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71.
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Summary Cattle in a communal farming area of Zimbabwe were identified and examined in the late dry and mid wet season of 1985/86. Ovarian activity rates were 17·9% and 38·6% in the dry and wet season respectively. Pregnancy rates were 16·1% and 24·6% respectively. A major limitation to reproduction was the percentage of anoestrous females. There was no evidence of a seasonal calving pattern. Median body condition score was 2·0 in the dry season and 1·5 in the wet season. Adult females of body condition score 2·5 and above had ovarian activity rates of 41·9% and pregnancy rates of 41·9 per cent. Those with a body condition score below 2·5 had rates of 26·8% and 16·4% respectively. Serum progesterone levels in pregnant animals were positively related to body condition score, with some animals having progesterone levels similar to non-pregnant animals. Metabolic profiles suggested that the major limiting nutrient in both seasons was nitrogen, although other micronutrients might also be involved in low reproductive rates.
Resumen Se identificó un grupo de ganado en un área comunal pastoril en Zimbabwe, el que se estudió al final de la estación seca y en la mitad de la estación lluviosa. El estudio se llevó a cabo de 1985 a 1986. La tasas de actividad ovárica fueron de 17·9% y 38·6% y las de pre?ez de 16·1% y 24·6%, en la estación seca y lluviosa, respectivamente. La mayor limitación para la reproducción, fue el porcentaje alto de hembras en anestro. No hubo un patrón claro de partos estacionales. La condición corporal media fue de 2·0 en la estación seca y de 1·5 en la estación lluviosa. Las hembras adultas que tenian una condición corporal de 2·5 ó mayor, tuvieron tasas de actividad ovárica de 41·9% y tasas de pre?ez de 41·9 por vaca. Aquellas con una condición corporal por debajo de 2·5, tuvieron tasas de actividad ovárica de 26·8% y tasas de pre?ez de 16·4%, respectivamente. Los niveles de progesterona en animales pre?ados, estuvieron positivamente relacionados con el puntaje obtenido en el análisis de la condición corporal, aunque algunos animales tuvieron niveles de progesterona bajos, como de animales no pre?ados. Los perfiles matabólicos revelaron, que el nutriente más deficitario fue el nitrógeno, aunque otros nutrientes tambien fueron deficitarios.

Résumé Dans une zone agricole de type communautaire, le bétail a été identifié et examiné à la fin de la saison humide et jusqu’au milieu de la saison sèche en 1985/1986. Les taux d’activité ovarienne étaient respectivement de 17,9 et 38,6 p. 100 au cours de la saison sèche et de la saison humide. Les taux de gestation étaient de 16,1 et 24,6 p. 100 respectivement. Un obstacle essentiel à la reproduction s’est révélé être le nombre de femmelles en anoestrus. Aucune preuve n’a pu être apportée d’un mode de mise bas lié à la saison. L’indice de condition corporelle moyenne mesuré à l’aide d’une échelle de points était de 2,0 en saison sèche et de 1,5 en saison humide. Les femelles adultes dont la condition corporelle était de 2,5 et au dessus, avaient des taux d’activité ovarienne de 41,9 p. 100 et des taux de gestation par co?t identiques. Celles dont l’indice était inférieur à 2,5 avaient des taux de 26,8 et de 16,4 p. 100 respectivement. Les taux de progestérone sérique chez les animaux en gestation étaient positivement liés à l’indice de condition corporelle, avec quelques sujets dont le taux de progestérone était identique à celui d’animaux non-gestants. Les profils métaboliques font penser que le facteur alimentaire limitant majeur pour les deux saisons était l’azote, quoique d’autres micronutriments aient pu être également en cause dans les taux de reproduction bas.
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73.
A three-tiered survey was devised comprising a detailed questionnaire, a serological survey and a sentinel herd scheme for disease surveillance. The survey was carried out in the traditional farming sector in 7 districts of Zambia to obtain background information on cattle management and productivity, data on the prevalence of tick-borne and other disease problems in these areas and to monitor changes in individual herds.In the questionnaire survey, 288 farmers were interviewed. They owned a total of 15 360 head of cattle, representing approximately one percent of the national herd. Mean herd sizes ranged from 31 to 114 for each district. Mean calving percentages were 44–80%. Average national offtake from these herds was 10%. Calf mortality rates ranged from 4 to 32%, while adult yearly mortality rates ranged from 4 to 16%. Factors affecting the regional variation of these figures are discussed.  相似文献   
74.
