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Biomedical subjects

E O Price

Publications and source records attributed to E O Price.

At least 37 records · Page 2Linked to original sources
PubMed1990

Short-term individual housing temporarily reduces the libido of bulls.

The objective of the present study was to determine the effects of short-term (6 wk) individual housing on the sexual interest (libido) of sexually experienced bulls. Twenty-two Hereford bulls reared with both males and females (BMF) or in all-male groups (BM) and approximately 21 mo of age were given free access for 40 min to five restrained females in hormonally-induced estrus and restricted access for 30 min to a single enclosed estrous female on two separate occasions. Free-access tests were administered to bulls in groups of five or six individuals, whereas bulls were tested individually in restricted-access tests. After testing, half the animals were housed individually (physically isolated from conspecifics) and half remained in group housing for a 6-wk period. Libido tests were administered again at the end of the treatment period and 2 wk after reinstatement of group housing for the experimental subjects. Individually housed bulls exhibited fewer mounts (P less than .001) and spent less time with females (P less than .01) in tests administered during physical isolation than before or after treatment. Individual housing did not affect BMF and BM bulls differentially. In conclusion, short-term individual housing temporarily reduced libido of beef bulls.

Aggression↗
PubMed1988

Social modulation of pituitary-adrenal responsiveness and individual differences in behavior of young domestic goats.

The effects of three variables known to influence pituitary-adrenal activity were examined in kid goats who were accompanied by adult goats in standard goat-human encounters. Serum corticosteroid concentrations in bold kids who characteristically spent above average amounts of time closely interacting with the person were never significantly different from control values. Corticosteroids in timid kids who spent little time near the person depended on the adult goat's behavior toward the person and the nature of the social relationship between the kid and the adult goat. When timid kids were accompanied by adult goats (familiar pen-mates or strangers) who behaved as if they were fearful of the person, their corticosteroids were significantly greater than control values. In contrast, bold pen-mates or bold strangers effectively reduced pituitary-adrenal responsiveness in timid kids. Only mothers unconditionally reduced kid pituitary-adrenal responsiveness and systematically affected kid behavior toward the person. The functioning of behavioral and pituitary-adrenal systems in young goats was influenced by consistent individual differences in responsiveness and the differing capacities of social companions to modulate this responsivity.

Adrenal Cortex Hormones↗
PubMed1988

Sexual behavior of male dairy goats: effects of deafferentation of the genitalia.

The following study examines the effects of deafferentation of the penis, scrotum, prepuce and adjacent cutaneous surfaces on the development of mounting behavior in male dairy goats. Ten males underwent surgical deafferentations and 10 males received sham operations at 8 to 12 weeks of age. Mounting and other sexual behaviors were monitored while subjects were cohabiting with male and female penmates and when individually exposed to estrous females. Denervated males mounted penmates less frequently than sham controls and lacked vigorous thrusting behavior. When exposed to estrous females denervated goats did not exhibit the normal progression from shallow to deep thrusting with successive mounts and failed to attain intromissions and ejaculations. However, frequency of mounting was similar to that of controls when the latter were prevented from attaining intromissions. It was concluded that sensory feedback from the genitalia and surrounding cutaneous areas is not required for the initiation of leg-kicking behavior in male dairy goats but plays an important role in the development and maintenance of normal patterns of thrusting behavior. Because it was not possible to determine the rate at which reinnervation occurred, the extent to which mounting behavior depends on sensory feedback could not be determined.

Afferent Pathways↗
PubMed1988

Sexual performance of rams reared with or without females after weaning.

