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1.
The oral and intra-osseous development of each of the six manidibular cheek teeth found in the permanent dentition of cattle was studied. The animals used were all British Friesians, of varying sex, and slaughtered at different weights at ages between 13 and 22 months. The various stages of development observed in each tooth together with the mean age and age range at which they were seen are recorded. Significant differences were found between the ages at which several of the developmental stages were seen in most of the teeth and indicated that tooth formation in the Friesian cattle studied tended to fall within well defined age limits.  相似文献   

2.
The mandibles of 78 Hereford cross Friesian steers all showing a full complement of temporary teeth were examined both visually and by radiography to determine whether it was possible to differentiate their various ages. All but one animal were slaughtered at the same weight (1020 lb-464 kg) and their ages at slaughter ranged from 1 year 3 months to 1 year 9 months. Differences were found between the mean ages for stages of resorption of the first temporary incisor roots, stages of first permanent incisor root formation and stages of second incisor crown formation, as determined by radiographic inspection. The results indicated that the age of a group of animals could be defined, but the age range within each development stage meant that it was not possible to define the age of individual cattle.  相似文献   

3.
Reasons for performing study: There are few published data to support the ages of emergence of permanent dentition widely reported in horses. Objectives: To clarify the chronology and sequence of permanent premolar (PM) tooth emergence in Thoroughbred racehorses. Methods: A prospective study was undertaken in which records were kept of deciduous PM ‘cap’ extractions performed during routine dental examinations in Thoroughbred racehorses. Mixed effects multiple regression analysis was used to relate the observed ages, measured in days, for PM ‘cap’ extractions simultaneously with different predictive variables. Care was taken to account for clustering of multiple observed outcomes within individual horses. Results: A total of 508 deciduous premolar ‘caps’ were removed from 207 horses, mean ages at removal from PM2, PM3 and PM4 were 35.1, 37.7 and 45.1 months, respectively. Age at which deciduous ‘cap’ removal occurred was associated significantly with tooth row, upper or lower jaw and gender of the horse concerned. There was a significant trend for later ‘cap’ extraction age with more caudal teeth, teeth in the upper jaw and female gender. Conclusions: Age at removal of deciduous premolar ‘caps’ in this population differed considerably from the ages of emergence of permanent dentition reported widely in equine publications. The results provide the first evidence of sexual dimorphism in the eruption of the permanent premolar dentition in horses. These findings strongly support a model of cheek tooth eruption in the horse in which chronology and sequence of emergence are more complex than previously thought, but which is consistent with understanding of tooth eruption in species that have been studied in greater detail. Potential relevance: Abnormalities of cheek tooth eruption are thought to be a factor in the pathogenesis of a variety of dental conditions, and a thorough understanding of the process of eruption is fundamental to the development of rational strategies for prevention and treatment.  相似文献   

4.
Reasons for performing study: Dental disorders have a high prevalence in older donkeys and horses, but the nature and pathogenesis of many of these disorders have yet to be established. Objectives: The identification and determination of the prevalence of important dental disorders in different age groups in a large single population of donkeys, to establish a better understanding of the nature and pathogenesis of these disorders. Methods: A prospective cross‐sectional study was performed on the donkey population at The Donkey Sanctuary with detailed oral examinations of 357 donkeys within 7 different age groups (age range 2–53 years) recorded. Results: The prevalence of dental disease in all donkeys was 73%, increasing in prevalence from 28% in the youngest to 98% in the oldest age group. There was an increase in prevalence of commonly recognised dental disorders with increasing age, such as: diastemata (3.8% in youngest to 86% in oldest group); missing teeth (0–56%); overgrown teeth (15–86%); worn teeth (8–84%); displaced teeth (0–38%); and periodontal disease (0–28%). Conclusions: There was a significant increase in the prevalence of dental disorders with increasing age with the largest significant increase for most dental disorders occurring in the 15–20 year age group. Potential significance: Most dental disorders significantly increase in prevalence in the 15–20 year age group and, therefore, prophylactic geriatric dental treatment in donkeys should be commenced from age 15 years.  相似文献   

