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1.
Segmentation of the main light period of an 8L:4D:2L:10D regimen into 30 min light, 30 min dark did not affect total feeding activity, rate of feeding or total intake of laying hens. When 15 min light and 45 min dark was provided each hour feeding activity and food intake were reduced, while rate of feeding and feeding during the dark periods increased. No feeding occurred in the 10 h 'night'. Hens subjected to interrupted lighting showed less feeding activity than those on a 14L:10D regimen. Insertion of a 4 h dark period in the 14 h subjective day of laying hens increased their rate of feeding, but reduced total intake. The pattern of feeding activity depended on the position of the 4 h dark period. The largest modification of feeding activity occurred on a 8L:4D:2L:10D regimen; 20% of activity occurred in the last 2 h of the apparent day. Feeding occurred during the 4 h dark period, but not during the 10 h 'night'. 相似文献
2.
Arai S Hanaya T Sakurai T Ikeda M Kurimoto M 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2005,67(2):215-217
When Syrian hamsters (Mesocricetus auratus) are bred in a cold and short-day environment, most animals go into hibernation after a certain period of time. However, to date it has not been possible to predict which hamster will enter hibernation. In this study, we subcutaneously implanted thermo-loggers in hamsters bred in the cold environment, and recorded the subcutaneous temperature at short intervals until they went into hibernation. A time series analysis of temperature disclosed that a fall of 0.4 to 0.8 degrees C in subcutaneous temperature was seen 5 to 16 days before entering hibernation, and this phenomenon continued for three days or more. No hamster went into the hibernation without displaying this signal. Although the mechanism by which this phenomenon takes place is not clear, it is a sign from the body, which is useful for indicating if a hamster will enter hibernation shortly. 相似文献
3.
Santiago-Moreno J López-Sebastián A del Campo A González-Bulnes A Picazo R Gómez-Brunet A 《Domestic animal endocrinology》2004,26(4):303-314
The aims of this study were to examine whether mouflons exposed to constant long and short day photoperiods are able to exhibit an annual cycle of hair growth and moult, and prolactin (PRL) secretion. Mouflon ewes were assigned to three groups of treatment. Ewes were maintained, either under natural photoperiod (control, n=9), or received a series of subcutaneous melatonin implants from December to April (n=8), or were exposed to a constant long day photoperiod (16-h light:8-h dark; 16L:8D) during 18 months (n=7). Blood was collected weekly to determine PRL concentrations, and hair samples were clipped weekly from the base of the neck to measure the length of predominant hair. Under constant long days and with melatonin implants, mouflons expressed an annual rhythm of PRL secretion, even though these treatments modified the times of rise or falling of PRL concentrations throughout the year. Hair growth initiation was almost coincident with the summer solstice in both control and melatonin-implanted mouflons but occurred two months earlier in long day hold mouflons (P<0.001). Long day hold mouflons had a lower hair growth rate than control and melatonin-implanted mouflons (P<0.001), and at the end of the experiment, a shorter hair length (3.4±0.24 cm; P<0.01) than control (4.3±0.17 cm), and melatonin-implanted mouflons (4.2±0.12 cm). Our data support the conclusion that in mouflon, an endogenous circannual rhythm of PRL secretion exists, and that the seasonal cycle of hair growth and moult appears to depend, at least in part, on circulating levels of PRL. 相似文献
4.
