Flehmen Research Articles

Patterns in bobcat (Lynx rufus) scent marking and communication behaviors

Intraspecific communication by solitary felids is not well understood, but it is necessary for mate selection and to maintain social organization. We used motion-triggered video cameras to study the use of communication behaviors in bobcats (Lynx rufus), including scraping, urine spraying, and olfactory investigation. We found that olfactory investigation was more commonly used than any other behavior and that—contrary to previous research—scraping was not used more often than urine spraying. We also recorded the use of cryptic behaviors, including body rubbing, claw marking, flehmen response, and vocalizations. Visitation was most frequent during January, presumably at the peak of courtship and mating, and visitation become more nocturnal during winter and spring. Our results add to the current knowledge of bobcat communication behaviors, and suggest that further study could enhance our understanding of how communication is used to maintain social organization. Videos relating to the behaviors in this article are available at: http://www.momo-p.com/showdetail-e.php?movieid=momo141104bn01a , http://www.momo-p.com/showdetail-e.php?movieid=momo141104bn02a , http://www.momo-p.com/showdetail-e.php?movieid=momo141104lr01a , http://www.momo-p.com/showdetail-e.php?movieid=momo141104lr02a , http://www.momo-p.com/showdetail-e.php?movieid=momo141104lr03a and http://www.momo-p.com/showdetail-e.php?movieid=momo141104lr04a .

Exposure of prepubertal beef bulls to cycling females does not enhance sexual development

The objective of this study was to determine whether continuous, long-term, fenceline exposure of prepubertal beef bulls to cycling beef females reduced age at puberty and influenced the percentage of bulls that passed an initial breeding soundness examination (BSE). Bulls (Angus, n = 37; Simmental, n = 22; Hereford, n = 10; Simmental × Angus, n = 8) at an average age of 202 ± 21.5 days were given either continuous fenceline and visual exposure to cycling females (exposed, n = 41) or no exposure (control, n = 36). Estrus was induced in cycling beef females so at least three females were in standing estrus each week during the 182 days of exposure to bulls. Scrotal circumference (SC), body weight, and blood samples were collected every 28 days. When bulls had SC of 26 cm or more, semen samples were obtained monthly via electroejaculation until puberty was achieved (≥50 × 106 sperm/mL with at least 10% progressive motility). Behavioral observations were conducted twice monthly: once when females were in estrus and once during diestrus. Homosexual mounting, flehmen responses, and number of times near penned females were recorded for each observation period. Breeding soundness examinations were conducted when the average age of bulls was 364 ± 21.5 days. Normal sperm morphology of at least 70% and sperm motility of at least 30% were required to pass the BSE. Age, body weight, and SC at puberty did not differ between exposed and control bulls (320 ± 28 and 311 ± 29 days; 466.2 ± 12.2 and 437.7 ± 13.5 kg; and 34.4 ± 2.5 and 34.9 ± 2.5 cm, respectively). Percentage of bulls passing their initial BSE did not differ between treatments (exposed, 87.8%; control, 75.0%). Treatment, month, and female estrous stage interacted (P = 0.05) to affect the number of mount attempts and flehmen responses. Exposed bulls entered the cow area more times (P < 0.001) during estrus than diestrus in Months 1, 2, and 3. We concluded that bulls given continuous, long-term, fenceline exposure to cycling beef females do not have enhanced sexual development.

Puma communication behaviours: understanding functional use and variation among sex and age classes

Intraspecific communication for mate selection sometimes varies between sexes based on different evolutionary life history patterns. Solitary felids use communication for territorial defence and location of mates, for which they use scent-marking behaviours including scraping, urine spraying, body rubbing, caterwauling, cheek rubbing, and the flehmen response, but these behaviours are not well understood in pumas (Puma concolor). We used motion-triggered video cameras to document the use of communication behaviours by male and female pumas, and used a series of experimental treatments to determine the mechanisms and importance of visual and olfactory cues in puma scrapes. We found that pumas use the physical scrape to locate communications, and then use urine to convey and interpret the communication itself. We also found significant differences among puma age and sex classes in the proportion of use and duration of time behaviours were displayed. Mature males spent significantly longer durations () on producing behaviours (scraping, body rubbing, and caterwauling behaviours) than mature females (), and males used scraping (78.5%) and body rubbing (12.4%) behaviours at a higher proportion of visits than females (13.6 and 2.7%, respectively). Mature females spent significantly longer durations () on consuming behaviours (investigating and flehmen response behaviours) than mature males (), and females used flehmen response (30.6%) and caterwauling (9.3%) behaviours at a higher proportion of visits than mature males (6.5% flehmen and 0.4% caterwauling). Male reproductive strategy appears based on advertisement for possible mates, while female reproductive strategy appears based on assessment of possible mates. The use of communication behaviours also appears to develop with age, as immature pumas rarely visited and acted as non-participants in communication behaviours.