5.
Radiographs were taken of both the right and left sets of maxillary teeth in 23 Friesian cattle of known age. The stage of development of each permanent tooth was ascertained and the degree of root resorption in the deciduous premolars was noted. All stages in individuals were later than for those of the mandibular cheek teeth except in the case of the first permanent premolar. As with mandibular cheek tooth development stages of formation occurred within certain age limits.  相似文献   

6.
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7.
The impact of pelleted diets with different mineral compositions on the crown size of the mandibular cheek teeth, as well as the mandibular bone and cheek teeth density, in degus (Octodon degus) was investigated. A total of 28 animals were randomly divided into four groups and fed different calcium or phosphorous dietary content, in the presence or absence of UV light, for 14 months. Dental radiographs and CT images of the head were taken, and the crown size of premolar and molar teeth was recorded. Apical and coronal crown elongation of all cheek teeth and significantly smaller relative cheek teeth and mandibular densities were recorded in degus fed a high-phosphorus diet with an improper calcium:phosphorus ratio. A diet with a calcium:phosphorus ratio of 1:1 was also responsible for the rapid development of dental disease with subsequent severe health impairment.  相似文献   

8.
Abstract

Sequential growth measurements were made on successive populations of Themeda triandra and Sporobolus fimbriatus tillers initiated at different times of the year. The independent influences of tiller age and time of year on tiller growth were isolated by deriving growth indices for tillers of the same age at different times of the year and for tillers of all ages at each time of the year respectively.

Isolating the effect of plant age on growth showed that T. triandra is most productive under a regime of long periods of undisturbed growth, while S. fimbriatus is better suited to frequent interruptions in growth. Isolating the effect of time of year shows that both species are particularly sensitive to perturbations in spring. However, the photosynthetic efficiency of T. triandra is strongly influenced by time of year while S. fimbriatus seems to be a more opportunistic assimilator of sunlight.  相似文献   

9.
Techniques for the age determination of highveld eland in Natal were investigated. Tooth eruption and replacement sequence, and growth in horn length, were suitable criteria for the age determination of young eland with deciduous dentition. The most accurate technique for the age determination of post mortem adult eland was based on counts of cementum annuli from molar teeth. Animals without distinctive cementum annuli may be assigned ages from measurements of M3 crown height. The ages of live restrained eland could be derived from measurements of I1 occlusal width or I1, crown height. Horn morphology was adequate for age and sex classification of free-ranging eland up to adult status.  相似文献   

10.
The effects of weaning on beef calves of different ages were investigated. Forty male and 40 female calves were either weaned at 6 (W6, n = 40) or 8 (W8, n = 40) months of age. The vocalization activity and behaviors (feeding, lying and standing/walking) were observed during the first 3 days following weaning. Body weight was recorded at 6 and 8 months and 2 weeks following weaning. W6 animals vocalized more often than W8 calves and females more than males on day 1 (P < 0.05). The vocalization activity decreased at a higher rate in W8 than in W6 from days 1 to 3. On day 2, W6 calves spent less time lying and more standing/walking than W8 calves (P < 0.05). The behaviors did not differ between males and females. The average daily gain after weaning did not differ between weaning ages (P > 0.05), but W8 calves gained more from 6 to 8 months of age. In conclusion, weaning distress was more pronounced in W6 than in W8 calves. W8 calves also had a superior growth performance during 6 to 8 months of age. The effect of the calves' sex was less pronounced. Therefore, it is recommended to wean beef calves later than 6 months of age.  相似文献   

