|
|
Bell, R. J. W., Kingston, J. K., Mogg, T. D., & Perkins, N. R. (2007). The prevalence of gastric ulceration in racehorses in New Zealand. N Z Vet J, 55(1), 13–18.
Abstract: AIM: To establish the prevalence and factors influencing the prevalence and severity of gastric ulceration in racehorses in New Zealand. METHODS: Horses (n=171) in active training for racing by trainers (n=24) located throughout New Zealand were examined using gastroscopy during 2003 and 2004. Images of the examination were recorded and reviewed, and an ordinal grade based on the severity of gastric ulceration present was assigned, using the grading system proposed by the Equine Gastric Ulcer Council (EGUC). Information about the horses such as age, breed, sex, stabling, time at pasture, pasture quality, and presence of clinical signs consistent with equine gastric ulcer syndrome (EGUS) was recorded. RESULTS: Of the 171 horses in the study, 133 (78%) were Thoroughbreds and 38 (22%) were Standardbreds. Evidence of gastric ulceration was present in 151 (88.3%) of these. Prevalence of ulceration was higher at the lesser curvature (LC) and greater curvature (GC) of the stomach than at the saccus caecus (SC; p<0.01), and ulceration was more severe at the LC than at either the GC (p=0.02) or the SC (p<0.001). The prevalence of ulceration did not differ between the two breeds (p=0.51) or between horses of differing ages (p=0.56). Gastric ulceration was evident in 125/141 (89%) horses kept at pasture for at least 4 h/day, in all 13 (100%) horses kept at pasture full time, and in 16/17 (94%) horses stabled full time. Prevalence and severity of ulceration did not differ between horses stabled full time, kept at pasture for part of the day or kept at pasture full time (p=0.33 and 0.13, respectively), and for horses grazed on pasture severity of ulceration did not vary significantly with the quality of the pasture (p=0.12). Neither prevalence (p=0.26) nor severity (p=0.49) of gastric ulceration varied significantly with duration of training. CONCLUSIONS: The prevalence of gastric ulceration in racehorses in New Zealand is similar to that reported elsewhere for horses in active training for racing. Access to pasture for some or all of the day did not appear to be protective.
|
|
|
|
Ogbourne, C. P. (1971). Variations in the fecundity of strongylid worms of the horse. Parasitology, 63(2), 289–298.
|
|
|
|
Czerlinski, G. H., Erickson, J. O., & Theorell, H. (1979). Chemical relaxation studies on the horse liver alcohol dehydrogenase system. Physiol Chem Phys, 11(6), 537–569.
Abstract: Chemical relaxation studies on the system horse liver alcohol dehydrogenase, nicotinamide adenine dinucleotide, and ethanol were conducted observing fluorescence changes between 400 and 500 nm. Temperature-jump experiments were performed at pH 6.5, 7.0, 8.0, and 9.0; concentration-jump experiments at pH 9.0. The reciprocal of the slowest relaxation time was found to be linearly dependent upon the enzyme concentration for relatively low enzyme concentrations, as predicted earlier. Use of the wide pH-range necessitated expression of the four apparent dissociation constants of the catalytic reaction cycle in terms of pH-independent constants. The system was described in terms of only one (or two) catalysis-linked protons not associated with the electron transfer. Protonic steps in a buffered system are in rapid equilibrium, too fast to be measured with the equipment available. Assuming only two of the four bimolecular reaction steps in the four-step cycle are fast compared to the remaining two, six cases may be considered with six expressions for the reciprocal of the slowest relaxation time. Comparison with the experimental data revealed that the bimolecular reaction steps governing the slowest relaxation time change with pH. Above the effective time resolution of the temperature-lump instrument with fluorescence detection (0.1 msec) only one other relaxation time was detectable and only at pH 9. This relaxation time, found to be independent of the concentration of all reactants within experimental error (r = 10 +/- 5 msec), is most likely due to an interconversion among ternary complexes.
|
|
|
|
Houpt, K. A., Thornton, S. N., & Allen, W. R. (1989). Vasopressin in dehydrated and rehydrated ponies. Physiol. Behav., 45(3), 659–661.