Behavioural signs of estrus in different parity of murrah buffaloes (Bubalus bubalis): a comparative study

In dairy bovines, estrus detection is the key determinant of the herd fertility. However, owing to silent heat in buffaloes, it is difficult to detect estrus at proper time which in turn affects the estrus detection efficiency and reduces conception rate. Further, it is not clear whether the buffaloes during different parities have differential expression of estrus behaviour. Therefore, the present study was designed to study the behavioural signs of estrus expressed by Murrah buffaloes (n= 94) belonging to different parities. Estrus detection was done by parading teaser bulls (4 times bull parading in a day), heat expectancy chart and visual observation of behavioural signs of estrus. The study revealed significantly (P< 0.05) higher bellowing/vocalization behaviour in primiparous (77.27%) and pluriparous buffaloes (72.88%) than heifers (38.46%). Micturition behaviour was significantly (P< 0.05) more pronounced in pluriparous (93.22%) and primiparous buffaloes (90.91%) as compared to heifers (69.23%). In pluriparous and primiparous buffaloes, tail raising behaviour during estrus was also expressed by higher(P< 0.05) proportion of buffaloes (96.61 and 90.91%, respectively) as compared to heifers (76.92%). However, there were no differences in tumefaction of vulval lips, reddening of vulval mucus membrane characteristics, standing to be mounted behaviour, chin resting and Flehmen reaction among pluriparous, primiparous and heifer buffalos. These results indicated that intensity of bellowing/vocalization, micturition and tail raising behaviours during estrus were poorly expressed in heifers and more focussed attention is needed to detect buffalo heifers in estrus.

Polymorphism of growth hormone gene and its association with seminal and sexual behavioral traits in crossbred cattle

The decline in the male reproductive ability in terms of sexual behavior and seminal traits might lead to nonavailability of required number of bulls in a progeny testing program. The present study was conducted in 493 crossbred cattle (Bos taurus × Bos indicus) bulls to study polymorphisms of growth hormone (GH) gene and its association with seminal and sexual behavioral characteristics. A 428-base pair fragment of GH gene spanning over the fourth exon, fourth intron, and fifth exon was amplified and digested with AluI restriction enzyme. Bulls were found to be polymorphic, with two variants, LL and LV, and higher genotypic frequency for LL being 0.88. Twelve nucleotide changes and a single nonsynonymous substitution of Leucine by Valine were observed from GH1 (L) to GH2 (V). Statistical analysis revealed that the genotype of the GH gene had a significant effect on libido score, reaction time, Flehmen response, requirement of mounting stimulus, sperm mass activity, number of semen doses per collection, individual fresh sperm motility, postthaw sperm motility, acrosome integrity, hypo-osmotic swelling test, live and dead count, total morphological abnormality, and head abnormality of sperm in crossbred bulls. Growth hormone gene might be considered a candidate gene for seminal and sexual behavioral traits in crossbred cattle.

Nasopalatine Ducts and Flehmen Behavior in the Mandrill: Reevaluating Olfactory Communication in Old World Primates

Compared to other modes of communication, chemical signaling between conspecifics generally has been overlooked in Old World primates, despite the presence in this group of secretory glands and scent-marking behavior, as well as the confirmed production and perception of olfactory signals. In other mammalian species, flehmen is a behavior thought to transport primarily nonvolatile, aqueous-soluble odorants via specialized ducts to the vomeronasal organ (VNO). By contrast, Old World primates are traditionally thought to lack a functional VNO, relying instead on the main olfactory system to process volatile odorants from their environment. Here, in the mandrill (Mandrillus sphinx), we document unusual morphological and behavioral traits that typically are associated with the uptake of conspecific chemical cues for processing by an accessory olfactory system. Notably, we confirmed that both sexes possess open nasopalatine ducts and, in response to the presentation of conspecific odorants, we found that both sexes showed stereotyped behavior consistent with the flehmen response. If, as in other species, flehmen in the mandrill serves to mediate social or reproductive information, we expected its occurrence to vary with characteristics of either the signaler or receiver. Flehmen, particularly in a given male, occurred most often in response to odorants derived from male, as opposed to female, conspecifics. Moreover, odorants derived during the breeding season elicited more flehmen responses than did odorants collected during the birthing season. Lastly, odorants from reproductively cycling females also elicited more responses than did odorants from contracepted females. Although confirming a link between the nasopalatine ducts, flehmen behavior, and olfactory processing in mandrills would require further study, our observations provide new information to suggest anatomical variability within Old World primates, calling further attention to the underappreciated role of chemical communication in this lineage.

