Serum testosterone and musth in captive male African and Asian elephants

Testosterone concentrations in serum samples collected weekly over a 5-year period from a young adult male Asian elephant (Elephas maximus) and a young adult male African forest elephant (Loxodonta africana cyclotis) were measured by radioimmunoassay. Testosterone profiles during this maturational period were compared between the two species and related to the occurrence of musth, a recurring physiological and behavioral condition exhibited by most mature Asian, and some African, bull elephants. Musth is characterized by secretion from the bull's temporal glands, dribbling urine, and increased aggression. Serum testosterone concentrations in the Asian bull were elevated substantially between April and September each year, coincident with the presence of temporal gland secretion, urine dribbling, and aggressive behavior. Testosterone levels from April through September averaged (± SEM) 41.2 ± 2.8 ng/ml, compared to 7.6 ± 1.0 ng/ml during the rest of the year. In contrast, the testosterone profile of the African bull showed greater variation and lower levels overall, the only pattern being a tendency for levels to be lowest from November to February (avg. 6.8 ± 1.5 vs. 10.3 ± 0.8 ng/ml during the rest of the year). Temporal gland secretion and other signs of musth were first observed in this bull in 1988, at age 17. While his testosterone profile did not show a pattern comparable to that in the Asian bull, average testosterone values were significantly greater in 1988 compared to previous years. The Asian bull showed sexual attention to preovulatory (estrous) cows whether in musth or not, and exposure to estrous cows did not appear to alter the highly consistent, annual pattern of musth as evidenced in temporal gland flow.     

Testosterone and dihydrotestosterone concentrations in elephant serum and temporal gland secretions

Serum and temporal gland secretions (TGS) were obtained from mature wild African (Loxodonta africana) and captive Asian elephants (Elephas maximus). Samples were obtained from five cows and eight bulls culled for management purposes in Kruger National Park, South Africa, and from four females and two males residing at the Washington Park Zoo, Portland, Oregon. Our purpose was to describe the levels of the androgens, testosterone (T), and dihydrotestosterone (DHT), and to correlate these observations with sex, species and behavioral status. Male-female differences in serum T were pronounced in the Asian species, whereas male and female concentrations overlapped in the African elephant serum. Serum T concentrations in African females were greater than in Asian females. Serum DHT reflected T levels, except that the striking elevation of testosterone in Asian bulls during musth was not paralleled by equal increases in DHT levels. A species difference observed among males was higher serum T levels in nonmusth Asian bulls (1.84-5.35 ng/ml) compared to the levels in African bulls (0.38-0.68 ng/ml), except for one dominant African bull (6.64 ng/ml). This single African value was still considerably lower than the serum T values of the Asian males during musth. These musth values were the highest serum androgen concentrations: T was between 19 and 40 ng/ml (average 26.10 ng/ml). The TSG values of T and DHT were much higher than serum levels except in the Asian female. T/DHT ratios in TGS were more similar than in serum. One dominant African bull had a T TGS value of 78 ng/ml, which was much higher than the rest of the African males or females, but considerably lower than as Asian bull in musth (547 ng/ml). It seems apparent that a change in androgen status as reflected in serum and TGS levels of T and DHT precedes or is concomitant with overt alteration in behavior in the Asian male. The temporal gland appears to actively concentrate androgens in both African males and females, but in the Asian male the gland secretes only during musth when the greatest concentration of both T and DHT were observed. The apparent difference in the degree of temporal gland secretory activity between the two species suggests a more specific communicative function within the Asian male.     

Endocrine Correlates of Musth in Free-Ranging Asian Elephants (Elephas maximus) Determined by Non-Invasive Faecal Steroid Hormone Metabolite Measurements

The occurrence of musth, a period of elevated levels of androgens and heightened sexual activity, has been well documented for the male Asian elephant (Elephas maximus). However, the relationship between androgen-dependent musth and adrenocortical function in this species is unclear. The current study is the first assessment of testicular and adrenocortical function in free-ranging male Asian elephants by measuring levels of testosterone (androgen) and cortisol (glucocorticoid – a physiological indicator of stress) metabolites in faeces. During musth, males expectedly showed significant elevation in faecal testosterone metabolite levels. Interestingly, glucocorticoid metabolite concentrations remained unchanged between musth and non-musth periods. This observation is contrary to that observed with wild and captive African elephant bulls and captive Asian bull elephants. Our results show that musth may not necessarily represent a stressful condition in free-ranging male Asian elephants.     

