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1.
A unilateral cryptorchid bull stationed in an AI center for 3.5 yr was studied to determine if maintaining such a bull could be justified. The following parameters were determined: quantity and quality of the ejaculates, basal and stimulated plasma testosterone concentrations, and the histology and testosterone concentrations of the testicles. The bull produced 232 ejaculates of which 125 (53.8%) were immediately discarded; the rest (107 ejaculations) were processed into pellets. Two of the 107 frozen ejaculates (2%) were found to be of excellent quality, 37 were (34.5%) of good quality, 45 were (42%) of satisfactory quality and 23 were (21.5%) of poor quality. Treatment of the calf with GnRH and hCG at 4 and 5 mo of age did not initiate the descent of the retained testicle. Testosterone concentrations measured at 14 mo, after hCG stimulus, indicated that the bull had impaired steroidogenesis when compared with 2 control bull calves. Post mortem examination revealed a small left testicle in the inguinal canal and a normal right testicle as well as normal secondary sex glands. During the breeding period at the AI center, the bull's peripheral testosterone concentrations decreased from 2.2 to 0.95 ng/ml Testosterone concentrations in the parenchymal tissue of the scrotal testicle were higher than in the parenchyma of the retained testicle (98.2 vs 53.9 ng/g). In contrast, the epididymis of the scrotal testicle had a lower testosterone concentration than the epididymis of the retained testicle (10.8 vs 33. 0 ng/g). On histological examination no spermatozoa were found in the retained testicle, the Sertoli cells showed fat degeneration, and fibrotic tissue surrounded the tubuli seminiferi. No pathological changes were found in the normal scrotal testicle. In conclusion, no justification was found for maintaining such a bull in the AI center for breeding purposes.  相似文献   

2.
A Simmental bull with a history of low fertility, both by natural service and artificial insemination, was presented for examination. Two previous semen evaluations had revealed no specific semen abnormalities that would support the breeding history. A comprehensive cytochemical analysis of the bull's ejaculate revealed a complex nuclear lesion affecting over 80% of sperm. This condition was expressed in abnormal shaping of the nuclei, with deficient distribution, condensation and stabilization of the nucleoplasm. These abnormalities were associated with various-sized intranuclear pouches or depressions. The acrosome was moderately involved and the tail was relatively free of abnormalities resulting in normal sperm motility.Two controlled breeding trials utilizing a total of 15 super-ovulated females were conducted to evaluate the bull's fertilization rate. Combined data demonstrated an 18% (23128) fertilization rate of recovered ova. At the same time, the fertilization rate of seven bulls classified as satisfactory potential breeders was 72% (353490).Data from two embryo transplant units regarding ova collected from eight donor females inseminated with semen from this bull revealed a fertilization rate of 41% (3073). Of the fertilized ova, 37% (1130) were degenerate and were not transferred. A pregnancy rate of 57% (1119) resulted from the transfer of 19 fertilized ova.A natural breeding pregnancy rate of 5% (242) and artificial breeding pregnancy rate of 8% (15180) support the breeding trial results.  相似文献   

3.
The objective of this case report was to identify the cause of apparent idiopathic infertility in a Red Angus (beef) bull. Semen was collected by electroejaculation and submitted to a series of assays, including evaluation of sperm motility by computer-assisted sperm analysis (CASA), sperm morphology and DNA integrity, semen cryopreservation, AI, IVF, induction of the acrosome reaction, and determination of the level of sperm proteins associated with bull fertility potential. Total (92 ± 2%) and progressive (79 ± 4%) sperm motility; sperm concentration (1647 ± 429 × 106 sperm/mL); proportions of morphologically normal sperm (83 ± 6%) and DNA integrity (96 ± 2), and acrosome-intact sperm (64 ± 4%) exceeded minimum acceptable values. Frozen sperm had good total (58.7 ± 6.7%) and progressive (43.9 ± 9.2%) motility immediately after thawing. However, AI of 16 heifers resulted in no pregnancies and blastocyst production rate (following IVF using sperm from this infertile bull) was nearly identical to that produced using dead sperm (a control of parthenogenesis; 2 ± 2 and 2 ± 3%; respectively P < 0.05). Treatment with a calcium ionophore (A23187) failed to induce the acrosome reaction in sperm from the infertile bull (P < 0.05). Evaluation of several proteins associated with the fertility potential of bulls revealed that the level of Binder Sperm Protein-1 (BSP1), known to be associated with the capacitation process, was much greater on sperm from the infertile bull compared to that of his sire. In conclusion, we inferred that the idiopathic infertility in this bull was caused by a failure to complete the capacitation process.  相似文献   

