The right to die: an up-date on the law.
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Hawaii↗
Biomedical subjects
S J Wallach
Publications and source records attributed to S J Wallach.
Development of sexual and aggressive behaviors in Hereford bulls.
The purpose of this study was to describe maturation-related changes in the sexual and aggressive behaviors of Hereford bulls. Two groups of 13 and 14 bulls, respectively, were tested for sexual and aggressive behaviors every 3 mo from 3 to 24 mo of age. At 3 and 6 mo of age, the bulls were exposed, as groups, to two estrous females, whereas at 9, 12, 15, 18, 21, and 24 mo these bulls were tested under each of the following several treatment conditions: 1) individual tests (single males were exposed to single females), 2) small-group tests (three or four bulls:three females), 3) large-group tests (13 or 14 bulls:3 females), and 4) male-only tests (13 or 14 bulls were placed in the test arena in the absence of females). Most bulls consistently mounted females by 9 mo of age. Twenty-one of the 27 bulls (78%) attained their first ejaculation at either 12 or 15 mo of age. The frequency of mounting without ejaculation was greatest in large-group tests at 12 mo of age, and ejaculation frequency peaked at 18 mo. The incidence of male-male mounting in large-group tests (with females) did not appreciably change from 3 to 24 mo, whereas male-male mounting in male-only tests was greatest at 9 and 24 mo. We conclude that sexual performance data obtained in serving capacity tests administered to yearling bulls before 18 mo of age may underestimate the mating potential of certain individuals.(ABSTRACT TRUNCATED AT 250 WORDS)
Aggression↗
Sexual and aggressive behaviors of Hereford bulls: interrelationship of variables and problems with the use of composite scores to describe overall sexual performance.
The purpose of this investigation was to determine the interrelationships of the various sexual and aggressive behaviors exhibited by Hereford bulls in sexual performance (serving capacity) tests and to determine the extent to which these interrelationships change with age (maturity). Correlation matrices were constructed for the frequencies of sexual and aggressive behaviors exhibited by two groups of 13 and 14 bulls, respectively, during 120-min tests with females when the bulls were 12, 18, and 24 mo of age. The frequencies of selected sexual behaviors recorded during individual tests at 18, 21, and 24 mo were factor-analyzed using a principle components analysis. Also, a comparison was made of the length of the refractory periods following various sexual behaviors at 12 and 24 mo of age. Bulls varied greatly in the way they responded to sexual stimuli. Few sexual behaviors were intercorrelated and the factor analysis of selected sexual behaviors was inconclusive. Frequencies of aggressive behaviors were more highly correlated. Age (maturation) did not affect the interrelationship of the sexual behaviors recorded. Aggressive behavior variables were more highly correlated at 12 mo than at 18 or 24 mo of age. The average length of the refractory period following ejaculation was longer (112 s; P less than .05) than the refractory period following mounts without ejaculation (50 s), and the latter had a longer (P less than .05) refractory period than mount attempts, mount intentions and head throws (26 to 38 s).(ABSTRACT TRUNCATED AT 250 WORDS)
Aggression↗
Effects of group size and the male-to-female ratio on the sexual performance and aggressive behavior of bulls in serving capacity tests.
The purpose of the following study was to determine the effects of group size and the male-to-female ratio on the sexual and aggressive behaviors of bulls in the context of serving capacity tests. Tests were administered to two groups of 13 and 14 polled Hereford bulls, respectively, under four test conditions in which the number of bulls and the ratio of males to females was varied. The test conditions were as follows: 1) individual tests (single males were exposed to single females), 2) small-group tests (three or four bulls:three females), 3) large-group tests (13 or 14 bulls:3 females), and 4) male-only test (13 or 14 bulls were placed in the test area in the absence of females). In addition, the sexual performance of 44 Hereford and 12 Angus bulls was compared when competing (small-group tests) vs not competing (individual tests) for females. Ejaculation rate (serving capacity) was similar in individual and small-group tests in which a male-to-female ratio of approximately 1:1 was maintained. Increasing the male-to-female ratio to approximately 4.5:1 enhanced levels of aggression and reduced overall sexual performance. Angus bulls were more aggressive than their Hereford counterparts when competing for females and exhibited lower (P less than .05) ejaculation rates in small-group tests than when evaluated individually. We concluded that the sexual performance of polled Hereford bulls can be reliably evaluated when tested in small groups as long as a 1:1 male-to-female ratio is approximated.(ABSTRACT TRUNCATED AT 250 WORDS)
Aggression↗
Inability to predict the adult sexual performance of bulls by prepuberal sexual behaviors.
The objective of this investigation was to determine the extent to which the sexual performance of adult bulls (18 to 24 mo of age) can be predicted by prepuberal sexual behaviors. Tests were administered to 121 polled Hereford bulls to determine whether adult sexual performance (especially serving capacity or ejaculation rate) was related to 1) whether or not the subjects mounted estrous females at 6 mo of age, 2) the age at which the bulls attained their first ejaculation, 3) the frequency of sexual behaviors exhibited in heterosexual interactions and 4) the frequency of male-male mounting exhibited in all-male groups. None of the above measures reliably predicted adult serving capacity. Prepuberal interest in mounting other males and estrous females and the age at which ejaculatory competence was attained bore little relationship to serving capacity at 18 to 24 mo. Individual differences in rate of ejaculation were consistent from one age to another only after the bulls had reached 18 mo. We concluded that the sexual behaviors of prepuberal beef bulls were of limited usefulness in predicting adult sexual performance.
Animals↗
Sexual performance of rams as determined by maturation and sexual experience.
The purpose of this study was to compare the sexual performance of rams that differed in age (maturation) and sexual experience. Twenty-four ram lambs (8 mo of age) and 21 rams (20 mo of age) were individually exposed to four females in hormonally induced estrus for 30 min on five occasions, 7 d apart. Half (12) the ram lambs and nine of the yearlings were sexually naive at the start of testing (had been denied access to females since weaning); the remaining males were sexually experienced. The sexual performance of the virgin rams was poorer during the initial exposure to females than in subsequent tests, whereas the sexual behavior of the sexually experienced males did not change over the days of testing. Sexually naive ram lambs and rams exhibited an improvement in sexual performance between Tests 1 and 2; during Test 3 to 5 the sexual performance (ejaculations per test) of sexually naive and experienced rams was similar. The only effects of age (maturation) on sexual performance during the last three test days were a higher frequency of mounts without ejaculation plus mount attempts (P less than .03) and a greater number of mount interactions per ejaculation (P less than .02) by ram lambs. In conclusion, one or two relatively brief exposures to estrous females can bring the sexual performance of virgin rams up to levels comparable to that of experienced males. Also, ram lambs in good condition exhibit acceptable levels of sexual performance.
Animals↗
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↗
Living wills and the right to die.
Two recent court decisions clarified whether and under what circumstances a patient may refuse life-sustaining medical treatment, including food and water. The Nancy Cruzan case, decided by the U.S. Supreme Court on June 25, 1990, and the case of Shirley Crabtree, decided by Family Court Senior Judge Daniel G. Heely in Hawaii on April 26, 1990, had differing outcomes. Moreover, Hawaii has a living will statute which purports to place limits on when and whether a person may choose to die rather than live in a severely disabled condition. This article will summarize the current law, and will offer practical advice to physicians on how to deal with these sensitive issues that affect their patients.
Coma↗
Medical complications of the use of cocaine.
There are many serious medical problems that are associated with the use of cocaine and "crack" cocaine.
Central Nervous System Diseases↗
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↗
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↗
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↗
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↗