Larry S. Katz

The relationship of male-male mounting to the sexual preferences of young rams

Abstract The purpose of this study was to determine the relationship between the frequency of male-male mounting of young rams in all-male groups and their subsequent preferences for female vs. male sexual partners. Mount interactions were monitored in the home pen of 29 rams reared in 1984 and 25 rams reared in 1985. At ∼ 8–10 months of age, and prior to copulatory experience, individual rams were simultaneously exposed to two unfamiliar estrous ewes and two unfamiliar rams. The four stimulus animals were restrained and cloth covers were placed over their perinea to prevent copulations. The Binomial Test was used to verify sexual preferences. Of the 44 rams that were sexually active in the sexual performance tests, 30 (68.2%) met the criterion for female preference, 4 (9.1%) preferred males and 10 (22.7%) exhibited no preference (i.e., were bisexual in orientation). There was little relationship between the frequency of male-male mounting by rams in all-male rearing groups and their subsequent sexual preferences. The majority of young rams prefer to mount ewes, even prior to copulatory experience, but in the absence of females will often mount other males.

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.

Role of the Vomeronasal Organ in Neonatal Offspring Recognition in Sheep

Abstract Twenty-five pregnant Dorsett ewes were randomly divided into three groups to test if ewes use their vomeronasal organs for offspring recognition during nursing. One group of eight ewes (procaine) were made anosmic by irrigation of the nasal olfactory apparatus with a zinc sulphate procaine solution. The second group of nine ewes (cauterized) had their vomeronasal organs rendered nonfunctional by cauterization of the nasoincisive duct. The third group of eight ewes were the controls. Parturition was synchronized in all ewes with betamethasone on Day 145 of gestation. Maternal responsiveness was tested two separate times with 1- to 2-day-old alien lambs. Each alien lamb trial was conducted 24 h apart. Cauterized ewes allowed alien lambs to suckle and they were unable to distinguish alien lambs from their own lambs, whereas the ewes in both groups with functional vomeronasal organs (procaine and control) violently rejected any alien lambs attempt to suckle. Thus, female sheep use their vomeronasal organs for neonatal offspring recognition.

Sexual stimulation of male dairy goats

Abstract The objective of the present study was to investigate methods for enhancing the sexual performance of male dairy goats in the context of controlled breeding (“hand-mating”) and semen collection. Nine male goats were individually exposed to a single restrained estrous female who served either as a natural-mating stimulus or as a teaser female for semen collection. Tests were conducted under four conditions: (1) with another male watching in a runway adjacent to the test arena (W); (2) after observing the previously tested male court and copulate with the stimulus female (S); (3) a combination of the aforementioned two treatments (SW); (4) an unstimulated control treatment (C). In the natural-mating tests, sexual performance was significantly enhanced by each of the forms of stimulation. Differences in sexual performance under the three stimulation treatments were not statistically significant. In the artificial-mating tests, latencies to mount and ejaculate (into the artificial vagina) were significantly shortened by the S and SW treatments, but not by being watched (W treatment). Again, stimulation treatments did not differ significantly. Sexual stimulation did not affect semen volume or concentration. The improved sexual performance of stimulated male goats may result in a significant sav saving of time and labor to animal breeders involved in hand-mating or semen collection.

Progesterone Facilitation and Inhibition of Estradiol-Induced Sexual Behavior in the Female Goat

The effect of progesterone (P4) on estradiol (E2)-induced sexual behaviors in ovariectomized French-Alpine goats, during both the breeding (fall) and the nonbreeding (spring) seasons, was examined. Progesterone facilitated E2-induced attractivity and receptivity in the nonbreeding season when P4 treatment occurred 48 or 72 hr prior to treatment with E2. During the breeding season, P4 facilitated attractivity when treatment occurred 72 hr prior to E2 injection. In contrast, P4 inhibited all sexual behaviors when treatment occurred 12 or 24 hr prior to injection of E2. Progesterone did not facilitate E2-induced proceptivity in either the breeding or the nonbreeding seasons. These findings demonstrate that both season and temporal sequence of P4 and E2 administration affect sexual behavior in ovariectomized French-Alpine goats.

Behavioral observations of adolescent Holstein heifers cloned from adult somatic cells

Cloning using somatic cells offers many potential applications in biomedicine and basic research. The objective of this study was to test whether clones from the same genotype can be used as models to study the genetic influences of behavior. Specifically, several aspects of the behavior of four prepubertal heifers cloned from somatic cells of a 13-year-old Holstein cow along with age-matched control heifers were compared to determine whether juvenile clones from an aged adult behave similarly to their age-matched controls, and whether clones with identical genetic makeup exhibit any behavioral trends. Behavioral observations or behavior challenge tests were conducted to compare the following traits: vocalization, play behavior, movement frequencies, grooming, curiosity, and companion preference, as well as dominance and aggressiveness. From play behavior, movements and vocalization, we observed that these four juvenile clones of an aged genetic donor did not show behavioral indications of aging and were similar to their counterparts of comparable chronological age except that they tended to play less than controls. Behavioral trends were also observed in the clones that indicated that they exhibited higher levels of curiosity, more grooming activities and were more aggressive and dominant than controls. Furthermore, these four clones preferred each other or the donor as companions, which may indicate genetic kin recognition.

Exposure to a recently mated male increases ram sexual performance

Abstract Previous studies reported that male sheep sexual performance does not improve following the observation of heterosexual behavior, which is in contrast to male cattle, goats, pigs and horses. The purpose of this study was to investigate the possibility that exposure to a recently mated ram may enhance ram sexual performance. Eight sexually experienced rams (1 year of age) were assigned to either mated ram stimulus (MRS) or non-mated ram stimulus (NMRS) conditions in a switchback design. The rams in the MRS condition were briefly (10 min) exposed to a penmate who had mated an ewe immediately beforehand. The males in the NMRS condition were exposed to a penmate who had been placed in an empty pen. The rams were allowed to freely investigate their respective stimulus penmate and then each male was placed with an estrous ewe for 15 min. The frequencies of anogenital sniffs, leg kicks, flehmen lip curls, mount attempts, mounts and ejaculations were recorded. Ejaculatory latencies were also recorded. Mean courtship (anogenital sniffs and leg kicks) and mounting (mount attempts and mounts) behavior frequencies were higher for the MRS condition (P = 0.010 for both). Similarly, the individual mean frequencies of anogenital sniffs, leg kicks, mount attempts and mounts were higher when males interacted with a ram which had just mated (P = 0.046; 0.016; 0.048; 0.029, respectively). Mean flehmen lip curl and ejaculation frequencies were not different between the two conditions (P = 0.900 and 0.700). These data suggest that an odor cue associated with the ewe or mating, perse, was emitted by the penmate which was allowed to mate. This cue then enhanced the sexual performance of rams in the MRS condition.

Sexual behavior of farm animals

The field of sexual behavior of domestic farm animals is discussed with emphasis on studies of cattle, sheep and goats. Descriptions are provided of behaviors related to the attractivity, proceptivity and receptivity of females, as well as environmental and physiological factors influencing both male and female sexual behavior. The organizational and activational actions of steroid hormones on behavior are also reviewed.

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 males overall fitness.

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.