4.
A large number of episodes of forest mortality associated with drought and heat stress have been detected worldwide in recent decades, suggesting that some of the world's forested ecosystems may be already responding to climate change. Here, we summarize a special session titled 'Drought-induced forest decline: causes, scope and implications' within the 12th European Ecological Federation Congress, held in ávila (Spain) from 25 to 29 September 2011. The session focused on the interacting causes and impacts of die-off episodes at the community and ecosystem levels, and highlighted recent events of drought- and heat-related tree decline, advances in understanding mechanisms and in predicting mortality events, and diverse consequences of forest decline. Talks and subsequent discussion noted a potentially important role of carbon that may be interrelated with plant hydraulics in the multi-faceted process leading to drought-induced mortality; a substantial and yet understudied capacity of many forests to cope with extreme climatic events; and the difficulty of separating climate effects from other anthropogenic changes currently shaping forest dynamics in many regions of the Earth. The need for standard protocols and multi-level monitoring programmes to track the spatio-temporal scope of forest decline globally was emphasized as critical for addressing this emerging environmental issue.  相似文献   

5.
Abstract. 1. Host relations of Palaearctic flowerhead-inhabiting tephritids (Diptera: Tephritidae) are reviewed in terms of the interaction between type of attack strategy and flowerhead size.
2. Three types of attack strategy are recognized, each associated with a particular phase of Compositae flowerhead development. These strategies are characteristic of a tribe or subfamily, viz the Tephritini (Tephritinae), Terelliini (Tephritinae) and Myopitinae.
3. Tephritini species show the most generalized feeding method, and this enables them to attack both large and very small flowerheads. In contrast, the more specialized requirements of members of the Terelliini and Myopitinae apparently restricts these groups to plant taxa with large flowerheads. As a result, over the whole range of Compositae flowerhead sizes, there exists a positive relationship between flowerhead size and the diversity of associated tephritids.
4. The occurrence of stem-feeding tephritids, and differences between a coevolutionary and functional (colonization) explanation for tephritid host-relations are discussed.  相似文献   

6.
Ectomycorrhizas and water relations of trees: a review   总被引:4,自引:0,他引:4  
Lehto T  Zwiazek JJ 《Mycorrhiza》2011,21(2):71-90
There is plenty of evidence for improved nutrient acquisition by ectomycorrhizas in trees; however, their role in water uptake is much less clear. In addition to experiments showing improved performance during drought by mycorrhizal plants, there are several studies showing reduced root hydraulic conductivity and reduced water uptake in mycorrhizal roots. The clearest direct mechanism for increased water uptake is the increased extension growth and absorbing surface area, particularly in fungal species with external mycelium of the long-distance exploration type. Some studies have found increased aquaporin function and, consequently, increased root hydraulic conductivity in ectomycorrhizal plants while other studies showed no effect of ectomycorrhizal associations on root water flow properties. The aquaporin function of the fungal hyphae is also likely to be important for the uptake of water by the ectomycorrhizal plant, but more work needs to be done in this area. The best-known indirect mechanism for mycorrhizal effects on water relations is improved nutrient status of the host. Others include altered carbohydrate assimilation via stomatal function, possibly mediated by changes in growth regulator balance; increased sink strength in mycorrhizal roots; antioxidant metabolism; and changes in osmotic adjustment. None of these possibilities has been sufficiently explored. The mycorrhizal structure may also reduce water movement because of different fine root architecture (thickness), cell wall hydrophobicity or the larger number of membranes that water has to cross on the way from the soil to the xylem. In future studies, pot experiments comparing mycorrhizal and nonmycorrhizal plants will still be useful in studying well-defined physiological details. However, the quantitative importance of ectomycorrhizas for tree water uptake and water relations can only be assessed by field studies using innovative approaches. Hydraulic redistribution can support nutrient uptake during prolonged dry periods. In large trees with deep root systems, it may turn out that the most important function of mycorrhizas during drought is to facilitate nutrient acquisition.  相似文献   