The objective of this study was to determine the effect of postweaning exposure to females on the subsequent sexual performance of young rams. Twenty-five crossbred rams were reared in a group with ovariectomized females from 4.5 to 9 mo of age. Ewes were brought into estrus every 2 wk during this period. A companion group of 23 crossbred rams was not exposed to females following weaning. Four 30-min sexual performance tests were administered at 10 mo of age. Rams reared with males and females (RMF) exhibited more mounts (P less than .001) and more ejaculations (P less than .002) than rams reared only with males (RM). The frequency of successful matings by the latter group did not increase with experience. Nine rams were sexually inactive in the sexual performance tests. Follow-up tests revealed that two of the RMF rams and one RM ram developed and maintained a sexual preference for males. The six remaining rams eventually mated with females when tested in familiar pens and subsequently exhibited normal levels of sexual performance even when tested in an unfamiliar enclosure. Exposure to ewes during the postweaning prepubertal period enhanced sexual performance. However, early exposure to females did not ensure that all males developed sexual preferences for females. The environmental context in which sexual performance tests are administered may inhibit the expression of heterosexual behavior in a small percentage of animals. After heterosexual behavior was expressed, the rams continued to show normal levels of sexual performance.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Bulls fail to show preference for estrous females in serving capacity tests.

Eighteen sexually experienced Hereford bulls were exposed individually to a pair of restrained hormone-induced estrous and nonestrous females to determine mating preferences in the context of serving capacity testing. No evidence was obtained to support the hypothesis that restrained estrous females are more attractive to bulls than restrained nonestrous females. Estrous and nonestrous females received similar numbers of mount intentions, mount attempts, mounts without ejaculations and ejaculations during the 20-min tests. Time spent with estrous and nonestrous females and latencies to leave initially chosen estrous and nonestrous females to investigate the alternative female also were similar. Bulls interacted more with the females that they contacted first, regardless of estrous condition. A female position effect was noted. We conclude that restrained nonestrous females are as effective as restrained estrous females in assessing the serving capacity of Hereford bulls.

Animals↗
PubMed1987

Male sexual behavior.

This article considers causes of variability in male sexual performance and identifies management techniques that can be used to improve the reproductive success and efficacy of our captive animal populations.

Animals↗
PubMed1987

Fostering lambs by odor transfer: the add-on experiment.

Lamb-specific odor is used by ewes to discriminate between their own and alien offspring. Recent studies have demonstrated that fostering can be facilitated by transferring own-lamb odor to alien lambs via cloth stockinettes. The objective of the present study was to investigate the effectiveness of the odor-transfer technique in enticing ewes with a single lamb to adopt an additional lamb ("add-on" procedure). Shortly after birth, nylon stockinettes were placed on the single offspring of 49 ewes and 49 additional alien lambs designated for fostering. Approximately 20 h following parturition, stockinettes were removed from 41 natural lambs and placed on alien lambs (experimental treatment). In the control treatment (eight ewes) own and alien lambs retained their own stockinettes. Four acceptance tests were conducted, 24 h apart, starting at the onset of fostering. Successful adoptions were attained for 21 of 31 experimental ewes (68%) exposed to add-on lambs similar in facial coloration to their own lambs. Only 2 of 10 experimental ewes (20%) with whiteface natural lambs adopted blackface add-on lambs. One of eight control ewes (12.5%) adopted an add-on lamb. Of the 24 ewes that adopted alien lambs 10 (41.7%) demonstrated immediate acceptance and 20 (83.3%) had adopted lambs by the second test day. A higher proportion of primiparous than multiparous ewes adopted alien lambs. The presence of own-lamb odor on stockinettes worn by add-on lambs appears to facilitate fostering. However, the presence of own-lamb odor may not be a significant-enough cue to override obvious differences in facial coloration between own and add-on lambs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Effects of the nonagouti pelage-color allele on the behavior of captive wild Norway rats (Rattus norvegicus).

The objective of the present study was to determine the extent to which the nonagouti pelage-color allele influences selected behaviors (including docility) of the wild Norway rat. Agouti and nonagouti (black) littermates were compared in tests for handling, open-field behavior, platform jumping, and response to a novel food item, all of which clearly differentiate wild and domestic rats. Nonagouti rats were significantly easier to approach, capture, and handle than their agouti sibs. However, differences between agouti and nonagouti rats for the other variables studied were not significant. Although the presence of the nonagouti allele cannot fully account for the behavioral differences between wild and domestic Norway rats, it may have facilitated the domestication of this species by improving ease of handling.

