall and again 1 wk. and 3 wk. later. Nutrients in runoff were also measured, and in year 1 total coliforms and E. coli. were assessed. Except for an initial preliminary test run, runoff from all plots and years never exceeded 10 ng/L E2Eq equivalent. Calcium concentrations in runoff were not related to estrogenicity, negating its use as a sentinel marker. Specific estrogens in animal waste and runoff were identified by mass spectrometry with concentrations in runoff dependant on manure source and timing of rainfall. As expected, total coliform and E. coli concentrations in runoff were increased by the application of layer litter. Concentrations of nutrients in runoff would not be expected to result in surface water concentrations higher than guidelines for protection of aquatic species. Animal wastes applied in quantities appropriate for crop nutrient requirements, tilled into the soil surface, in observance of regulations avoiding application within 24 h of a predicted rain event, should not result in estrogen levels of environmental concern.

Endocrine correlates of gender and throat coloration in the southern ground-hornbill (Bucorvus leadbeateri)

The southern ground-hornbill (SGH) is a cooperatively breeding bird endemic to eastern and southern Africa, but is endangered in its southern distributional range. The national conservation restoration program harvests redundant chicks for captive breeding and reintroduction; with sexing and social grouping of the species evaluated by throat-skin coloration, with adult males displaying a completely red color compared to dark blue within the red observed in adult females. However, recent findings indicate that dominant and subordinate adult males exhibit patches of blue throat-skin. To optimize SGH management practices, it is vital to determine the role of red and blue coloration, as well as the possible drivers thereof. As a prerequisite, an enzyme immunoassay for monitoring fecal androgen metabolite (fAM) concentrations in SGH was established. Following this, fresh fecal samples were collected from 78 SGH, of various demographics and origin, across 12 captive institutions, to determine whether fAM concentrations differ between blue (B), partially blue (sB), and fully red (R) throat-skin colored SGH. Furthermore, fAM concentrations were compared between males housed in different social groups of different age and sex classes. Individual median fAM concentrations of B, sB, and R adult males did not differ significantly but were considerably higher in B and sB males compared to R males. Social dynamics within captivity, for example, dominance, played no role as a driver of male gonadal activity or throat skin coloration. The results of the study indicate that androgens and apparent social dynamics are not primary determinants of throat coloration in male SGH.

Estrogenic activity and nutrient losses in surface runoff after winter manure application to small watersheds

Confined Animal Feeding Operations generate large amounts of wastes that are land-applied to provide nutrients for crop production and return organic matter to the soil. Production practices and storage limitations often necessitate that wastes be applied to frozen and snow-covered soil. Use of application setbacks have reduced concerns related to nutrient losses in surface runoff from manure, but the estrogenic activity of runoff under these conditions has not been evaluated. Therefore, we measured and sampled surface runoff when manure was applied in the winter at a rate to meet crop N needs and measured estradiol equivalents (E2Eqs) using E-Screen. In year one, six small watersheds used to produce corn were evaluated, treatments: 2 no-manure controls, 2 liquid swine manure with 30-m setbacks, and 2 turkey litter with 30-m setbacks. In addition, beef manure was applied to six frozen plots of forage. For years 2 and 3, applications were repeated on the swine manure watersheds and one control watershed. E2Eqs and nutrient concentrations generally peaked in the first runoff event after application. The highest measured E2Eq (5.6 ng L(-1)) was in the first event after swine manure application and was less than the 8.9 ng L(-1) Lowest Observable Effect Concentration (LOEC) for aquatic species and well below the concentrations measured in other studies using ELISAs to measure hormone concentrations. No runoff occurred from plots planted with forage, indicating low risk for environmental impact, and therefore plots were discontinued from study. In years 2 and 3, estrogenic activity never exceeded the Predicted No Effect Concentrations for E2 of 2 ng L(-1). When post-application runoff contained high estrogenic activity, strong correlations (R(2) 0.86 to 0.96) of E2Eq to Ca(2+), Mg(2+), and K(+) concentrations were observed, indicating under some condition these cations might be useful surrogates for E2Eq measurements.

Egg wash wastewater: estrogenic risk or environmental asset?

