Risk factors associated with the salmonella status of dairy farms in England and Wales

Between October 1999 and February 2001 the salmonella status of 449 dairy farms in England and Wales was determined by environmental sampling on up to four occasions. Data were collected through interview-based questionnaires, and multivariable analyses were used to identify risk factors associated with the farms either being Salmonella positive (prevalence data) or becoming Salmonella positive (incidence data). Region, herd size, month of visit and the lack of a clean visitor parking area were significantly associated with the prevalence of Salmonella species, and there was a significant trend towards an increased risk in late summer and autumn. The introduction of six- to 24-month-old cattle into a herd was associated with a reduced prevalence, but the introduction of adult cattle only, or calves with other cattle, was associated with an increased (but not significant) risk of farms being Salmonella positive. Month of visit, the lack of a clean visitor parking area, the use of part-time workers and not feeding calves whole milk, but not region or herd size, were associated with an increased incidence of salmonella.     

Risk factors for and reproductive outcomes of phantom cows on New Zealand dairy farms

AIMS: To determine some of the risk factors for cows not observed in oestrus within 35–42 days of an unsuccessful artificial insemination (AI; phantom cows), and the reproductive outcomes and effect of treatment of phantom cows.

MATERIALS AND METHODS: Over 2 years, in dairy herds from the Waikato (n=10) and Canterbury (n=4) regions of New Zealand, pregnancy diagnosis was carried out 35–42 days after AI on cows that had been inseminated in the first 3 weeks after the start of mating (PSM) but had not been seen returning to oestrus. Risk factors for phantom cows were analysed using a generalised linear mixed effect model.

In Year 1, all phantom cows were left untreated. In Year 2, phantom cows were categorised as having a corpus luteum (CL) (CL+ n=120), or having ovarian follicles ≥10 (n=101) or <10 (n=40)?mm in diameter. Cows with a CL were treated with cloprostenol or untreated and placed with bulls. Cows with no CL received intravaginal progesterone (P4) for 7 days, with injection of gonadotrophin-releasing hormone (GnRH) on Days 0 and 9, and cloprostenol on Day 7 followed by AI. Pregnancy diagnosis of all cows took place 100–120 days after PSM and interval to conception and final pregnancy rate determined.

RESULTS: Overall, of cows inseminated in the first 3 weeks after PSM that did not return to oestrus, 610/6,734 (9.1%) were phantom cows. From the final multivariable analysis, treatment for anoestrus, BCS ≤4.0 at mating, being 2 or >6 years of age, and pure-bred, and decreasing interval between calving and mating, until 98 days post calving, were associated with increased odds of being a phantom cow. Compared to all other groups of cows, phantom cows had a longer interval to conception (p<0.001) and a lower final pregnancy rate (p<0.001).

Treatment of CL+ cows or cows with follicles ≥10?mm did not affect reproductive outcomes (p>0.3). For cows with follicles <10?mm treatment decreased the final percentage not pregnant (3/27; 11%; p=0.01) and interval to conception (21 days; p=0.02) compared with controls (7/13; 54% and 37 days, respectively).

CONCLUSIONS AND CLINICAL RELEVANCE: Risk factors for phantom cows were identified that could be manipulated to reduce the number of phantom cows in a herd, in particular increasing BCS. Treatment of the majority of phantom cows did not improve reproductive performance.     

Prevalence of microorganisms associated with udder infections in dairy goats on small-scale farms in Kenya

Six hundred and thirty clinically-normal milk samples from dairy goat flocks comprising a mixed population of German Alpine, Toggenburg, Saanen and Galla crosses were examined over a 3-month period to determine the prevalence of bacterial organisms. Bacteria were isolated in 28.7% of the milk samples (181/630) either singly (92.8%) or in combination (7.2%). The most prevalent bacterial organisms were Staphylococcus spp. (60.3%), followed by Micrococcus spp. (17.7%), Acinetobacter spp. (5%), Actinomyces spp. (5%) and Streptococcus spp. (1.1%). The Staphylococcus spp. were mainly coagulase negative (64.3%). Coagulase-negative staphylococci and coagulase-positive staphylococci accounted for 37.5% and 22.7% respectively of the total bacteria isolated. The isolation of bacteria, some of which are important in clinical and subclinical mastitis, in apparently normal caprine milk, indicates that particular attention should be given to the management of these dairy goat flocks in order to avoid the development of cases of clinical mastitis.     