Florida Panther Flehmen Response Recorded at Baited Trail Camera Site

Although flehmen behavior is reported in felids, this display has been rarely documented in wild pumas. On 11 Nov. 2008, we recorded a female Puma concolor coryi (Florida Panther) exhibiting the flehmen response and scent marking in reaction to a baited trail camera site in Everglades National Park. The addition of scent lures to our camera sites increased the number of exposures per panther visit, enhancing the possibility of gender identification, an essential component of our annual survey.

Chemocommunication among domestic cats, mediated by the olfactory and vomeronasal senses. I. Chemocommunication.

Chemocommunication functions are known in many social mammals, such as gerbils, hamsters, and deer. But also mammals known as at least partly solitary do communicate by chemical signals. The existence and use of pheromones in domestic cats was the subject of this study. It turned out that male and female cats spent much time in exploring their own and foreigners' urine and skin gland secretion rubbed off on several objects. Male receivers performed sniffing and flehmen more frequently than females on the same urine, whereas female cats paid more attention to skin gland secretion. Both urine and cheek gland secretion of the female donor appeared to contain pheromones which inform the tomcat about her hormonal phase.

169 BEHAVIORAL ASPECTS OF ESTRUS IN THE COMMON ELAND ANTELOPE, TAUROTRAGUS ORYX

Knowledge of the estrous cycle and behavior is important in managing captive breeding programs. However, such information is negligible in spiral-horned antelopes, including the eland. In the present study, conducted between September 2007 and March 2008, we sought to characterize mounting activity and courtship behavior in a group of eight adult eland females. Estrus was induced in groups of four females by treatment with 25 mg PGF2 ∝ (IM, Lutalyse®, Pharmacia and Upjohn Company, Kalamazoo, MI, USA) administered after 7 days of daily oral progestin (5 mL of 2.2% altrenogest, DPT Laboratories, San Antonio, TX, USA) or 11 days after an initial treatment of PGF2 ∝ (25 mg). The eight females received each treatment in a crossover design. Females were induced and monitored during the induced and subsequent natural estrus for 34 to 38 days. Observations for estrus behavior were initially assisted by using Estrotect™ heat detector patches (Rockyway, Inc., www.estrotect.com). Since January 2008, the HeatWatch® electronic heat detection system (CowChips, Denver, CO, USA) and an androgenized eland female were used to assist with heat detection. For androgenization, 8 pellets of Synovex-H® (Fort Dodge Animal Health, Fort Dodge, IA) comprising a total dose of 1600 mg testosterone propionate and 160 mg estradiol benzoate were implanted (SC) on the convex side of the ear. To confirm mounting activity detected by Estrotect™ or HeatWatch®, eland behavior was recorded continuously using an 8-channel real time DVR. Chi-square analysis was used to test the association between time of day (day or night) and the frequency of standing to be mounted. The cycle length (n = 6 females) was the time interval (d) between the first mounts at the induced and natural estrus. The time of mounts was determined for a total of 52 mounts. More than half of the mounts (n = 32 or 61.5%) occurred between 6 pm and 6 am (night); however, there was no association between the number of mounts and time of the day (p = 0.886). Analysis of mounts by quarters of the day showed that mounts were evenly distributed between early afternoon (noon to 6 pm: 29%), late afternoon (6 pm to midnight: 33%) and early morning (midnight to 6 am: 29%) but were less frequent during late morning, between 6 am and noon (10%) possibly due to interference by human activities. The number of mounts observed per female ranged from 1 to 20. Mounts lasted for 2 seconds or less. The duration of estrus ranged from 2.1 to 29.0 hours. Typical courtship behaviors included prolonged head butting, flehmen response and following the female in estrus before mounting. The average length of the estrous cycle, based on mounting activities, was 19.3 d (range: 17–24). Although further studies are required in herds with eland males, the present results suggest that estrus detection for captive breeding or application of reproductive technologies in the eland should be spread around different times of the day and night. We have also demonstrated that an electronic mount detection system can be applied to assist with determination of estrus in the eland.