Commercial production of eggs and egg products requires the washing of eggs to remove urinary-fecal material and broken egg residue. In the case of one Ohio farming facility, 1.6 million birds produce 1.4 million eggs per day, using approximately 50 mL of wash water/egg or approximately 70,000 L per day. The aqueous waste stream was evaluated for estrogenicity to determine if potential for endocrine disruption would result from agricultural application of such wastewater. Samples collected the Fall (October) of 2010 included: water from 2 egg washers operating in series, inlet pipe to the treatment lagoon, a lagoon composite, and products used within the facility in the cleaning of equipment and treatment of the waste. In February 2011, the treatment lagoon was fitted with an extensive aeration system and subsequent sample sets were collected on 3 consecutive days in May and November. Samples were extracted by solid phase extraction and assayed for estrogenic activity using the in vitro E-Screen assay. Raw untreated wastewater from the egg washers contained 17β-estradiol equivalents (E2 Eqs) ranging from 9 to 18 ng/L, pipe grab samples entering into the treatment lagoon ranged from <0.14 to 4.4 ng/L (variability related to time of emptying of egg wash tanks), whereas treatment lagoon water contained 0.3 to 4.0 ng/L E2 Eq. Addition of an aeration system to the treatment lagoon eliminated surface "frothing," reduced noxious odor emission, and E2 Eqs were lower than the pre-aeration concentrations (4 ng/L [n = 1, no statistical comparison possible] vs 0.3 to 1.4 ng/L in 2011). Because of matrix effects, estrogens were not quantifiable by LC-MS2 in even egg washwater extracts, at concentrations in which internal deuterated estrogen standards were quantifiable. Estrone and E2 parent ions were detected in egg washwater samples only, and confirmatory ion fragments were detected in only one of these samples. Estrogenicity of the wastewater from the treatment lagoon was already at the proposed aquatic no effect concentration for 17β-E2 and would be expected to decrease further as wastewater passes through 2 consecutive storage ponds before application on field crops for irrigation. The original project plan was to follow the wastewater as it was applied by aerial irrigation and concomitant surface runoff, but based on the consistent and extremely low concentration of estrogenic activity of the wastewater from the treatment lagoon, it was concluded that activity would be below limits of quantitation by E-Screen in water used for irrigation from the storage ponds. Use of egg wash wastewater--or gray water--to irrigate crops removes the cost and burden of wastewater treatment by the local wastewater plant, poses little to no potential threat of estrogenic endocrine disruption, and supports the conservation of water resources through the use of wastewater irrigation.

Review: Minimally invasive sampling media and the measurement of corticosteroids as biomarkers of stress in animals

Cook, N. J. 2012. Review: Minimally invasive sampling media and the measurement of corticosteroids as biomarkers of stress in animals. Can. J. Anim. Sci. 92: 227–259. The measurement of corticosteroid hormones is commonly used as a biomarker of an animal's response to stress. The difficulties in obtaining blood samples and the recognition of the stressor effect of blood sampling are primary drivers for the use of minimally invasive sample media. In mammals these include saliva, feces, urine, hair, and milk. In birds, samples include excreta, feathers, egg yolk and albumin. In fish, corticosteroids have been measured in excreta and swim-water. Each of these sample media incorporate corticosteroids in accordance with the processes by which they are formed, and this in turn dictates the periods of adrenocortical activity that each sample type represents. Cortisol in saliva represents a time-frame of minutes, whereas the production of feces may be hours to days depending on the species. The longest time-integrations are for hair and feathers which could be over a period of many weeks. The sample media also determines the structural changes that may occur via processes of conjugation to glucuronides and sulfides, metabolic conversion via enzymatic action, and bacterial breakdown. Structural changes determine the optimum methodologies used to measure corticosteroid hormones. In most sample media, measurement of a specific corticosteroid is a requirement depending on the species, e.g., cortisol in most mammals, or corticosterone in birds. However, in samples involving products of excretion, methodologies that measure a broad range of structurally related compounds are probably optimal. The utility of minimally invasive sample media as biomarkers of stress responses depends on the degree to which the corticosteroid content of the sample represents adrenocortical activity. Commonly, this involves comparisons between corticosteroid concentrations in blood plasma with concentrations in the alternative sample media. This review focuses on the methodological and biological validation of corticosteroid measurements in minimally invasive samples as biomarkers of adrenocortical responses to stress.

Non-invasive monitoring of adrenocortical activity in European badgers (Meles meles) and effects of sample collection and storage on faecal cortisol metabolite concentrations

Due to the increasing demand for methods to quantify adrenal activity in response to stressors in wild animals, we evaluated whether stimulation with adrenocorticopic hormone (ACTH) increases faecal cortisol metabolite levels in European badgers. We also conducted several experiments to evaluate the effect of storage time and collection methods on cortisol metabolite levels of faecal samples. Faecal samples were collected from five captive European badgers (Meles meles) and cortisol metabolites were quantified by an enzyme immunoassay. Faecal cortisol metabolite levels increased 1-2 days after ACTH injection and dropped to pre-treatment levels 3 days after ACTH stimulation. We found that cortisol metabolite levels were not affected by the 8-hour time lapse from collection in the field until freezing of faecal samples, environmental exposure (temperature 25.66 ± 2.55°C; range 21.20-32.20) or mean relative humidity 62.77 ± 9.90% (range 42.00-79.00). Cortisol metabolites were not homogenously distributed in the scats. Cortisol metabolite levels were significantly lower when faecal extracts and samples were frozen for long periods of time (14 weeks or more). Thus, the measurement of faecal cortisol metabolites is a suitable method for the non-invasive evaluation of adrenocortical activity in European badgers. However, some aspects related to the collection and storage of faecal samples should be considered in future studies conducted with this species.