11.
The study describes crown and root formation of the permanent mandibular cheek teeth of fallow deer from a gestational age of 22–23 weeks up to a post‐natal age of 33 months. Tooth development was recorded using a scoring scheme based on morphological criteria ranging from crypt formation to completion of root growth. The morphological appearance of the enamel surface during three different stages (secretory‐stage enamel, maturation‐stage enamel and mature enamel) was described, and the approximate age at termination of the secretory stage of amelogenesis in the deciduous and permanent mandibular cheek teeth was determined. The data enable an age estimation of fallow deer up to 3 years of age and provide a basis for assessing the timing of stress episodes that affect tooth crown formation. This information is useful for the management of the species as well as in bioarchaeological and bioindication studies.  相似文献   

12.
Teeth from cattle, sheep, and horses that ingested various fluoride intakes and teeth from field studies of these species plus deer, elk, and bison were examined for abnormalities. Approximately 99,000 animals in 322 herds were examined for fluorosis. From field studies, 988 cattle of various ages and with different degrees of dental fluorosis were slaughtered and necropsied. The severity of fluoride-induced mottling, hypoplasia, and abnormal abrasion of paired permanent incisor teeth was correlated with abrasion of premolar and molar (cheek) teeth that form and mineralize at approximately the same age. Severe irregular wear of cheek teeth impaired mastication and resulted in poor utilization of feed and unthriftiness. Excessive amounts of fluoride during tooth formation and mineralization induce characteristic dental changes. Offspring from the fluoride-affected animals did not have discernible fluoride-induced lesions in the deciduous teeth.  相似文献   

13.
The purpose of this study was to gain information concerning chronology of postnatal dental eruption in degus (Octodon degu). Specific findings pertain to the estimation of postnatal age at tooth emergence through the gingiva and to the age when a particular tooth is in functional occlusion. Fifty newborn degu pups were included in this study. The oral cavity endoscopy was carried out under isoflurane anesthesia in all animals 3 to 4 and 24-hours after birth, then at 1-day intervals until the age of 40-days, and subsequently at 2-day intervals until 75-days of age. Tooth emergence was considered to have occurred when any portion of the crown had penetrated the gingiva. The stage when the teeth come into occlusion was defined as the functional occlusion. The degus were born with completely erupted permanent incisors that were already in functional occlusion. All the premolar teeth and all the first molar teeth erupted on days 2 - 3 and 4 - 5 of life, respectively. The first signs offunctional occlusion ofall the first 2 cheek teeth were observed on days 9 - 11. Maxillary and mandibular second molar teeth emerged between days 17 - 19 and 18 - 20, respectively. First signs of functional occlusion were observed on days 30 - 31 and 31 - 33for maxillary and mandibular second molar teeth, respectively. Maxillary third molar teeth emerged on days 38 - 44 and erupted into occlusion on days 48 - 58. Mandibular third molar teeth emerged on days 39 - 46 and erupted into occlusion on days 58 - 72.  相似文献   

14.
Reasons for performing study: Dental disease often presents a diagnostic challenge in the horse. Computed tomography (CT) is increasingly used in the evaluation of head related disease in the horse, but the CT appearance of the most common dental diseases of horses has not yet been fully described. Objective: To describe the CT appearance of the peripheral enamel, pulp, infundibular enamel and cement in equine cheek teeth with macroscopic occlusal or CT lesions. Methods: In this study, 126 cadaveric cheek teeth with eruption ages of between 0.5 and 19 years were evaluated for lesions of their infundibulae, pulp and enamel using occlusal surface morphology, 2‐ (2D) and 3‐dimensional (3D) CT and anatomical sectioning. Variations in teeth with no macroscopic lesions have been described in a previous study. The infundibular lesions were categorised further into one of 6 classifications. Results: Infundibular lesions were identified on CT in 90% (115/128) of infundibulae. Of these, 65% (83/128) had infundibular lesions on occlusal surface examination. The extent of infundibular lesions observed varied with age group. All infundibulae over 6 years post eruption had detectable lesions. Peripheral enamel hypoplasia and enamel prolapses, were observed in 10% (12/126) and 1.6% (2/126) of teeth, respectively. The CT appearance of teeth with pulp infections was seen to vary with differing pathologies. Conclusions and potential relevance: The high prevalence of infundibular lesions should encourage consideration of their clinical significance, in addition to the role of infundibulae in dental disease of the horse. Two‐dimensional and 3D CT proved to be highly valuable imaging modalities for dental disease, enabling lesions within the enamel, infundibulae and pulp of equine cheek teeth to be easily detected. The results of this study will facilitate the use of 2D and 3D CT as clinical diagnostic tools for dental disease and aid in the selection of the most appropriate treatment protocol.  相似文献   

