Descriptive spatial epidemiology of subclinical Salmonella infection in finisher pig herds: application of a novel method of spatially adaptive smoothing

We describe the spatial epidemiological features of the 6.8 million meat-juice serological tests that were conducted between 1995 and 2004 as part of the Danish swine Salmonella control programme. We investigated pig and farm density using edge-corrected kernel estimations. Pigs were aggregated at the county level to assess county-level risk, and then we investigated farm-level risk by giving farms a case or non-case label using a cut-off of 40% of pigs positive. Conditional probability surfaces, correcting for the underlying population at risk, were produced for each year of the study period using a novel kernel estimator with a spatially adaptive smoothing bandwidth. This approach improves on previous methods by allowing focussed estimation of risk in areas of high population density while maintaining stable estimates in regions where the data are sparse. Two spatial trends in the conditional probability of a farm being a case were evident: (1) over the whole country, with the highest risk in the west compared to the east; and (2) on the Jutland peninsula with the highest risk in the north and south. At the farm-level a consistent area of risk was the south-west of Jutland. Case farms tended to aggregate indicating spatial dependency in the data. We found no association between pig or farm density and Salmonella risk. We generated hypotheses for this spatial pattern of risk and we conclude that this spatial pattern should be considered in the development of surveillance strategies and as a basis for further, more detailed analyses of the data.     

Pulsatile or continuous infusion of luteinizing hormone-releasing hormone and hormonal concentrations in prepubertal beef heifers

An experiment was conducted to determine if exogenous luteinizing hormone-releasing hormone (LHRH) administered iv intermittently as pulses (P) or by continuous sc infusion (I) using osmotic minipumps could sustain pulsatile LH release and induce estrous cyclicity in prepubertal heifers. Prepubertal heifers were assigned randomly to: 1) receive pulses of LHRH (n = 6; 2.5 micrograms LHRH/2 h for 72 h), 2) be infused with LHRH (n = 11; 1.25 micrograms LHRH/h for 72 h), or 3) serve as controls (n = 16). Blood was collected at 20-min intervals for 8 h (0900 to 1700 h) from six heifers in each group on d 1, 2, 3 (during treatment), and on d 4 (during 8 h after terminating LHRH treatments). Heifers given LHRH had higher (P less than .01) LH concentrations than controls. Preovulatory-like LH surges occurred in three I, two P and no control heifers during treatment. Pulse frequencies of LH (no. LH pulses/8 h) were greater (P less than .001) for P heifers than for I and control heifers due to pulsatile LHRH treatment. Serum estradiol was higher (P less than .01) during treatment for LHRH-treated heifers than for controls. Serum follicle-stimulating hormone, cortisol, and progesterone were unchanged during treatment. High levels of cortisol on d 1 declined (P less than .001) to baseline by d 2. Characteristic progesterone rises or short luteal phases occurred within 10 d of treatment initiation in more (P less than .05) LHRH-treated heifers (I = 45%, P = 33%) than controls (6%), although days to first observed estrus and first ovulation were unaffected by treatments. Although both continuous and pulsatile administration of LHRH successfully induced LH and estradiol release as well as preovulatory-like LH surges in some heifers, earlier initiation of estrous cycles was not achieved. Estrous cycles appeared to be delayed by exposure to continuous LHRH infusions during the peripubertal period.     

A Bayesian meta-analysis of the effects of administering an intra-vaginal (CIDR) device in combination with other hormones on the reproductive performance of cycling, anoestrous and inseminated cows

AIMS: To evaluate the effectiveness of treatment programmes that included controlled internal drug-releasing (CIDR) devices containing progesterone (P4) in improving synchrony of oestrus, and conception and pregnancy rates in cycling, anoestrous and inseminated dairy cows, using meta-analysis. To describe the difference in response between cycling and anoestrous cows to CIDR-based synchrony programmes. METHODS: Scientific papers written in the English language between 1989 and 2002 that investigated the effects of treatment programmes including CIDR devices on reproductive performance in dairy heifers or lactating dairy cows were identified using a computerised literature search. The criteria for inclusion incorporated evidence that treatment allocation was completely randomised; the population studied was lactating dairy cows; and that data were available on submission, conception and pregnancy rates and their associated measures of variability. Reproductive outcomes from 25 synchrony trials (total n=11,058 cows) were analysed. Summary measures of the effect of treatment on reproductive outcome were assessed using fixed- and random-effects Bayesian meta-analysis models. RESULTS: Treatment programmes including a CIDR device increased the risk of submission in cycling cows (predicted Bayesian RR=2.86, 95% credible interval=1.46-5.67). Compared with controls, synchrony programmes including CIDR devices in cycling dairy cows had no effect on the risk of conception to first service post-treatment (predicted Bayesian RR=1.00, 95% credible interval=0.80-1.24). Compared with controls, synchrony programmes including CIDR devices had no effect on the risk of pregnancy throughout the mating period (predicted Bayesian RR=1.02, 95% credible interval=0.89-1.17). In anoestrous cows, CIDR treatment had no effect on the risk of conception to first service post-treatment and no effect on the risk of pregnancy throughout the mating period, compared with anoestrous, untreated controls (predicted Bayesian RR=0.91 and 0.97, respectively; 95% credible interval=0.68-1.26 and 0.59-1.60, respectively). CONCLUSION: The results of this meta-analysis showed that synchrony programmes using CIDR devices combined with other hormones reliably enhanced submission rates in lactating dairy cows. The relatively small number of trials with data suitable for analysis and the heterogeneity of results at the individual trial level limited our ability to confirm either a beneficial or deleterious effect of treatment on conception or pregnancy rates. Further randomised, controlled trials to evaluate the effectiveness of this form of reproductive therapy in commercial dairy farms are needed.     