Testicular dynamics in Syrian hamsters exposed to both short photoperiod and low ambient temperature
Sato T Tachiwana T Takata K Tay TW Ishii M Nakamura R Kimura S Kanai Y Kurohmaru M Hayashi Y 《Anatomia, histologia, embryologia》2005,34(4):220-224
The object of this study was to determine the details of morphological dynamics of spermatogenesis in Syrian hamsters exposed to both short photoperiod and low ambient temperature. Eight-week-old male hamsters, kept in a long photoperiod (14 h L, 10 h D), were transferred to a short photoperiod (6 h L, 18 h D) and kept there for 13 weeks to induce testicular regression. Some hamsters were then transferred from the room at 23 degrees C to that at 5 degrees C (5 degrees C group). Remaining hamsters were continuously kept at 23 degrees C (23 degrees C group). Thereafter, the morphology was examined. As a result, it took only 8 weeks until spermatogenesis recovered in the 23 degrees C group. However, it was not until 20 weeks that spermatogenesis was recognized in the 5 degrees C group. As the regulation of seasonal testicular activity is characterized by coordinated shifts in the relationships among mitosis, meiosis, and apoptosis, the changes in the proliferative and apoptotic activities were examined. Although no significant difference in proliferative activity of spermatogonia between the 5 degrees C and the 23 degrees C groups was confirmed, a notable increase in the rate of apoptosis was observed in the 5 degrees C group. Furthermore, this increase was more salient during the hibernation period. These findings suggest that both cold ambient temperature and hibernation caused the delay of testicular recrudescence and this delay arose from the increase of apoptotic activity but not the change in proliferative activity in spermatogonia in the 5 degrees C group. 相似文献
5.
The ability of interrupted photoperiods to induce early estrus and ovulation was examined. Horse mares were exposed to long (16 h light) or short (10 h light), noninterrupted photoperiods, ambient light, or various interrupted photoperiod treatments from December 1 to April 15 (135 d). Follicular development was assessed by rectal palpation and estrous behavior was determined by teasing with a stallion. Serum concentrations of progesterone were used as an indicator of corpus luteum function. Differences among the light treatment groups were compared for the following behavioral and ovarian characteristics: days to first detectable 3-cm follicle, days to first estrous behavior, days to first ovulation, the number of mares ovulating within the treatment period, and the number of ovulations within the treatment period per mare. Compared with the ambient and 10L:14D (L = h of light and D = h of darkness) photoperiod treatments, ovulation was advanced to the greatest extent by a photoperiod of 16L:8D and the interrupted photoperiod 10L:8D:2L:4D. These two stimulatory photoperiod treatments were characterized by the presence of light 8 to 10 h after dusk. Therefore, the present data are consistent with an external coincidence model for the induction of seasonal breeding in horses, with the photoinducible phase occurring within the period 8 to 10 h after dusk. 相似文献
6.
1. The energy expenditure (H) and physical activity of laying hens were measured under lighting regimes of 14L:10D (standard), 2L:10D:2L:10D (interrupted) and (15 X (13 min L:47 min D]: 9D (fragmented). 2. Neither of the intermittent regimes produced a significant change in total daily energy expenditure, although large alterations occurred in the distribution of H between the lighting phases. The absence of change in total H resulted from the combined effects of greater H in the light in the intermittent regimes, greater H in darkness during the interrupted day than at night and slightly greater H at night in the intermittent regimes. 3. Physical activity count, like H, was redistributed over time but, unlike H, was also significantly reduced in total; changes in the energy cost of unit activity, however, were such that no reduction occurred in the total amount of H attributable to activity. 4. In the standard groups, 90% of total activity costs were incurred in the light; in the fragmented-day and interrupted-day groups, respectively, 7% and 55% of total activity costs were incurred in the light periods and 85% and 30% in daytime darkness. 5. In terms of both H and activity, there was clear differentiation between night darkness and subjective-day darkness. 6. Even when the energy cost of activity was excluded, significant differences remained between H at night, H in the light and H in daytime darkness. 相似文献
7.
Reasons for performing study: Pituitary pars intermedia dysfunction (PPID) is a common endocrinopathy, frequently diagnosed via plasma adrenocorticotropic hormone (ACTH) concentrations. Seasonal variation in plasma ACTH concentrations has been described in normal horses prompting caution in diagnosing PPID at certain times of the year. The aims of this study were to determine appropriate reference intervals for equine plasma ACTH throughout the year; and to examine the circannual variation of plasma ACTH concentrations in PPID cases. Hypothesis: Plasma ACTH can be used as a test for PPID throughout the year with the use of appropriate reference intervals. Methods: Data for reference interval calculations were obtained from samples collected from inpatients of Liphook Equine Hospital (non‐PPID group, n = 156). Data from PPID cases (n = 941) were obtained from samples submitted to the Liphook Equine Hospital Laboratory from horses with a clinical suspicion of PPID found to have plasma ACTH concentrations greater than our upper reference interval for that time of year. Results: Upper limits for reference interval of plasma ACTH were 29 pg/ml between November and July and 47 pg/ml between August and October. Circannual variation in plasma ACTH occurred in both non‐PPID and PPID horses with the highest ACTH concentrations found between August and October in both groups (P<0.0001). The greatest difference between the 2 populations also occurred between August and October. Conclusions: Plasma ACTH can be used for the diagnosis and monitoring of PPID throughout the year with the use of appropriate reference intervals. These findings demonstrate an increase in pituitary gland secretory activity during the late summer and autumn in both normal and PPID cases. 相似文献
8.