15.
The teeth in the severed heads of 501 cull cows, all over 30 months of age, were examined at an abattoir in the north of England in 1997/98; 80 per cent of them were Friesians or Holsteins. Seventy-three animals (14.6 per cent) had one or more missing incisors, most of which were acquired losses. Rotation and overlapping of rostral teeth were also common, as was attrition. Congenitally absent first lower premolars, other missing teeth, large and often multiple interdental spaces, and a few cases of macrodontia, cavitation, multiple defects and fractures were observed in the cheek tooth arcades. There were some unusual patterns of premolar and molar attrition, often attributable to malocclusion, one result of which was the formation of a hook at the posterior extremity of the third maxillary molar.  相似文献   

16.
The clinical and pathological findings after a natural intra‐uterine infection with BVD‐virus in a Friesian dairy herd are described. The virological and serological aspects will be discussed in a separate paper (30).

In a period of 4 years, 11 calves were hum with the following nervous symptoms: more or less serious incoördination, tremor, oscillating nystagmus, and a negative blinking reflex. The pupillary and sucking reflexe's were normal. No ocular defects, such as lenticular opacity or retinal atrophy were observed.

The first calf was born in 1979. Within 6 months the symptoms disappeared. After a normal conception and pregnancy this animal gave birth to 2 clinically normal calves in 1981 and 1982. The second calf died at the age of 2 months, due to an ulcerating enteritis.

In 1980, again 8 calves with the same nervous symptoms were born within a period of 3 months. Two calves died at the age of 3 days and 5 weeks respectively; 2 calves were sold when 10 days and 3 weeks old; one calf did not improve and was necropsied at the age of 17 days. The remaining 3 calves showed only a slight hypermetria when examined after 6 months. At that time nystagmus was only visible with ophthalmoscopy. Two calves were slaughtered when 10 months old. The last one, a bull, proved to be sterile and was necropsied at the age of 1 ½> year.

A calf, born in 1981, recovered within a week and was necropsied at the age of 15 days. The last calf, born in 1982, did not improve at all and was necropsied at the age of 14 days.

During these 4 years none of the other animals in the herd showed any symptoms due to an acute or chronic BVD‐virus infection.

At post mortem examination of 6 animals no macroscopically visible malformations were found. Hypomyelination and abnormal glial cells were evident in 5 cases, especially in the two youngest calves which did not show any improvement. One of them had an obvious thymic hypoplasia. The calf which recovered within a week showed only very slight changes. In one of the calves slaughtered at 10 months, inflammatory lesions were found in the brain. The diagnosis was confirmed by virological investigations.

Clinically as well as pathologically there was a close resemblance to Border disease in lambs and congenital tremor in piglets after prenatal exposure to Hog cholera virus.  相似文献   

17.
U. Rahm 《African Zoology》2013,48(1):149-164
1. C. kraussi in the Swartkops river estuary in South Africa has a major breeding period in winter-spring (May-July/August) and a minor breeding period in summer (November-January).

2. A maximum of 43 per cent of ovigerous mature females was recorded. Females in the 8 and 9 mm carapace-size classes make the major contribution to the breeding effort.