Keratoconjunctivitis sicca attributable to parasympathetic facial nerve dysfunction associated with hypothyroidism in a horse

A 6-year-old 680-kg (1,496-lb) German Warmblood gelding was evaluated because of bilateral blepharospasm and head shaking. Moderate blepharospasm was evident bilaterally, and both eyes had hyperemic and edematous conjunctivas and lusterless corneas. For each eye, the Schirmer tear test value was only 7 mm/min. The horse's nasal mucosa was dry. Abnormal behaviors included mild repetitive vertical movement of the head, snorting, and flehmen response (classic signs of head shaking). Touching the horse's nostrils and face revealed paresthesia and dysesthesia with slight nasolabial muscle hypertrophy bilaterally. Cranial nerve examination revealed no other abnormalities. Serum thyroxine concentration was low, and results of thyrotropin-releasing hormone and thyroid-stimulating hormone stimulation tests were negative, indicating that the horse had hypothyroidism. The diagnoses included keratoconjunctivitis sicca and dry nares attributable to parasympathetic facial nerve dysfunction, head-shaking syndrome with paresthesia and dysesthesia of the face attributable to sensory trigeminal nerve disorder, and hypothyroidism. The 2 nerve dysfunctions were considered peripheral neuropathies that were most likely caused by hypothyroidism. Treatment of both eyes was initiated with topical applications of cyclosporine, 0.5% sodium hyaluronate, and vitamin A ointment. Levothyroxine (20 microg/kg [9.1 microg/lb], PO, q 24 h) was administered. Within 3 weeks to 4 months, serum thyroxine concentration was within reference range, and clinical signs and Schirmer tear test values improved. Hypothyroidism should be considered as a differential diagnosis in horses with peripheral neuropathy or keratoconjunctivitis sicca. In affected horses, administration of levothyroxine may lead to resolution of neurologic signs.

Oestrus cycle characteristics and prediction of ovulation in Catalonian jennies

The Catalonian donkey breed is in danger of extinction, and much needs to be learned about the reproductive features of its females if breeding and conservation programmes are to be successful. This study reports the oestrous behaviour, oestrus cycle characteristics and dynamic ovarian events witnessed during 50 oestrous cycles (involving 106 ovulations) in 10 Catalonian jennies between March 2002 and January 2005. These jennies were teased, palpated transrectally and examined by ultrasound using a 5 MHz linear transducer—daily during oestrus and every other day during dioestrus. Predictors of ovulation were sought among the variables recorded. The most evident signs of oestrus were mouth clapping (the frequent vertical opening and closing of the mouth with ears depressed against the extended neck) and occasional urinating and winking of the vulval lips (homotypical behaviour). Interactions between jennies in oestrus were also recorded, including mounting, herding/chasing, the Flehmen response, and vocalization (heterotypical behaviour). Nine jennies ovulated regularly throughout the year; one had two anovulatory periods (54 and 35 days). The length of the oestrus cycle was 24.90 ± 0.26 days, with oestrus itself lasting 5.64 ± 0.20 days (mean ± S.E.M.) and dioestrus 19.83 ± 0.36 days. The incidence of single, double and triple ovulations was 55.66% ( n = 59), 42.45% ( n = 45) and 1.89% ( n = 2), respectively. No significant difference was seen in the number of ovulations involving the left and right ovaries (52.63% [ n = 70] compared to 47.37% [ n = 63] respectively; P > 0.05). The mean interval between double ovulation was 1.44 ± 3.98 days. The mean diameter of the preovulatory follicle at day −1 was 44.9 ± 0.5 mm; the mean growth rate over the 5 days before ovulation was 3.7 mm/day. Data on preovulatory changes in oestrous behaviour, follicle size, follicle texture, the echographic appearance of the follicle and uterus, and uterine tone were subjected to stepwise logistic regression analysis to detect predictors of ovulation. The logit function showed the best predictors to be follicle size, follicular texture and oestrous behaviour. Certain combinations of these three variables allow the prediction of ovulation within 24 h with a probability of >75%.