Alleles↗
PubMed1986

The role of penile stimulation and ejaculatory experience on the development and maintenance of reproductive behavior in the bull (Bos taurus).

To determine the role of afferent input from the penis and copulatory experience on the ontogeny of reproductive behavior, 49 bulls were randomly assigned to the following groups: control; surgical penile deflection (penis deviation), which prevents intromission; penile neurectomy; or penis deviation plus neurectomy. Sexual performance tests were conducted at 3-month intervals from 9 to 24 months of age. Bulls deviated but not neurectomized mounted more frequently than bulls in the other groups. The low mount frequency for control bulls in tests in which copulation occurred was due to the sexually quiescent postejaculatory refractory period. Preventing control bulls from copulating by affixing cloth patches to females' perinea increased mount frequency to the level of deviated bulls. It is concluded that copulatory experience is not essential to the development and maintenance of normal mounting activity. However, sensory stimulation from the penis facilitates the expression of sexual behaviors.

Afferent Pathways↗
PubMed1986

Inability to predict sexual and aggressive behaviors by plasma concentrations of testosterone and luteinizing hormone in Hereford bulls.

The relationships between sexual and aggressive behaviors and levels of plasma testosterone and luteinizing hormone (LH) were examined in Hereford bulls at 18 and 24 mo of age. Concentrations of hormones in bulls during periods of sexual rest (13 blood samples collected from each animal during a 24-h period) were compared with individual differences in sexual and aggressive behaviors when exposed to restrained females, either individually or in groups. Nearly all correlation coefficients were low and nonsignificant. It was concluded that individual differences in sexual performance and aggressive behavior cannot be predicted based on circulating levels of testosterone and LH in bulls during periods of sexual rest.

Aggression↗
PubMed1984

Behavior of ewes and lambs subjected to restraint fostering.

The objective of this study was to investigate the development of maternal-filial social attachments between ewes and alien lambs using the technique of "restraint fostering." Forty-eight to 72 h after parturition, 22 Targhee -type ewes were separated from their natural lambs, placed in restraining devices ( stanchions ) and each exposed to a single alien lamb. After a period of 1 or 4 d of restraint, the ewes were subjected to five 10-min lamb acceptance tests over a 48-h period. The observer recorded butts and butt attempts by the ewe and successful and unsuccessful suckle attempts by the lamb. The ewe-lamb pairs were then housed in pens with other groups of ewes and lambs and observed intermittently for acceptance behaviors. Six of the 14 ewes restrained for 4 d and none of the eight ewes restrained for 24 h met the criterion for successful adoption within 48 h. After being housed in group pens, adoptions were achieved by three ewes in the 1-d group and an additional four ewes in the group restrained for 4 d. Ewes restrained for 24 h were significantly more aggressive toward fostered young than ewes restrained for 4 d. In addition, the proportion of successful suckling attempts was significantly lower for lambs fostered on ewes in the 1-d group. Both groups showed a decline in butts and butt attempts over successive acceptance tests, but while the proportion of successful suckling attempts declined for lambs housed with 1-d ewes, they increased over time for lambs fostered on ewes restrained for 4 d.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The effects of sexual stimulation on the sexual performance of Hereford bulls.

In the present study, 12 Hereford bulls approximately 22.5 mo of age were individually introduced to a restrained nonestrous stimulus female for 15 to 30 min under four treatment conditions: (1) without prior sexual stimulation and visually isolated from male conspecifics (control), (2) being watched by another male during matings, (3) after observing the copulatory activities of another male and (4) after being restrained in close proximity to a female. During sexual performance tests, an observer recorded the times at which the bulls exhibited ejaculations, mounts without ejaculation, mount attempts, mount intentions, head throws and Flehmen responses. The observer also recorded the percentage of time spent in proximity to the stimulus female and objectively rated the bulls for overall sexual performance and mating efficiency. Relative to the control treatment, the greatest improvement in sexual performance was noted when the bulls had observed the copulatory activities of conspecifics. Sexual performance was improved, albeit to a lesser degree, by being watched by another male and by restraint in the presence of the stimulus female. The advantages of sexual stimulation should be considered when breeding farm animals and when evaluating the sexual performance of males to be used in a breeding program.

