Study of an attenuated Anaplasma marginale vaccine in Mexico natural challenge of immunity in an enzootic area.

An evaluation was made of the protection induced by an attenuated Anaplasma marginale vaccine in young purebred cattle against the challenge exposure of naturally transmitted anaplasmosis in enzootic areas of Mexico. The cattle, which were raised in isolation units free of arthropods, consisted of 10 Brown Swiss calves (1 to 13 months of age) and 8 Holstein calves (5 to 7 months of age). They were paired by breed, age, and body weight, and allotted to 2 equal groups. Calves in 1 group were vaccinated, and at 6 weeks after vaccinations were done, calves in both groups were placed in the field where they were raised for approximately 1 year. Two Holstein and 3 Brown Swiss calves of the nonvaccinated group (group 2) developed clinical anaplasmosis, and the remaining calves of this group had hematologic evidence of the disease during the 2 to 4 months after introduction to the field. The vaccinated group, which remained free of anaplasmosis, showed consistently greater weight gain than did the controls. Among the Holstein calves, the maximum weight difference in favor of the vaccinated group was 50 kg/head at 5.5 months after field exposure, and among the Brown Swiss calves, the differences in weight gain in favor of vaccinated calves at the end of the 12-month period was between 11 and 30 percent. It is concluded that the vaccine provided a means for safe adaptation of high-quality young cattle to the tropics by protecting them against what appears to be the major obstacle to this practice, anaplasmosis.     

Effect of adding crude glycerine to diets with feed additives on the feed intake,ruminal degradability,volatile fatty acid concentrations and in vitro gas production of feedlot Nellore cattle

The effects of adding crude glycerine with sodium monensin or essential oils to beef cattle diets on the intake, degradability of DM and nutrients, rumen concentration of volatile fatty acids (VFA) and in vitro gas production were evaluated. Five ruminally cannulated Nellore steers were randomly assigned to a 5 × 5 Latin square design. The treatments were as follows: CONT, without crude glycerine and additives; EO, with essential oils and without crude glycerine; MON, with sodium monensin and without crude glycerine; EOG, with essential oils and crude glycerine; MONG, with sodium monensin and crude glycerine. Treatments with essential oil and sodium monensin increased the NDF and STC intake and the DM degradability. When crude glycerine was combined with either sodium monensin or essential oil, there was a reduction in DM, NDF and STC intake and an increase in DM and CP degradability of the diets. The adding crude glycerine to essential oil diets reduced the CH₄ production. Sodium monensin treatments reduced DM and NDF intake and the production of total gas, CH₄, total VFA and acetic acid concentration. In conclusion, the adding crude glycerine (200 g/kg DM) with either sodium monensin (0.03 g/kg DM) or essential oil (0.5 g/kg DM) can be utilized in diets for Nellore cattle without causing detrimental effects on feed intake and improving the DM degradability.     

Accounting for population structure in selective cow genotyping strategies

The objective of the present study was to investigate the impact of considering population structure in cow genotyping strategies over the accuracy and bias of genomic predictions. A small dairy cattle population was simulated to address these objectives. Based on four main traditional designs (random, top‐yield, extreme‐yield and top‐accuracy cows), different numbers (1,000; 2,000 and 5,000) of cows were sampled and included in the reference population. Traditional designs were replicated considering or not population structure and compared among and with a reference population containing only bulls. The inclusion of cows increased accuracy in all scenarios compared with using only bulls. Scenarios accounting for population structure when choosing cows to the reference population slightly outperformed their traditional versions by yielding higher accuracy and lower bias in genomic predictions. Building a cow‐based reference population from groups of related individuals considering the frequency of individuals from those same groups in the validation population yielded promising results with applications on selection for expensive‐ or difficult‐to‐measure traits. Methods here presented may be easily implemented in both new or already established breeding programs, as they improved prediction and reduced bias in genomic evaluations while demanding no additional costs.     