7.
As the world population grows, there is a pressing need to improve productivity from water use in irrigated and rain-fed agriculture. Foliar diseases have been reported to decrease crop water-use efficiency (WUE) substantially, yet the effects of plant pathogens are seldom considered when methods to improve WUE are debated. We review the effects of foliar pathogens on plant water relations and the consequences for WUE. The effects reported vary between host and pathogen species and between host genotypes. Some general patterns emerge however. Higher fungi and oomycetes cause physical disruption to the cuticle and stomata, and also cause impairment of stomatal closing in the dark. Higher fungi and viruses are associated with impairment of stomatal opening in the light. A number of toxins produced by bacteria and higher fungi have been identified that impair stomatal function. Deleterious effects are not limited to compatible plant-pathogen interactions. Resistant and non-host interactions have been shown to result in stomatal impairment in light and dark conditions. Mitigation of these effects through selection of favourable resistance responses could be an important breeding target in the future. The challenges for researchers are to understand how the effects reported from work under controlled conditions translate to crops in the field, and to elucidate underlying mechanisms.  相似文献   

8.
Fifteen cases of chondrodysplasia characterized by disproportionate dwarfism occurred in the progeny of a single Holstein bull. A de novo mutation event in the germline of the sire was suspected as cause. Whole-genome sequencing revealed a single protein-changing variant in the stop codon of FGFR3 gene on chromosome 6. Sanger sequencing of EDTA blood proved that this variant occurred de novo and segregates perfectly with the observed phenotype in the affected cattle family. FGFR3 is an important regulator gene in bone formation owing to its key role in the bone elongation induced by FGFR3-dimers. The detected paternally inherited stop-lost variant in FGFR3 is predicted to add 93 additional amino acids to the protein’s C-terminus. This study provides a second example of a dominant FGFR3 stop-lost variant as a pathogenic mutation of a severe form of chondrodysplasia. Even though FGFR3 is known to be associated with dwarfism and growth disorders in human and sheep, this study is the first to describe FGFR3-associated chondrodysplasia in cattle.  相似文献   

9.
The economic importance of dystocia in terms of calf losses and subsequent impaired reproductive performance has been well documented (1, 2, 3, 4, 5). The incidence of dystocia must be minimized to improve reproductive performance and maximize profits.The occurrence of dystocia in primiparous heifers is primarily a function of two factors: size of the calf and pelvic area of the dam (6, 7, 8, 9). There are medical (ie- late abortion, hydrops, monsters) and hormonal reasons for dystocia these will not be reviewed in this paper. Primarily, the relationship of calf size and pelvic area and the factors which affect them will be reviewed.  相似文献   

10.
11.

Background

Accurate information on the prevalence and causes of musculoskeletal impairment (MSI) is lacking in low income countries. We present a new survey methodology that is based on sound epidemiological principles and is linked to the World Health Organisation''s International Classification of Functioning.

Methods

Clusters were selected with probability proportionate to size. Households were selected within clusters through compact segment sampling. 105 clusters of 80 people (all ages) were included. All participants were screened for MSI by a physiotherapist and medical assistant. Possible cases plus a random sample of 10% of non-MSI cases were examined further to ascertain diagnosis, aetiology, quality of life, and treatment needs.