Students in Reproductive Management (a senior-level course with approximately 20 to 50 students per semester) at the University of Missouri-Columbia are required to participate in a simulation exercise that is designed to improve reproductive efficiency in a beef herd. During a simulated 5-yr period, students must 1) improve reproductive efficiency in a beef cow-herd through implementation of reproductive management principles; 2) determine the economic impact of reproductive management decisions in a beef herd; and 3) evaluate the constraints of different geographical locations on approaches to reproductive management. Groups of three to four students are provided with the reproductive and economic records of a farm/ranch located in different parts of North America. Students create reproductive management plans consisting of 1) detailed discussion of farm/ranch environment (climate, terrain, forage and grain availability, and stocking rate; season for breeding and calving; and justification for choice of breed); 2) assessment of current level of reproductive performance; 3) identification and economic justification of specific (measurable) objectives; 4) discussion of alternatives for accomplishing specific objectives; 5) prediction of reproductive performance (pregnancy rate, quantity of calf weaned per cow exposed, and cost per quantity of calf weaned) in response to implementation of specific management practices; and 6) an annual and 5-yr reproductive and economic summary. Students obtain livestock marketing information for their assigned location via the Internet. Spreadsheets were developed to calculate the reproductive efficiency of postpartum cows and replacement heifers based on management decisions made by the groups and to calculate a yearly economic summary for each of the 5 yr. Management decisions are justified in a written report, and oral presentations are given to the class when the project is completed. Greater than 85% of students indicated that the exercise increased their understanding of how management decisions affect reproductive efficiency and profitability in a beef operation and also provided added confidence for students that applied for beef management positions.  相似文献   
75.
1. The effects of light source and intensity on leg health and performance of female ROSS 308 broiler chickens were investigated in a 2 x 2 experimental design (8 groups of 275 chicks) of two light sources (Osram biolux and Osram warm-white) and two light intensities (5 and 100 clux, adjusted to fowl-perceived illuminance). 2. At 41 d of age, body weight, gait-score, footpad dermatitis and hock-burn were measured on 50 birds from each light environment. In addition, weekly feed intake and body weight were determined on a group basis and mortality was recorded continuously. 3. The light environment did not affect the severity of the gait-score or hock-burns. The risk of moderate to severe lameness and hock-burns increased with body weight. Birds weighing more than 2400 g had an increased probability of moderate footpad lesions in biolux light. 4. Weight and gait-score, as well as gait-score and hock-burn were positively correlated. Podo-dermatitis was weakly correlated with hock-burn, which contradicts earlier findings. The light environment did not affect feed intake, body weight or mortality. 5. The light sources and intensities employed in this study did not adversely affect production or leg health of broiler chickens reared semi-commercially.  相似文献   
76.
The objectives of this research were to partition variation in ovulatory follicle size into genetic and nongenetic components and to assess the utility of ovulatory follicle size as an indicator trait associated with reproductive success in beef cattle. Data were collected during the years 2002 to 2005 from 780 beef females that ranged in age from 1 to 12 yr (mean of 2.4 observations per female). Data were analyzed with a multiple trait Gibbs sampler for animal models to make Bayesian inferences from flat priors. A chain of 500,000 Gibbs samples was thinned to every 200th sample to produce a posterior distribution composed of 2,500 samples. Heritability estimates (posterior mean +/- SD) were 0.16 +/- 0.03 for follicle size and 0.07 +/- 0.02 and 0.02 +/- 0.01 for pregnancy rate as a trait of the female and service sire, respectively. Posterior means of genetic correlations were all <0.10, with 0.00 contained within the respective 90% probability density posterior intervals. Results indicate that whereas follicle size is of greater heritability than pregnancy rate, its usefulness to improve reproductive rate is greatest as an ancillary phenotype in multiple trait selection.  相似文献   
77.
Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history.  相似文献   
78.
Prostatic masses were detected in two geldings that were presented to our referral hospital for evaluation of dysuria. The masses were detected during transrectal palpation and ultrasonography of the prostate gland and were further evaluated using urethral endoscopy. A 10-year-old gelding underwent intraurethral debulking of the prostatic mass. Histopathological diagnosis was prostatic cystadenoma. The mass regrew within 9 months, and the horse was euthanized due to deteriorating clinical control of urinary continence. In another case, a 12-year-old gelding was scheduled for transurethral debulking; however, the owners decided against treatment and the horse was euthanized due to progression of clinical disease. Postmortem examination revealed the prostate to be nearly completely obliterated by the mass. Histopathological diagnosis was adenocarcinoma incorporated into a spindle cell population of unknown histogenesis. To our knowledge, these represent the first reported cases of equine prostatic cystadenoma and adenocarcinoma. In both horses, referring complaint was dysuria, and identification of the prostatic mass was made on palpation and ultrasonographic examination per rectum. Treatment options for prostatic masses in horses are limited because of the difficulty of obtaining prostatic tissue via biopsy, the surgical inaccessibility of the gland, and the apparent low incidence of occurrence. We have subsequently identified prostatic masses in two additional geldings, both also presenting for dysuria. However, the exact nature of these two apparent prostatic masses has not been definitively diagnosed with histopathological examinations to date. The prostate should be evaluated in male horses presenting for dysuria.  相似文献   
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