Effect of proximity to females on integument damage caused by self-enurination in male goats.

In male goats, self-enurination (SE) is the downward turning of the head and shoulders while urinating onto the face and front legs. Although it provides important chemical cues to females, other males, and even self, it is a costly behavior that can create a range of problems including erythema, irritation, hair loss, and compromised skin. It was hypothesized that the extent of integument damage from SE on bucks' faces and front legs would be increased by housing bucks near females. Four bucks were housed with fence-line contact to females ("Near" bucks), and four bucks were housed without fence-line contact to females ("Far" bucks). Each buck was photographed every other week over an 18-wk period during the breeding season. During each imaging session, seven different photographic views were captured, and burn areas were quantified for each buck. Overall, more Near bucks had urine burn than Far bucks, and Near bucks developed urine burn earlier in the breeding season than did Far bucks. Housing bucks close to females increases the extent of integument damage from SE. These findings may help goat breeders develop management practices to improve animal well-being by minimizing urine burn injury to bucks.

Differential effects of androgens, estrogens and socio-sexual context on sexual behaviors in the castrated male goat.

The behavioral and endocrine activation of sexual behaviors exhibited by male goats, especially self-enurination (SE), is poorly understood. In the first experiment, to assess the influence of socio-sexual context on SE in bucks, the effects of distance from does, the presence of estrous versus non-estrous does and the presence of another buck on SE and courtship frequencies of intact male goats (bucks; n = 12) were tested using a unique behavior test apparatus. For experiments 2 and 3, to test the relative contributions of sex steroid hormones and socio-sexual context on SE, castrated male goats (wethers; n = 20) were randomly divided into five groups and injected for seven weeks with one of the following: 25 mg testosterone propionate (T), 25 mg dihydrotestosterone propionate (DHT), 100 µg estradiol benzoate (E), 100 µg E and 25 mg DHT (E + DHT), or oil (CON). The effects of these treatments on frequency of SE and courtship were assessed using the behavior test apparatus (social scenarios) adapted from the findings in experiment 1. In one scenario, a wether could observe (from 4.6 m) a buck and estrous female (doe) together in a wire mesh holding pen. In a different scenario, the wether could observe (from the same distance) a buck that could only court the estrous doe through a wire mesh barrier. Finally, to observe the effects of steroid treatment on mounting and ejaculation frequencies, in addition to SE and courtship, each wether was placed in a pen with an estrous doe for 10 min. After a five-week, treatment-washout period, wethers were randomly assigned to different treatment groups and retested. In experiment 1, bucks that were distanced from females displayed more SEs than those with fence-line contact, while those with fence-line contact displayed more bouts of courtship (P < 0.05). In experiments 2 and 3, courtship frequencies displayed in all three scenarios were greater than CON only for groups exposed to estrogen directly or via aromatization (T, E + DHT, E; P < 0.05). Frequencies of SE exhibited during behavior tests in which the wether was watching were greater than CON only for androgen-treated groups (T, E + DHT, DHT; P < 0.05). In contrast, when the wether was free to interact with the female, only the DHT group displayed SE at a higher frequency than CON (P < 0.05). Treatment had no effect on mount frequencies in this test scenario, however ejaculation frequencies were highest for T and E + DHT (P < 0.05). These studies suggest that the courtship behaviors of the male goat are estrogen-dependent. However, SE appears to be activated by androgens. It was also demonstrated that social context contributes as much to behavior expression as steroid treatment, as in social scenario 2 some sexual behaviors were displayed in similar frequencies across groups, despite differing sex steroid treatments.

Seasonal variation of urinary microRNA expression in male goats (Capra hircus) as assessed by next generation sequencing.

Testosterone plays a key role in preparation of a male domesticated goat (Capra hircus) to breeding season including changes in the urogenital tract of a male goat (buck). microRNAs are important regulators of cellular metabolism, differentiation and function. They are powerful intermediaries of hormonal activity in the body, including the urogenital tract. We investigated seasonal changes in expression of microRNAs in goat buck urine and their potential consequences using next generation sequencing (microRNA-Seq). We determined the location of each microRNA gene in the goat genome. Testosterone was measured by radioimmunoassay and the androgen receptor binding sites (ARBS) in the promoters of the microRNA genes were determined by MatInspector. The overall impact of regulated microRNAs on cellular physiology was assessed by mirPath. We observed high testosterone levels during the breeding season and changes in the expression of forty microRNAs. Nineteen microRNAs were upregulated, while twenty-one were downregulated. We identified several ARBS in the promoters of regulated microRNAs. Notably, the mostly inhibited microRNA, miR-1246, has a unique set of several gene copy variants associated with a cluster of androgen receptor binding sites. Concomitant changes in regulated microRNA expression could promote transcription, proliferation and differentiation of urogenital tract cells. Together, these findings indicate that in a domesticated goat (Capra hircus), there are specific changes in the microRNA expression profile in buck urine during breeding season, which could be attributable to high testosterone levels during breeding, and could help in preparation of the urogenital tract for high metabolic demands of that season.