Abstract: Six pony mares deprived of water for 24 hours showed significant increases in plasma vasopressin (2.8 pg/ml) and osmolality (9 mosmol/kg). When water was made available the ponies drank rapidly (5 of 6 drank to satiety within 90 seconds) and corrected their fluid deficits precisely. Vasopressin did not return to predehydration levels until osmolality did after 15 minutes of access to water. The horse differs from rodents and humans, but is similar to pigs in that vasopressin levels do not fall before osmolality returns to normal. Oropharyngeal factors, therefore, may not be as important in vasopressin release in horses as in other species.
|
|
|
|
Kutsukake, N., & Castles, D. L. (2004). Reconciliation and post-conflict third-party affiliation among wild chimpanzees in the Mahale Mountains, Tanzania. Primates, 45(3), 157–165.
Abstract: This study investigated post-conflict (PC) behavior among wild chimpanzees (Pan troglodytes) of the M-group in the Mahale Mountains, Tanzania, and examined what types of behavior characterize the PC situation in this group, and the factors that influence the occurrence of PC affiliation between opponents soon after the end of an aggressive conflict (i.e., reconciliation). We found that the opponents affiliated selectively soon after the end of aggression, suggesting that reconciliation occurred in this group. The mean individual corrected conciliatory tendency (CCT) (Veenema et al. 1994 in Behav Proc 31:29-38) was 14.4%, which is similar to or lower than frequencies observed in studies of captive and wild chimpanzees. The valuable relationship hypothesis predicts that the CCT is higher among individuals who share valuable relationships (e.g., males or affiliative dyads) than among individuals who do not (e.g., females or less-associative dyads). However, the analysis based on data for aggression between unrelated individuals (including one incident between an adult and non-adult) and aggression between unrelated adults, did not uncover this difference. Affiliation by a previously uninvolved individual with the victim (“consolation”) and with the aggressor (“appeasement”) occurred more frequently following aggression than in the control condition. The results are compared with previous studies of captive and wild chimpanzees.
|
|
|
|
Gruter, C. C. (2004). Conflict and postconflict behaviour in captive black-and-white snub-nosed monkeys (Rhinopithecus bieti). Primates, 45(3), 197–200.
Abstract: Black-and-white snub-nosed monkeys (Rhinopithecus bieti) have almost never been the subject of any behavioural observations in captivity. This study was aimed at providing preliminary information about agonistic and reconciliation behaviour in a group kept at the Kunming Institute of Zoology in China. Established procedures were used for this investigation (i.e., the postconflict/matched-control method and the time-rule method). Intra-group aggression rates were quite low. Postconflict affiliation as well as selective attraction of former opponents to each other following conflicts was demonstrated. Former opponents contacted each other earlier in postconflict periods than in matched-control periods. The average conciliatory tendency of all focal individuals combined was 54.5%. After an agonistic interaction, the first affiliative contact between former aggressors usually took place within the first minute. The behaviours most often shown as first affiliations after a conflict were body contact, mount, touch, and “hold-lumbar”, of which the latter is an explicit reconciliatory gesture. Furthermore, the adult male intervened non-aggressively in 84% of all conflicts (n=25) among the adult females. Overall, the patterns of aggression and reconciliation observed in R. bieti bear many of the traits that characterise tolerant primate species.
|
|
|
|
Cameron, E. Z. (2004). Facultative adjustment of mammalian sex ratios in support of the Trivers-Willard hypothesis: evidence for a mechanism. Proc Biol Sci, 271(1549), 1723–1728.