Effect of breed and age on sexual behaviour of rams

The objective of this study was to highlight the problems that arise during the reproduction between thin-tailed rams and fat-tailed ewes. At the same time, particular emphasis laid on the influence of sheep breed, sheep age, time after ram introduction and day of the ewe estrus cycle on ram and ewe sexual behaviour. Rams were subjected to sexual performance tests by being individually exposed to 12 ewes for 3 h daily, 19 consecutive days. The 16 rams of the experiment were separated according to their age (9 and 21 months old) and breed (Chios and Karagouniki), and the 96 ewes of Chios fat-tailed breed, were divided by age (9 and 21 months old). The main characteristics of courtship behaviour, like sniffing, nudging, flehmen response and following were recorded and studied in detail. Mature Chios rams, which were the only one with previous experience of Chios ewes, exhibited higher rates of sexual interest per ewe than the other rams ( P < 0.05). On the other hand, rams sniffed and nudged more young than mature ewes ( P < 0.05), probably due to the fact that young ewes did not express intense symptoms of estrus. Young rams exhibited substandard sexual interest towards mature ewes, when they first came in contact with them ( P < 0.05). In general, Karagouniki thin-tailed rams exhibited reduced rates of mating behaviour when they courted with Chios fat-tailed ewes in comparison with Chios rams ( P < 0.05). Moreover, as the time after ram introduction passed, the frequency and duration of sexual behaviour components decreased ( P < 0.001). Finally, the effect of the day of the experiment was only significant in the case of sniffing, which increased during the first 2 days and then declined and stabilized ( P < 0.01). As it was demonstrated, ram age and ram breed played a fundamental role in the exhibition of sexual interest elements.

Effects of sequential or group exposure to unrestrained estrual females on expression of sexual behavior in sexually experienced beef bulls1,2

We tested the hypothesis that expression of sexual behavior in bulls is affected by the manner in which they are exposed to unrestrained, sexually receptive females. Twelve Angus bulls were used in a crossover design involving two treatments, each tested four times for a total of eight tests for each bull. Sexual interactions were quantified for each of four, 30-min periods under the following treatments: 1) exposure to each of four estrual females in sequence (SEQ); or 2) exposure to four estrual females as a group (GRP). Bulls were blocked into three testing groups, the order of which was stratified across eight test days. The order in which bulls were tested on a particular day had no effect on bulls' expression of mount interactions, or flehmen responses, suggesting that each group of bulls had similar sexual motivation at the beginning of each test. However, the bull testing order x treatment x time interaction influenced mounting interval (P = 0.08), copulation frequency (P <0.05), and copulation success ratio (P <0.05). When bulls were in GRP and tested first on test days, more (P <0.05) copulations were distributed to the first three females encountered compared with either the fourth female (P <0.05) or to each of the other females in SEQ (P <0.05). During later tests, other bulls in GRP were not able to copulate as frequently (P <0.05) with each female, displayed lower (P <0.05) copulation success ratios, and were allowed copulations by fewer (P <0.05) females during each 30-min test. When bulls were in SEQ, they displayed similar numbers of copulations regardless of the order in which they were tested, and had stable mounting intervals; however, copulation success ratio decreased (P <0.05) more rapidly during subsequent tests. Flehmen responses were initially displayed more frequently (P <0.05) when bulls were in GRP, but this effect diminished during subsequent 30-min tests. In conclusion, exposure of bulls to GRP induced greater sexual responsiveness than SEQ; however, this effect was due to enhanced sexual activity during the early stages of sexual encounters and with females that were not recently mated. Interestingly, bulls seem to repeatedly copulate with each individual female until, apparently, female sexual receptivity became attenuated. Thereafter, recently mated females allowed fewer episodes of repeated copulations, but they did not completely cease copulating with novel bulls.