Female goats use courtship display as an honest indicator of male quality.

Due to the differential cost of reproduction in promiscuous species, like domesticated goat(s) (Capra hircus), it is expected that females should mate with higher quality males, while males should mate with a greater number of females. Females may use conspicuous secondary sexual characteristics of males such as courtship display to distinguish among high and low quality males. Testosterone (T) controls a large suite of secondary sexual characteristics and variation in T concentrations may account of differences in courtship rates. Two studies were conducted to examine the relationship between T concentrations and courtship rate and its role in mammalian female mate choice. Experiment 1 utilized bucks (intact males) and Experiment 2 utilized T-replaced wethers (castrated pre-pubertally). During the first year of Experiment 2, T-replaced wethers received either vehicle control (CON), 25mg or 100mg testosterone propionate (TP). During the second year of Experiment 2, T-replaced wethers were treated with either 5mg, 15 mg or 25mg TP. For all experiments, mean courtship rates and circulating T concentrations were measured, as well as female preference for males displaying different courtship frequencies. T concentrations and courtship rate were positively correlated for bucks and estrous females preferred high courting bucks. Males receiving 25mg and 100mg TP courted females at a similar rate, but both were significantly higher than courtship rates of the CON wethers. Courtship rates of the 25mg, 15 mg and 5mg TP-treated males were all significantly different. Females did not show a preference between the 100mg or 25mg TP-treated wethers, however both were preferred in comparison to the CON wethers. Females did not show preference between the 25mg or 15 mg TP-treated wethers, however both were preferred in comparison to the 5mg TP-treated wethers. Taken together, these studies suggest that courtship rate is T-dependent. Further, females can use courtship rate to distinguish among males.

Female tail wagging enhances sexual performance in male goats.

Preference testing has shown that sexually experienced male goats choose females that are tail wagging, a behavior that may function as both attractivity and proceptivity, over those that are not. We hypothesized that exposure to females expressing high rates of tail wagging would arouse males, increasing sexual performance. Tail wagging rate could be manipulated because we have shown previously that flutamide treatment increases the frequency of tail wagging in estrous goats. Sexually experienced males observed different stimuli for 10 min before a 20 min sexual performance test (SPT). The stimuli were an empty pen (MT), or groups of three females that were all estrous (E), non-estrous (NE), estrous+flutamide (E(F)) or non-estrous+flutamide (NE(F)). During the stimulus observation period, tail wagging was recorded. During SPT, frequencies and latencies of sexual behaviors were recorded. E(F) females displayed the most tail wagging. Viewing E(F) females before SPT increased the number of ejaculations attained by males and decreased the latencies to first and second ejaculation, as well as the inter-ejaculatory interval. Viewing estrous females (E and E(F)) before SPT decreased the latency to first mount, as compared to non-estrous females (NE and NE(F)). We conclude that male goats are sexually aroused by tail wagging. This study and previous work demonstrate that tail wagging functions as both attractivity and proceptivity in goats.

Estrous female goats use testosterone-dependent cues to assess mates.

In a promiscuous species like the domestic goat (Capra hircus), in which maternal investment is greater than paternal investment, a female may mate selectively with a more-fit male to improve her reproductive fitness. Testosterone (T) controls a large suite of male-typical behaviors and morphological characteristics. High T concentrations may be energetically costly or even detrimental to survival; thus, preventing lower quality males from falsely advertising their fitness. Three preference studies were conducted to examine if females use T-dependent cues to assess potential mates. For Experiment 1, females were given a choice between a pair of morphologically similar males, bucks (intact males) and stags (post-pubertally castrated males), during the breeding and non-breeding seasons. In both seasons, females preferred the bucks compared to stags. In Experiment 2, females were given a choice between bucks, stags and wethers (pre-pubertally castrated males) during the non-breeding season. For some comparisons, castrated males received 25 mg testosterone propionate (TP) or were untreated. Females preferred TP-treated males compared to untreated males and showed no preference when given a choice between either two TP-treated or two untreated males. In Experiment 3, females were given a choice between a pair of bucks and a pair of stags treated with 25 mg TP during monthly tests in the breeding season. At each monthly test, females preferred the males with higher T concentrations near the time of the behavior test. These studies suggest that females use T-dependent cues to assess potential mates, and T concentrations may indicate a male's overall fitness.