Nelson OL McEwen MM Robbins CT Felicetti L Christensen WF 《Journal of the American Veterinary Medical Association》2003,223(8):1170-1175
OBJECTIVE: To evaluate cardiac function parameters in a group of active and hibernating grizzly bears. DESIGN: Prospective study. ANIMALS: 6 subadult grizzly bears. PROCEDURE: Indirect blood pressure, a 12-lead ECG, and a routine echocardiogram were obtained in each bear during the summer active phase and during hibernation. RESULTS: All measurements of myocardial contractility were significantly lower in all bears during hibernation, compared with the active period. Mean rate of circumferential left ventricular shortening, percentage fractional shortening, and percentage left ventricular ejection fraction were significantly lower in bears during hibernation, compared with the active period. Certain indices of diastolic function appeared to indicate enhanced ventricular compliance during the hibernation period. Mean mitral inflow ratio and isovolumic relaxation time were greater during hibernation. Heart rate was significantly lower for hibernating bears, and mean cardiac index was lower but not significantly different from cardiac index during the active phase. Contrary to results obtained in hibernating rodent species, cardiac index was not significantly correlated with heart rate. CONCLUSIONS AND CLINICAL RELEVANCE: Cardiac function parameters in hibernating bears are opposite to the chronic bradycardic effects detected in nonhibernating species, likely because of intrinsic cardiac muscle adaptations during hibernation. Understanding mechanisms and responses of the myocardium during hibernation could yield insight into mechanisms of cardiac function regulation in various disease states in nonhibernating species. 相似文献
9.
The effect of melanocortin (Mc3 and Mc4) antagonists on serotonin-induced food and water intake of broiler cockerels 总被引：3，自引：0，他引：3
Morteza Zendehdel Farshid Hamidi Vahab Babapour Kasra Mokhtarpouriani Ramin Mazaheri Nezhad Fard 《Journal of veterinary science (Suw?n-si, Korea)》2012,13(3):229-234
The current study was designed to examine the effects of intracerebroventricular injections of SHU9119 [a nonselective melanocortin receptor (McR) antagonist] and MCL0020 (a selective McR antagonist) on the serotonin-induced eating and drinking responses of broiler cockerels deprived of food for 24 h (FD24). For Experiment 1, the chickens were intracerebroventricularly injected with 2.5, 5, and 10 µg serotonin. In Experiment 2, the chickens received 2 nmol SHU9119 before being injected with 10 µg serotonin. For Experiment 3, the chickens were given 10 µg serotonin after receiving 2 nmol MCL0020, and the level of food and water intake was determined 3 h post-injection. Results of this study showed that serotonin decreased food intake but increased water intake among the FD24 broiler cockerels and that these effects occurred in a dose-dependent manner. The inhibitory effect of serotonin on food intake was significantly attenuated by pretreatment with SHU9119 and MCL0020. However, the stimulatory effect of serotonin on water intake was not altered by this pretreatment. These results suggest that serotonin hypophagia and hyperdipsia were mediated by different mechanisms in the central nervous system, and that serotonin required downstream activation of McRs to promote hypophagia but not hyperdipsia in the FD24 chickens. 相似文献
10.