Animals↗
PubMed1984

Fostering lambs by odor transfer: the substitution experiment.

Lamb-specific odor is used by ewes to discriminate between their own and alien offspring. The objective of the present study was to investigate the feasibility of transferring own-lamb odor to alien young to facilitate fostering. Shortly after birth, cloth stockinettes (body suits) were placed on the offspring of 37 multiparous ewes. At 48 to 72 h after parturition, a lamb from each ewe was replaced by an alien lamb. In 31 cases the odor-impregnated stockinette of the ewe's own lamb was placed on the alien lamb; in the remaining six cases the alien lamb retained its own stockinette (control condition). Lamb acceptance tests were conducted every 12 h for 2 d after fostering and once daily for the following 2 d. Twenty-six of the 31 experimental ewes (84%) adopted alien lambs using the odor-transfer technique. All of the control lambs were rejected. Of the 26 ewes that adopted foster young, 10 (38%) showed immediate acceptance and 22 (85%) were exhibiting acceptance behaviors by 36 h after fostering. There were no significant differences in the fostering success of ewes bearing single lambs and those with twins. The presence of own-lamb odor rather than the absence of alien lamb odor appears to be the salient cue for lamb acceptance. Lamb-specific odor transfer represents a relatively inexpensive and rapid technique to achieve maternal acceptance of alien lambs by postpartum ewes.

Animals↗
PubMed1981

Sexual maturation and fecundity of wild and domestic Norway rats (Rattus norvegicus).

A population of captive-reared wild Norway rats and two stocks of domestic rats were compared for various parameters of sexual maturation and fecundity. Males did not differ in age at the first appearance of spermatozoa in the testes but wild males were significantly older than Long--Evans and Sprague--Dawley domestic males at first copulation with a hormone-induced oestrous female. Wild females were significantly older than domestic females at the time of vaginal opening, first oestrus and first conception. Stocks did not differ in length of the first oestrous cycle. Wild females produced significantly smaller litters than their domestic counterparts. Domestic rats were significantly heavier than wild rats at the various stages of sexual maturation. The results support the hypothesis that domestication of the rat has been accompanied by genetic and/or environmental changes that accelerate sexual development and improve breeding success under laboratory conditions.

Age Factors↗
PubMed1980

Sexual behaviour and reproductive competition in male wild and domestic Norway rats.

The copulatory behaviour of male wild Norway rats (Rattus norvegicus) exposed individually to females in hormone-induced oestrus is characterized by fewer mounts and intromissions per ejaculatory series, shorter ejaculation latencies, and longer ejaculatory clasps than the copulatory behaviour of domestic males. Competition between wild and domestic males testes simultaneously in pairs produced only minor changes in copulatory behaviour. The reproductive success of wild and domestic male pair simultaneously exposed to naturally cycling females was nearly equal in both the laboratory and an outdoor enclosure. Genotype of the female had little effect on male copulatory behaviour. The copulatory behaviour of sexually naive and experienced domestic rats did not differ. However, most sexually naive wild males failed to exhibit copulatory behaviour under the test conditions employed.

Animals↗
PubMed1980

Discrimination learning in horses: effects of breed, age and social dominance.

The discrimination learning ability of Quarter Horses and Thoroughbreds was compared by means of visual cues in a three-choice test with food as a reward. Quarter Horses learned significantly faster than Thoroughbreds, and learning progressed more rapidly for both breeds in a second discrimination task. Significant negative correlations were observed between age and rate of learning. Quarter Horses tended to be less reactive than Thoroughbreds, but individual emotional reactivity ratings and learning scores were not correlated. No correlation was found between social dominance and learning scores. Learning studies with horses may provide a better understanding of the behavioral traits that influence trainability in this species.

Aging↗