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La Riviere, J. W. (1969). Ecology of yeasts in the kefir grain. Antonie Van Leeuwenhoek, 35, Suppl:D15–6.
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Muscatello, G., Anderson, G. A., Gilkerson, J. R., & Browning, G. F. (2006). Associations between the ecology of virulent Rhodococcus equi and the epidemiology of R. equi pneumonia on Australian thoroughbred farms. Appl Environ Microbiol, 72(9), 6152–6160.
Abstract: The ecology of virulent strains of Rhodococcus equi on horse farms is likely to influence the prevalence and severity of R. equi pneumonia in foals. This study examined the association between the ecology of virulent R. equi and the epidemiology of R. equi pneumonia by collecting air and soil samples over two breeding seasons (28 farm-year combinations) on Thoroughbred breeding farms with different reported prevalences of R. equi pneumonia. Colony blotting and DNA hybridization were used to detect and measure concentrations of virulent R. equi. The prevalence of R. equi pneumonia was associated with the airborne burden of virulent R. equi (both the concentration and the proportion of R. equi bacteria that were virulent) but was not associated with the burden of virulent R. equi in the soil. Univariable screening and multivariable model building were used to evaluate the effect of environmental and management factors on virulent R. equi burdens. Lower soil moisture concentrations and lower pasture heights were significantly associated with elevated airborne concentrations of virulent R. equi, as were the holding pens and lanes, which typically were sandy, dry, and devoid of pasture cover. Few variables appeared to influence concentrations of virulent R. equi in soil. Acidic soil conditions may have contributed to an elevated proportion of virulent strains within the R. equi population. Environmental management strategies that aim to reduce the level of exposure of susceptible foals to airborne virulent R. equi are most likely to reduce the impact of R. equi pneumonia on endemically affected farms.
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Gorecka, A., Golonka, M., Chruszczewski, M., & Jezierski, T. (2007). A note on behaviour and heart rate in horses differing in facial hair whorl. Appl. Anim. Behav. Sci., 105(1-3), 244–248.
Abstract: The relationship between facial hair whorl position and reactivity, as assessed by behavioural measures (handling score = HS; startle reaction to a suddenly appearing novel object = SR; latency to touch a novel object = LNO) and heart rate measures (mean HR; increase in heart rate = IHR) were studied using 55 Konik horses reared either under conventional stable conditions or in the forest reserve. Horses were classified into four groups according to the whorl position and/or shape: (1) high, single whorl above the top eye line, n = 9; (2) medium, single whorl between the top and the bottom eye line, n = 30; (3) low, single whorl below the bottom eye line, n = 10; and (4) elongated or double whorl, n = 6. Horses with a high whorl position demonstrated a lesser degree of manageability as expressed by a lower HS compared to individuals with medium (P = 0.002) or low whorl positions (P = 0.016). Horses with different whorl positions did not differ significantly in their startle response to a suddenly appearing novel object (P = 0.685). The horses with an elongated or double whorl, which appeared only in the forest group, took significantly longer to approach the novel object than horses with medium (P = 0.006) or low (P = 0.005) whorl positions. No significant differences in mean HR and IHR between groups (HR: P = 0.629 and IHR: P = 0.214) were found. In conclusion, this study supports the relationship between the position of the hair whorl on the horses' head and their manageability during handling, as well as the latency to approach an unknown object.
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Minero, M., Zucca, D., & Canali, E. (2006). A note on reaction to novel stimulus and restraint by therapeutic riding horses. Appl. Anim. Behav. Sci., 97(2-4), 335–342.
Abstract: Little research has been done to measure reactivity objectively in therapeutic riding horses (TRH). As individual reactivity and chronic stress could be assessed by exposing animals to acute, novel stressors, the authors of this work aimed at comparing reactions of TRHs and jumping horses (JH) to two challenges. Four TRHs and four JHs were exposed to a restraint covering their head with a hood for 1 h and to a startling stimulus (a 40 cm long, red and white synthetic holiday garland shaken with a rustling noise inside the box). Heart rate (HR) and heart rate variability (HRV) were recorded continuously and telemetrically, the reaction was video-recorded and analysed with a software for behavioural analysis. Blood samples were collected before and after each challenge to determine lymphocyte proliferation and other biochemical parameters. Horses spent most of the time immobile, during the challenges (p < 0.05). TRHs had a significantly higher average basal HR than JH (p < 0.05), probably due to their better condition. HR varied among different behaviours during the restraint (p < 0.05): the average HR during “pawing” was higher than during other behaviours (p < 0.005). A significant decrease in the proliferation of lymphocytes in samples taken after the removal of the hood (p < 0.05) was found, while the other stress related parameters did not vary significantly after the challenges. The authors conclude that TRHs did not react less than JHs to the new stimuli and this should be taken into consideration while planning their daily work and management.