Risk factors associated with mastitis in dairy goats

Prevalence of intramammary infection in healthy goats was determined from 4,662 composite udder samples taken over a 9-month period. For each doe, a colostral sample and 2 milk samples were collected. Breed, age, number of days not lactating before kidding, number of lactation days, and kidding date were recorded. Coagulase-negative Staphylococcus spp were isolated from 17.5% of does, Staphylococcus aureus from 3.1%, Mycoplasma spp from 1.2%, Streptococcus spp from 0.3%, and gram-negative bacteria from 2.0%. Gram-negative organisms were associated with intermittent infections, whereas coagulase-negative staphylococci were associated with persistent infections. Intramammary infection was related to breed, number of days not lactating, and number of lactation days, as determined by log-linear analysis. Does of the Nubian breed, does with nonlactating periods of greater than 60 days, and does in the first and last third of a standard 305-day lactation appeared to be at higher risk for intramammary infection.     

Temporal trends in reproductive performance in Irish dairy herds and associated risk factors

: Irish dairy herd fertility has been declining since the 1980s. The extent, nature and causes of this decline in fertility and the current status of Irish dairy herd fertility were described. An increase in calving interval of approximately one day per year has been recorded. The principal components of this trend have been an increased incidence of postpartum endocrinopathies, reduced expression of oestrus and a fall in conception rate. Both submission rate and calving-to-service interval have increased slightly over time. Significant risk factors associated with these trends have been strain substitution within the Holstein-Friesian breed and single trait selection for milk production. Critically, these changes have been reflected in loss of body condition. Contributory factors included increased herd size and possibly increased use of DIYAI. The most recent Irish study showed that 48% of cows conceived to first service and 14% of cows were not pregnant at the end of the industry-average 15-week spring breeding season. However, the top quartile of herds achieved a first-service conception rate of 59%, illustrating the wide variation between herds. These phenotypic trends were attributed to both genetic and environmental factors and their interactions. Recent Irish dairy herd fertility performance falls short of the targets set for seasonal compact calving.     

Risk factors for prebreeding pyometra on four Colorado dairy farms

Risk factors associated with pyometra were studied in 4 confinement managed dry-lot dairies in Colorado. The incidence of pyometra for the 3-year study was 7.0%. The first risk factor to enter the step-wise logistic regression model was “lactation number”. Cows in their first lactation were at lesser risk of developing pyometra (P<0.001) than cows in all other lactations. The second and final variable to enter the logistic regression model was “dairy farm”. Cows on 1 of the dairy farms were at lesser risk of pyometra than the other herds, (P<0.005), after adjusting for the lactation number of the cows. There was no statistical association for year or season with the incidence of pyometra; however, the probability of three consecutive spring seasons having the greatest frequency of pyometra was 0.0045.     

Characterization of small-scale dairy farms and its relation to water use efficiency in the Mexicali Valley,Mexico

A survey was completed to determine water use by small-scale dairy farms in Mexicali Valley of Mexico and to associate it with dairy production parameters. Mexicali Valley surrounds the capital city of the state Baja California, Mexicali. Sixty-one smallholders were interviewed in person in this rural area of northwestern Mexico. On average, small dairy holders had more than 20 years of experience and were ~ 55 years of age; people working on their farms are especially relatives. A low percentage was literate (20%), and they belong to a local dairy association. Milk yield/cow/year does not reach 4000 kg of milk and 75% of producers do not follow a defined management program for their cattle. Hand-milking is still practiced by 27% of the producers, and there is a general lack of infrastructure to maintain milk in a refrigerated state so that there is a very high risk of zoonotic diseases. Water use efficiency (WUE) was linearly correlated (P < 0.05) with total irrigated area, but not with animal production parameters. Regression equations constructed to explain WUE exhibited low adjustment, and WUE was not associated (P > 0.05) with milk yield. Small dairy producers in Mexicali Valley are in a generally poor situation with low water use practices; however, required more government support to increase their benefits from this livestock activity.