Supplementation of broiler diets with high levels of microbial protease and phytase enables partial replacement of commercial soybean meal with raw,full‐fat soybean

A 3 × 3 + 1 factorial, involving three levels of protease (0, 15,000 or 30,000 PROT/kg) and three levels of phytase (1,000, 2,000 or 3,000 FYT/kg), was used to evaluate the effect of replacing commercial soybean meal (SBM) with raw, full‐fat soybean (RFSB) at 75 g/kg of diet for broilers. A control diet was used for comparison. Each treatment was replicated six times, with nine birds per replicate. The concentration of trypsin inhibitors (TIs) in the test diets was approximately 10,193.4 TIU/kg. Regardless of enzyme supplementation, feed intake (FI) and body weight gain (BWG) of birds in the control group were superior to those on the test diets. Birds that received the protease‐free test diets had reduced FI and BWG, but when supplemented with protease, were similar to the control diet in BWG, FI (except 0–35 days) and feed conversion ratio (FCR). When the test diet was supplemented with elevated levels (extradose) of protease and phytase, the BWG was improved during 0–10 days (p = .05) and 0–24 days (p < .01). Regardless of protease supplementation, the weight of thighs was lower for birds fed the test diets. Birds that received the control diet had smaller weight of pancreas. Increasing the level of phytase supplementation reduced (p < .05) the weight of the pancreas. The apparent ileal digestibility (AID) of CP and AA was higher in birds on the control diets, but this was also improved in test diets by protease supplementation. The activities of trypsin (7%), general proteolytic (11%) and lipase (12%) were slightly increased because of protease supplementation. Mucosal depth and apparent villus surface areas were increased by about 2.9% and 20%, respectively, due to supplementation of elevated level of phytase. It can be concluded that RFSB could partially replace SBM in broiler diets, provided the diets are supplemented with elevated levels of protease and phytase.     

The influence of soil and biosolids type,and microbial immobilisation on nitrogen availability in biosolids‐amended agricultural soils – implications for fertiliser recommendations

Soil microbial biomass interactions influencing the mineralisation of N in biosolids‐amended agricultural soil were investigated under field conditions in two soil types, a silty clay and a sandy silt loam, with contrasting organic matter contents. Soil treatments included: dewatered raw sludge (DRAW); dewatered and thermally dried, mesophilic anaerobically digested biosolids (DMAD and TDMAD, respectively); lime‐treated unstabilised sludge cake (LC); and NH₄Cl as a mineral salt control for measuring nitrification kinetics. Soil mineral N and microbial biomass N (MBN) concentrations were determined over 90 days following soil amendment. Despite its lower total and mineral N contents, TDMAD had a larger mineralisable pool of N than DMAD, and was an effective rapid release N source. Increased rates of mineralisation and nitrification of biosolids‐N were observed in the silty clay soil with larger organic matter content, implying increased microbial turnover of N in this soil type compared with the sandy silt loam, but no significant difference in microbial immobilisation of biosolids‐N was observed between the two soil types. Thus, despite initial differences observed in the rates of N mineralisation, the overall extent of N release for the different biosolids tested was similar in both soil types. Therefore, the results suggest that fertiliser guidelines probably do not need to consider the effect of soil type on the release of mineral N for crop uptake from different biosolids products applied to temperate agricultural soils.     

预处理对巴西盾柱木种子吸涨、活力测试及其加速老化的影响

对巴西盾柱木(Peltophorum dubium)种子进行了4种处理的吸胀实验,即将种子分别置于10℃和27℃下0.2% Captan溶液中和-1.0MPa的PEG6000溶液中,每个处理有四个重复,40粒种子,置于培养皿中浸满实验溶液的双层过滤纸上,覆以透气良好的薄膜.种子在实验前均用98%的浓硫酸处理15分钟以打破机械休眠.吸胀曲线显示,种子在吸胀过程中最终重量的增加值为70%-150%,以后进入一个停滞期.在5种处理下(对照组,PEG6000溶液中10℃和27℃下预处理,Captan溶液中10℃和27℃下预处理),对种子萌发所受到的影响进行了实验.每一个处理分别进行3个次级处理,即在实验前,将种子用蒸馏水分别浸泡12、24和36小时.萌发率最高的是经过蒸馏水浸泡12小时对照组种子和PEG 27℃组的种子,萌发率达到100%;萌发率最低的是蒸馏水中浸泡36小时的PEG 27℃组的种子,萌发率为52%;经过蒸馏水浸泡24小时的PEG 10℃组种子的平均萌发时间为1.08天.蒸馏水中浸泡12小时的PEG 27℃组种子平均萌发时间为2.42天,其它处理的萌发时间值介于两者之间.对预处理和未经预处理种子通过加速老化实验,对其活力和生存力进行了测试.经72小时加速老化,种子萌发率低或没有萌发力.对照组种子在培养皿(27℃)和室温条件下蛭石中的萌发率都比处理组高,表现了对老化更强的抗性.     