Effects of rainfall, host demography, and musth on strongyle fecal egg counts in African elephants (Loxodonta africana) in Namibia

Wild African elephants (Loxodonta africana) are commonly infected with intestinal strongyle parasites. Our objective was to determine baseline fecal strongyle egg counts for elephants in the northeast region of Etosha National Park, Namibia and determine if these numbers were affected by annual rainfall, elephant demography (age of individuals and composition of groups), and hormonal state of males. We found that matriarchal family group members have significantly higher fecal egg counts than male elephants (bulls). Among family group members, strongyle egg counts increased with age, whereas among bulls, strongyle egg counts decreased with age. Years of higher rainfall were correlated with decreased numbers of strongyle eggs among bulls. Finally, bulls were not affected by their physiologic (hormonal) status (musth vs. nonmusth). These results suggest that infection by strongyle parasites in Namibian African elephants is a dynamic process affected by intrinsic and extrinsic factors including host demography and rainfall.     

Reproductive hormone secretion and testicular growth in bull calves actively immunized against testosterone and oestradiol-17 beta

Groups of bull calves received a primary immunization against testosterone (Group T; N = 7) or oestradiol-17 beta (Group E; N = 9) at 3 months of age and booster injections on four occasions at approximately 2 month intervals. Controls (Group C, N = 7) were immunized against human serum albumin alone using the same protocol. Immunity was achieved against both steroids as judged by the secondary antisteroid antibody titres in Group T (730 +/- 231; reciprocal of titre) and Group E (12,205 +/- 4366) bulls; however, peak antibody titres generally declined with successive booster injections. Mean plasma concentrations of LH, FSH and testosterone during the period from 3 to 10 months of age were higher (P less than 0.05) in Group T bulls than in Groups C and E. Group T bulls had larger testes compared with controls from 6 months of age onwards. At castration at 14 months of age, testes of Group T bulls were heavier (P less than 0.05) than those of Groups C and E (179 +/- 13, 145 +/- 8 and 147 +/- 6 g, respectively). At 10 months of age, there were no differences among treatment groups in LH responses to LHRH, but the testosterone responses were greater (P less than 0.05) in bulls in Group T (26.2 +/- 4.9 ng/ml) and Group E (16.6 +/- 1.8 ng/ml) compared with those in Group C (6.9 +/- 0.6 ng/ml). Testosterone responses to hCG determined at 13 months of age were also greater (P less than 0.05) in Groups T and E relative to controls. At 14 months of age daily sperm production rates per bull (X 10(-9)) were higher (P less than 0.10) in Group T bulls (2.2 +/- 0.1) than those in Groups C (1.6 +/- 0.2) and E (1.6 +/- 0.1). These results indicate that early immunity against testosterone is associated with increased gonadotrophin secretion and accelerated growth of the testes in prepubertal bulls. Also, chronic immunity against testosterone or oestradiol-17 beta enhances the steroidogenic response of bull testes to gonadotrophic stimulation. If the above responses observed in young bulls are shown to be sustained, then immunity against gonadal steroids early in life may confer some reproductive advantage in mature animals.     