Testosterone: from initiating change to modulating social organisation in domestic fowl (Gallus gallus domesticus)

Testosterone (T) concentrations in many species are sensitive to seasonal changes and to changes in social conditions. However, the effect of the natural or endogenous T increase in the juvenile on their social behaviour is not well understood. In this study, T and behaviour were measured from the pro-social juvenile to the adult stage in semi-feral domestic fowl. During the pro-social phase T levels and the distance chicks maintained between each other, i.e. inter-individual distance (IID) were low. Then, as T increased, a corresponding increase in IID occurred and continued in males until dispersal to individual adult male territories. In the new and initially stable adult social structure, T declined and IID remained high, indicating a new behavioural mechanism was in place. Males first mated as T levels were declining. They were then challenged; then T increased, and then IID increased again. Adult male T levels fluctuate, being low or declining in a socially stable environment and increasing following a challenge, suggesting a regulatory or modulating role for T. The results are consistent with T having an endogenous role: in the juvenile, driving behavioural change towards adulthood, and in adulthood, a modulating role regulating social organisation.

Fecal steroid monitoring for assessing gonadal and adrenal activity in the golden eagle and peregrine falcon

We examined the efficacy of noninvasive monitoring of endocrine function via fecal steroid immunoassays in the golden eagle and peregrine falcon. High-pressure liquid chromatography analyses of fecal glucocorticoid metabolites (fGCM) revealed that minor percentages of immunoreactive fGCM co-eluted with [(3)H]corticosterone in both sexes of the eagle (2.5-2.7%) and falcon (7.5-11.9%). In contrast, most fecal estrogen metabolites in eagle and falcon females co-eluted with radiolabeled estradiol-17beta ([(3)H]; 57.6, 64.6%, respectively) or estrone ([(3)H]; 26.9, 4.1%, respectively). Most fecal progestin metabolite immunoreactivity in the female eagle (24.8%) and falcon (21.7%) co-eluted with progesterone ([(14)C]). Most fecal androgen metabolite immunoreactivity in eagle (55.8%) and falcon (63.7%) males co-eluted with testosterone ([(14)C]). Exogenous adrenocorticotropin hormone induced increased fGCM excretion above pre-treatment in both species, but only significantly (P < 0.05) in the eagle. Both species showed increased fGCM after saline administration, suggesting the detection of 'handling stress.' Both species exhibited enterohepatic and renal recirculation of administered steroids as demonstrated by biphasic and triphasic excretion patterns. Thus, noninvasive fecal hormone monitoring is a valid and promising tool for assessing gonadal and adrenal status in rare and threatened birds-of-prey.

Display activity and seasonality of faecal sexual steroids in male great bustard (Otis tarda L.)

The non-invasive faecal sampling and RIA was used to measure faecal equivalents of testosterone (T), dehydroepiandrosterone (DHEA), oestradiol-17beta (E2) and progesterone (P4) in juvenile and adult great bustard males. Possible connections of diurnal and seasonal changes of sexual steroid levels and display activity were studied. Correlations were found between sexual steroid equivalent levels of faeces and display activity and agonistic behaviour in the different phases of annual cycle of adult males. In early display period increasing levels of androgens were measured, during main display period very high androgen dominance was observable against E2 and P4. During postnuptial moult strong T decrease and DHEA and P4 increase were detected. Elevation of E2 was measured during wintering. In juveniles level of DHEA was higher than level of T suggesting its importance in immature males. Decrease of T was detected between reproductive period and postnuptial moult and DHEA between reproduction and wintering, accompanying with E2 elevation. The inhibiting effect of inclement weather on gonad functions also was detected in our study. We suppose that the unexpected cold weather with strong wind depressed the levels of androgens both in juveniles and adults and the increase of faecal E2 was also detected.

Estrogenic activity and steroid hormones in swine wastewater through a lagoon constructed-wetland system

Anaerobic lagoons and treatment wetlands are used worldwide to treat wastewater from dense livestock production facilities; however, there is very limited data on the hormonal activity of the wastewater effluent produced by these treatment systems. The objectives of this experiment were to measure (1) the hormonal activity of the initial effluent and (2) the effectiveness of a lagoon-constructed wetland treatment system for producing an effluent with a low hormonal activity. Wastewater samples were taken in April, July, and November 2004 and July 2005 from a lagoon-constructed wetland system at a swine farrowing facility. Estrogenic activity (in vitro E-screen assay), 17 beta-estradiol (E2), and testosterone concentrations (LC/MS-MS) were measured. A high correlation was found between estradiol equivalents determined by E-screen and LC/MS-MS (R2 = 0.82). Nutrient removal was measured to ensure that the wetlands were functioning in a manner similar to literature reports. Nutrient removals were typical for treatment wetlands: TKN 59-75% and orthophosphate 0-18%. Wetlands decreased estrogenic activity by 83-93%. Estrone was the most persistent estrogenic compound. Constructed wetlands produced effluents with estrogenic activity below the lowest equivalent E2 concentration known to have an effect on fish (10 ng/L or approximately 37 x 10(-12) M).

Experimental evidence that corticosterone affects offspring sex ratios in quail

Recent studies have shown that some species of birds have a remarkable degree of control over the sex ratio of offspring they produce. However, the mechanism by which they achieve this feat is unknown. Hormones circulating in the breeding female are particularly sensitive to environmental perturbations, and so could provide a mechanism for her to bias the sex ratio of her offspring in favour of the sex that would derive greatest benefit from the prevailing environmental conditions. Here, we present details of an experiment in which we manipulated levels of testosterone, 17beta-oestradiol and corticosterone in breeding female Japanese quail (Coturnix coturnix japonica) using Silastic implants and looked for effects on the sex ratio of offspring produced. Offspring sex ratio in this species was significantly correlated with faecal concentrations of the principal avian stress hormone, corticosterone, and artificially elevated levels of corticosterone resulted in significantly female-biased sex ratios at laying. Varying testosterone and 17beta-oestradiol had no effect on sex ratio alone, and faecal levels of these hormones did not vary in response to corticosterone. Our results suggest that corticosterone may be part of the sex-biasing process in birds.

