Ultrastructure of porcine circovirus in persistently infected PK-15 cells.

The ultrastructure of porcine circovirus was examined in persistently infected porcine kidney (PK)-15 cells. Virus-infected PK-15 cells had large numbers of intracytoplasmic inclusions, and a few cells had intranuclear inclusions. Intracytoplasmic inclusions were dispersed throughout the cytoplasm but were most numerous in the perinuclear cytoplasm. Inclusion were of various sizes, round to oval, and electron dense and were of two general types. Inclusions of the first type were small (0.1-0.5 microm diameter), not surrounded by trilaminar membranes, and granular with indistinct margins that blended with surrounding cytoplasm. Some contained 12+/-2-nm-diameter icosahedral virions in loose aggregates or rarely forming paracrystalline arrays. Small inclusions could be sites of viral assembly or maturation. Intracytoplasmic inclusions of the second type were larger (0.5-5.0 microm diameter) and more numerous and had abrupt margins surrounded by trilaminar membranes. They were more electron dense than small inclusions and were heterogeneous, containing various proportions of aggregated virions, electron-dense crystalline lamellae of 5 nm periodicity, and/or whorls of myelinoid membranes. Virions usually formed paracrystalline arrays and occasionally were loosely aggregated. Larger inclusions were typical of autophagolysosomes. Intranuclear inclusions were not membrane bound and were often associated with reticulated nucleoli or aggregates of heterochromatin. Some inclusions were irregularly shaped aggregates of indistinct, circular 10-12-nm-diameter viruslike particles. Others were 0.1-1.0 microm in diameter, round or ring shaped, dense, and finely granular, with sharply demarcated margins.     

Twice daily suckling but not milking with calf presence prolongs postpartum anovulation.

Two experiments were conducted to determine whether milking beef cows two or five times daily in the presence or absence of their own nonsuckling calves would alter postpartum interval to first ovulation. Multiparous Angus x Hereford cow-calf pairs were assigned randomly between 13 and 18 d postpartum to treatments for 4 wk. In Exp. 1, pairs were assigned to six treatments: 1) calf was weaned permanently from its dam (CW; n = 9); 2) same as CW, but dam was milked twice daily (CW+2xM; n = 9); 3) calf was present continuously with its dam but restricted from contact with the udder (CR; n = 9); 4) same as CR, but dam was milked twice daily (CR+2xM; n = 9); 5) same as CR, but calf was allowed to suckle twice daily (CR+2xS; n = 8); and 6) calf was present continuously with its dam and suckled ad libitum (CP; n = 9). The interval from onset of treatments to first postpartum ovulation was shorter (P<.05) in the CW (14.1+/-3.1 d), CR (14.2+/-3.1 d), CW+2xM (13.0+/-3.1 d), and CR+2xM (17.2+/-3.1 d) than in the CP (34.7+/-3.1 d) and CR+2xS (33.9+/-3.3 d) treatments. Daily milk yield during treatment was greater (P<.01) for CR+2xM cows (7.1+/-.6 kg) than for CW+2xM cows (3.5+/-.6 kg). In Exp. 2, cow-calf pairs were assigned to three treatments: 1) CR+2xM (n = 10); 2) same as CR+2xM but cows were milked five times daily (CR+5xM; n = 10); or 3) CP (n = 10). The interval to first postpartum ovulation was shorter (P<.05) in the CR+2xM (23.6+/-3.5 d) and CR+5xM (26.1+/-3.7 d) treatments than in the CP (37.7+/-3.7 d) treatment. Daily milk yield during treatment was greater (P<.05) for CR+5xM cows (7.7+/-.6 kg) than for CR+2xM cows (6.4+/-.6 kg) by 17%. We conclude that suckling twice daily was sufficient to prolong postpartum anestrus as much as suckling ad libitum. Furthermore, milk removal by suckling, but not by milking two or five times daily, even in the presence of the cow's own nonsuckling calf, is essential to prolong postpartum anovulation.     

Temporal aspects of the epidemic of bovine spongiform encephalopathy in Great Britain: individual animal-associated risk factors for the disease

The objectives of this study were first to determine the cumulative incidence of bovine spongiform encephalopathy (BSE) in the British cattle population from July 1986 to June 1997, secondly, to identify individual animal-associated risk factors that influenced the age of onset of clinical signs in confirmed BSE cases, and, thirdly, to assess the effectiveness of the measures introduced to control BSE during the epidemic. The analyses were based on the population of British cattle at risk, derived from agricultural census data collected between 1986 and 1996, and BSE case data collected up to June 30, 1997. The unit of interest was individual adult cattle recorded on annual agricultural censuses between June 1986 and June 1996. Univariate and multivariate survival analysis techniques were used to characterise the age of onset of clinical signs. In total 167,366 cases of BSE were diagnosed in Great Britain up to June 30, 1997. The cumulative incidence of BSE between July 1986 and June 1997 was 1.10 (95 per cent confidence interval [CI] 1.09 to 1.10) cases per 100 adult cattle at risk. Cattle from the South east, South west and Eastern regions of England had 4.26 to 5.96 (95 per cent CI 4.15 to 6.14) times as great a monthly hazard of being confirmed with BSE as cattle from Scotland. Compared with cattle born before June 1985, those born between July 1987 and June 1988 had 22.5 (95 per cent CI 22.1 to 22.8) times the monthly hazard of being confirmed with BSE, whereas those born in the 12 months after July 1988 had only 7.39 (95 per cent CI 7.24 to 7.54) times the monthly hazard of being confirmed with BSE. This reduction in hazard was directly attributable to the ban on the use of ruminant protein as a feed instituted in July 1988. Successive cohorts from 1989 to 1991 experienced further reductions in the hazard of experiencing BSE. The additional decrease in hazard observed for the 1990 cohort may be attributed to the effect of the Specified Bovine Offal ban instituted in September 1990.     