Electroejaculation, semen characteristics and serum testosterone concentrations of free-ranging african elephants (Loxodonta africana)

A regimented electroejaculation protocol (120 electrical stimulations; 10-30 V) was used to collect semen and characterize ejaculate quality from 9 adult, free-ranging African elephants under anaesthesia. Eight of the 9 ejaculates contained high concentrations of progressively motile spermatozoa. The overall mean ejaculate volume, sperm concentration/ml ejaculate, sperm motility, sperm status and ejaculate pH were 93.3 ml, 2408.6 X 10(6) spermatozoa/ml, 70%, 3.9 and 7.4, respectively. A high percentage (mean 77.5%) of spermatozoa within each ejaculate was morphologically normal. Of the aberrant spermatozoa, 72% had a cytoplasmic droplet defect. When sperm viability was tested in vitro at 37 degrees C, sperm motility rating declined by at least half of the initial assessment within 3.5 h of semen collection. Generally, spermatozoa maintained motility in vitro for less than 6 h. Serum testosterone ranged from 1.4 to 8.2 ng/ml in 4 males evaluated in the morning (07:30-08:00 h). In 4 of the 5 bulls assessed in the afternoon (15:00-18:00 h), testosterone levels were less than 0.9 ng/ml. The remaining bull, evaluated at 16:00 h, had exceptionally high testosterone concentrations (peak 25.6 ng/ml) and a preputial discharge potentially indicative of 'musth'. The present study demonstrates that high quality semen can be collected consistently from the African elephant and that striking differences exist in serum testosterone amongst free-ranging males which may be due, in part, to a diurnal rhythm.     

The sexually active states of free-ranging male African elephants (Loxodonta africana): defining musth and non-musth using endocrinology, physical signals, and behavior

Musth in male African elephants, Loxodonta africana, is associated with increased aggressive behavior, continuous discharge of urine, copious secretions from the swollen temporal glands, and elevated androgen levels. During musth, bulls actively seek out and are preferred by estrous females although sexual activity is not restricted to the musth condition. The present study combines recently established methods of fecal hormone analysis with long-term observations on male-female associations as well as the presence and intensity of physical signals to provide a more detailed picture about the physical, physiological, and behavioral characteristics of different states of sexual activity in free-ranging African elephants. Based on quantitative shifts in individual bull association patterns, the presence of different physical signals, and significant differences in androgen levels, a total of three potential sub-categories for sexually active bulls could be established. The results demonstrate that elevations in androgen levels are only observed in sexually active animals showing temporal gland secretion and/or urine dribbling, but are not related to the age of the individual. Further, none of the sexually active states showed elevated glucocorticoid output indicating that musth does not represent an HPA-mediated stress condition. On the basis of these results, we suggest that the term "musth" should be exclusively used for the competitive state in sexually active male elephants and that the presence of urine dribbling should be the physical signal used for defining this state.     

Influence of age and gender on secretion of anti-Müllerian hormone in Asian (Elephas maximus) and African (Loxodonta africana) elephants

Anti-Müllerian hormone (AMH) secretion was studied in Asian and African elephants varying in age and reproductive status. Overall mean concentrations did not differ (P > 0.05) between species, but were markedly higher in male than female Asian elephants (31.01 ± 4.22 ng/mL and 0.19 ± 0.02 ng/mL, mean ± SEM) and African elephants (40.27 ± 3.18 ng/mL, 0.17 ± 0.04 ng/mL), respectively. Anti-Müllerian hormone secretion was not significantly affected by ovarian cyclicity status (cycling vs noncycling), but was higher (P < 0.05) in prepubertal (0.40 ± 0.10 ng/mL) than reproductive age (8-35 y; 0.18 ± 0.04 ng/mL) and aged (≥ 36 y; 0.16 ± 0.03 ng/mL) females. In males, AMH secretion was not significantly affected by musth status, but was age-related, with higher concentrations (P > 0.05) in prepubertal (49.08 ± 6.11 ng/mL) as compared to aged (≥36 y; 22.27 ± 5.82 ng/mL) bulls; concentrations in mature bulls (8-35 y; 37.01 ± 3.17 ng/mL) were similar to prepubertal and older bulls. We concluded that circulating AMH concentrations in elephants were similar between species and not affected by reproductive status; however, concentrations were significantly higher in males than females, and in younger animals. The diagnostic value of AMH to assess fertility status of individual elephants remains to be determined.     