     

Risk factors associated with hemorrhagic bowel syndrome in dairy cattle

OBJECTIVE: To determine risk factors associated with hemorrhagic bowel syndrome (HBS) among dairy cattle in the United States and identify characteristics of HBS in individual cows. DESIGN: Cross-sectional, population-based survey. SAMPLE POPULATION: A stratified random sample of 1,013 dairy operations with > or = 30 cows located in 21 states. PROCEDURE: Information on management and animal health-related topics was collected with a questionnaire. RESULTS: HBS was estimated to have been observed on 9.1% of operations during the preceding 5 years and on 5.1% of operations during the preceding 12 months. Factors found in multivariable analysis to be associated with the occurrence of HBS during the preceding 12 months were large herd size, administration of bovine somatotropin, and routine use of milk urea nitrogen concentration to determine ration composition. Use of pasture as part of the lactating cow ration during the growing season was associated with decreased odds of HBS in operations with rolling herd average milk production < or = 20,000 lb, whereas in operations with higher milk production, use of pasture was not associated with occurrence of HBS. For individual cows with signs consistent with HBS, the third lactation was the median of the parity distribution and the median time between parturition and the onset of clinical signs was 104 days. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that management practices implemented to achieve high milk production may increase the risk of developing HBS in dairy cattle. Increased consumption of a high-energy diet seems to be the most plausible common pathway for all of the risk factors that have been described.     

Risk factors associated with on-farm mortality in Swedish dairy cows

Dairy cow mortality (unassisted death and euthanasia) has increased, worldwide and in Sweden. On-farm mortality indicates suboptimal herd health or welfare and causes financial loss for the dairy producer. The objective of this study was to identify cow-level risk factors associated with on-farm cow mortality. Cows with at least one calving between 1 July 2008 and 30 June 2009 from herds enrolled in the Swedish official milk recording scheme with >40 cow-years were included. Each cow was followed from the day of calving until she calved again or left the herd (died, slaughtered or sold). The effects of potential risk factors on on-farm cow mortality were analysed using a Weibull proportional hazard model with a gamma distributed frailty effect common to cows within herd. The event of interest (failure) was euthanasia or unassisted death. An observation was right censored if the cow was slaughtered, sold, calved again or had an on-going lactation at 500 days after calving. The lactations were split into seasons (January to April, May to August and September to December) and at 30 and 100 days in milk in order to evaluate seasonal effects and the effect of disease in different lactation stages. Primiparous and multiparous cows were analysed separately. The highest hazards for both primiparous and multiparous cows were found for traumatic events and diseases, both in the lactation stage in which the cow died and in the preceding stage. The hazard was higher in early lactation and lower in 2nd parity compared to higher parities. Increased age at first calving (for primiparous cows), calving between January and April, dystocia and stillbirth also increased the mortality hazard. Differences were also found between breeds, between milk production parameters at first test milking and between management types. The results from this study show the importance of good management and preventive health actions, especially around calving, to avoid mortality in dairy cows.     

Frequency of infection by Neospora caninum in wild rodents associated with dairy farms in Aguascalientes,Mexico

The purpose of this study was to detect the presence of Neospora caninum in tissues from wild rodents associated with dairy farms in Aguascalientes, Mexico. Individuals from Mus musculus, Rattus novergicus and Spermophilus variegatus were caught in dairy farms with history of positive status to N. caninum. A total of 33 rodents were caught from which samples were taken of brain, spinal cord, liver and heart and were tested with nested PCR and Immunohistochemistry (IHC). Results obtained with PCR showed that M. musculus had 77% (10/13) positive samples to N. caninum, S. variegatus had 71% (10/14) and R. novergicus had 50% (3/6). The results obtained with IHC showed that 15% (2/13) of M. musculus individuals were positive, while 43% (6/14) of S. variegatus and 33% (2/6) R. novergicus were also positive. This is the first report of the presence of N. caninum in S. variegatus.     