Simplified Dilute Acetic Acid Based Extraction Procedure for Fractionation and Analysis of Wheat Flour Protein by Size Exclusion HPLC and Flow Field‐Flow Fractionation

A simple, highly efficient and reproducible two‐step extraction procedure using dilute acetic acid without (AN) and then with sonication (AS) has been developed for the fractionation of wheat flour protein. Approximately 97% of total protein was extracted from a Canadian hard red spring wheat flour; an additional 1.2% protein could be recovered by further extraction with 1% DDT and 50% 1‐propanol (AR). Size‐exclusion HPLC (SE‐HPLC) and flow field‐flow fractionation (flow FFF) showed that the AN extract, which accounted for most of the total extractable protein (AN + AS + AR), consisted primarily of monomeric protein. The AS extract was composed primarily of polymeric proteins. Flow FFF showed that AN polymeric protein, including that eluting at the SE‐HPLC void volume, showed smaller Stokes diameters than AS polymeric protein. Flow FFF profiles of AS SE‐HPLC subfractions showed that the void volume subfraction contained monomeric and small polymeric protein in addition to large polymeric protein, indicating formation of larger complexes through interaction between some or all of the components. AN and AS extracts, as well as SE‐HPLC and flow FFF fractions thereof, showed a fairly wide range of values among 12 Canadian hard red and white spring wheat cultivars. The proportion of total protein in the AS extract and in the larger sized polymeric protein fractions from SE‐HPLC and flow FFF were highly positively correlated to farinograph mixing time.     

Characterization of microsatellites in Fusicladium effusum,cause of pecan scab

Pecan scab, caused by the plant pathogenic fungus Fusicladium effusum, is the most destructive disease of pecan. Little is known of the population genetic diversity of this pathogen. In this study, microsatellites were mined from the F. effusum genome, and flanking primers were subsequently designed. A total of 275 microsatellites were screened, and 33 selected primers produced reliable, polymorphic markers against 46 isolates of F. effusum from 11 diverse locations in the southeastern USA. The number of alleles per microsatellite locus ranged from two to 17, and the polymorphic information content (PIC) from 0.475 to 0.911. A unique pattern informative combination (UPIC) analysis of three groups of 12 isolates each and 33 primers consistently showed a minimum number of markers required for the maximum discrimination of isolates equal to 3. The characteristics of the unique patterns (UP) and informative contents (IC) were very similar. However, the primers that were selected by UPIC were not necessarily the same for each of the three groups. Using all 46 isolates showed each locus was polymorphic, with a single‐population level Shannon's information index of 1.516, indicating substantial diversity. These markers show a range in polymorphic content and power of discrimination that will be valuable tools for studies of genetic diversity in F. effusum.     

Influence of a controlled internal drug release after fixed-time artificial insemination on pregnancy rates and returns to estrus of nonpregnant cows

We determined whether an ovulatory estrus could be resynchronized in previously synchronized, AI nonpregnant cows without compromising pregnancy from the previous synchronized ovulation or to those inseminated at the resynchronized estrus. Ovulation was synchronized in 937 suckled beef cows at 6 locations using a CO-Synch + progesterone insert (controlled internal drug release; CIDR) protocol [a 100-microg injection of GnRH at the time of progesterone insert, followed in 7 d by a 25-mg injection of PGF(2alpha) at insert removal; at 60 h after PGF(2alpha), cows received a fixed-time AI (TAI) plus a second injection of GnRH]. After initial TAI, the cows were assigned randomly to 1 of 4 treatments: 1) untreated (control; n = 237); 2) progesterone insert at 5 d after TAI and removed 14 d after TAI (CIDR5-14; n = 234); 3) progesterone insert placed at 14 d after TAI and removed 21 d after TAI (CIDR14-21; n = 232); or 4) progesterone insert at 5 d after TAI and removed 14 d after TAI and then a new CIDR inserted at 14 d and removed 21 d after TAI (CIDR5-21; n = 234). After TAI, cows were observed twice daily until 25 d after TAI for estrus and inseminated according to the AM-PM rule. Pregnancy was determined at 30 and 60 d after TAI to determine conception to the first and second AI. Pregnancy rates to TAI were similar for control (55%), CIDR5-14 (53%), CIDR14-21 (48%), and CIDR5-21 (53%). A greater (P < 0.05) proportion of nonpregnant cows was detected in estrus in the CIDR5-21 (76/110, 69%) and CIDR14-21 (77/120, 64%) treatments than in controls (44/106, 42%) and CIDR5-14 (39/109, 36%) cows. Although overall pregnancy rates after second AI service were similar, combined conception rates of treatments without a CIDR from d 14 to 21 [68.7% (57/83); control and CIDR5-14 treatments] were greater (P = 0.03) than those with a CIDR during that same interval [53.5% (82/153); CIDR5-21 and CIDR14-21 treatments]. We conclude that placement of a progesterone insert 5 d after a TAI did not compromise or enhance pregnancy rates to TAI; however, conception rates of nonpregnant cows inseminated after a detected estrus were compromised when resynchronized with a CIDR from d 5 or 14 until 21 d after TAI.     