Assessment of testicular endocrine function in captive African elephants by measurement of urinary and fecal androgens

Androgen measurements in urine and/or feces represent a potentially important tool for monitoring testicular endocrine function in the African elephant. To assess the feasibility of this approach, the aims of the present study were to: 1) examine the presence and relative abundance of immunoreactive testosterone (iT) and its 5α‐reduced 17‐oxometabolite epiandrosterone (iEA) in African elephant excreta, and 2) compare urine and fecal androgen profiles in animals of different ages and during the musth and non‐musth condition. Urine and fecal samples were collected over periods of up to 3 years from five bulls (ages 7–24 years) living in three mixed social groups. In parallel, indications of musth were recorded by keeper staff as an independent marker of male androgen status. Measurements of iT and iEA were carried out by enzymeimmunoassay (EIA) following methanolic extraction of hydrolyzed urine and lyophilized fecal powder. High‐pressure liquid chromatography (HPLC) of musth phase samples confirmed the presence of substantial quantities of testosterone (T) and epiandrosterone (EA) in both urine and feces. EA was predominant in feces, whereas T was more abundant in urine. In each male, the two androgen measures were significantly correlated (feces, r = 0.71–0.93, P < 0.0001; urine, r = 0.86–0.91, P < 0.0001), as were fecal and urinary concentrations of each of the two androgens measured (r = 0.35–0.77, P < 0.0001). Moreover, in the two oldest males that showed clear signs of musth, levels of iEA and iT were markedly elevated during musth compared to non‐musth periods (differences were significant for feces in both animals, but in urine only for one). Collectively, the data show that measurement of urinary and fecal androgens generates useful information on gonadal status in male African elephants, and as such should provide new opportunities to improve the management and welfare of bulls maintained in captivity, as well as to examine physiological correlates of reproductive function in free‐ranging animals. Zoo Biol 21:27–36, 2002. © 2002 Wiley‐Liss, Inc.     

Seminal ribonuclease of bulls - biosynthesis in normal and orchitic bulls and correlation with blood plasma hormone levels

In sexually mature and healthy bulls, seminal ribonuclease (AS RNase) is synthesized in the distal part of the corpus epididymidis, the cauda epididymidis, the ampullary glands and the seminal vesicles. Indirect immunofluorescence demonstrated AS RNase binding to the cytoplasmic droplets of bull spermatozoa.In bulls with orchitis, AS RNase synthesis decreases in accordance with the degree of damage to the Leydig cells and the drop in the blood plasma testosterone level. The organ most sensitive to decreased testosterone levels, from the aspect of AS RNase synthesis, is the epididymis and the least sensitive are the seminal vesicles. Hypertrophy of the adrenal cortex (in particular of the zona fasciculata and the zona reticularis) and elevated adrenocortical secretion - demonstrated by a raised cortisol concentration in the blood plasma of severely orchitic bulls - failed to inhibit AS RNase synthesis. Injections of Gn RH-LH and HCG raised the blood plasma cortisol, but not testosterone, concentrations in bulls with very severe orchitis. This also indicates serious damage to the Leydig cells in these bulls.     

Effects of an anabolic treatment before puberty with trenbolone acetate-oestradiol or oestradiol alone on growth rate, testicular development and luteinizing hormone and testosterone plasma concentrations

Scrotal circumference, growth and hormonal status after prepubertal anabolic treatments were studied in 18 conventional Belgian White Blue bulls from 3 to 13 mo of age. Young bulls were assigned into three groups: six untreated (control) bulls, six bulls implanted with 140 mg trenbolone acetate + 20 mg oestradiol (Revalor; TBA-E2) and six bulls treated with 45 mg oestradiol (Compudose; E2). Mean scrotal circumference was similar in the three groups at Day O (between 13.0 +/- 0.3 cm to 13.4 +/- 0.7 cm). From Days O to 230, scrotal circumference was strongly inhibited in implanted bulls, 23.2 +/- 1.4, 21.7 +/- 1.0 cm, respectively, for TBA-E2 and E2 at Day 210, as compared with 29.5 +/- 2.2 cm in control bulls (P < 0.001). Afterwards, differences lessened gradually and no significant divergence was observed between the three groups from Day 310. Average plasma luteinizing hormone (LH) concentrations were similar in the three groups throughout the assay. Mean testosterone levels remained extremely low upto Day 150 in TBA-E2 and E2 groups (0.6 +/- 0.6, 1.2 +/- 0.7 ng/ml, respectively) before they increased abruptly and reached values observed in control bulls at Day 180 (4.0 +/- 1.9 ng/ml). The pulsatil character of LH and testosterone profiles was abolished by the anabolic treatments. Luteinizing hormone-releasing hormone (LHRH) injection was followed by an immediate and sharp increase in plasma LH concentrations in all groups at Day 0. Anabolic treatments strongly reduced LH and testosterone responses to LHRH in treated groups.     

