Fish meal supplementation increases bovine plasma and luteal tissue omega-3 fatty acid composition.

The objective of this experiment was to determine if dietary inclusion of fish meal would increase plasma and luteal tissue concentrations of eicosapentaenoic and docosahexaenoic acids. Seventeen nonlactating Angus cows (2 to 8 yr of age) were housed in individual pens and fed a corn silage-based diet for approximately 60 d. Diets were supplemented with fish meal at 5% DMI (a rich source of eicosapentaenoic acid and docosahexaenoic acid; n = 9 cows) or corn gluten meal at 6% DMI (n = 8 cows). Body weights and jugular blood samples were collected immediately before the initiation of supplementation and every 7 d thereafter for 56 d to monitor plasma n-3 fatty acid composition and BW. Estrous cycles were synchronized using 2 injections of PGF(2α) administered at 14-d intervals. The ovary bearing the corpus luteum was surgically removed at midcycle (between d 10 and 12) after estrus synchronization, which corresponded to approximately d 60 of supplementation. The ovary was transported to the laboratory, and approximately 1.5 g of luteal tissue was stored at -80°C until analyzed for n-3 fatty acid content. Initial and ending BW did not differ (P > 0.10) between cows supplemented with fish meal and those with corn gluten meal. Plasma eicosapentaenoic acid was greater (P < 0.05) beginning at d 7 of supplementation and docosahexaenoic was greater (P < 0.05) beginning at d 14 of supplementation for cows receiving fish meal. Luteal tissue collected from fish meal-supplemented cows had greater (P < 0.05) luteal n-3 fatty acids and reduced (P < 0.05) arachidonic acid and n-6 to n-3 ratio as compared with tissue obtained from cows supplemented with corn gluten meal. Our data show that fish meal supplementation increases luteal n-3 fatty acid content and reduces available arachidonic acid content, the precursor for PGF(2α). The increase in luteal n-3 fatty acids may reduce PGF(2α) intraluteal synthesis after breeding resulting in increased fertility in cattle.

40- and 70-kHz vocalizations of mice (Mus musculus) during copulation.

Ultrasonic vocalizations were tape recorded from five pairs of copulating mice and subjected to spectrographic analysis. As expected, the mice emitted numerous 70-kHz vocalizations. At the beginning of the test, before copulation began, 70-kHz calls were emitted almost continuously, while calls with lower spectrographic frequencies were not observed. Subsequently, bursts of 70-kHz calling generally began shortly before mounts and intromissions and persisted until dismount. Intermixed with these 70-kHz calls were additional vocalizations of about 40 kHz. Calling rates were highest just prior to intromission. Once intromissions began, 70-kHz calls continued at a lower rate until dismount; however, 40-kHz calls occurred infrequently. In a second experiment, the male was found to emit the majority of the 70-kHz calls and all of the 40-kHz calls. When the male was devocalized, few calls were detected, regardless of whether the female was able to call. If the male was not devocalized, high rates of calling were detected, even if the female was devocalized.

Pup's broadband vocalizations and maternal behavior in the rat.

Rat pups emit broadband vocalizations with components extending from the audible to the ultrasonic range. Three experiments were undertaken to determine the circumstances under which the calls are emitted, and the effects that they might have on the maternal female's behavior. In the first study, pups were manipulated by the experimenter in several different ways. Broadband calling occurred when the pup was picked up and moved off the horizontal plane. In a second study, the mother was observed interacting with her litter. Vocalizations occurred most often when the mother engaged in behaviors that brought her into contact with the pups, such as nest entry, moving while in the nest, and pup licking. In another experiment, females were temporarily deafened. Relative to controls, deafened females engaged in more incidental contact with the pups, although only if the female was deafened during the first of two tests, when the pups were two days old. Broadband calling may function to reduce rough handling or inadvertent contact by the mother.

Do vocalizations of the male rat elicit calling from the female?

Female rats emit calls during copulation that appear to be associated with their own proceptive behavior. In an earlier study, we had determined that females emit calls when presented with odor cues from a sexually competent adult male. Two experiments were undertaken to determine whether females would vocalize when presented with tape recorded male ultrasonic vocalizations. In the first females were presented with no calls, male mating calls or male preejaculatory calls. They received one test in each sound condition with a devocalized male in the immediate vicinity and one test with no male present. Females tested alone called at a lower level than those tested in the presence of a devocalized male. The presence of male calls did not significantly increase the frequency of calling in females tested in the presence of a male. When females were tested alone, however, calling did increase significantly when male mating calls were presented, but not when preejaculatory calls were presented. In a second experiment, it was confirmed that male mating vocalizations elicited more calls from the female. Thus, male mating calls may elicit vocalizations from the female, but are less effective than male odor cues.

Regulation of rat maternal behavior by broadband pup vocalizations.

