Denitrification, N2O and CO2 fluxes in rice-wheat cropping system as affected by crop residues, fertilizer N and legume green manure

Use of renewable N and C sources such as green manure (GM) and crop residues in rice-wheat cropping systems of South Asia may lead to higher crop productivity and C sequestration. However, information on measurements of gaseous N losses (N₂O+N₂) via denitrification and environmental problems such as N₂O and CO₂ production in rice-wheat cropping systems is not available. An acetylene inhibition-intact soil core technique was employed for direct measurement of denitrification losses, N₂O and CO₂ production, in an irrigated field planted to rice (Oryza sativa L.) and wheat (Triticum aestivum L.) in an annual rotation. The soil was a coarse-textured Tolewal sandy loam soil (Typic Ustochrept) and the site a semi-arid subtropical Punjab region of India. Wheat residue (WR, C:N=94) was incorporated at 6 t ha^-1 and sesbania (Sesbania aculeata L.) was grown as GM crop for 60 days during the pre-rice fallow period. Fresh biomass of GM (C:N.=18) at 20 or 40 t ha^-1 was incorporated into the soil 2 days before transplanting rice. Results of this study reveal that (1) denitrification is a significant N loss process under wetland rice amounting to 33% of the prescribed dose of 120 kg N ha^-1 applied as fertilizer urea-N (FN); (2) integrated management of 6 t WR ha^-1 and 20 t GM ha^-1 supplying 88 kg N ha^-1 and 32 kg FN ha^-1 significantly reduced cumulative gaseous N losses to 51.6 kg N ha^-1 as compared with 58.2 kg N ha^-1 for 120 kg FN ha^-1 alone; (3) application of excessive N and C through applying 40 t GM ha^-1 (176 kg N ha^-1) resulted in the highest gaseous losses of 70 kg N ha^-1; (4) the gaseous N losses under wheat were 0.6% to 2% of the applied 120 kg FN ha^-1 and were eight- to tenfold lower (5-8 kg N ha^-1) than those preceding rice; (5) an interplay between the availability of NO₃^- and organic C largely controlled denitrification and N₂O flux during summer-grown flooded rice whereas temperature and soil aeration status were the primary regulators of the nitrification-denitrification processes and gaseous N losses during winter-grown upland wheat; (6) the irrigated rice-wheat system is a significant source of N₂O as it emits around 15 kg N₂O-N ha^-1 year^-1; (7) incorporation of WR in rice and rice residue (C:N=63) in wheat increased soil respiration, and increased CO₂ production in WR- and GM-amended soils under anaerobic wetland rice coincided with enhanced rates of denitrification; and (8) with adequate soil moisture, most of the decomposable C fraction of added residues was mineralized within one crop-growing season and application of FN and GM further accelerated this process.     

Ileal impaction in the horse: 75 cases

Records of 75 horses with ileal impactions were examined retrospectively. There was a sex predilection towards mares. Arabians were over-represented compared to the hospital population. The average age was 8.3 years. Abdominal pain was observed in 96% of horses. Nasogastric reflux was present in 56% of horses, small intestinal distention was found on rectal palpation in 96% and an ileal impaction in 25%. Exploratory celiotomy was performed in 69 horses, the mass was reduced by extramural massage in 67 horses, and ingesta was removed via enterotomy in 2. Jejunocecostomies were performed in 47 horses. Twenty-five horses developed postoperative ileus, and 11 developed laminitis. Twenty-seven horses survived. Significant differences (p less than 0.05) between survivors and non-survivors were found for rectal temperature (37.7 and 38.2 degrees C, respectively), plasma protein concentration (7.8 and 8.9 g/dl, respectively) and anion gap (15 and 21.3 mEq/l, respectively). Survival decreased with increasing duration of clinical signs. Enterotomy, enterectomy, and/or jejunocecostomy performed during surgery had a deleterious effect on survival.     

家禽业中的革新生物技术

对鸡基因组序列草图的分析为研究鸡RNA提供了有价值的信息.分析所有脊椎动物基因组后发现鸡体内能转录大量非蛋白编码RNAs(ncRNA).目前已发现这其中的一组小RNA在发育和细胞功能上扮演着关键的角色.所有的真核生物中都发现有微小RNA(miRNAs).在多细胞动物体内,有大量的证据表明微小RNA在正常发育过程中起着关键作用.它们通过在细胞质中的RNA干扰过程在细胞内发挥作用.     

Extensive bilateral odontogenic cysts in the mandible of a dog

A 5-year-old female neutered Boxer dog was diagnosed with extensive odontogenic cysts that affected the left and right mandibles. Rostral mandibular swelling was detectable clinically, and bilateral cystic mandibular lesions were identified radiographically. The dog's owners elected for euthanasia. A full postmortem was performed. Cystic cavities were confirmed in the body of each mandible, extending from the incisor teeth to the mid premolar region. Incisor, canine, and premolar tooth roots indented each cavity. Histologic examination of the cystic cavities reflected an inner lining of attenuated stratified squamous epithelium overlying a fibrous layer infiltrated by a mixed, predominantly mononuclear, inflammatory infiltrate.     