Findings

6757 of 8368 enumerated individuals (80.8%) were screened. There were 352 cases, giving an overall prevalence for MSI of 5.2%. (95% CI 4.5–5.9) The prevalence of MSI increased with age and was similar in men and women. Extrapolating these estimates, there are approximately 488,000 MSI diagnoses in Rwanda. Only 8.2% of MSI cases were severe, while the majority were moderate (43.7%) or mild (46.3%). Diagnostic categories comprised 11.5% congenital, 31.3% trauma, 3.8% infection, 9.0% neurological, and 44.4% non-traumatic non infective acquired. The most common individual diagnoses were joint disease (13.3%), angular limb deformity (9.7%) and fracture mal- and non-union (7.2%). 96% of all cases required further treatment.

Interpretation

This survey demonstrates a large burden of MSI in Rwanda, which is mostly untreated. The survey methodology will be useful in other low income countries, to assist with planning services and monitoring trends.  相似文献   

12.
The midtarsal break was once treated as a dichotomous, non-overlapping trait present in the foot of non-human primates and absent in humans. Recent work indicates that there is considerable variation in human midfoot dorsiflexion, with some overlap with the ape foot. These findings have called into question the uniqueness of the human lateral midfoot, and the use of osteological features in fossil hominins to characterize the midfoot of our extinct ancestors. Here, we present data on plantar pressure and pedal mechanics in a large sample of adults and children (n = 671) to test functional hypotheses concerning variation in midfoot flexibility. Lateral midfoot peak plantar pressure correlates with both sagittal plane flexion at the lateral tarsometatarsal joint, and dorsiflexion at the hallucal metatarsophalangeal joint. The latter finding suggests that midfoot laxity may compromise hallucal propulsion. Multiple regression statistics indicate that a low arch and pronation of the foot explain 40% of variation in midfoot peak plantar pressure, independent of age and BMI. MRI scans on a small subset of study participants (n = 19) reveals that curvature of the base of the 4th metatarsal correlates with lateral midfoot plantar pressure and that specific anatomies of foot bones do indeed reflect relative midfoot flexibility. However, while the shape of the base of the 4th metatarsal may reliably reflect midfoot mobility in individual hominins, given the wide range of overlapping variation in midfoot flexibility in both apes and humans, we caution against generalizing foot function in extinct hominin species until larger fossils samples are available. Am J Phys Anthropol 156:543–552, 2015. © 2015 Wiley Periodicals, Inc.  相似文献   

13.
This paper reviews a range of studies under controlled conditions (glasshouse and growth cabinet) focusing on the effects of the interaction between waterlogging (hypoxia) and salinity on the ion relations, growth and survival of higher plants. The literature shows that in general, waterlogging under saline conditions causes increased Na+ and Cl concentrations in the shoot, due initially to increased rates of transport. These increased concentrations in the shoots have adverse effects on plant growth and survival. It is argued that the interaction between waterlogging and salinity has major implications for saltland management, and for the selection and breeding of plants adapted to saltland.  相似文献   

14.
There is a missing link between tree physiological and wood-anatomical knowledge which makes it impossible mechanistically to explain and predict the radial growth of individual trees from climate data. Empirical data of microclimatic factors, intra-annual growth rates, and tree-specific ratios between actual and potential transpiration (T PET(-1)) of trees of three species (Quercus pubescens, Pinus sylvestris, and Picea abies) at two dry sites in the central Wallis, Switzerland, were recorded from 2002 to 2004 at a 10 min resolution. This included the exceptionally hot and dry summer of 2003. These data were analysed in terms of direct (current conditions) and indirect impacts (predispositions of the past year) on growth. Rain was found to be the only factor which, to a large extent, consistently explained the radial increment for all three tree species at both sites and in the short term as well. Other factors had some explanatory power on the seasonal time-scale only. Quercus pubescens built up much of its tree ring before bud break. Pinus sylvestris and Picea abies started radial growth 1-2 weeks after Quercus pubescens and this was despite the fact that they had a high T PET(-1) before budburst and radial growth started. A high T PET(-1) was assumed to be related to open stomata, a very high net CO2 assimilation rate, and thus a potential carbon (C)-income for the tree. The main period of radial growth covered about 30-70% of the productive days of a year. In terms of C-allocation, these results mean that Quercus pubescens depended entirely on internal C-stores in the early phase of radial growth and that for all three species there was a long time period of C-assimilation which was not used for radial growth in above-ground wood. The results further suggest a strong dependence of radial growth on the current tree water relations and only secondarily on the C-balance. A concept is discussed which links radial growth over a feedback loop to actual tree water-relations and long-term affected C-storage to microclimate.  相似文献   