Effect of testosterone loading on the kinetic of faecal testosterone excretion in mallards

Intestinal passage time of coloured fodder and testosterone turnover were examined by faecal steroid analysis in mallards in the reproductive and postrefractory period. In the latter, the discharge of coloured fodder began 36 minutes after ingestion in males, and 56 minutes in females. During reproduction the discharge began 93 minutes and 112 minutes after ingestion in males and females, respectively. Total passage time was similar in the reproductive and postrefractory period in both sexes. After intraperitoneal testosterone injection, faecal samples were collected for 8 hours and testosterone levels were measured using RIA. In the postrefractory period, 1-2 hours after testosterone loading a strong increase of faecal testosterone content developed in males, meanwhile a slighter testosterone peak appeared in females. During reproduction testosterone excretion began 1.5-2 hours after injection in both sexes but in females its increase was smaller. The duration of response to testosterone loading was 5 hours in both periods and both sexes. Intensive excretion after T loading appeared earlier in males than in females, but total passage time finished at the same time: 5 hours after loading. The character of testosterone excretion was corresponding to the passage of fodder-chimus-faeces in the reproductive and postrefractory period in both sexes.

Behaviour as a tool in the assessment of animal welfare

A central issue in animal welfare research is how to assess the welfare state of animals objectively and scientifically. I argue that this issue can be approached by asking two key questions: 1) is the animal physically healthy and 2) does the animal have what it wants? Behaviour is used to answer both of these questions. In the assessment of physical health, it can be used for clinical and pre-clinical diagnosis. In the assessment of what animals want, it has a major role through choice and preference testing. It is particularly important that applied ethologists develop methods for assessing welfare in situ--in the places where concern for animal welfare is greatest such as on farms and in zoos.

Synthesis of Measuring Steroid Metabolites in Goose Feces

The reliability of noninvasively measuring steroid hormones from feces in greylag geese (Anser anser) and domestic geese (A. domesticus), both qualitatively and quantitatively, was tested experimentally. Geese are mainly herbivorous birds with a short gut-passage time (2-3 h). Groups of eight outdoor-housed male domestic geese were subjected to two different experiments, injection of either GnRH or ACTH, which were replicated in three different seasons (spring, summer, and fall). GnRH stimulation resulted in significant increases of response fecal testosterone metabolites (TM; 17beta-OH-androgens) in spring and fall, but not during the summer photorefractoriness. Testosterone response patterns obtained from plasma samples paralleled those from feces; however, no direct correlation between individual immunoreactive plasma and feces contents was observed. To improve the sample handling during extraction and the assay sensitivity, we promote the use of a group-specific antibody against 17-oxoandrogens that does not require deconjugation prior to the analysis. ACTH robustly increased fecal corticosterone in all seasons. The polar nature of glucocorticoids, however, seems to make a distinction between conjugated and nonconjugated types difficult, and the available avian literature on this topic is discussed.

Estrogenic activity in the environment: municipal wastewater effluent, river, ponds, and wetlands

Estrogenic activity of regional water samples was evaluated. Samples obtained from wetlands and ponds involved in various agricultural land uses, from three river sites over four seasons, and from municipal wastewater effluent held in storage lagoons were evaluated. The estrogen-responsive cell line MCF-7 BOS was used in the E-screen assay to determine 17beta-estradiol equivalents (E2 Eq) of water samples extracted by solid-phase extraction. Estrogenic activity in surrounding wetlands and ponds from different land uses was not different, with 10(-12) M E2 Eq (0.3 ppt). Estrogenic activity of Red River samples was within the same range as wetland-pond samples. The highest activity was found downstream from municipal wastewater treatment effluent discharge sites, in winter when river flow was lowest (approximately 6 x 10(-13) M E2 Eq). Results showed that 7 of 20 wetland-pond samples and 5 of 12 river samples were below the limits of quantitation (approximately 3 x 10(-14) M E2 Eq). Toxicity was found in fall and summer river samples upstream from municipal wastewater release sites. The timing of toxicity did not coincide to the presence of elevated fecal coliforms. Estrogenic activity in wastewater effluent from lagoons decreased over time (approximately 25 to 5 x 10(-13) M E2 Eq) with an apparent half-life of 8 d for one lagoon. The median concentration of detectable estrogenic activity in regional water samples was approximately 50-fold less than the median 17beta-estradiol concentration of estradiol detected in some U.S. streams in previous studies.