The aim of this study was to determine the effect of different light sources and light schedules on the growth and quality of commercial broilers. In each experiment 810 broiler chicks were divided into 3 groups, 3 replicates per group. All were reared at 20 lux. Body weight and food consumption were recorded weekly. Experiment 1. Birds were reared under 3 light sources: incandescent light bulb, warm-white fluorescent light tube or warm-white mini-fluorescent light bulb. Experiment 2. Birds were reared on 3 light schedules. 23 h light and 1 h dark (23L: 1D) throughout; an increasing light schedule with initial 23L:1D then 8L: 16D increasing daylight gradually to 16L:8D or an intermittently increasing daylight schedule (16:8P) where light and dark periods were shorter but portioned to achieve the same total hours per day up to 16L:8D. Broilers reared under mini-fluorescent light bulb were heavier than those under fluorescent tubes or incandescent bulbs by 49 d. Until 42 d of age, photoperiod had no effect on growth. However, at 49 d broilers reared under 16:8P and 16L:8D regimens were heavier than those or 23L:1D. At 42 d, female broilers on 23L:1D, were heavier than those on 16L:8D and 16:8P. Mortality was higher in groups on 23L:1D than on 16L:8D on 16:8P. At 49 d incidence of leg condemnation was higher in the 16:8P group. However, skin damage was lower in this group than in those on 23L: 1D and 16L:8D. 相似文献
11.
Data for incidence of summer mastitis in 14 veterinary practices in Jutland (Denmark) were related to meteorological factors using statistical methods. A correlation and regression analysis showed that summer mastitis occurred earlier in years with high temperature and precipitation in early summer. The annual number of cases markedly increased over the years 1953 to 1980. This increase was described by applying a linear increase with with year to a logarithmic transformation of the annual incidence.Analysis of 10-day incidences from the veterinary practices and daily incidence from a test site at St. Vildmose (Jutland) showed that incidence of summer mastitis could be related to temperature and wind velocity within the previous 10 days. High temperature and low wind velocity in this period increase the incidence. This indicates that the incubation period of summer mastitis is at maximum about 10 days. The activity of the fly (Hydrotaea irritans Fall), which acts as mechanical vector for the bacteria is influenced by temperature and wind velocity. This may explain the variation in incidence of summer mastitis during the season and from year to year. 相似文献
12.
Even mildly hypothermic body or limb temperatures can retard healing processes in mammals. Despite this, we observed that hibernating American black bears (Ursus americanus Pallas, 1780) elicit profound abilities in mounting inflammatory responses to infection and/or foreign bodies. In addition, they resolve injuries during hibernation while maintaining mildly hypothermic states (30-35 °C) and without eating, drinking, urinating or defecating. We describe experimental studies on free-ranging bears that document their abilities to completely resolve cutaneous cuts and punctures incurred during or prior to hibernation. We induced small, full-thickness cutaneous wounds (biopsies or incisions) during early denning, and re-biopsied sites 2-3 months later (near the end of denning). Routine histological methods were used to characterize these skin samples. All biopsied sites with respect to secondary intention (open circular biopsies) and primary intention (sutured sites) healed, with evidence of initial eschar (scab) formation, completeness of healed epidermis and dermal layers, dyskeratosis (inclusion cysts), and abilities to produce hair follicles. These healing abilities of hibernating black bears are a clear survival advantage to animals injured before or during denning. Bears are known to have elevated levels of hibernation induction trigger (delta-opioid receptor agonist) and ursodeoxycholic acid (major bile acid within plasma, mostly conjugated with taurine) during hibernation, which may relate to these wound-healing abilities. Further research as to the underlying mechanisms of wound healing during hibernation could have applications in human medicine. Unique approaches may be found to improve healing for malnourished, hypothermic, diabetic and elderly patients or to reduce scarring associated with burns and traumatic injuries. 相似文献
13.