Risk factors associated with cystic ovarian disease in Norwegian dairy cattle

Background

The aims of this study were to establish the incidence of cystic ovarian disease (COD) and its geographical and seasonal variation in Norway, investigate the effect of COD on culling rates, and describe the effects of COD on subsequent reproductive performance and its association to twins.

Methods

Diagnosis of COD was made by veterinary surgeons in the field. Four statistical models were made all including herd as random effect: The four different dependent variables investigated were: 1) Diagnosis of COD between 40 and 165 days in milk or not; (n = 511,657); 2) Twins or singleton; data restricted to lactations with new calving (n = 156,661): 3) Culling/removal or not (n = 573,184): 4) Culling due to reproductive problems; data included only lactations which ended in culling (n = 234,232). Model 1, 3 and 4 applied Cox regression models, and model 2 logistic regression. Independent variables were parity, twins/singletons, calving season, herd size, region, COD occurrence in present lactation (if not dependent), and COD diagnosis in previous lactation.

Results

The incidence was 0.82% per lactation. COD increased with increasing parity, was smallest at herd size between 35 and 85 cows. Cows in 1^st parity and calved in spring had lowest hazard of COD and hazard for COD diagnosis was highest in autumn with HR = 2.6 (1.9 - 3.4) compared to spring. There was an interaction between parity and season. COD incidence was lower south of 60°N. Cows which experienced COD had an increased odds of giving birth to twins OR = 2.2 (1.7 - 2.7). Of those that were culled, those with COD were culled more frequently because of reproductive problems; HR = 2.1 (1.9 - 2.3) for higher parity than 2. Having COD diagnosed in the preceding lactation was a hazard for diagnosis in the lactation studied.

Conclusion

COD diagnosis is strongly associated with season (autumn calving) and parity. Herds north of 60°N have more COD. Occurrence of COD is associated with twin births as well as culling due to reproduction.     

Risk factors and the economic impact of ovarian cysts on reproductive performance of dairy cows in Korea

The objectives of this study were to determine the risk factors for development of postpartum ovarian cysts by evaluating several reproductive factors in individual cows, and to determine the economic impact of ovarian cysts on subsequent reproductive performance in dairy herds in Korea. The data, including cow parity, abnormal puerperium, endometritis, body condition score (BCS), and breeding status were collected from 634 cows in 9 dairy herds. We used logistic regression to evaluate the effects of these factors on ovarian cysts. A stepwise procedure, used to obtain the appropriate model with alpha=0.05, revealed that cow parity was the most important risk factor for ovarian cyst development within 8 weeks postpartum, while development of endometritis and BCS loss>or=1 from the dry period to 8 weeks postpartum were the most important risk factors for ovarian cyst development beyond 8 weeks postpartum. The occurrence of ovarian cysts beyond 8 weeks postpartum prolonged (P<0.01) the mean intervals from calving to first service (27 days) and conception (77 days), and increased (P<0.05) the culling rate (7.8%), while ovarian cyst development within 8 weeks postpartum did not affect (P>0.05) the mean intervals from calving to first service and conception or the culling rate. The economic loss resulting from the occurrence of ovarian cysts was estimated at approximately 823,996 won ($687) due to effects on the cost of nutrition, average growth of calves, labor and medical costs, and culling. These results suggest that cow parity is correlated with the development of ovarian cysts within 8 weeks postpartum, and endometritis and BCS loss>or=1 from the dry period to 8 weeks postpartum are correlated with the development of ovarian cysts after 8 weeks postpartum, which decreases reproductive performance and results in economic loss in dairy herds in Korea.     