15.
16.
17.
Collection of semen with a bovine artificial vagina (AV) was attempted with each of 14 camels over a period of 2 years. Semen samples were evaluated, extended and cryopreserved. Frozen thawed semen, diluted cooled semen or whole semen was used to inseminate some female camels which were induced to ovulate with hCG. Males ejaculated semen into the AV in 74.6% collection attempts. The male copulated for at least 200s in 62.9% attempts. The remaining copulations were of shorter duration. Similarly, 49.3% ejaculates were at least 3ml of semen. Libido and donation of semen improved from December onwards and reached a peak after mid January with peak performance persisting until April. It declined during May. The majority of camels had lost libido and refuse to donate semen by the end of May. Camel semen is in gel form. While 35.9% of 203 semen samples exhibited no individual sperm motility, 28.5% exhibited low to fair grade individual sperm motility and only 35.4% exhibited >50% sperm motility. Differences existed between animals (P<0.01) and months (P<0.05) of collection, while effect of copulation time was not significant. Mass motility was not observed in camel semen. Individual sperm motility develops after liquefaction of semen. Addition of caffeine but not chymotrypsin improved the individual motility. The mean live percent sperm count and normal acrosome were 73.3+/-1.0 and 92.0+/-0.5, respectively. Only 51.1% of 45 semen samples with pre-freeze motility of >50% and 25% of 16 semen samples from low pre-freeze motility group with an overall success of 44.2% of 61 semen samples were successfully preserved. Wide variation was observed in the freezability of semen from different males. Attempts to impregnate female camels with liquid semen, frozen thawed semen and whole semen after hCG induced ovulation resulted in 0/10, 1/13 and 4/10 pregnancies.  相似文献   

18.
The European cattle was domesticated 10 000 years ago in eastern Turkey, 1000 years later pottery-associated milk fats identify cattle-based dairy activity in western Turkey. Subsequently, the Indo-European language, domesticated animals and plants travel as a Neolithic package along two major routes across Europe. A striking south-east to north-west gradient of a mutation in the current European population (lactase persistence into adulthood) documents the expansion of a Neolithic dairy culture into a Mesolithic hunter society. Using oral tradition (myths), archaeological and written historical evidence and biological data, it is asked whether highly transmissible viral diseases like measles and smallpox entered during the Neolithic from domesticated animals into the human population. The bovine origin of paramyxovirus infections is likely; smallpox comes from camels or from rodents via cattle while mycobacteria and Helicobacter infected humans already before the Neolithic. Microbes adapt constantly and quickly to changing ecological situations. The current global environmental changes will lead to another highly dynamic phase of viral transmissions into the human population.  相似文献   

19.
20.
Cold stress was identified as an important factor influencing both reservoir-wide mortality and impingement of threadfin shad, Dorosoma petenense , during the period October 1976 to April 1977 in Watts Bar Reservoir, Tennessee. Relative numbers and size frequency of impinged threadfin shad were similar to the relative numbers and size frequency of shad preyed upon by sauger, Stizostedion canadense , and skipjack herring, Alosa chrysochloris . This relationship implies that the factor mainly responsible for impingement, low temperature, also influences prey vulnerability. Threadfin shad made up 99% of the combined diet of sauger and skipjack herring from November until the threadfin shad disappeared in January. These predators did not readily switch to alternative prey in the short term, but by the next autumn 25–100% of the diet was alternative prey. Reappearance of threadfin shad the year following mass mortality and ability of the predators to vary their diet emphasize the resilient nature of some predator-prey systems.  相似文献   

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