Male song quality affects circulating but not yolk steroid concentrations in female canaries (Serinus canaria)

Male song complexity is a sexually selected trait found in many songbirds,including strains of the domestic canary. Studies on several species have shown that male song can affect the hormonal state of females and may also influence concentrations of maternal hormones in the yolk of their eggs. In this study, we show that the level of circulating androgens and oestrogens of female canaries, as measured in faeces, varies with the quality of male song to which they are exposed. The female-perceived quality of male canary song depends on the production of special `sexy syllables' to which females respond with more sexual displays. Using playback of synthetic song we show that females hearing songs with sexy syllables have higher levels of faecal testosterone than control females hearing songs without them. However, unlike previous studies on the canary, we found no evidence that such females laid eggs with more testosterone (or other steroids) in their egg yolks. We discuss these results in relation to the evolution of male signalling and maternal investment strategies.

Noninvasive monitoring of hormones in bird droppings: physiological validation, sampling, extraction, sex differences, and the influence of diet on hormone metabolite levels

During the past several years, the noninvasive measurement of steroid metabolites from mammalian feces and bird droppings has become more and more popular. With an increasing acceptance of the method, investigators may become less aware of the need to validate their assays. It is shown why such validations are essential for each new species investigated and various ways to physiologically validate such noninvasive methods are described. Using the European stonechat (Saxicola torquata rubicola) as a model, it is explained why a validated method to measure androgen metabolites in males does not necessarily work in females. In addition the difficulties that may be neglected owing to the superficial ease of sampling and processing of excreta are investigated. Various issues that may arise during sampling, storage, and extraction of excreta are addressed. Finally, results suggesting that experimental manipulations of the diet may affect hormone metabolite levels in European stonechats are presented. So far, only a few studies have investigated the impact of diet on hormone metabolite levels, and these are the first data to report such an impact in birds. More studies are urgently needed to learn more about differences between the sexes, individuals, and populations and the impact of diet and energy metabolism on hormone metabolites.

Environmental and management factors affecting the welfare of chickens on commercial farms in the United Kingdom and Denmark stocked at five densities

Data from a large commercial-scale experiment in which 10 major broiler producer companies stocked whole houses of birds at 30, 34, 38, 42, and 46 kg/m2 were analyzed to identify 1) temperature and humidity profiles achieved throughout the growth cycle, 2) management practices and equipment that contributed to observed variation in environmental conditions, and 3) the extent to which environmental variables affected bird welfare. The study involved a total of 2.7 million birds in 114 houses on commercial farms with measurement of a wide range of environmental and bird variables. Much of the variation in broiler health and welfare was associated with the percentage of time a company could maintain house temperature and RH within limits recommended by the breeder company. RH in the first week of life was particularly important to later health, suggesting that better control of humidity might lead to improved welfare. Key management factors affecting bird welfare were those relating to good ventilation and air control such as the type of ventilation, type of drinker, numbers of stockmen, and litter type. Controlling the environment, particularly temperature, humidity, and air and litter quality, is crucial to broiler chicken welfare. This does not mean that stocking density is unimportant, but lowering stocking density on its own, without regard to the environment the birds experience, is not sufficient. Genuine improvements in bird welfare will come from setting standards that combine stocking density, safeguards on the environment, and the genetic makeup of the birds.

Nonbreeding season pairing behavior and the annual cycle of testosterone in male and female downy woodpeckers, Picoides pubescens

Studies in birds show that testosterone (T) concentrations vary over the annual cycle depending on mating system and life history traits. Socially monogamous species show pairing behavior throughout the year and low levels of male-male aggression and are underrepresented in these studies, yet the function of testosterone could be particularly important for sexual and social interactions occurring outside the breeding season. We measured fecal T concentrations over the annual cycle and the frequency of interactions between male and female downy woodpeckers (Picoides pubescens) from late fall through early spring. We validated the fecal assay by collecting blood in conjunction with a subsample of our fecal samples: fecal T correlated with circulating levels in the blood. The annual peak level of T in males was relatively low and short-lived, similar to that of other bird species with low levels of male-male aggression and high paternal care. The annual cycle of female T resembled the male pattern, and the ratio of male T to female T was close to 1.0. Likewise, the frequency of aggression among females was similar to the frequency among males. Overall, testosterone levels in both sexes were variable, even in winter. In other bird species, sexual behavior during nonbreeding periods correlates with circulating levels of T in males. Based on this observation, we tested the hypothesis that T in winter was positively related to the frequency of interaction between mated downy woodpeckers. The results showed no such relationship. We discuss this finding and further relate the annual cycle of T in both males and females to behaviors that appear to facilitate mate choice and retention of the pair bond during conspecific challenge.

Time course of changes in egg-shell quality, faecal corticosteroids and behaviour as welfare measures in laying hens

The aim of this study was to assess the extent to which three non-invasive measures of welfare in laying hens (egg-shell quality, corticosteroid levels as measured from the birds' faeces, and behavioural preferences) were correlated over a period of five days in two groups of birds. One group had access to an enriched test area (bark chips on the floor and a tray of sprouted wheat); the other group had access to a comparably sized barren area (bare wire mesh floor). The measure of preference used was the amount of time hens spent in the test area as measured each day. It was predicted that birds with access to the less preferred environment would show higher levels of faecal corticosteroids and egg-shell anomalies. However, although the birds showed a preference for the enriched environment from Day 1, the other two measures did not follow the same pattern. Faecal corticosteroid metabolites showed an initial increase in both groups, which declined significantly by Day 4, with the ‘enriched’ birds in fact showing a trend for higher levels than the ‘barren’ birds. Shell thickness also showed a change over the five days, but with a different time course: declining to a minimal level on Day 3 and then rising again by Day 5. No measure of shell quality was significantly different between the two environments, but there was a trend for changes in shell thickness to be more pronounced in eggs from enriched birds. The results indicate the caution that needs to be exercised in using shell quality or corticosteroid measurements in isolation from assessments of what the animals themselves prefer.