Seroprevalence and associated risk factors of bovine brucellosis in Addis Ababa dairy farms

A cross-sectional study was carried out on bovine brucellosis in Addis Ababa dairy farms from November 2003 to April 2004. A total of 1,202 blood samples were collected from non-vaccinated, cross-bred dairy cattle. The Rose Bengal plate test (RBPT) was used as a screening test. Those serum samples reacting positively to RBPT were subjected to the complement fixation test (CFT) for confirmation. The RBPT detected 30 of 1,202 (2.5%) of the samples as brucellosis positive. The positive sera when further retested using CFT, 18 out of the 30 RBPT positive sera were confirmed to be positive. The prevalence of brucellosis based on CFT in the study area was 1.5%, and all positive sera were from female cattle. Result of the questionnaire survey revealed that percentage of 4.4% abortion and 9.5% retained fetal membranes. Abortion and retained fetal membranes were associated with Brucella antibodies (P?相似文献   

Risk factors for postpartum endometritis and the effect of endometritis on reproductive performance in dairy cows in Korea

The objectives of this study were to determine the risk factors for postpartum endometritis by evaluating several reproductive factors in individual cows, and to determine the effect of endometritis on the subsequent reproductive performance in dairy herds in Korea. The data, including health status, parity and body condition score (BCS) of cows, and calving date, were collected from 320 cows in eight dairy herds calving from January 2001 to October 2002. We used logistic regression to evaluate the effects of these factors on endometritis. A stepwise procedure, used to obtain the appropriate model with alpha=0.05, revealed that retained placenta, metabolic disorders and parity are the important risk factors for endometritis. The mean intervals from calving to first service and conception were prolonged (P<0.01) by 23 and 36 days, respectively, in the endometritis group compared to the non-endometritis group. The first service conception rate was lower (P<0.05) in the endometritis group (47.6%) than in the non-endometritis group (62.6%). The number of services per conception was higher (P<0.05) in the endometritis group (1.9) than in the non-endometritis group (1.6). We conclude that retained placenta, metabolic disorders and cow parity are strongly correlated with the development of postpartum endometritis, which decreases reproductive performance in dairy herds in Korea.     

Risk factors associated with extended spectrum beta-lactamase Escherichia coli (CTX-M) on dairy farms in North West England and North Wales

This study investigated the potential spread of CTX-M-14 Escherichia coli from a known ESBL E. coli positive farm and risk factors for the presence of CTX-M E. coli on dairy farms. Between November 2009 and March 2010, 65 farms in North West England and North Wales were visited and animals sampled for E. coli producing CTX-M ESBLs. Seventeen of these were known to have received animals from a known ESBL E. coli positive 'index' farm since 2005 (linked farms). The prevalence of CTX-M E. coli in the population of linked farms was 58.8% (10/17; CI(95%) 32.9-81.6%) and in the randomly selected control population was 35.4% (17/48; CI(95%) 22.2-50.5%). There was no significant (p>0.05) linkage for the detection of any CTX-M E. coli or specifically a CTX-M-14 E. coli to the index farm. Group 1 (CTX-M-15, CTX-M-55, CTX-M-1, CTX-M-32), group 2 (CTX-M-2) and group 9 (CTX-M-14, CTX-M-14B, CTX-M-27) CTX-M E. coli were identified on the study farms. Molecular analysis revealed that three plasmids from linked farms had similar sizes (95kbp), replicon type (IncK) and backbone genes as that from the index farm. Logistic regression analysis revealed that farms that had used a 3rd or 4th generation cephalosporin (ceftiofur, cefoperazone and cefquinome) in livestock in the last 12months were nearly 4times more likely to have ESBL E. coli present (p=0.037; OR=3.93). There was no significant association between presence of CTX-M E. coli and the use of any 1st or 2nd generation cephalosporins. Several other risk factors for the presence of CTX-M E. coli were identified, such as storage of slurry in a pit, operating an open herd policy and infrequent cleaning of calf feeding equipment.     