Ameliorative Effects of Melatonin against Hydrogen Peroxide‐Induced Oxidative Stress on Boar Sperm Characteristics and Subsequent In Vitro Embryo Development

Melatonin, the major secretory product of the pineal gland, scavenges a variety of reactive oxygen and nitrogen species in vivo and in vitro, indicating that melatonin is a potent function as an antioxidant. The objective of this study was to investigate the effect of melatonin in the presence or absence of hydrogen peroxide (H₂O₂) on sperm characteristics (motility, viability, survival rate, membrane integrity, lipid peroxidation (LPO) and mitochondria activity) and also to examine the developmental rates to the blastocysts stage of porcine oocytes fertilized in vitro with semen treated with or without melatonin (100 nm ) in the presence or absence of H₂O₂ (250 μm ). The sperm were treated with melatonin in the presence or absence of H₂O₂ for 3, 6, 9 and 12 h at 37°C and then analysed for the sperm characteristics. The porcine embryos were produced by in vitro maturation and in vitro fertilization (IVM/IVF) using semen treated with or without melatonin (100 nm ) in the presence or absence of H₂O₂ (250 μm ) for 6 h. The semen characteristics, including motility, viability, survival rate, membrane integrity and mitochondria activity, were higher in the groups that were treated with melatonin in comparison to other groups, irrespective of incubation periods. Malondialdehyde levels in control, melatonin and melatonin + H₂O₂ groups were lower than H₂O₂ only group. A positive correlation was shown among motility, viability, survival rate and membrane integrity, but a negative correlation was observed between LPO and the other evaluation methods. The developmental rates to blastocysts of IVM/IVF porcine oocytes fertilized by semen treated with melatonin were significantly increased compared with any other groups, with the cell number of blastocysts shown to have a similar trend to the developmental rates. These results demonstrate that melatonin can improve the semen characteristics during in vitro storage and support the developmental ability of IVM/IVF embryos in pigs.     

Area-level risks for BSE in British cattle before and after the July 1988 meat and bone meal feed ban

In this paper we investigate area-level risk factors for BSE for the cattle population present in Great Britain between 1986 and 1997. By dividing this population into two birth cohorts, those born before the July 1988 ban on feeding ruminant-derived meat and bone meal to ruminants and those born after, second-order regional influences are distinguished from the strong first-order south-to-north gradient of area-level BSE risk using Bayesian hierarchical models that account for structured (spatially correlated) and unstructured heterogeneity in the data. For both cohorts area-level risk of BSE was increased by a more southerly location and greater numbers of dairy cattle, relative to non-dairy cattle. For the cohort of cattle born after the July 1988 ban on feeding ruminant-derived meat and bone meal area-level BSE risk was additionally associated with greater numbers of pigs, relative to cattle. These findings support the role of low level cross-contamination of cattle feed by pig feed as an influence on BSE incidence risk as the epidemic evolved. Prior to the 1988 meat and bone meal ban unexplained BSE risk was relatively uniformly distributed across the country whereas after the ban there were spatially aggregated areas of unexplained risk in the northern and eastern regions of England suggesting that local influences allowed BSE control measures to be less-successfully applied in these areas, compared with the rest of the country. We conclude that spatially localised influences were operating in divergent ways during the two phases of the epidemic.     

Proteome-determined type-specific proteins of Mycobacterium avium subspecies paratuberculosis

Mycobacterium avium subspecies paratuberculosis (M. a. paratuberculosis) is a pathogen of ruminants, causing paratuberculosis (characterized by severe emaciation). The disease is endemic in many countries including the UK and places a severe economic burden on the global livestock industry. Two types of M. a. paratuberculosis can be classified by pulsed-field electrophoresis (I/III and II), which are phenotypically distinct and appear to have different host preferences. Proteomes of Type I and Type II M. a. paratuberculosis were analyzed by 2-D gel electrophoresis to determine if any significant differences existed between the subtypes. Seven different strains of Type I and 18 strains of Type II were analyzed and compared to detect type-specific differences. These 'type-specific' differences existed regardless of growth phase and were also exhibited in cells isolated directly from pathogenic lesions. Twenty-three spots predominated on the Type I profile, from which 17 proteins were identified. Twenty-one spots predominated on the Type II profile, from which 16 proteins were identified. None of the proteins identified as differentially represented on the profiles of Type I or Type II corresponded to open reading frames of the defining genomic regions as previously described for the Type I (sheep) and Type II (cattle). Sequence polymorphisms existing in Type I and II strains were identified in some open reading frames or regulatory regions of genes that correspond to proteins expressed in a type-specific fashion. The consequence of these is discussed in relation to protein expression and their impact on the type phenotype is discussed.     

Effects of tissue antigen matching on the healing of fresh cancellous bone allografts in dogs

The radiographic and histologic healing patterns of fresh cancellous bone allografts were compared with those of fresh cancellous autografts in dogs. Two groups of allografts were studied: 1 group of littermate pairs with minor histocompatibility mismatches, and 1 group of unrelated pairs with major histocompatibility mismatches. Pairs were chosen on the basis of preoperative serologic typing and mixed lymphocyte cultural assay of lymphocyte-defined compatibility. Generally, grafts with minor mismatches and autografts achieved bony union in 6 weeks with grafted bone serving as a scaffold for new bone formation. Grafts with major mismatches were resorbed and replaced by fibrocartilage. Healing of osteotomy sites grafted with mismatched bone occurred by ingrowth of host periosteal and endosteal new bone.