Excreted corticosterone metabolites co-vary with ambient temperature and air pressure in male Greylag geese (Anser anser)

In many species, seasonal activities such as reproduction or migration need to be fine-tuned with weather conditions. Air pressure and temperature changes are the best parameters for such conditions. Adapting to climatic changes invariably involves physiological and behavioral reactions associated with the adrenals. In the present study, we investigated the effects of ambient temperature and air pressure on excreted immuno-reactive metabolites of corticosterone (BM) and androgens (AM). Focal individuals were 14 paired male greylag geese (Anser anser) from a semi-tame, unrestrained flock. BM and AM were measured in individual fecal samples over 25 days in November and December. Two different ACTH-validated assays were used for the assessment of BM: the first one cross-reacting with 11beta,21-diol-20-one structures ("old assay") and the second one with 5beta,3alpha,11beta-diol structures ("new assay"). With the "new assay," BM correlated negatively with the minimum ambient temperature of the night before, which may reflect corticosterone involvement in thermoregulation. BM also correlated positively with the minimum air pressure of the previous afternoon, which supports the value of air pressure for predicting weather conditions. Together, these reactions suggest a role of the adrenals in responding behaviorally and physiologically to changes in weather. Preliminary analysis indicated a higher sensitivity to the excreted glucocorticosteroid metabolites in the "new assay." As expected for outside the mating season, no relationships were found between excreted AM and the weather parameters considered. The gradual changes in BM excretion in parallel with weather conditions may be part of the fine-tuning of physiology and behavior by environmental clues.

Using behaviour to assess animal welfare

Rather than construct lists of many different welfare indicators and give each of them the same weight, I argue that the assessment of animal welfare should be directed at answering two key questions: I) Are the animals healthy? 2) Do they have what they want? Behaviour has a major role in answering both. Behaviour is currently used to help answer the first question through its use in the clinical and pre-clinical assessment of pain, injury and disease, and potentially could have an even greater role, particularly if used in conjunction with new technology. Behaviour is also of crucial importance in gauging what animals want, most obviously in the use of choice and preference tests, but also through other methods that are particularly suitable for on-farm welfare assessment. These include quantitative observations of the spatial distribution of animals and of behavioural ‘indicators’ of what animals want, such as vocalisations.

Chicken welfare is influenced more by housing conditions than by stocking density

Intensive broiler (meat) chicken production now exceeds 800 million birds each year in the United Kingdom and 2 x 10(10) birds worldwide, but it attracts accusations of poor welfare. The European Union is currently adopting standards for broilers aimed at a chief welfare concern--namely, overcrowding--by limiting maximum 'stocking density' (bird weight per unit area). It is not clear, however, whether this will genuinely improve bird welfare because evidence is contradictory. Here we report on broiler welfare in relation to the European Union proposals through a large-scale study (2.7 million birds) with the unprecedented cooperation of ten major broiler producers in an experimental manipulation of stocking density under a range of commercial conditions. Producer companies stocked birds to five different final densities, but otherwise followed company practice, which we recorded in addition to temperature, humidity, litter and air quality. We assessed welfare through mortality, physiology, behaviour and health, with an emphasis on leg health and walking ability. Our results show that differences among producers in the environment that they provide for chickens have more impact on welfare than has stocking density itself.

A comparative methodical study of the faecal steroid analysis on birds: looking for a valid method of testosterone determination

In a comparative study, a relatively simple and high sensitivity method was developed for analysis of testosterone-equivalent(s) in the faeces of different bird species. To determine the recovery of extractions and purifications, tritium-labelled testosterone was added to the wet samples. Then the samples were treated with sodium dodecil sulphate (SDS), an emulsificator to "open-up" the complex, lipid-coated particles of faecal samples. This emulsification resulted in the decrease of the quantity of interfering substances after diethyl-ether extraction and the linearity of the measured testosterone equivalents from aliquots in the range of 2 and 10 mg of faeces. In the RIA, we applied a group specific polyclonal testosterone antibody which cross-reacted with reduced metabolites and at a certain level with sulphate conjugates as well. The use of Helix enzymes did not modified significantly the results of the analysis relating to a low level of conjugated androgens in the faecal extracts. The biological validity of the method was tested on domestic cockerels, where between the plasma and faecal testosterone values a four hours phase shift was observed, with a correlation of 0.6355. This method is suitable for "non invasive", behavioural-ethological studies.