Testosterone secretion in young and adult buffalo bulls

Studies were conducted to determine the 24-hour fluctuations in blood serum testosterone concentration in adult buffalo bulls, and to measure testosterone secretion before and after GnRH administration in male buffaloes of different age groups. Testosterone levels in three sexually mature bulls ranged from 0.2 to 2.7 ng/ml with a mean of 0.6 +/- 0.2 ng/ml. Samples collected in November had significantly higher (P<0.05) testosterone than those drawn in February (dry season) as did samples collected during the day as opposed to the night. Sera testosterone concentrations were lower in younger bulls with a range of 0.2 to 0.6 ng/ml. GnRH induced an increase in testosterone in 6, 12, 24 and 36-month old bulls with the greatest response being observed at 36 months. GnRH did not elicit a response in one-month old bulls. It may be concluded that baseline sera testosterone concentrations in buffalo bulls, as well as responsiveness to GnRH injection, increase with sexual maturity and are subject toseasonal and diurnal variations.     

Group Dynamics of Young Asian Elephant Bulls (Elephas maximus Linnaeus, 1758) in Heidelberg Zoo – Integration of a Newcomer in an Established Herd

The social organisation of elephants is based on female philopatry and male natal dispersal. The separation of males from their family group is a behavioural strategy of inbreeding avoidance. In the course of this gradual process young bulls increasingly have contact to males belonging to other herds, mainly same-aged, in form of sparring (Kurt and Gara?, 2006, Evans and Harris, 2008, Chiyo et al., 2011) with spending more and more time away from their own family (Kurt, 2001, Kurt and Gara?, 2006, Poole and Moss, 2008). After leaving the natal herd they join other males and form loose all-male groups (McKay, 1973, Kurt, 2001, Poole and Moss, 2008). This natural process during the development of male elephants, however, raises a problem for the elephant keeping in zoological gardens because of the increasing intolerance by the herd in combination with the lack of adequate keeping facilities for bulls. As the keeping of young bulls without or limited contact to conspecifics is an unnatural way of handling them, as described above, efforts are made for establishing an appropriate husbandry. Zoo Heidelberg is the first German facility, which keeps a group of young elephant bulls. Moreover it is the first zoo which undertakes the experiment to integrate another young bull in an established group.The aim of this study was to assess the group dynamics, particularly the individual personalities and social bonds, in a group of young bulls in captivity during the integration of a new bull.By means of the focal animal sampling (Altman, 1974) the social behaviour of the four young bulls during the first four months of integration of the new bull was continuously recorded. It was quantified by the frequencies of defined social events and the individual duration of social isolation and association with another elephant. The durations and the frequencies were standardised as the percentage of the individual observation period and the number of occurrences per hour, respectively, in order to allow the comparison of the individuals.The four young bulls showed distinct personalities, which affected the strength and kind of social bonds between them. In general the members of the initial group interacted more frequently among themselves than they did with the new one. Particularly the initial three elephants exhibited physical contact and friendly behaviours to a greater extent than the new bull did. But the frequency and the motivation of the associations depended on the social partner both in the case of the initial group members and the new one. Furthermore the behaviour of the new elephant indicated social isolation and an elevated stress level. Beside a high frequency of social interactions, the existence of a dominance hierarchy and the progressive integration of the new bull suggest a stable social structure and therefore support the concept of keeping young bulls in same-sex groups.     