Abstract: Evolutionary theory predicts that mothers of different condition should adjust the birth sex ratio of their offspring in relation to future reproductive benefits. Published studies addressing variation in mammalian sex ratios have produced surprisingly contradictory results. Explaining the source of such variation has been a challenge for sex-ratio theory, not least because no mechanism for sex-ratio adjustment is known. I conducted a meta-analysis of previous mammalian sex-ratio studies to determine if there are any overall patterns in sex-ratio variation. The contradictory nature of previous results was confirmed. However, studies that investigated indices of condition around conception show almost unanimous support for the prediction that mothers in good condition bias their litters towards sons. Recent research on the role of glucose in reproductive functioning have shown that excess glucose favours the development of male blastocysts, providing a potential mechanism for sex-ratio variation in relation to maternal condition around conception. Furthermore, many of the conflicting results from studies on sex-ratio adjustment would be explained if glucose levels in utero during early cell division contributed to the determination of offspring sex ratios.
|
|
|
|
Zentall, T. R., Weaver, J. E., & Clement, T. S. (2004). Pigeons group time intervals according to their relative duration. Psychon Bull Rev, 11(1), 113–117.
Abstract: In the present research, we asked whether pigeons tended to judge time intervals not only in terms of their absolute value but also relative to a duration from which they must be discriminated (i.e., longer or shorter). Pigeons were trained on two independent temporal discriminations. In one discrimination, sample durations of 2 and 8 sec were associated with, for example, red and green hue comparisons, respectively, and in the other discrimination, sample durations of 4 and 16 sec were associated with vertical and horizontal line comparisons, respectively. If pigeons are trained on a temporal discrimination and tested with intermediate durations, the subjective midpoint typically occurs close to the geometric mean of the two trained values. The 4- and 8-sec values were selected to be the geometric mean of the two values in the other discrimination. When a 4-sec test sample was presented with the comparisons from the 2- and 8-sec discrimination, the pigeons preferred the comparison associated with the shorter sample. Similarly, when an 8-sec test sample was presented with the comparisons from the 4- and 16-sec discrimination, the pigeons preferred the comparison associated with the longer sample. Thus, a relative grouping effect was found. That is, durations that should have produced indifferent choice were influenced by their relative durations (shorter than or longer than the alternative) during training.
|
|
|
|
Clement, T. S., Feltus, J. R., Kaiser, D. H., & Zentall, T. R. (2000). “Work ethic” in pigeons: reward value is directly related to the effort or time required to obtain the reward. Psychon Bull Rev, 7(1), 100–106.
Abstract: Stimuli associated with less effort or with shorter delays to reinforcement are generally preferred over those associated with greater effort or longer delays to reinforcement. However, the opposite appears to be true of stimuli that follow greater effort or longer delays. In training, a simple simultaneous discrimination followed a single peck to an initial stimulus (S+FR1 S-FR1) and a different simple simultaneous discrimination followed 20 pecks to the initial stimulus (S+FR20 S-FR20). On test trials, pigeons preferred S+FR20 over S+FR1 and S-FR20 over S-FR1. These data support the view that the state of the animal immediately prior to presentation of the discrimination affects the value of the reinforcement that follows it. This contrast effect is analogous to effects that when they occur in humans have been attributed to more complex cognitive and social factors.
|
|
|
|
Kirkpatrick, J. F., & Turner, A. (2002). Reversibility of action and safety during pregnancy of immunization against porcine zona pellucida in wild mares (Equus caballus). Reprod Suppl, 60, 197–202.
Abstract: Contraceptive management of publicly valued wildlife species requires safeguards to ensure that these populations are preserved in a healthy state. In addition, reversibility of contraceptive effects and safety in pregnant animals are major concerns. A population of wild horses has been immunized against porcine zona pellucida (PZP) over a 12 year period on Assateague Island National Seashore, MD (ASIS). Mares initially received one or two 65 microg inoculations and once a year 65 microg booster inoculations, all delivered by dart. All young mares aged > 2 years were treated with PZP for 3 consecutive years regardless of whether they have bred successfully and they were then removed from treatment until they had foaled. All mares vaccinated for 1 or 2 consecutive years became fertile again and 69% of mares treated for 3 consecutive years returned to fertility. All five mares treated for 4 or 5 consecutive years have also returned to fertility, but over longer periods of time. Mares treated for 7 consecutive years have not returned to fertility, but several, while still infertile, have started ovulating again. There was no difference in survival rates between foals born to treated and untreated mares, and PZP treatment of pregnant mares did not affect subsequent fertility of their female offspring.
|
|