Excreted metabolites of gonadal steroid hormones and corticosterone in greylag geese (Anser anser) from hatching to fledging

Steroid hormones play major roles in the organization of the phenotype and in the activation of behavior. From hatching to fledging, they are involved in growth, development, and learning. We investigated the relationship between the ontogenetic patterns of steroid hormones and the sexual and social development of greylag goslings (Anser anser). Two groups of individually marked goslings (n = 10/5) were hand-raised under near-field conditions. 17beta-OH-androgen (AM), estrogen (EM), and corticosterone (BM) immunoreactive metabolites were measured noninvasively by enzyme immunoassay of individual fecal samples. Feces were regularly sampled from hatching to fledging. All excreted steroids were found to peak at hatching and to decrease thereafter. Gonadal steroids fluctuated more than BM, which remained at low levels throughout ontogeny after a slow decrease during the first 20 days. The pattern of BM is discussed in relation to learning processes (i.e., filial imprinting) and social stress. It is suggested that high initial BM may constrain energy allocation to growth. AM increased around the age of 20 days, when the feathers start growing, and later, together with EM, at the age of 40 days. These elevated values of gonadal steroids are discussed in relation to the sensitive phase of sexual imprinting. Females show higher EM levels than males throughout ontogeny. Furthermore, the ratio of excreted estrogen to androgen (EM/AM) of females before fledging correlates with the number of hatched and fledged goslings in their first years of reproduction. In conclusion, our data suggest a role for steroid hormones in the modulation of behavioral and morphological development in the precocial greylag geese, in agreement with the organizational-activational hypothesis.

Seasonal relationships between plasma and fecal testosterone in response to GnRH in domestic ganders

In two groups (eight individuals each) of socially acquainted, outdoor-kept, domestic ganders (male Hungarian white: Anser domesticus), basal and GnRH-stimulated plasma testosterone (T) concentrations were compared with fecal testosterone metabolites (TM) in and between three seasons, spring peak of reproductive activity, summer photorefractoriness, and fall sexual reactivation. Plasma was sampled 90 min following the challenge and T was analyzed by radioimmunoassay following the GnRH challenge. Fecal TM were measured by enzyme immunoassay using two group-specific antibodies against 17beta-OH-androgens or a novel antibody against 17-oxo groups, which was found to react with major testosterone metabolites without prior hydrolytic deconjugation. Baseline plasma T and systemic levels were high in spring and fall but low in summer. Plasma T increases in response to GnRH were followed by significantly elevated fecal TM levels 2 to 6 h following the challenge in spring and fall. In fall, at high plasma T levels, fecal TM levels were disproportionally lower than in spring. Variability of TM levels was two to five times higher in feces than in plasma, which explains why correlations between individual plasma T and fecal TM levels generally remained nonsignificant. This points to a low-level short-term relationship between the excreted TM and the plasma T levels. However, the reliability of the method was demonstrated by standard inter- and intraassay variabilities and by a high correspondence between results obtained by the two assays. It is suggested that, with appropriate sample size, fecal TM reflects plasma T increase. However, fecal TM was more variable than the plasma T, and fecal TM responses to GnRH did not always parallel the plasma T response. In addition, seasonal changes in androgen excretion regimes must be taken into account.

Seasonal patterns of sex steroids determined from feces in different social categories of Greylag geese (Anser anser)

Seasonal patterns of fecal 17beta-OH-androgen, estrogen, and progesterone equivalents of male and female greylag geese (Anser anser) were analyzed in a flock of free-living geese. These were compared among social categories determined by pairbond status and breeding success. The annual cycle was divided into 13 phases. Phasewise intra-sexual comparisons were made between social categories. The seasonal variation obtained from feces was in general agreement with the literature on plasma patterns in geese and other temperate-zone birds. However, there were distinct differences in seasonal hormone patterns among the social categories. In unpaired males, androgen was elevated for a longer period of time during sexually active phases compared with paired males. In male geese, high levels of androgen did not interfere with parenting but were related to pairbond status, whereas in females, androgen and progesterone were positively related to parental behavior. In the Fall, androgen, progesterone, and estrogen peaked only in unpaired males. In unsuccessful females, estrogen started to increase earlier in the Winter and was higher in amplitude and duration than that in females guarding offspring. In general, fecal steroids showed a clear-cut difference only between sexually active and parental phases of the year in the successfully breeding pairs, whereas unpaired males retained a hormonal state closer to sexually active phases throughout the year.

Recent advances in noninvasive techniques to monitor hormone-behavior interactions

This paper reviews recent advances in field endocrinology, a focus as well as a method in primatology and behavioral ecology that permits the examination of social behavior and life history through hormonal investigations in natural settings. Endocrine data complements the traditional behavioral data collected by field scientists by providing quantitative measures for the examination of adaptive tradeoffs, costs of social strategies, and reproductive and social significance of mating events. Further, investigations of the physiological mechanisms of reproductive constraint provide tests of the adaptive significance of reproductive skew in cooperative and competitive breeders. Hormone data also can provide insights into the costs of competition and aggression and the role of temperament in individual reproductive success and the evolution of social systems. New, noninvasive methods for the collection of this information have augmented and expanded field endocrinology through the use of techniques that do not require potentially confounding physical or physiological manipulations. Specifically, urine and fecal samples can be collected from free-ranging animals and contain gonadal and adrenal hormones that parallel profiles of serum hormones. Sampling, preservation, extraction, and assay methods for the analysis of excreted steroids are reviewed along with the species and questions to which these methods have been applied.