Large White commercial tom poults were grown from 1 day to 8 weeks of age in the following light treatments: (i) continuous incandescent light (24LL); (ii) 23 hours of incandescent light and 1 hour of darkness/day (23L:1D); (iii) 12 hours of incandescent light and 12 hours of darkness/day (12L:12D); or (iv) natural decreasing day lengths (natural). At 8 weeks of age, significant (P less than 0.05) morphologic changes in eyes occurred. Poults exposed to the 24LL or 23L:1D had heavier eyes than did poults exposed to the 12L:12D or natural day length. In addition, the eye size (anterior to posterior diameter and horizontal width) exposed to the 24LL treatment was greater than those exposed to 23L:1D, 12L:12D, or natural day length. Cornea heights of poults exposed to 24LL or 23L:1D were smaller than cornea heights of those exposed to 12L:12D or natural day length. Marked differences did not occur in intraocular pressure among treatments. 相似文献
14.
The wild South American camelids developed a strategy of seasonal reproduction during spring and summer with singleton birth. The photoperiod is one of the factors that may modulate this seasonality where light would be translated into a hormonal signal. This study evaluated the influence of changes in daily light intensity on melatonin concentration in captive guanacos under a long‐day photoperiod (16 hr light/8 hr dark; 33 ‘28′S). Mean melatonin concentration was 28.3 ± 20.3 pg/ml, with a maximum of 52.14 ± 17.19 pg/ml at 23:30 and minimum of 14.29 ± 6.64 pg/ml at 08:30 (p < .001). There was a negative association between light intensity and melatonin concentration (r = ?0.57; p < .001). The results indicate that guanacos respond to variation in daily environmental light with a hormonal response and point to a circannual rhythm as a function of the photoperiod. 相似文献
15.
K H Lahrmann 《Berliner und Münchener tier?rztliche Wochenschrift》1989,102(7):227-233
In 7 herds half of the sows of each service area have been illuminated, additionally to the natural daylight, with artificial light during 2 years (year 1: 100 1 x; year 2: 300 1 x). From 2965 services parameters of fertility of the natural and artificial light groups have been recorded and compared within and between herds as well as seasons. Seasonal variations of fertility, as reported by other authors, have been confirmed under natural and artificial light. Generally the results under additional artificial light were better in all seasons. The duration of daylight seems to be one of the main reasons for seasonal variations of fertility. During the period of April, May and June (increasing daylength from 13 h to 17 h, but moderate temperatures from 13 degrees C to 22 degrees C) fertility was most depressed, followed by the period of July, August and September (decreasing daylength from 17 h to 12 h, temperatures from 24 degrees C to 22 degrees C). The best fertility has been recorded during winter (October to March, less than 12 h daylength). In addition to increased light intensity a period of 12 h artificial lighting appears to be favourable in winter with less than 12 h natural daylength, but it is not effective during summer with daylengths longer than 12 h. In respect to these results reducing natural daylength to 12 h during summer maintaining sufficient light intensity might be useful. 相似文献
16.
17.
草食偶蹄动物魏氏梭菌病及预防 总被引：1，自引：0，他引：1
为探讨国内野生和家养动物魏氏梭菌病发生的特点与规律,收集了近32 a间的文献资料,设立魏氏梭菌病发生的时间、区域、动物种类、细菌血清型等因素,统计分析流行病特征。结果：①魏氏梭菌病每隔4 a左右就会有高发病出现,各种血清型发病高峰的年际不一样,野生动物和家养动物高发病的年际、血清型有差别。②魏氏梭菌病在一年四季中均可发生,各季节的发生率不同,春季是高发季节,家养动物尤为明显,秋季野生动物的发病较为明显。4个季节中,D型菌引起的发病较多,在春季和夏季中D型菌发病尤为明显,在秋季中仅A型菌和D型菌有发病记录,冬季中都不突出。③魏氏梭菌病在1 a 12个月中均可发生,3、4月是高发病时期,6、11月的发病比率次之。3月西部区域发病较多,4月黄河与长江之间区域发病为多,6月长江以南区域发病高,11月则是黄河以北区域发病较多。野生动物发病多集中在6月和11月,家养动物4月发病较突出。2月C型菌引起的发病较明显,11月A型菌发生的比率明显高于其他血清型,D型菌则全年发生的较多。④黄河以北、黄河与长江之间、西部区域发病主要集中在春季,长江以南则主要在夏季发病。黄河以北区域D型菌最高,A型菌其次,C型菌最低。黄河与长江之间区域A型菌落高于D型菌,C型菌仍是最低。长江以南区域D型菌为主,A型菌其次,没有C型菌发病。西部区域则是D型菌明显高于A型菌和C型菌。结论：魏氏梭菌病的发生有一定的规律,每间隔4 a左右会有高发病出现。不同区域,魏氏梭菌病发生的时间有差别。野生动物和家养动物发病的时间和致病血清型有区别。疫苗接种预防是有效的,综合措施是较好的预防措施。预防时慎用磺胺嘧啶和多黏菌素类抗生素。兽医诊断水平亟待提高。 相似文献
18.