Steroid-protein interactions in bovine plasma.

The binding of testosterone, corticosterone and 17alpha-hydroxyprogesterone by bull plasma protein was studied by equilibrium dialysis. Testosterone in bovine plasma was bound by a CBG-like protein and by a specific protein (testosterone-binding protein or TBP) of limited capacity and high affinity. The TBP was specific for C18 and C19 steroids with a 17 beta-hydroxy group. Precision of the steroid-protein binding measurements was tested and was satisfactory. The testosterone-binding capacity in bull plasma samples did not seem to be related to testosterone levels in peripheral plasma. Significant differences between bulls and cows with regard to the binding capacity were observed.     

Relationship between group dynamics and spatial distribution of African elephants in a semi‐arid environment

Group dynamics related to distribution of African elephants in the semi‐arid environment of Tsavo East National Park, Kenya was studied between 2007 and 2010. I examined the seasonal distribution of lone bulls, bull groups, family units and mixed groups and group size. Lone bulls were widely distributed in the dry season and localized in the wet season, whereas bull groups were localized in both seasons. On average bull group size did not differ with seasons or areas, but larger groups were observed in preferred areas in the dry season. Family units were widely distributed in the dry season and localized in the wet season, whereas mixed groups were localized in both seasons. Although family units and mixed groups tended to be large in all areas in the wet season, large groups were also observed in the dry season. Large family units were widely distributed, whereas large mixed groups were localized. The relationship between group dynamics and distribution was attributed to the combination of social, ecological and poaching factors. This study provided insight into distribution patterns that can be applied to the security of the Tsavo elephant population.     

Increasing browse and social complexity can improve zoo elephant welfare

While recent work has assessed how environmental and managerial changes influence elephant welfare across multiple zoos, few studies have addressed the effects of management changes within a single institution. In this paper, we examine how management changes related to social structure and diet affect the behavior of a group of zoo elephants over a 23‐month period while also considering underlying factors, such as time of day, hormonal cycle, and individual differences. We recorded individual behaviors using 2‐min scan samples during 60‐min sessions. We analyzed behavioral changes across several study variables using generalized linear mixed models. We found that increasing browse can improve opportunities for foraging throughout the day but may not be sufficient to reduce repetitive behaviors. We observed that increasing group size and integration of bulls with cows can lead to increased social interaction in African elephants. Our results highlight the importance of using multiple management alterations to address elephant welfare, and considering environmental factors, when making management decisions.     

Infertility in a cryptorchid bull: a case report

A unilateral cryptorchid bull stationed in an AI center for 3.5 yr was studied to determine if maintaining such a bull could be justified. The following parameters were determined: quantity and quality of the ejaculates, basal and stimulated plasma testosterone concentrations, and the histology and testosterone concentrations of the testicles. The bull produced 232 ejaculates of which 125 (53.8%) were immediately discarded; the rest (107 ejaculations) were processed into pellets. Two of the 107 frozen ejaculates (2%) were found to be of excellent quality, 37 were (34.5%) of good quality, 45 were (42%) of satisfactory quality and 23 were (21.5%) of poor quality. Treatment of the calf with GnRH and hCG at 4 and 5 mo of age did not initiate the descent of the retained testicle. Testosterone concentrations measured at 14 mo, after hCG stimulus, indicated that the bull had impaired steroidogenesis when compared with 2 control bull calves. Post mortem examination revealed a small left testicle in the inguinal canal and a normal right testicle as well as normal secondary sex glands. During the breeding period at the AI center, the bull's peripheral testosterone concentrations decreased from 2.2 to 0.95 ng/ml Testosterone concentrations in the parenchymal tissue of the scrotal testicle were higher than in the parenchyma of the retained testicle (98.2 vs 53.9 ng/g). In contrast, the epididymis of the scrotal testicle had a lower testosterone concentration than the epididymis of the retained testicle (10.8 vs 33. 0 ng/g). On histological examination no spermatozoa were found in the retained testicle, the Sertoli cells showed fat degeneration, and fibrotic tissue surrounded the tubuli seminiferi. No pathological changes were found in the normal scrotal testicle. In conclusion, no justification was found for maintaining such a bull in the AI center for breeding purposes.     