3. Recruitment is very marked with 60-80 per cent of the population consisting of juveniles at times.

4. Both sexes live for about two years. Females hatching in winter-spring may breed first in summer at an age of about 16-18 months and then again in the following winter at an age of about two years. Females hatching in summer breed first in winter at an age of about 18 months and some in the following summer at an age of about two years.

5. Breeding and growth in C. kraussi is compared with that in other known callianassids, and discussed in relation to estuarine eco-systems and conservation measures.  相似文献   

18.
Abstract

Litter sizes (LS) for the three largest breeds of sheep represented in the Swedish sheep recording scheme, Pelt (P), Swedish Crossbred (X) and Landrace Finewool (F), were studied. Average LS for different ewe ages were seen to increase from yearling to full maturity, around 4 years of age, and then remained the same until around 9 years of age for P and X, which thereafter showed a slight decrease. Landrace Finewool, a more prolific breed, peaked at 5 and 6 years of age and started to decline the year after. Flock size in itself did not significantly affect LS for any breed. The addition of an effect of flock-year increased the coefficient of determination (R 2) in a linear model. SAS Proc CATMOD estimated noticeable differences between LS distributions for different breeds and ewe ages, and smaller differences between LS distributions for individual ewe deviations from flock average lambing date. It was concluded that the effects of flock-year and age of ewe were the major fixed effects that need to be accounted for when evaluating LS within breed.  相似文献   

19.
Reasons for performing study: Removal of cheek teeth in all but the aged horse or pony is a serious undertaking with potentially deleterious sequellae. Rigid endoscopy permits detailed examination of the oral cavity and erupted dental tissues and has the potential to assist in the correct identification of the diseased tooth. Objectives: To document oral endoscopic findings associated with infected equine cheek teeth in cases without gross oral pathological changes and thereby determine the usefulness of rigid oral endoscopy as an aid to diagnosis of such infections. Methods: Records of all cases of equine cheek tooth removal attempted under standing sedation over a 38 month period were examined. Cases were excluded from the study if apical infection was associated with gross dental fracture, malalignment, diastema/periodontal pocketing or supernumerary teeth. Endoscopic and radiographic findings were analysed and correlated to diseased tooth location. Results: Seventeen cases of apical dental infection fitting the inclusion criteria (nonresponsive to antibiotics and with no gross oral abnormality of the affected arcade) were identified in which oral endoscopy was used as an aid to diagnosis. In 15 (88%) of the 17 cases, oral endoscopy revealed abnormalities specific to the infected tooth. Focal gingival recession (10/17 cases) was the most common visible abnormality associated with infected teeth. Conclusions: In the majority of cases of apical infection of equine cheek teeth there is visible intraoral evidence implicating the affected tooth. Potential relevance: Oral endoscopy facilitates detailed examination of the mouth and should be considered along with radiography as an important aid to diagnosis in cases of equine dental infection.  相似文献   

20.
Summary

The prevalence of S. bovis in the intestinal tract of healthy racing pigeons was determined. Crop and cloaca swab samples obtained from 810 pigeons from 14 different lofts and from 122 pigeons that were presented for routine health control were examined for the presence of S. bovis. Pooled faecal samples were also obtained from pigeons in 82 different pigeon lofts. S. bovis was isolated from crop or cloaca samples of approximately 40 % of pigeons of all ages by direct culture and from 80 % of the pooled faecal samples by enrichment culture.

In a longitudinal study, crop and cloaca samples were collected every 3 months from pigeons in seven different pigeon lofts. The prevalence of S. bovis in these pigeons ranged from 0 to 100 %. The carriage rate was not related to the season or to the age of the pigeons.

The prevalence of S. bovis in organ lesions of pigeons examined at necropsy was investigated over a 35‐month period. S. bovis was isolated from 10 % of the birds examined. The incidence of S. bovis septicaemia was significantly higher in January to August than in September to December. It was concluded that S. bovis is an opportunistic pathogenic agent in pigeons.  相似文献   

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