Prevalence of and risk factors for influenza in southern Ontario swine herds in 2001 and 2003

This research included 2 prevalence studies and a risk-factor investigation conducted in 2001 at 93 sites with sows only, finishers only, or both. In 2001, 1300 serum samples from sows in 65 herds and 720 serum samples from finisher pigs in 72 herds were tested for antibodies to swine influenzavirus (SIV) of H1N1 subtype with an enzyme-linked immunosorbent assay (ELISA). In 2003, 1140 serum samples from sows in 76 herds were tested for antibodies to SIV of H3N2 subtype with a hemagglutination-inhibition assay based on A/Swine/Colorado/1/77 and A/Swine/Texas/4199-2/98 isolates. The apparent pig-level H1N1 seroprevalence in 2001 was 61.1% and 24.3% in sows and finishers, respectively. The apparent pig-level seroprevalence in 2003 for H3N2 A/Sw/CO/1/77 and A/Sw/TX/4199-2/98 in sows was 0.6% and 0.7%, respectively. The factors associated with sow-herd H1N1 positivity included pig or farm density at different geographic levels, an external source of breeding pigs, number of animals on site, and decreasing proximity to other barns. Higher-parity sows had higher odds of seropositivity, but there was significant random variability in this association among herds. The odds of finisher-herd SIV positivity were higher with large herd size, high pig farm density, and farrow-to-finish type of farm. Finisher herds were SIV-positive only if source sow herds were positive. Simultaneously, 45% of finisher herds were SIV-negative although sow source herds were positive.     

应用聚合酶链式反应检测禽痘病毒田间分离株及疫苗株中网状内皮组织增殖病毒LTR片断,env及re1基因

本文利用聚合酶链式反应对来自澳大利亚昆士兰州、维多利亚州和新南维尔士州的４株禽痘病毒田间分离株及二疫苗株中网状内皮组织增殖病毒的ＬＴＲ片断、ｅｎｖ及ｒｅｌ基因因进行了检测。所有４株痘病毒分离株均为ＬＴＲ片断、ｅｎｖ阳性，曾被ＰＣＲ证实为ＬＴＲ阳性的一疫苗株在本实验中也为ＬＴＲ、ｅｎｖ阳性，另一疫苗株为ＬＴＲ、ｅｎｖ阴性，所有上述禽痘病毒株均为ｒｅｌ阴性。     

Performance of Four Rice Cultivars Transplanted Monthly over Full Year under Irrigated Conditions in Tanzania

In Tanzania,the phenology and seasonal variations of the yields of different rice cultivars have rarely been studied,especially under fully-irrigated conditions. A trial was conducted to identify the most suitable calendar for rice production in Tanzania under fully-irrigated conditions. Four popular rice cultivars,NERICA1,Wahiwahi,IR64 and TXD306,were transplanted monthly from January to December 2011. The four cultivars recorded similarly higher or lower yields than the annual means when transplanted in July(0.50–0.57 kg/m2) and April(0.07–0.31 kg/m2). A yield-ranking analysis showed that plants transplanted in July was the most productive while those transplanted in April was the least productive,and also revealed a yield-seasonality for irrigated rice in Tanzania,a low-yield season(April–May),a high-yield season(June–August),and an unstable-yield season(September–March). These yield seasons would appear to be closely linked to seasonal temperature variations. When transplanted in April–May,plants were exposed to very low temperatures between panicle initiation and flowering,apparently reducing yield through cold-induced sterility. Those transplanted in June–August prolonged their growth under relatively low temperatures and increased yield through increasing biomass production. In September–March,yield levels varied greatly due to the shortened phenological growth durations at higher temperatures. We conclude that under fully-irrigated conditions in Tanzania,rice should be transplanted in July to ensure the maximum production and yield stability. The yield-seasonality suggests that implementing measures to protect plants from low and high temperature stress at critical phenological stages may allow year-round rice production under fully-irrigated conditions in Tanzania.     