日粮蛋白质浓度和降解率对泌乳奶牛瘤胃保护蛋氨酸反应的影响

选用32头经产和16头初产荷斯坦奶牛进行不完全8×8拉丁方设计试验（4周为期,共12周）,进行评估粗蛋白（CP）、可消化瘤胃非降解蛋白（RUP）和瘤胃保护蛋氨酸（RPM,饲喂的是美国乔治亚州肯尼索德固赛公司的产品Mepron）。日粮舍（按干物质（DM）计）苜蓿青贮21％、玉米青贮34％、高水分玉米22％-26％、豆粕10％-14％、大豆皮4％、添加脂肪2％、矿物质和维生素13％、中性洗涤纤维27％-28％。添加或不添加压榨大豆粕的瘤胃降解蛋白（RUP）,配制为15.8％或17.1％日粮粗蛋白,0或9g RPM／d的2×2×2因子设计。结果表明,二向或三向交互作用都不显著。高日粮CP增加表明采食量1.1kg·d^-1 DM、产奶量1.7kg·d^-1、3.5％乳脂校正乳（FCM）2.2kg·d^-1、乳脂量0.10kg·d^-1、真蛋白0.05kg·d^-1,改善了表观氮平衡及干物质与纤维的消化率。然而,母牛采食较高日粮CP时,乳中尿素氮和估计尿液尿素氮和总氮排泄也增加,表观氮效率（牛奶中氮量,采食氮量）从33％下降到30％。饲喂较多RUP的积极效果在于提高饲料转化率和乳脂肪含量（FCM增加1.8kg·d^-1,乳脂量增加0.08kg·d^-1）,但是乳蛋白含量下降,乳中尿素氮和尿液尿素排泄增加..添加RPM增加DM采食量0.7kg·d^-1,FCM增加1.4kg·d^-1,乳脂量增加0.06kg·d^-1,并有提高乳脂率、产奶量和乳蛋白产量的趋势。     

Bayesian zero-inflated predictive modelling of herd-level Salmonella prevalence for risk-based surveillance

The national control programme for Salmonella in Danish swine herds introduced in 1993 has led to a large decrease in pork-associated human cases of salmonellosis. The pork industry is increasingly focused on the cost-effectiveness of surveillance while maintaining consumer confidence in the pork food supply. Using national control programme data from 2003 and 2004, we developed a zero-inflated binomial model to predict which farms were most at risk of Salmonella. We preferentially sampled these high-risk farms using two sampling schemes based on model predictions resulting from a farm's covariate pattern and its random effect. Zero-inflated binomial modelling allows assessment of similarities and differences between factors that affect herd infection status (introduction), and those that affect the seroprevalence in infected herds (persistence and spread). Both large (producing greater than 5000 pigs per annum), and small herds (producing less than 2000 pigs per annum) were at significantly higher risk for infection and subsequent seroprevalence, when compared with medium sized herds (producing between 2000 and 5000 pigs per annum). When compared with herds being located elsewhere, being located in the south of Jutland significantly decreased the risk of herd infection, but increased the risk of a pig from an infected herd being seropositive. The model suggested that many of the herds where Salmonella was not detected were infected, but at a low prevalence. Using cost and sensitivity, we compared the results of our model based sampling schemes with those under the standard sampling scheme, based on herd size, and the recently introduced risk-based approach. Model-based results were less sensitive but show significant cost savings. Further model refinements, sampling schemes and the methods to evaluate their performance are important areas for future work, and these should continue to occur in direct consultation with Danish authorities.     

Prevalence of Cysticercus bovis in Australian cattle

Objective The first national abattoir survey of Cysticercus bovis (‘beef measles’) in cattle was conducted in February 2008. Methods During the data collection period, 493,316 cattle were subjected to standard postmortem procedures, including incision of the masseter and heart muscles. On-site veterinarians were asked to record the location of any C. bovis cysts, as well as the National Livestock Identification System ear tag numbers of infected animals. Veterinarians were asked to submit samples for laboratory confirmation by histology and polymerase chain reaction testing. Results Of the 23 samples submitted, none was positive for C. bovis by either diagnostic method. Conclusions Occasional, isolated diagnoses of beef measles are still made in most states of Australia, but since the last regional surveys were conducted 30 years ago, when the estimated prevalence was 50 to 200 per 100,000 cattle slaughtered, the parasite has become extremely rare.