Gonadotrophin-releasing hormone treatment in cattle: a meta-analysis of the effects on conception at the time of insemination

SUMMARY Data from 40 trials described in 27 published papers were analysed by meta-analysis (pooling of data from numerous trials into a single analysis) to evaluate the effects of injecting gonadotrophin-releasing hormone (GnRH) In cattle at the time of Insemination on the risk of pregnancy. A total of 19 019 cows were involved In these studies. Analyses were stratified by trial and by the effects of dose of GnRH, type of GnRH and Insemination number (first, second or third and greater). Mantel-Haenszel analysis revealed that use of GnRH at Insemination significantly Increased the overall risk of pregnancy by 12.5% In treated cows (P < 0.05). However, Increases In risk of pregnancy were greatest (22.5%) when repeat breeders were treated. Results for use of GnRH or analogue at first service were similar, with Increased risks of pregnancy in treated cows of 5.2 and 8.0%, respectively. The risk of pregnancy tended to be higher (11.1%) when the dose of GnRH was 250 μg and when used at second Insemination (9.9%). The analyses demonstrated that while treatment at Insemination with GnRH and GnRH analogues Increased conception rates In dairy cattle, some variation In study results was attributable to the number of Inseminations after calving at which GnRH Is administered. Further efforts should be made to determine characteristics of populations of cows that have good fertility responses to GnRH and to determine the mode of action of GnRH in Increasing fertility. Meta-analysis proved to be a useful technique for evaluating the apparently conflicting results from trials and in evaluating the effect of factors such as Insemination number, dose and type of GnRH on responses to treatment.     

Effect of Variable Temperature on Infection Severity of Podosphaera macularis on Hops

ABSTRACT The effect of variable temperature on the infection severity of Podosphaera macularis was investigated. Potted 'Symphony' hop plants were inoculated and exposed to different temperature regimes that included supraconducive temperatures (30 to 42 degrees C) for varying periods of time (2 to 9 h). Infection severity (lesions per cm(2) of leaf area) was calculated 7 to 10 days after inoculation. Immediately exposing inoculated plants to 30 degrees C for as little as 2 h significantly (P 相似文献   

Congenital hypothyroidism in Scottish Deerhound puppies

Two Scottish Deerhound puppies had clinical and pathological features consistent with the diagnosis of congenital non-goitrous hypothyroidism. They were from separate litters, but were the progeny of the same sire and dam. The puppies were smaller, had shorter limbs and shorter, broader heads than their littermates. They also had histories of weakness, difficulty in walking and somnolence. A characteristic radiographic feature was the absence of epiphyseal growth centres. Both had depressed serum thyroxine (T4) levels and one did not respond to exogenous thyroid stimulating hormone. On necropsy, the thyroid glands were small, the follicles varied in size and contained little or no colloid. The adenohypophysis contained many cells with markedly vacuolated cytoplasm. It is suggested that the clinicopathological pattern is the result of a primary thyroid abnormality. Possible mechanisms include either primary thyroid hypoplasia or an unresponsiveness to thyroid stimulating hormone.     

The chemistry of water on alumina surfaces: reaction dynamics from first principles

Aluminas and their surface chemistry play a vital role in many areas of modern technology. The behavior of adsorbed water is particularly important and poorly understood. Simulations of hydrated alpha-alumina (0001) surfaces with ab initio molecular dynamics elucidate many aspects of this problem, especially the complex dynamics of water dissociation and related surface reactions. At low water coverage, free energy profiles established that molecularly adsorbed water is metastable and dissociates readily, even in the absence of defects, by a kinetically preferred pathway. Observations at higher water coverage revealed rapid dissociation and unanticipated collective effects, including water-catalyzed dissociation and proton transfer reactions between adsorbed water and hydroxide. The results provide a consistent interpretation of the measured coverage dependence of water heats of adsorption, hydroxyl vibrational spectra, and other experiments.     