Bayesian estimation of Tritrichomonas foetus diagnostic test sensitivity and specificity in range beef bulls

Accuracy of culture for diagnosis of Tritrichomonas foetus was investigated in 2832 naturally exposed range beef bulls from 124 herds. Preputial fluid samples were inoculated into the culture medium, incubated at 37 degrees C, and daily examined. Diagnostic test was evaluated using Bayesian techniques to estimate sensitivity and specificity without a gold standard. Median posterior test sensitivity was 72.04% (95% probability interval: 58.07-86.38%) and specificity was 95.37% (95% probability interval: 94.07-96.65%). Low diagnostic test accuracy may have resulted from host and/or diagnostic test procedure related factors. Under natural range conditions, more accurate methods for T. foetus diagnostic and repeated preputial samplings of bulls may be necessary on trichomonosis control programs.     

Stable isotope and trace element profiling combined with classification models to differentiate geographic growing origin for three fruits: effects of subregion and variety

Classifications of geographic growing origin of three fresh fruits combining elemental profiles with various modeling approaches were determined. Elemental analysis (Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, V, and Zn) of strawberry, blueberry, and pear samples was performed using inductively coupled plasma argon atomic emission spectrometer. Bulk stable carbon and nitrogen isotope analyses in pear were performed using mass spectrometry as an alternative fingerprinting technique. Each fruit, strawberry (Fragaria x ananassa), blueberry (Vaccinium caesariense/corymbosum), and pear (Pyrus communis), was analyzed from two growing regions: Oregon vs Mexico, Chile, and Argentina, respectively. Principal component analysis and canonical discriminant analysis were used for data visualization. The data were modeled using linear discriminant function, quadratic discriminant function, neural network, genetic neural network, and hierarchical tree models with successful classification ranging from 70 to 100% depending on commodity and model. Effects of Oregon subregional and variety classification were investigated with similar success rates.     

Host and environmental risk factors associated with Cryptosporidium scophthalmi (Apicomplexa) infection in cultured turbot, Psetta maxima (L.) (Pisces, Teleostei)

An epidemiological cohort study of Cryptosporidium scophthalmi in cultured turbot Psetta maxima L. of Northwestern Spain was conducted along a four-year period. Four different ongrowing cohorts were monitored monthly from introduction into the ongrowing tanks (10–50 g) until reaching market size (400–1400 g). The association of host and environmental factors with five categories of parasite abundance was assessed using a multivariable regression framework. Epidemiological factors assessed here were water temperature, weight, length, month of collection, season, age, origin, condition factor, water filtration, and status to the myxozoan Enteromyxum scophthalmi infection. E. scophthalmi was included into the analysis because it targets the same organ than C. scophthalmi and it was prevalent in the studied population. The multivariable analysis demonstrated the statistically significant association between several factors and parasite abundance. C. scophthalmi abundance was associated (P < 0.05) with age, condition factor, season, and status to E. scophthalmi infection. Young animals, with poor condition factor, during spring or summer, and not infected with the myxozoan were most likely to be highly infected by C. scophthalmi. Inclusion of these four variables significantly (P < 0.05) improved the model, compared to the model that did not include any of these epidemiological factors. Increasing levels of C. scophthalmi abundance were associated (P < 0.01) with higher severity of C. scophthalmi-compatible lesions. The frequency of distribution of C. scophthalmi abundance was clearly right-skewed and fitted a negative binomial distribution, whereas the intensity of infection fitted a Poisson distribution. The quantification of the variance-to-mean ratio stratified by age demonstrated overdispersion for 8–16 months old fish, although this bivariate association is likely affected by several other factors, as suggested by the results of the multivariable analysis. The negative relation between C. scophthalmi abundance and status to E. scophthalmi infection suggests differences in the transmission, onset, and course of both infections. The coarse filtration used in some cohorts did not significantly affect the levels of infection. C. scophthalmi was probably introduced into the ongrowing tanks mainly with carrier fish, though the involvement of infective oocysts from the water supply cannot be disregarded. Infection prevalence and mean intensity decreased with fish age and a seasonal distribution was found. Results presented here will help to understand the epidemiology of C. scophthalmi in turbot, to estimate the expected levels of infection associated with presence or absence of epidemiological factors, and to quantify the impact that the disease may have on susceptible turbot populations. The multivariable model used here is more powerful than the visual inspection of graphics for exploring associations in cooperative processes and can be easily extended to the assessment of epidemiological associations in other population and parasitic diseases.     

Development of DNA Extraction and PCR Amplification Protocols for Detection of Mycoplasma bovis Directly from Milk Samples

Veterinary Research Communications - Cremonesi, P., Vimercati, C., Pisoni, G., Perez, G., Miranda Ribera, A., Castiglioni, B., Luzzana, M., Ruffo, G. and Moroni, P., 2007. Development of DNA...