Pups emit a broadband vocalization ranging from 2 to 40 kHz that generally occurs when the mother sits or steps on her pups. In an earlier study (Ihnat, White, and Barfield, under review), we noted that the mother was more likely to move on the pups and step on them when she was temporarily deafened with ear plugs. This research was extended in the present study by using two different methods to prevent 2-day-old pups from emitting broadband vocalizations. In the first experiment, the female was presented with six of her pups for a 10-min test. In half the tests, the pups had been anesthetized with pentobarbital; in the other half, the pups received saline. In the second experiment, females were presented with pups whose mouths had been sealed with an adhesive substance. In a final study, pups received the adhesive substance on their ventral surface as a control. When the pups were unable to vocalize, there was an increase in the amount of time per bout that the mother spent in incidental contact with her pups; in the sham condition, however, there was no change in her behavior. In addition, the female was less likely to group all her pups within the 10-min duration of the test when the pups could not call. Since pups emit primarily broadband vocalizations in response to handling prior to 4 days of age, broadband calls appear to reduce incidental contact and facilitate retrieval into a group.

Variations in scent marking and ultrasonic vocalizations by Long-Evans rats across the estrous cycle.

The purpose of the present study was to investigate whether the signaling behaviors of female Long-Evans rats varies over the estrous cycle. Scent marking and 50-kHz ultrasonic mating vocalizations, in response to a devocalized sexually experienced male, changed in frequency across the cycle, both behaviors being highest at proestrus/early estrus. Vocalizations were recorded on every day of the cycle and also in females showing no regular cycles. In contrast, scent marking was rarely observed during the estrous cycle except at proestrus/early estrus. These results suggest that both behaviors, which increase around the time of sexual receptivity, may help to coordinate reproduction and further suggest an endocrine basis for the changes observed over the estrous cycle.

Sensory cues that elicit ultrasonic vocalizations in female rats (Rattus norvegicus).

Female rats emit ultrasonic vocalizations during copulation. Female vocalizations are associated with darting and other proceptive behavior. In addition, females frequently call while approaching the male. A series of experiments was undertaken to determine whether female rats emit ultrasonic vocalizations in response to other rats or to their odors. Females were exposed either to bedding soiled by males or females or to devocalized conspecifics separated from the subject by a barrier. Females vocalized more to male cues than to female cues, regardless of whether the odor cues were from soiled bedding or from a devocalized conspecific. In addition, subjects vocalized more when presented with a devocalized female rather than a neutral stimulus. Furthermore, devocalized adult males, separated by a barrier, were more effective than either devocalized castrated or juvenile males in eliciting vocalizations; in turn, castrates and juveniles were more effective than neutral stimuli. Female calling was likely induced by odors from the male. In one experiment, the female subject was positioned in such a way that she could neither see or touch the stimulus male. Presentation of tape-recorded male vocalizations did not affect calling by the female. Vocalizations emitted by females in response to male odors may attract males or may facilitate subsequent copulatory behavior by the male.

Changes in mating vocalizations over the ejaculatory series in rats (Rattus norvegicus).

Rats (Rattus norvegicus) produce ultrasonic calls during mating. We examined changes in the structure and pattern of such vocalizations over the ejaculatory series. In Experiment 1, vocalizations were recorded from 11 pairs of rats through 3 ejaculatory series and analyzed spectrographically. We classified 4 categories of call by spectral frequency and duration. Calls of low frequency, long duration, and high intensity occurred more often shortly before the ejaculation and were associated with mounting without intromission, a behavior that often occurs shortly before ejaculation. The high-frequency calls did not vary in number across the series. In Experiment 2, vocalizations were recorded from males paired with devocalized females. Males produced all vocalization patterns produced by pairs in Experiment 1. Results suggest that most pre-ejaculatory calls are produced by males and may potentially affect female sexual behavior.

Effects of male pre-ejaculatory vocalizations on female receptive behavior in the rat (Rattus norvegicus).

Both male and female rats (Rattus norvegicus) emit ultrasounds during copulation. Bursts of ultrasounds from males that occur as ejaculation approaches are lower in frequency, longer in duration, and louder than those that appear earlier in the ejaculatory series. We attempted to determine if these pre-ejaculatory calls affect female sexual behavior. The behavior of females paired with devocalized males was compared with that of females paired with intact males, and in a second experiment tape-recorded vocalizations were played to females paired with devocalized males. Females were less receptive when paired with devocalized males; they were less likely to remain stationary when males attempted to mount. Playback of both types of calls restored female immobility toward control levels, although pre-ejaculatory calls were more effective than mating ones. Pre-ejaculatory calls restored running and training levels somewhat toward control level but to a lesser extent than female immobility.

Receptivity of the female rat (Rattus norvegicus) after male devocalization: a ventral perspective.

Male rats (Rattus norvegicus) emit at least two patterns of vocalization during copulation, the mating call and the pre-ejaculatory call. Both calls promote immobility of the female during lordosis, but the pre-ejaculatory calls are more effective. We undertook, through ventral observations of the mating pair, to determine if the female failed to assume or maintain the lordosis posture when mounted by a devocalized male and also to determine if the devocalized male was providing adequate stimulation to induce receptive behavior. Females were more likely to move away from the devocalized males before assuming the full lordosis posture. Furthermore, they were more likely to move away before the males had a chance to engage in intromissive behavior. However, when the females remained immobile long enough for the males to achieve a mount or intromission, there was little difference in the behavior of either animal that resulted from the devocalization of the male.