Organic By-Product Effects on Soil Chemical Properties And Microbial Communities

Soil management practices that contribute to increased soil productivity and longterm sustainable agricultural production have been neglected over the last four decades. The need to increase soil productivity led to the evaluation of a system of disposing of large quantities of organic by-products and poultry litter on agricultural land. Our objectives were to evaluate the effects of applying noncomposted municipal solid waste (MSW), amended with either poultry litter (PL) or NH₄NO₃ to adjust C:N ratios in the soil surface in either the spring or fall. Changes in soil chemical properties, bacteria population shifts, changes in species richness and evenness of indigenous soil bacteria, and response by cotton (Gossypium hirsutum L.) were evaluated. Soil P, K, Ca, and Mg were increased in the surface 0–15 cm by a factor of three or four times by application of organic by-products. After two annual applications, soil Cu increased slightly, Zn doubled, Co and Cr decreased, while Pb increased by a factor of two. Soil organic matter content increased on average by 89 percent for treatments containing newsprint, yard trimmings, and cotton gin trash. Newsprint plus NH₄NO₃ resulted in a shift to more Gram positive bacteria, while newsprint plus poultry litter resulted in a shift to more Gram negative bacteria. Both N sources resulted in a reduction in Bacillus sp. Shifts in the bacterial populations and changes in species richness (number of species detected) and evenness (relative abundance of each species) were induced by organic by-product additions. These shifts appear to be the result of increased substrate for C mineralization rather than any properties of biological control. Shifts in the microbial community structure towards Gram negative organisms may benefit plant growth and may be useful as an indicator of soil quality.     

Detection of Erysiphe necator in Air Samples Using the Polymerase Chain Reaction and Species-Specific Primers

ABSTRACT A polymerase chain reaction (PCR) assay employing species-specific primers was developed to differentiate Erysiphe necator from other powdery mildews common in the northwest United States. DNA was extracted from mycelia, conidia, and/or chasmothecia that were collected from grape leaves with a Burkard cyclonic surface sampler. To differentiate E. necator from other erysiphaeceous fungi, primer pairs Uncin144 and Uncin511 were developed to select unique sequences of the internal transcribed spacer regions of E. necator. Using these primers in PCR amplifications, a 367-bp amplicon specific to E. necator was generated, but no amplicons were generated from other erysiphaceous species collected from 48 disparate hosts representing 26 vascular plant families. The PCR limit of detection was one to five conidia of E. necator placed directly into reaction mixtures or 100 to 250 conidia placed on glass rods coated with silicon grease. During field studies, this PCR assay facilitated the detection of E. necator inoculum in air samples within hours of sample rod collection and prior to disease onset. Amplification of E. necator DNA did not occur when the PCR assay was conducted on vineyard air samples collected while grapes were dormant or during periods when vine growth occurred but E. necator remained dormant. The initial PCR detection of E. necator of the season occurred during seasonal ascospore releases caused by precipitation events between bud burst and the prebloom period during the 3 years of the study. Detection ceased for 7 to 11 days following ascospore release and then resumed several days prior to the observance of microscopic symptoms and signs of powdery mildew in the field. Results of this study represent the initial step toward the goal of incorporating an inoculum availability component into current and future grapevine powdery mildew risk assessment models.     

A survey of bone integrity from cull sows in Ireland

The objective of this study was to examine the differences in sow metacarpal properties through various parities and to compare the incidence of locomotory problems between stalled and loose-housed sows. Metacarpals (n = 110) of sows from six farms were collected at slaughter and stored at -20°C. Bones from one forelimb of sows in stalls (n = 36) and loose-housed (n = 20) were collected and their articular surfaces examined for Osteochondrosis Dissecans (OCD), these sows were also scored for lameness pre-slaughter. Metacarpals were CT scanned for cross sectional area and moment of inertia. Cylindrical sections from the diaphysis were used for mechanical testing and calculating bone strength indices. The results show there was little change in bone mineral status throughout the range of parities examined and overall metacarpal integrity was not compromised by multiple production cycles. There were no differences detected in the incidence of lameness or joint pathology between housing systems.     