用自制的营养菌剂在枯草期和青草期对青海省湖东种羊场的种羊和土种羊分别进行灌服试验，１５ｄ灌服１次，枯草期灌服８次，青草期灌服７次，每次每只羊５ｍｌ，结果表明，在枯草期，种羊试验组平均增重４．０３ｋｇ，对照组增重３．１４ｋｇ，土种羊试验组平均增重０．０１ｋｇ，对照组增重－１．２１ｋｇ；在青草期，种羊试验组平均增重４．１５ｋｇ，对照组增重３．４０ｋｇ，土种羊试验组平均增重１．７２ｋｇ，对照组增重１．３ 相似文献
19.
The objectives of the present study were to characterize in dogs circannual and ultradian prolactin (PRL) secretory patterns and also to compare gender differences in the ultradian period of study in the Southern hemisphere. Blood samples were collected at 15‐min intervals for 2.5 h from seven male and seven female dogs and a single monthly sampling, over a 1‐year time span, from six male dogs for the ultradian and circannual studies, respectively. Plasma PRL was measured by a homologous enzyme immunometric assay. The ultradian study evidenced PRL elevations suggesting pulsatile secretion in both genders. Significantly higher mean smoothed baseline (ng / ml [7.02 ± 1.2 vs 1.23 ± 1.0, p < 0.01]) and AUC (ng/ml * 2.5 h [25.2 ± 3.8 vs 4.4 ± 3.8, p < 0.01]) were found in females when compared with males. In the circannual study, plasma PRL concentrations did not statistically differ among the months of the year. When grouped together the 3 months with a longer daylight had significantly higher PRL concentrations than the 3 months with the shortest (2.31 ± 0.37 vs 0.96 ± 0.37, p < 0.01). The correlation between length of daylight and PRL concentrations was 0.24, p < 0.05. It is concluded that PRL does have a circannual rhythmicity and that there are ultradian gender‐related differences in the period under study in these groups of dogs. This study also demonstrates plasma PRL elevations suggesting pulsatile secretion in male dogs. 相似文献
20.
旨在研究光照节律对肉兔生长性能、肉品质、血清生化指标和行为的影响。选取135只35日龄断奶伊拉公兔,随机分为3个处理,每个处理15个重复,每个重复3只肉兔,设置12 h光暗循环(12L∶12D)、24 h光照(24L)和24 h黑暗(24D)的3种光照节律,光照强度为100 lx,预试期为7 d,试验期为35 d。结果表明,与12L∶12D组相比,24D组肉兔21~35 d的平均日采食量(ADFI)、饲料转化率(FCR)、半净膛率、背最长肌pH和熟肉率显著提高(P<0.05),血糖浓度显著降低(P<0.05),其中FCR和半净膛率在各个处理组中最高(P<0.01)。24L组的皮指数显著低于12L∶12D和24D组(P<0.01),而白蛋白(ALB)和肌肉失水率显著高于于12L∶12D和24D组(P<0.01)。各个处理组间肌肉肉色以及肌肉常规营养指标没有显著差异(P>0.05)。24D组的肉兔坐的行为持续时间最少(P<0.01),啃咬行为频率较低(P<0.05),运动、直立、站立行为频率最高(P<0.05)。结果显示,长时间黑暗环境可以提高肉兔的生长性能,降低血糖浓度。同时,肉兔在长期的黑暗中表现出更多的社会性、较少的恐惧和焦虑,显示出良好的动物福利。 相似文献