Partner preference: assessing the role of the female goat.

For domestic ruminants, the male is thought to have the control over mate choice. The aim of this study was to assess the potential role the female goat plays in choosing a sexual partner. Approach frequency and proximity time to various social or sexual stimuli in a Y-maze apparatus were used as partner preference assessment parameters. Ovariectomized females were either induced into estrus (n=8) or induced into anestrus (n=8) and exposed to various goal stimuli - intact unfamiliar females (estrous and diestrous), intact males, and neutral (empty) in six separate trials. Total arm entries and time spent within one body length of the goal (proximity time - used to calculate preference scores) were recorded for subjects. With a male present, anestrous subjects had significantly more total arm entries than estrous subjects. Estrous subjects showed a significant preference for the male goal (M) versus the estrous female (ES), diestrous female (DS), and empty goals, respectively. Estrous subjects also showed a preference for the ES and DS goals when one goal was left empty. Anestrous subjects showed a preference for the goal containing ES, DS, and M compared to empty goals. They also showed a preference for ES vs. DS. The Y-maze is a tool that can be used to assess sexual and social partner preferences in female goats. The role the female plays in choosing a partner may be much greater than previously considered.

Variation in male sexual behavior.

Relaxation of natural selection on sexual performance traits in male ruminants has increased phenotypic variation in these heritable traits. Thus, males with sub-standard sexual performance continue to reproduce. This has created a "dud" phenomenon that is costly to animal agriculture. Identification and culling of these lesser performers at an early age and identification of high performing males are critical management goals that must be addressed, and for which greater research priority is needed.

Sexual behavior of domesticated ruminants.

Domesticated ruminants have lived in close association with humans for thousands of years and knowledge of the behavior of these organisms has contributed to their successful domestication, as well as to the management of animals in captivity, both extensive and intensive. Here we describe the reproductive behavioral endocrinology of cattle, goats and sheep. These relatively large and tame animals provide opportunities to conduct a wide range of behavioral studies from short-term to longitudinal or developmental in nature. Highlighted is some of the work from our laboratory describing the social, environmental and endocrine factors that influence the expression of sexual behavior in male and female goats.

Female-female mounting among goats stimulates sexual performance in males.

The hypothesis that female-female mounting is proceptivity in goats, in that male goats are aroused by the visual cues of this mounting behavior, was tested. Once a week, male goats were randomly selected and placed in a test pen in which they were allowed to observe one of six selected social or sexual stimulus conditions. The stimulus conditions were one familiar male with two estrous females (MEE); three estrous females that displayed female-female mounting (E(m)); three estrous females that did not mount (E(nm)); three non-estrous females (N(E)); three familiar males (M); and no animals in the pen (Empty). After 10 min, the stimulus animals were removed, and an estrous female was placed in the test pen with the male for a 20-min sexual performance test. During sexual performance tests, the frequencies and latencies of all sexual behaviors were recorded. This procedure was repeated so all males (n = 6) were tested once each test day, and all the stimulus conditions were presented each test day. This was repeated weekly until all males had been exposed to each stimulus condition. Viewing mounting behavior, whether male-female or female-female, increased the total number of sexual behaviors displayed, increased ejaculation frequency, and decreased latency to first mount and ejaculation, post-ejaculatory interval, and the interval between ejaculations. We conclude that male goats are aroused by the visual cues of mounting behavior, and that female-female mounting is proceptivity in goats.

Divergent roles for estrogens and androgens in the expression of female goat sexual behavior.

We tested the hypothesis that the activation of the androgen receptor (AR) is required for full expression of female goat sexual behavior. Once a week for 6 weeks, ovariectomized (OVX) females were given priming doses of progesterone 72 and 48 h before behavioral observation. Estradiol (E(2); 100 microg), testosterone (T; 100 mg), or sesame oil was supplied 14 h before behavioral testing. Six goats received the AR antagonist flutamide (9 mg/kg sc) 8 h before and 4 h after steroid injection. Six goats received the carrier only. After 3 weeks, flutamide and carrier treatments were switched so that all females received all treatments. Treatments with E(2) and T were equally effective in eliciting estrus-typical behaviors (sniffing, courting, leg kicks, mount attempts by males, bouts of thrusting by males, ejaculations, and flehman responses) compared to treatment with oil. Flutamide treatment enhanced proceptive behaviors in E(2)-treated females compared to other treatment groups; this was most likely via enhanced tail wagging. Moreover, compared to goats given T + carrier, T + flutamide significantly reduced receptivity in females. The results of this experiment implicate the AR as an important facilitator of some aspects of the female goat sexual behavior. However, the results of this experiment do not show whether androgens influence estrous behaviors alone or in some combination with estrogen.