Development of a Body Condition Scoring Index for Female African Elephants Validated by Ultrasound Measurements of Subcutaneous Fat

Obesity-related health and reproductive problems may be contributing to non-sustainability of zoo African elephant (Loxodonta africana) populations. However, a major constraint in screening for obesity in elephants is lack of a practical method to accurately assess body fat. Body condition scoring (BCS) is the assessment of subcutaneous fat stores based on visual evaluation and provides an immediate appraisal of the degree of obesity of an individual. The objective of this study was to develop a visual BCS index for female African elephants and validate it using ultrasound measures of subcutaneous fat. To develop the index, standardized photographs were collected from zoo (n = 50) and free-ranging (n = 57) female African elephants for identifying key body regions and skeletal features, which were then used to visually determine body fat deposition patterns. This information was used to develop a visual BCS method consisting of a list of body regions and the physical criteria for assigning an overall score on a 5-point scale, with 1 representing the lowest and 5 representing the highest levels of body fat. Results showed that as BCS increased, ultrasound measures of subcutaneous fat thickness also increased (P<0.01), indicating the scores closely coincide with physical measures of fat reserves. The BCS index proved to be reliable and repeatable based on high intra- and inter-assessor agreement across three assessors. In comparing photographs of wild vs. captive African elephants, the median BCS in the free-ranging individuals (BCS = 3, range 1–5) was lower (P<0.001) than that of the zoo population (BCS = 4, range 2–5). In sum, we have developed the first validated BCS index for African elephants. This tool can be used to examine which factors impact body condition in zoo and free-ranging elephants, providing valuable information on how it affects health and reproductive potential of individual elephants.     

The Seronera bull problem: The elephants

(1) The activities of bull elephants in the vicinity of the Serengeti National Park headquarters at Seronera was monitored from 1968 to 1971. (2) Elephant bulls congregate in small groups of ever–changing composition; a dominance heirarchy cuts across group integrity. (3) Occupancy of the drainage area of the Seronera river is predictable by rainfall; changes in occupancy level are a question of duration rather than amplitude. (4) The feeding behaviour of the bulls is described. It is argued that large Acacia trees are uprooted for nutritional rather than social reasons. The effects of the bulls on the Seronera woodlands will be analysed in Part II (Croze, 1974).     

The acute effect of bull presence on plasma profiles of luteinizing hormone in postpartum, anoestrous dairy cows

The objective of this study was to investigate whether bull exposure affects LH profiles in postpartum, anoestrous dairy cows. Eight cows between 10 and 17 days after parturition were used. On Day 1, blood samples were taken at 10 min intervals for 8 h. On Day 2, blood sampling continued at 10 min intervals and after 2 h a bull was introduced behind a fence, and blood sampling continued for another 8 h. Time of resumption of luteal activity was between 25 and more than 80 days after parturition for these animals and was not related (P>0.1) with frequency of LH pulses, amplitude of pulses and basal LH concentration on either Day 1 or Day 2. In 6 of the 8 cows, average and basal LH concentration were greater (P<0.001) during the 8 h of bull presence (0.56 +/- 0.33 and 0.39 +/- 0.26 ng/ml, respectively) compared to the 8 h without a bull (0.50 +/- 0.30 and 0.35 +/- 0.24 ng/ml, respectively). Pulse amplitude did not differ (P=0.85) between Day 2 (0.45 +/- 0.24 ng/ml) or Day 1 (0.45 +/- 0.14 ng/ml). LH pulse frequency was greater (P<0.1) on Day 2 (5.3 pulses/8h) compared to the Day 1 (4.6 pulses/8h). In conclusion, fenceline bull exposure early postpartum seems to have an acute effect on LH-release in anoestrous dairy cows. Whether sustained bull exposure can hasten first ovulation after calving through an effect on LH release in dairy cows is an interesting area of research.