Serological survey of exposure to Erysipelothrix rhusiopathiae in poultryin New Zealand

Abstract

AIMS: To estimate the seroprevalence of antibodies to Erysipelothrix rhusiopathiae in chickens in New Zealand, and to estimate the effect of housing type, geographical location and age on seroprevalence.

METHODS: A cross-sectional serological survey of a convenience sample of 545 broiler, breeder, and layer chickens in 55 flocks was conducted in 2010–2011. Birds were aged 5–83 weeks; housing types were free-range, shed, caged, and unknown; and flocks were located in the Auckland, Manawatu, North Canterbury, Otago, Taranaki, Waikato, and Wairarapa regions of New Zealand. An ELISA was used to measure antibodies to E. rhusiopathiae. Samples with an optical density reading ≥1.50 were considered to be positive. Logistic regression analysis was used to model the effect of housing type, geographical location and flock age on the prevalence of samples positive for antibodies to E. rhusiopathiae.

RESULTS: The overall prevalence of samples with antibodies to E. rhusiopathiae was 39.8 (95% CI=35.68–44.06)% for the 545 samples, and 46/55 (84%) farms that were tested had at least one positive sample. Mean seroprevalence for types of housing was 44.2 (95% CI=37.79–50.70)% for free-range (n=240 birds), 23.7 (95% CI=17.83–30.38)% for shed (n=190), 73 (95% CI=56–86)% for caged (n=37) and 50 (95% CI=38–62)% for unknown (n=78). The disease was present in all seven geographical locations from which samples were obtained for this study. Seroprevalence increased with increasing age of birds (p<0.001); for birds ≤12 weeks of age it was 2 (95% CI=0.3–8)% (n=91), 13–24 weeks 29.1 (95% CI=23.34–35.46)% (n=230), 25–36 weeks 47 (95% CI=32–64)% (n=40), 37–48 weeks 75 (95% CI=51–91)% (n=20), >48 weeks 63.8 (95% CI=54.78–72.12)% (n=127). Neither housing type nor geographical location had a significant effect on the likelihood of samples being positive for antibodies to E. rhusiopathiae.

CONCLUSIONS: The results of this study suggest the prevalence of erysipelas under New Zealand field conditions may be higher than expected and that the disease is significantly associated with increasing age. Housing type and geographical location appear to be unrelated to seroprevalence.

CLINICAL RELEVANCE: Further study of the epidemiology of E. rhusiopathiae in chickens in New Zealand should be considered in order to minimise the extent of birds' exposure to the organism. These findings will assist in the design of further studies.     

Spatial and temporal stability of the estimated parameters of the binary power law

The incidence of hop powdery mildew on leaves, caused by Podosphaera macularis, collected from 1,606 transects in 77 commercial hop yards in Oregon and Washington over 9 years was used to assess variability in heterogeneity of disease and the estimated binary power law parameters. Spatial analyses of data sets were conducted at the level of individual rows (row level) and multiple rows within a yard (yard level). The binary power law provided a good fit to all data sets, with R(2) values ranging from 0.933 to 0.993. At the row level, the intercept parameter ln(A(x)) was >0 for 8 years, but was not significantly greater than 0 in 2006. The parameter b was greater than 1 for all row-level data sets collected from 1999 to 2005, but was <1 in 2006 and not significantly different from 1 in 2007. Covariance analysis indicated the factor 'region' affected ln(A(x)) in 3 years, and b in 2 years. 'Cultivar' had an effect on ln(A(x)) in 3 years and b in year. At the yard level, ln(A(x)) was greater than 0 for 6 years, but in 2006 and 2007, ln(A(x)) was not significantly different from 0. The slope parameter b was greater than 1 in 6 years, but was not significantly different from 1 in 2006 and 2007. Differences in b among years were large enough to have practical implications for sample sizes and precision of fixed and sequential sampling. Although the binary power law parameter tended to be relatively stable, variability of the estimated parameters may have practical consequences for sampling precision and costs.