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Krueger, K. (2007). Behaviour of horses in the “round pen technique”. Appl. Anim. Behav. Sci., 104(1-2), 162–170.
Abstract: I investigated the behavioural background of the way horses learn to follow humans in the “round pen technique” suggested by “horse whisperers” as a gentle method for initial horse training. Though the practicability of this technique has been adequately demonstrated in the past, the horses' behaviour during such training has not yet been documented in detail. In a riding arena, horses, that did not follow the trainer immediately, were chased away so that they galloped around the trainer. Galloping horses showed specific behaviour such as turning the ear to the trainer, chewing, licking, and stretching head and throat downwards. In subsequent trials horses needed to be chased for less time and finally followed immediately, even when conditions were changed or the trainer was replaced by another person. This suggests that horses learn to follow in this particular situation and also show some generalisation. However, following did not occur on a pasture even after several successful trials in the riding arena.
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Ninomiya, S., Sato, S., Kusunose, R., Mitumasu, T., & Obara, Y. (2007). A note on a behavioural indicator of satisfaction in stabled horses. Appl. Anim. Behav. Sci., 106(1-3), 184–189.
Abstract: We observed the behaviour of six stabled horses (stallions n = 3; geldings n = 3) in an attempt to identify behavioural measures of eating satisfaction. The horses were required to perform an operant response (pressing a button with the muzzle) in order to access a food reward in an experimental box stall. After each horse had successfully learned the experimental situation, it participated in the experimental protocol on 4 days. Horses were brought to the experimental box stall for the operant response sessions (1 h duration per session), and upon completion, they were returned to their own (home) box stalls. The number of presses for the reward was a Fixed Ratio schedule of either 3 or 12 muzzle presses (FR3, FR12) and the FR procedure for each horse was as follows: FR3 FR12 FR12 FR3 or FR12 FR3 FR3 FR12. Number of rewards obtained during each session, and behaviour and heart rate after each session were recorded for each horse. A repeated measures ANOVA showed that the number of rewards obtained in FR3 was higher than in FR12 (P < 0.05). The horses spent more time in standing-rest, (with ears rotating laterally and exhibiting a low neck position) indicating sleep, in the home box stall, after FR3 compared to FR12 treatments (P < 0.05). Mean heart rate after standing-sleep was significantly lower than mean heart rate in the home box stall (P < 0.01). These results suggest that eating satisfaction induces sleep in stabled horses, and that episodes of standing-sleep behaviour may be a useful indicator of appropriate or enhanced welfare in the horse.
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Hansen, M. N., Estvan, J., & Ladewig, J. (2007). A note on resting behaviour in horses kept on pasture: Rolling prior to getting up. Appl. Anim. Behav. Sci., 105(1-3), 265–269.
Abstract: In previous studies on lying behaviour in horses kept in individual boxes we observed that most horses that had been lying down resting sometimes made a rolling behaviour prior to getting up. The rolling behaviour was seen in approximately 30% of the times the horses stood up. To analyse whether the behaviour was caused by individual housing in a box or whether it is a behaviour occurring also under free range conditions, we observed a group of 43 horses kept on pasture throughout the day and night. The horses were observed from 03:00 to 10:00 h over four consecutive mornings, at a time when lying behaviour was frequent. Of the 43 horses observed, the rising procedure was seen in 41 horses, and 25 of these horses (60.9%) performed the rolling behaviour at least once. A total of 135 rising episodes were observed, and 41 followed the performance of a rolling behaviour (30.4%). In contrast to the rolling behaviour seen indoors, the behaviour was more varied outdoors in that some horses rolled anywhere from 45 to 180[degree sign], some even repeatedly, whereas horses in a box only rolled 90[degree sign] and back. In all cases when horses rolled 180[degree sign] they rolled back to the original side before getting up. Also in contrast to previous observations, no horse was observed changing position during the roll. We conclude that the behaviour is a kind of comfort behaviour but that further studies are necessary to explain its function.