Mediation of rat postejaculatory 22 kHz ultrasonic vocalization by dopamine D2 receptors.

We investigated the role of dopamine receptor subtypes in the regulation of ultrasonic vocalization and masculine copulatory behavior. Intact sexually experienced male Long-Evans rats were treated with saline, selective dopamine D1 (SKF 38393) and D2 (LY 171555) receptor agonists and with selective dopamine D1 (SCH 23390) and D2 (raclopride) receptor antagonists 15 and 30 min before the 30-min test session, respectively. Mating stimuli were ovariectomized female rats injected SC with estradiol benzoate (8 micrograms/0.1 ml/rat) and progesterone (200 micrograms/0.1 ml/rat), 48 and 4 hr before the test session, respectively. We found a decrease in the number of intromissions required to reach ejaculation in animals treated with SKF 38393 (10 mg/kg/IP), LY 171555 (doses ranging from 0.01 to 0.5 mg/kg/SC) and with raclopride (0.1 mg/kg/SC). LY 171555 reduced the postejaculatory vocalization (PEV) in a dose-dependent fashion with complete suppression at the highest dose. No other parameters of sexual behavior were affected by this treatment. Raclopride, a dopamine D2 receptor antagonist, antagonized the suppressive effects of the D2 agonist LY 171555 on the PEV (and also decreased the number of intromissions to reach ejaculation), whereas SCH 23390, a dopamine D1 receptor antagonist, did not. Raclopride, given alone at the dose of 0.5 mg/kg/SC, almost completely suppressed all behavioral activity, whereas the lower dose (0.1 mg/kg) decreased intromission frequency and increased the length of the 22 kHz PEV. Therefore, we suggest that 22 kHz PEV is under the control of dopamine D2 receptors.

Playback of female rat ultrasonic vocalizations during sexual behavior.

Both male and female rats emit ultrasonic vocalizations during mating. In an earlier study, female vocalizations were shown to be associated with female darting: when the female was devocalized, she increased her rate of darting. In a preliminary playback study, tape-recorded female ultrasounds were presented to devocalized females paired with intact males. Darting was reduced towards presurgical control levels. In this study, the playback experiment was replicated using a refined procedure to present female ultrasounds to the mating rats. Taped vocalizations were obtained from females, and were presented in a manner which more closely approximated the patterning of ultrasound production seen in the intact female. Each rat pair was tested three times: once prior to the devocalization of the female, and twice afterwards. In one postsurgical test, taped ultrasounds were presented during mating; in the other, tape hiss was presented. Several patterns of behavior increased in frequency when the female was devocalized relative to the control condition, but decreased when tape recorded ultrasounds were presented. These patterns included female darting and approaches towards the partner by both males and females. The darting results confirm and extend the findings of our earlier paper. Changes in approach behavior were not observed previously because the male was confined in the earlier study. This study contains the first direct evidence that female vocalizations affect the socio-sexual behavior of the male.

Subtle behavioural changes produced in rat pups by in utero exposure to haloperidol.

Prenatal exposure to a dopamine receptor blocking agent such as haloperidol (given to the mother at a dose of 0.5 mg/kg s.c. from day 4 to day 15 of gestation) produced subtle behavioural changes in rat pups. Haloperidol decreased the rate of ultrasonic vocalization in 4-day-old male pups removed from the nest. The changes in ultrasonic emission elicited by in utero exposure to this neuroleptic were markedly different from those produced by its administration during the early postnatal period. Moreover, adult male rats treated prenatally with haloperidol exhibited a significant increase in the intensity of ultrasonic 22 kHz post-ejaculatory calls emitted during sexual behaviour. The duration of the period of the 22 kHz calls emission was also significantly increased by haloperidol treatment. These results confirm that ultrasonic vocalization in rats is a sensitive indicator of subtle changes in adverse treatments administered during development.

Role of the ultrasonic vocalization of the female rat (Rattus norvegicus) in sexual behavior.

Both male and female rats vocalize ultrasonically during mating. Whereas male calls are known to facilitate female proceptive behavior, the female mating call has not been studied beyond spectrographic analysis. In this article, a series of experiments were done to examine the effects of the female's mating call on rat mating behavior. In the first experiment, females copulated with intact males before and after surgical devocalization. In the second experiment, intact females copulated twice with a male: once when they were able to hear and once when they were temporarily deafened with a medical ear mold. In the third experiment, tape recorded ultrasounds were placed in the presence of devocalized females while they were copulating with intact males. In the control condition, tape hiss was presented. In each experiment, it was observed that the female darted more if communication were disrupted (i.e., female devocalized or male deafened). Playback partially reduced darting to control levels. No other behavior was affected consistently across all experiments. Female calls might facilitate self-regulation of mating behavior, or they might focus the male's attention on her proceptive behaviors. It is also possible that the female calls could alter the stimulus properties of the male's behavior, indirectly affecting her own behavior.