Effects of novel females and stage of the estrous cycle on sexual behavior in mature beef bulls1,2

The objective of this experiment was to determine the effects of unrestrained females on sexual behavior of bulls. Twelve Angus bulls were used in three Latin square replicates where sexual interactions between one bull and one female were quantified for each of four 60-min tests (T1, T2, T3, and T4, respectively). All bulls received the following treatments: 1) exposure to four estrual females in sequence (A-B-C-D); 2) exposure to two estrual females in alternating sequence (E-F-E-F); 3) exposure repeatedly to one estrual female (G-G-G-G); and 4) exposure repeatedly to one diestrous female (CON). During T1, mount interactions, mounts with intromission and mounting intervals were similar when bulls were in A-B-C-D, E-F-E-F, or G-G-G-G. Fewer mount interactions, no mounts with intromission, and increased mounting intervals (P < 0.05) occurred in CON. During T2, there were more mount interactions, more mounts with intromission, and decreased mounting intervals (P < 0.05) when bulls were in A-B-C-D or E-F-E-F compared with when they were in G-G-G-G or CON. More mount interactions (P < 0.05) occurred in G-G-G-G compared with CON, but mounts with intromission and mounting intervals did not differ. During T3, more mount interactions (P < 0.05) occurred in G-G-G-G than in CON; otherwise, sexual behaviors were similar among treatments. Mounting intervals during T3 were similar among A-B-C-D, E-F-E-F, and G-G-G-G, but were all decreased (P < 0.05) compared with CON. During T4, more mount interactions, more mounts with intromission, and decreased mounting intervals (P < 0.05) occurred when bulls were in A-B-C-D compared with other treatments. Mount interactions were similar when bulls were in E-F-E-F, G-G-G-G, or CON; however, more (P < 0.05) mounts with intromission occurred when bulls were in E-F-E-F compared with G-G-G-G or CON. Mounting intervals during T4 were decreased (P < 0.05) in E-F-E-F compared with the CON treatment, whereas in G-G-G-G, they were intermediate. Mounts without intromission were not affected by female novelty or receptivity, but novel females induced more flehmen responses. In conclusion, novel, females, overall, enhanced sexual activity of bulls; however, bull sexual responses diminished after 2 h, even when a novel female was presented. Estrual females that were repeatedly paired with bulls displayed diminished sexual receptivity, but if mated females were rested for 60 min, they allowed further copulation from familiar bulls that were not sexually sated.

Considerations about the function of the mimic muscles and the vomeronasal organ of horses during the Flehmen reaction

Considerations about the function of the mimic muscles and the vomeronasal organ of horses during the Flehmen reaction

Flehmen response in bull: role of vaginal mucus and other body fluids of bovine with special reference to estrus

The present investigation was carried out with a view to evaluate the frequency of Flehmen behaviour in bull in response to body fluids of cows in various stages of the estrous cycle, in the context of estrus detection. The study was performed on free moving bulls under natural conditions. Samples of vaginal mucus, saliva, faeces and milk of pro-estrus, estrus and di-estrus stages collected from donor cows were rubbed individually onto the genital regions of non-estrus animals (dummy cows) and the bulls were observed for 30 min for assessment of Flehmen behaviour. The duration of Flehmen behaviour shown by bulls was maximum towards the dummy cows receiving estrus sample. Such Flehmen behaviour, however, did not occur in bulls in response to the cows receiving samples of other stages. The statistical significance was higher (P < 0.001) in exhibiting repeated Flehmen behaviour towards estrus as compared to those of pro-estrus and di-estrus. Among the various body fluids tested, the exhibition of Flehmen behaviour was significantly higher (P < 0.01) in response to estrus vaginal fluid. No response was observed on dummy cows (control) to which only water was applied on the genital region. The results suggest that vaginal mucus may act as an additional/secondary source along with urine in eliciting copulatary behaviour and executing coitus in bulls during estrus. The results further suggest that in addition to vaginal mucus, other body fluids like saliva, faeces and milk have estrus-related odours and are probably involved in bovine bio-communication.

Preliminary study of the development of the Flehmen response in Equus caballus

The flehmen response is commonly seen in most ungulates as well as in several other species (e.g. felids). The behavior is most often thought to be part of the sexual behavioral repertoire of males. One reigning hypothesis suggests that this behavior allows the male to determine the estrous state of a female through the chemosensory functions of the vomeronasal organ. However, females and young of both sexes also exhibit this behavior. Horse foals most frequently show the flehmen response during their first month of life with colts showing the behavior more often than fillies. This study tested the flehmen response on male and female foals throughout their pre-pubertal period. Foals were separately presented estrous and non-estrous urine weekly during the first month of life and then monthly until they were approximately 7 months of age. No significant differences were found between male and female foals for the following variables: latency to flehmen, duration of flehmen, frequency of flehmen and sniffs.