Use of a tilapia skin xenograft for management of a large bite wound in a dog

A 13-year-old neutered male miniature dachshund suffered ~30% total skin loss following an attack by another dog. After numerous failed attempts at wound management and closure, the wound was successfully healed by epithelialization using tilapia skin grafts. At each tilapia skin graft placement, the wound bed appeared pink, clean, and healthy with excellent progression of epithelialization at all edges. With use of the tilapia grafts, epithelialization occurred at a rate of 1.76 mm/day. As a result, the wound reached complete closure by epithelialization with no evidence of wound contracture in 102 days.Key clinical message:Tilapia skin grafts were successfully used for management of a large bite wound in a dog and may promote accelerated epithelialization in full thickness skin wounds.     

Transgene-mediated resistance to <Emphasis Type="Italic">Papaya ringspot virus</Emphasis>: challenges and solutions

Global papaya production is severely affected by papaya ringspot disease caused by Papaya ringspot virus (PRSV). Management of this potyvirus is challenging, due to 1) its non-persistent transmission by numerous aphid species and 2) the diversity of PRSV strains that exists within a country or between different geographical regions. Papaya cultivars with transgenic resistance have reduced the impact of the disease. There are no effective alternatives to transgenic resistance available in areas where disease pressure is high. In Hawaii, transgenic papayas such as “SunUp” and “Rainbow” have remained resistant to PRSV more than two decades saving the commercial papaya industry. Following the success in Hawaii, researchers from other countries have focused on developing PRSV-resistant transgenic papaya. These transgenic cultivars often demonstrated an initial transitory resistance that was ultimately overcome by the virus. For other cases, resistance was inconsistent. That is, some transgenic lines were resistant while others were not. Transgenic cultivars are now losing PRSV-resistance for various reasons in China and Taiwan. In this review, we present an update on work with transgenic papaya with resistance to PRSV. The focus is on factors affecting transgenic resistance in papaya and our attempt to explain why the Hawaiian scenario of complete and durable resistance has not been replicated in other regions. The utilization of more recent technologies to the development of virus resistance in papaya is also discussed.     

Colostral antibody induced interference of inactivated bluetongue serotype-8 vaccines in calves

Since its introduction into northern Europe in 2006, bluetongue has become a major threat to animal health. While the efficacy of commercial vaccines has been clearly demonstrated in livestock, little is known regarding the effect of maternal immunity on vaccinal efficacy. Here, we have investigated the duration and amplitude of colostral antibody-induced immunity in calves born to dams vaccinated against bluetongue virus serotype 8 (BTV-8) and the extent of colostral antibody-induced interference of vaccination in these calves. Twenty-two calf-cow pairs were included in this survey. The median age at which calves became seronegative for BTV was 84 and 112 days as assayed by seroneutralisation test (SNT) and VP7 BTV competitive ELISA (cELISA), respectively. At the mean age of 118 days, 13/22 calves were immunized with inactivated BTV-8 vaccine. In most calves vaccination elicited a weak immune response, with seroconversion in only 3/13 calves. The amplitude of the humoral response to vaccination was inversely proportional to the maternal antibody level prior to vaccination. Thus, the lack of response was attributed to the persistence of virus-specific colostral antibodies that interfered with the induction of the immune response. These data suggest that the recommended age for vaccination of calves born to vaccinated dams needs to be adjusted in order to optimize vaccinal efficacy.     

Nitrogen applications modify seed and oil yields and fatty acid composition of winter mustard

Winter mustard (Brassica juncea L.) is not a common crop in the Southeastern United States. With increased interest in biodiesel production, there has been corresponding interest in mustard in this region. The objective of this study was to evaluate the effect of N fertilization (0, 50, 100, 150 kg N ha⁻¹) on productivity, oil content, and oil composition of winter mustard ‘Pacific Gold’ grown at three locations in Mississippi (Stoneville, and two locations at Verona, namely Verona silt loam (Verona-SL) and Verona clay (Verona-C)). Nitrogen did not affect oil content (percent oil). Seed and oil yields (kg ha⁻¹) increased with N application relative to the unfertilized control. At the Verona-C location, the concentration of oleic acid was higher in the 50 kg N ha⁻¹ treatment. At Stoneville, linolenic acid concentration was higher in the 150 kg N ha⁻¹ and lower in the 100 kg/N ha⁻¹ treatment, while it was not different in the other treatments. Overall, the yield of the fatty acids (FA) palmitic, palmitoleic, stearic, oleic, linoleic, linolenic, arachidic, eicosanoic, behenic, erucic, lignoceric, and nervonic acid increased with higher N rates (100 or 150 kg N/h). The highest yield of FA in the two Verona locations were achieved in the 100 kg N ha⁻¹, while greatest yield of FA at Stoneville was achieved in the highest N rate (150 kg N ha⁻¹). Means of mustard oil yields in our study in the higher fertility treatment ranged from 737 to 1094 kg ha⁻¹. This study demonstrated winter mustard production in Mississippi and possibly other areas in the Southeastern United States can be successful and could provide seed and oil yields comparable to yields from other production areas.     