Risk factors associated with Neospora caninum abortion in Ontario Holstein dairy herds

The objective of this epidemiological study was to identify risk factors for Neospora caninum-related abortions in Ontario Holstein dairy herds. A total of 88 herds, consisting of 5080 cattle, and utilizing Dairy Herd Improvement (DHI) services, were divided into three groups. Case (n = 30) and first control (n = 31) herds were selected from 1998 and 1999 fetal abortion submissions to the Animal Health Laboratory, University of Guelph, that were histopathologically positive or negative, respectively, for N. caninum. A second control group (n = 27) was selected from multiple sources of herds sampled within the previous 4 years that had a low seroprevalence (<7%) to N. caninum. Between May and December 1999, all available cows on all farms, in parity one or greater, were blood sampled. The sera were then analyzed for antibody to N. caninum using a kinetic ELISA. A survey administered at the time of sampling recorded information on housing, animal species present, manure management, reproduction, biosecurity practices, wildlife observations, peri-parturient cow management, herd disease history and nutrition. Production and other herd parameters were obtained from DHI records. Logistic regression indicated that the following parameters were positively associated with a N. caninum abortion in a herd: the N. caninum herd seroprevalence (OR = 1.1), the total number of dogs on a farm (OR = 2.8), the frequency that dogs were observed defecating in mangers (OR = 2.8), the number of horses on a farm (OR = 3.1), the observed annual rate of retained fetal membranes (OR = 1.2) and the observed annual rate of cows returning to estrus after pregnancy confirmation (OR = 1.2). Factors negatively associated were the frequency of stray cats and wild canids observed on a farm (OR = 0.4 and OR = 0.7, respectively) and the housing of heifers on loafing packs (a housing pen divided into feed manger, scrape alley and bedded pack areas, OR = 0.1).     

The effects of lameness on reproductive performance, milk production and culling in Dutch dairy farms

A retrospective cohort study design was used to investigate the effect of lameness on reproductive performance on 13 commercial Dutch dairy farms. The data were collected during a routine herd health and production control program.

The cumulative 100-DIM (days in milkl) production in the previous lactation of lame cows was higher and the culling rate lower than that of the controls. The 100- and 270-DIM production of the cows with a sole ulcer was higher than that of the control cows. There was no difference in 100- and 270-DIM production between cows with a lameness diagnosis other than sole ulcer and the controls.

Lameness prolonged the interval from calving to first service and the interval from first service to conception. The pregnancy rate at first service was not affected by lameness.     

Risk factors for neonatal calf diarrhoea and enteropathogen shedding in New Zealand dairy farms

To investigate the risk factors for neonatal calf diarrhoea, a cross-sectional study was conducted on 97 New Zealand dairy farms. Faecal specimens from 1283 calves were scored as liquid, semi-solid or solid, and analysed for bovine rotavirus (BRV) and coronavirus (BCV), enterotoxigenic K99⁺ Escherichia coli (K99), Salmonella spp. and Cryptosporidium parvum. Calf- and farm-level data were collected by means of a questionnaire and the odds of liquid faeces calculated using mixed effects logistic regression models.Among the infectious agents, only C. parvum (odds ratio [OR] = 2.6; 95% confidence interval [CI], 1.3–5.6; P = 0.02), BRV (OR = 2.7; 95% CI, 1.3–5.9; P = 0.01) and co-infection with more than one agent (compared with mono-infection: OR = 2.5; 95% CI, 1.3–4.8; P = 0.01) were associated with increased odds of liquid faeces in calves which were 9 to 21 days old. Housing of calves in open barns so exposing them to the weather was also associated with increased odds of liquid faeces compared with closed barns (OR = 2.1; 95% CI, 1.1–12.2; P = 0.03). Vaccinating cows against calf enteropathogens (OR = 0.2; 95% CI, 0.1–0.9; P = 0.03), administering waste milk (from mastitis and/or containing antibiotics; OR = 0.4; 95% CI, 0.1–0.8; P = 0.01), the sex of calves (females compared to males OR = 0.2, 95% CI, 0.07–0.7; P <0.01), and the use of straw for bedding (OR = 0.2; 95% CI, 0.03–0.9; P = 0.03) decreased the odds of liquid faeces. Conversely, in calves that were 1 to 5 days old, only K99 was associated with liquid faeces (OR = 4.6; 95% CI, 1.2–16.1; P = 0.02). In this age group, the odds of liquid faeces were smaller on farms where females took care of the calves, compared with males (OR = 0.4; 95% CI, 0.01–0.9; P = 0.04).