Statewide Cross-Sectional Survey of Cryptosporidium and Giardia in California Cow-Calf Herds

Cryptosporidium spp. and Giardia duodenalis are common protozoal parasites in livestock including beef cattle on rangeland and irrigated pasture. A statewide cross-sectional study was conducted to determine the prevalence, species or genotype, and risk factors for fecal shedding of Cryptosporidium and Giardia by cattle from California cow-calf operations. Species and genotypes of Cryptosporidium and Giardia were determined by molecular fingerprinting. Prevalence of Cryptosporidium (19.8%) and Giardia (41.7%) in fecal samples from calves were approximately twice as high as fecal samples from cows (9.2% and 23.1%, respectively). In addition to age, multivariable logistic regression showed that higher stocking density and a higher number of replacement heifers were positively associated with fecal shedding of Cryptosporidium while longer calving interval, a winter/spring calving season, and higher numbers of replacement heifers were positively associated with shedding of Giardia. The dominant species and genotypes of Cryptosporidium and Giardia in feces from these cow-calf herds were Cryptosporidium ryanae (75%) and assemblage E for Giardia duodenalis (90%), which have low impact on public health compared with other zoonotic species/genotypes of these two parasites. We identified host and potential management practices that can be used to protect cattle health and reduce the risk of surface water contamination with protozoal parasites from cow-calf operations. In addition, this work updated the scientific data regarding the predominance of low zoonotic genotypes of Cryptosporidium and Giardia shed in the feces of commercial cow-calf herds on California rangeland and irrigated pasture.     

Transpalpebral enucleation using a chain écraseur

This study was undertaken to describe the technique, complications and outcome of the use of a chain écraseur for transpalpebral enucleation in horses under general anaesthesia. We report its use in 53 horses, reviewing the subject details, reasons for enucleation, surgical technique, intra‐ and post operative complications, and long‐term outcome. Intraoperative complications included mild to moderate bleeding in 4 horses. Post operative complications included mild periorbital post operative swelling in one horse, transient head tilt in one horse and severe enterocolitis, which resulted in euthanasia in one horse; another 2 horses were subjected to euthanasia after long bone fractures that occurred during recovery from general anaesthesia and 2 horses had the prosthesis removed as a result of inflammatory reaction or infection. Long‐term outcome was available for 38 horses, 25 of which returned to their previous activities and 13 were retired. Twelve horses were lost for follow‐up. Transpalpebral enucleation using a chain écraseur is a feasible alternative to traditional enucleation techniques that can provide adequate haemostasis during transection of the optic pedicle when used properly.     

Potential of clones in improving the financial benefits of essential oil production from <Emphasis Type="Italic">Melaleuca alternifolia</Emphasis> plantations

Australian tea tree (Melaleuca alternifolia) is a woody plant that produces an essential oil with antiseptic, anti-bacterial, anti-fungal, and anti-inflammatory properties and is widely formulated into many products. Yield and financial analyses were done to compare the viability of replanting 20 ha tea tree plantations using elite clones and improved seedlings over a 15 year time frame were carried out. Four plantation options were modelled: (1) plantations established using genetically improved seedlings (ATTIA 2B) planted at a stocking of 33,333 plants/ha and (2) 16,667 plants/ha, (3) plantations established using the best three selected clones planted at a stocking of 33,333 plants/ha and (4) 16,667 plants/ha. Financial analysis showed that, at an oil price of $45/kg (as at Sep 2008), replacement plantations of either elite clones or improved seedlings are both highly profitable irrespective of the stocking employed. The Net Present Values per hectare at 7% discount rate was $45/kg (as at Sep 2008), replacement plantations of either elite clones or improved seedlings are both highly profitable irrespective of the stocking employed. The Net Present Values per hectare at 7% discount rate was 107,824, 63,640,63,640, 163,162 and 104,055 for plantation options 1, 2, 3 and 4, respectively. Plantation option 3 was predicted to give the greatest profit at any of the oil prices tested, followed by plantation option 1, 4 and 2. The break-even prices for tea tree oil production, using the production parameters in this model were104,055 for plantation options 1, 2, 3 and 4, respectively. Plantation option 3 was predicted to give the greatest profit at any of the oil prices tested, followed by plantation option 1, 4 and 2. The break-even prices for tea tree oil production, using the production parameters in this model were 11.81/kg, 15.19/kg,15.19/kg, 10.72/kg and $12.96/kg for plantation options 1, 2, 3 and 4 respectively.