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Martin, T. I., Zentall, T. R., & Lawrence, L. (2006). Simple discrimination reversals in the domestic horse (Equus caballus): Effect of discriminative stimulus modality on learning to learn. Appl. Anim. Behav. Sci., 101(3-4), 328–338.
Abstract: The cognitive capacity of an organism, relative to that of other species, can be assessed by using a relative measure of learning. One such measure is the ability of an organism to learn about the reversal of a discrimination. The present study compared the performance of two groups of horses on a simple discrimination reversal task when the only difference between the groups was the modality of the relevant cue. For the visual group (absence or presence of a light), the spatial position was irrelevant. For the spatial group, a spatial cue (left/right) was available and the visual cue was irrelevant. Horses in the spatial group learned the original discrimination and six reversals; they also showed evidence of learning to learn. Horses in the visual group did not reach criterion during the study. As a result, there was no evidence of learning to learn.
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Mills, D. S., & Riezebos, M. (2005). The role of the image of a conspecific in the regulation of stereotypic head movements in the horse. Appl. Anim. Behav. Sci., 91(1-2), 155–165.
Abstract: Weaving is a common locomotor stereotypy in horses, which has been shown to be reduced by the presence of a mirror in the stable; however, it remains unclear whether this effect is due to the reflected image of a horse or some other property associated with the introduction of a mirror. To investigate this further, the response of six known weaving horses to each of three different types of poster was recorded. The poster images consisted of a life-size image of a horse's face (true image), a version of the same image cut into 54 squares, which were then randomly rearranged (pixilated image) and a blank (white image) display of the same size as the other posters. Four observation periods were included in each of the two days of observation per treatment condition: 08:00-08:30 h, 10:00-10:30 h, 12:00-12:30 h and 16:00-17:00 h. The first observation period was followed by the provision of concentrate feed and forage, the second observation period by exercise, the third by further forage and the fourth by concentrate feed and forage. The horses' activities and positions in the box were scanned at 1 min intervals and the number of observations registering each activity and position was calculated as a percentage of the total number of observations for each observation period. Weaving was significantly less when the horses were provided with the image of a horse's face (mean percentage of observations +/- S.E.M.; 5.56 +/- 1.57), compared to both the pixilated (14.85 +/- 3.06) and white (20.52 +/- 4.12) images. Nodding was significantly less when provided with the true image of a horse (0.45 +/- 0.15) compared to the pixilated image (2.15 +/- 0.67). The pattern of weaving throughout the day differed from that of nodding, and together these results suggest that the two behaviours are not analogous. The presence of the image of the horse's face was associated with a significant increase in alertness (F112,2 = 11.31, p < 0.001) and recorded time spent looking at the poster(F112,2 = 3.46, p < 0.05). The timing of stereotypic head movements in the horse in this study suggests that they are not associated with boredom, or lack of stimulation but rather acute frustration.
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Sondergaard, E., & Halekoh, U. (2003). Young horses' reactions to humans in relation to handling and social environment. Appl. Anim. Behav. Sci., 84(4), 265–280.
Abstract: Forty Danish warmblood colts in two replicates were used to investigate the effect of housing and handling in the rearing period on the reactions to humans. The horses entered the experiment after weaning and were housed either individually (n=16) or in groups of three (n=24). Half of the horses from each housing group were handled three times per week for a period of 10 min. Approach tests were performed in the home environment when the horses were 6, 9, 12, 18, 21, and 24 months old, and an Arena and Human Encounter test was performed in a novel environment when the horses were 12 and 24 months old, respectively. In the home environment, single-housed horses approached sooner and were more easily approached by a human than group-housed horses where no effect of handling was observed. Horses approached sooner and were more easily approached with increasing age. In the Arena and Human Encounter test, single-housed horses expressed less restless behaviour, more explorative behaviour, and less vocalisation than group-housed horses. Handled horses showed lower increase in heart rate during the test than non-handled horses. There was no difference between the number of times single or group-housed horses touched an unfamiliar person in the Arena and Human Encounter test but handled horses approached sooner than non-handled horses. It is concluded that the social environment affected the way horses reacted to humans when tested in the home environment but not in a novel environment. In contrast, handling affected the reactions to humans when tested in the novel environment but not in the home environment. However, handled horses also reacted less to the novel environment in general, thus indicating that handling is a mean of avoiding potential dangerous situations.
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