1-Hydroxypyrene in milk and urine as a bioindicator of polycyclic aromatic hydrocarbon exposure of ruminants

Urinary 1-hydroxypyrene (1-OH-pyrene) is now largely considered to be a valuable biomarker of exposure of man and animals to pyrene and other polycyclic aromatic hydrocarbons (PAHs). However, from a practical and agronomic standpoint, the question remains whether such biomarking capability still holds when 1-OH-pyrene is analyzed in milk produced by ruminants. To assess this hypothesis, four goats were daily submitted to three different amounts of pyrene oral ingestion, together with phenanthrene and benzo(a)pyrene (1, 7, and 49 mg/day during 1 week each). An HPLC-fluorometric analysis of 1-OH-pyrene in milk revealed a perfect correlation between pyrene doses and 1-OH-pyrene detected in milk, thus fully confirming the biomarking capability of 1-OH-pyrene and providing information on its transfer coefficient toward milk. Transfer equations such as the ones found in the present study could be used as a valuable and practical risk assessment tool in (i) the accurate monitoring of exposure of ruminants to pyrene and (ii) the evaluation of occupational and environmental exposure of ruminants to PAH mixtures.     

Protein content, oil content and fatty acid profiles as potential criteria to determine the origin of commercially grown chia (Salvia hispanica L.)

Chia (Salvia hispanica L.), an annual herb of the Labiatae family, produces seeds which were one of the basic foods of Central American civilizations in pre-Columbian times. Chia seed contains the highest known percentage of α-linolenic fatty acid of any plant source. In recent years, chia seed has become increasingly important for human health and nutrition because of its high content of α-linolenic fatty acid, and the beneficial health effects that arise from its consumption. A study was undertaken to characterize protein and oil contents as well as fatty acid composition of chia seeds grown in some larger commercial fields, in an attempt to determine how these components are affected by location. Oil saturation tended to decrease as elevation of seed production increased, with decreasing levels of palmitic, stearic, oleic, and linoleic fatty acids found. The main constituent in the chia oil was ω-3 α-linolenic fatty acid, and ranged from 64.8% to 56.9%. Differences were significant (P < 0.05) among locations. Significant differences in protein content and fatty acid composition were also found for the commercially grown chia originating from three ecosystems. It is possible that these differences could be used to distinguish chia's origin, if additional research was undertaken to characterize such differences.     

甘蔗对生物胁迫抗性的育种

甘蔗生育期长,容易吸引大量昆虫和感染各种病害。在甘蔗品种选育程序中,甘蔗对这些生物胁迫的耐性或抗性成为首要考虑因素。要了解甘蔗生物抗性来源,需要熟悉甘蔗的分类,而各种甘蔗野生品种因具有生物抗性特征,亟待开发利用。现今种间杂交是许多甘蔗抗病育种程序的基础。文章试图简要探讨甘蔗育种的历史和今后甘蔗品种生物抗性培育的策略,详细讨论了世界大范围内出现的甘蔗病害如宿根矮化病、锈病、黑穗病等存在的主要问题。文章指出了分子标记的应用范围,基因识别的困难以及对一些抗病抗虫性状遗传转化试验取得的进展,还讨论了一些可作为目前甘蔗系谱选育方法的有效补充方法,例如先进的计算机化杂交设计方法和群体选育等,这些方法在今后甘蔗抗性品种选育中将具有很大的利用前景,可保正蔗糖生产的可持续发展。