Morphological characteristics of the vomeronasal organ of the newborn Asian elephant (Elephas maximus).

The 6-week-old Asian elephant (Elephas maximus) has a well-documented precocious flehmen response to pheromones, suggesting that the pheromone-detecting vomeronasal organ (VNO) is functional very early in the life of this species. To further document this, the VNOs of two newborn elephants were examined in situ and analyzed by light microscopy (LM) to ascertain their structural maturity at birth. A tubular, cartilage-encased VNO was located along the anterior base of each side of the nasal septum. Its rostral end was connected to a duct to the roof of the mouth; the caudal end was attached to a well-defined vomeronasal nerve projecting toward the brain. LM revealed distinctive differences in the mucosae bordering the horseshoe-shaped lumen: a concave, sensory mucosa, and a convex, nonsensory mucosa. Small groups of receptor neurons were observed among ciliated columnar cells in the sensory epithelium. Numerous unmyelinated nerve bundles and blood vessels filled the underlying lamina propria (LP) and a small section of the vomeronasal nerve was conspicuous at one edge. The nonsensory mucosa manifested a thinner epithelium that principally consisted of ciliated columnar cells, some of which showed a granular cytoplasm, and a conspicuous row of basal cells. The LP was replete with acinar glands and ducts that opened into the lumen. This study shows that the VNO of the newborn elephant has reached an advanced stage of structural maturity, closely resembling that of the adult. Its composition supports the view that flehmen at 6 weeks delivers pheromones to a functional VNO.

Castration increases pulsatile luteinizing hormone release, but fails to diminish mounting behavior in sexually experienced bulls

We tested the hypothesis that mounting and chemoinvestigatory behaviors are testosterone-dependent in bulls. Eighteen bulls were divided into three treatment groups: intact (I), castrated (C) and castrated+testosterone (T). Sexual behaviors of all bulls were tested with an unrestrained receptive female 1 week prior to and weekly for 4 weeks after castration. Mounts with intromissions, aborted mounts and flehmen responses were quantified for each test period. In addition, patterns of LH and testosterone secretion were assessed at these times. Neither mounts with intromissions nor aborted mounts were affected by treatment. In contrast, numbers of flehmen responses were lower in C bulls than in the other groups following castration. Before castration, concentrations of LH were not different among groups and LH pulse frequency was approximately one pulse per hour. Castration resulted in a 2-fold increase in mean concentrations of LH and a 6-fold increase in LH pulse frequency. Neither mean concentration of LH nor LH pulse frequency changed in I or T bulls. The data fail to support the hypothesis that mounting behavior is T-dependent, but supports the hypothesis that this steroid hormone regulates flehmen behavior in sexually experienced bulls.

Effects of melengestrol acetate on reproductive behavior and concentrations of LH and testosterone in bulls.

We investigated the use of an orally active progestin (melengestrol acetate; MGA) to suppress reproductive activity in yearling beef bulls. Twenty-four crossbred bull calves were given a daily dose of 0, 0.5, 1.0, or 2.0 mg MGA for 99 d. Pulsatile patterns of LH and concentrations of testosterone and MGA were characterized on d 8, 36, 63, and 92 of the experiment. Numbers of aborted mounts, mounts with intromission, total mounts, and flehmen responses were assessed on d 15, 43, 71, and 99. Plasma concentrations of MGA were proportional to dose of MGA. Melengestrol acetate did not consistently affect mounting behavior in a dose-related manner, but, on d 99, number of total mounts for MGA-treated bulls was lower (P = 0.07) than that for control bulls. On d 15, MGA suppressed (P = 0.07) numbers of flehmen responses in a dose-dependent manner, but this effect was not sustained throughout the experiment. On d 8, concentrations of testosterone in control bulls were higher (P = 0.02) than in MGA-treated bulls, but this effect was not observed at other time periods. Overall, MGA caused slight decreases in mean concentrations of LH (P = 0.09) and LH pulse frequency (P = 0.06). Scrotal circumference was not affected by MGA. None of the behavioral traits was correlated with mean concentrations of LH or LH pulse frequency. Mounting activity was not correlated with testosterone concentrations, but number of flehmen responses was positively correlated with testosterone concentrations (P = 0.01). These results fail to support the hypothesis that progestins impair male sexual behavior or fertility in males.