Development and validation of a fecal testosterone biomarker in Mus musculus and Peromyscus maniculatus

This is a report on the development and validation of an ELISA method to determine fecal testosterone levels, and on their evaluation as a biomarker for adverse effects of endocrine-disrupting chemicals on reproductive health using male rodents of the Peromyscus maniculatus and Mus musculus species as an animal model. The ELISA antibody had the highest specificity for testosterone (100%), followed by dihydrotestosterone (57.4%) and androstenediol (0.27%). Radiolabeled testosterone was injected i.p. into three mice. Fecal samples were collected, extracted, and analyzed by liquid scintillation counting. The ELISA was performed to characterize the excretion kinetics and metabolic fate of circulating testosterone. Solubilization of feces with 10% methanol overnight provided an extraction efficiency of 87% for all metabolites; an ethyl ether extraction was more selective for testosterone. The fecal excretion of the testosterone was a biphasic process with a majority of the radioactivity recovered in the first 24 hours. HPLC analysis revealed at least five testosterone metabolites in feces, with most metabolites being less polar than testosterone. This study forms the initial evaluation of what will become a field monitoring tool.

The relationship between social stress and dominance is seasonal in greylag geese

Studies of captive animals have suggested that social stress affects subdominants, whereas recent data from the wild have revealed that stress mainly affects dominants. We used a non-invasive approach to investigate, for the first time in a social bird, the circannual stress-dominance relationships between low-ranking single males, intermediately positioned paired ganders without offspring and high-ranking paired males with offspring from a flock of semi-tame, free-ranging greylag geese, Anser anser. We collected 933 faecal samples from 43 individuals, 12 singletons, 18 paired males without offspring and 13 paired males with offspring over an entire year and analysed them for corticosterone metabolites by enzyme immunoassay. During the mating season (February-April), singletons had marginally higher corticosterone than paired males (P<0.1), whereas during the parental season (May-January), the paired males with offspring had significantly higher corticosterone than both paired males without offspring and singletons. All three male categories had significantly higher corticosterone during the mating season than during the rest of the year. These results suggest that social stress in ganders is caused mainly by competition between males and by constrained access to females during the mating season, but by parental commitment during the rest of the year. We suggest that dominance per se may not be a direct cause of stress. Rather, the amount of social stress may co-vary with the behavioural investment individuals need to make to optimize their fitness and with the relationship between such demands and the individuals' rank positions. This relationship seems to be seasonal in geese. Copyright 1998 The Association for the Study of Animal Behaviour.

Environment modifies the testosterone levels of a female bird and its eggs

Past studies have shown that the yolk of the canary (Serinus canaria) egg contains maternal testosterone, that its concentrations increase in the subsequently formed eggs of a clutch, and that testosterone influences development. The present study investigated 1) if the testosterone levels vary in the female during yolk formation; 2) how such putative variations may be related to the concentrations of maternal testosterone in the yolk; and 3) if environmental factors, such as day length, can modify the testosterone levels in the mother and her eggs. Maternal testosterone levels, measured in the females' feces, increased during yolk formation and egg laying, and decreased during incubation. This pattern was modified by day length. In a photoperiod of 12 h of light and 12 h of darkness (12L 12D), female testosterone levels decreased after the last egg of the clutch was laid while in a photoperiod of 16L 8D, they decreased after the first egg was laid. These different patterns were reflected in the testosterone concentrations in the egg yolk. Further, the eggs of subsequent clutches that were produced under a naturally changing photoperiod differed significantly in their testosterone concentrations. Finally, the doses of testosterone in the yolk of individual eggs were positively correlated with the concentrations of testosterone in the female during the yolk phase of each egg. I conclude that here we have a mechanism which communicates environmental conditions from the mother to the offspring, and that this mechanism serves to optimize reproduction and/or modify offspring traits.

Environment modifies the testosterone levels of a female bird and its eggs

Past studies have shown that the yolk of the canary (Serinus canaria) egg contains maternal testosterone, that its concentrations increase in the subsequently formed eggs of a clutch, and that testosterone influences development. The present study investigated 1) if the testosterone levels vary in the female during yolk formation; 2) how such putative variations may be related to the concentrations of maternal testosterone in the yolk; and 3) if environmental factors, such as day length, can modify the testosterone levels in the mother and her eggs. Maternal testosterone levels, measured in the females' feces, increased during yolk formation and egg laying, and decreased during incubation. This pattern was modified by day length. In a photoperiod of 12 h of light and 12 h of darkness (12L 12D), female testosterone levels decreased after the last egg of the clutch was laid while in a photoperiod of 16L 8D, they decreased after the first egg was laid. These different patterns were reflected in the testosterone concentrations in the egg yolk. Further, the eggs of subsequent clutches that were produced under a naturally changing photoperiod differed significantly in their testosterone concentrations. Finally, the doses of testosterone in the yolk of individual eggs were positively correlated with the concentrations of testosterone in the female during the yolk phase of each egg. I conclude that here we have a mechanism which communicates environmental conditions from the mother to the offspring, and that this mechanism serves to optimize reproduction and/or modify offspring traits.