Assessing individual sow risk factors for coliform mastitis: a case-control study

In order to investigate sow-specific risk factors associated with coliform mastitis, a case-control study was performed over the course of 28 months. Data of three farms were collected under production conditions. Sows suffering from coliform mastitis after farrowing served as cases, and healthy half- or full-sib sows from the same farm served as controls. Individual sow characteristics and the seasonal influence were analysed by conditional logistic regression. The final multivariate model identified four risk factors: the risk of suffering from coliform mastitis increased with a higher number of piglets born alive and stillborn piglets. Gilts had an increased risk for the disease, and birth intervention was also associated with a higher prevalence of mastitis. Birth induction and season had no significant influence on the occurrence of coliform mastitis. The time during and soon after farrowing is a very sensitive period in pig production demanding great attention by the farmer. With respect to the economic losses, monitoring of potentially endangered sows as well as detailed documentation and selection of disease cases are of particular importance when coping with coliform mastitis.     

Seroprevalence and risk factors associated with seropositivity in sows from 67 herds in north-west Germany infected with Mycoplasma hyopneumoniae

Risk factors for the spread of Mycoplasma hyopneumoniae in sows have not been studied although vertical transmission from sows to their offspring is considered a significant risk factor in the development of enzootic pneumonia in growers and finishers. Seropositivity for M. hyopneumoniae in sows, as assessed by commercial ELISA, is a possible indicator of infection pressure among sows. The objective of this study was to estimate seroprevalence and associated risk factors of a sow being seropositive for M. hyopneumoniae. A cross-sectional study was carried out in 2578 sows from 67 herds in north-west Germany. Data concerning general herd characteristics, acclimatisation practices, indoor and outside contacts, as well as data describing the immediate local environment were collected during a herd visit via questionnaire. Blood samples were seropositive in 65% of the 2578 sows, and all herds had ≥14% seropositive sows. Data analysis was performed in two steps. First, univariate analysis of predictor variables for the risk of a sow being seropositive for M. hyopneumoniae was performed using chi-square test. Secondly, all variables associated with the risk of a sow being seropositive (P ≤ 0.25) were included in a multivariate model using a generalised linear model. The risk of a sow being seropositive for M. hyopneumoniae was increased in herds with two- or three-site production (OR 1.50), when piglets were not vaccinated against M. hyopneumoniae (OR 1.81), in herds with a 2-week farrowing intervals (OR 1.84) and in herds without all-in/all-out management of the farrowing units (OR 1.37). The lack of an acclimatisation period for replacement boars was also associated with the risk of a sow being seropositive (OR 2.10). The results indicate that M. hyopneumoniae seropositivity is common in sows in north-west Germany and is influenced by various management factors. It is recommended that evaluation of sow herd management should be included in any strategic health plan to control M. hyopneumoniae infection.     

Associations between genetics, farm characteristics and clinical disease in field outbreaks of porcine reproductive and respiratory syndrome virus

Porcine reproductive and respiratory syndrome (PRRS) is a disease of domestic swine characterized by exceptionally high clinical variability. This study addresses the question of whether clinical variability in PRRS results from (a) genetic variation among viral isolates and/or (b) variation in management practices among farms on which isolates are found. Genetic data (open reading frame 5 gene sequences) and data on farm characteristics and associated clinical disease signs were collected for 62 PRRS virus (PRRSV) field isolates, representing 52 farms. Clinical disease signs were interrelated — confirming that a true reproductive syndrome exists (involving abortions, infertility in sows, deaths of sows and preweaning mortality).

Pairs of farms experiencing deaths in their sow populations also tended to share viral isolates which were more similar to one another than expected by chance alone. This implies that sow death (one of the more-severe manifestations of PRRS) is under genetic influence. Large herd size was a significant risk factor for the death of sows and for respiratory disease in nursery pigs. All-in–all-out management practices in the nursery were protective against reproductive signs in the sow herd. All-in–all-out management practices in the finishing stages of production were protective against respiratory disease in nursery pigs — but were paradoxically associated with an increased risk of infertility in sows. These results suggest that farm-management practices can also influence which PRRS clinical signs are manifested during an outbreak. In general, signs associated with PRRS appear to result from a combination of genetic factors and herd-management characteristics. The relative contributions of these two influences differ depending on the specific clinical sign in question.     

Risk factors for bovine mastitis in the Central Province of Sri Lanka

A study of the risk factors associated with mastitis in Sri Lankan dairy cattle was conducted to inform risk reduction activities to improve the quality and quantity of milk production and dairy farmer income. A cross-sectional survey of randomly selected dairy farms was undertaken to investigate 12 cow and 39 herd level and management risk factors in the Central Province. The farm level prevalence of mastitis (clinical and subclinical) was 48 %, similar to what has been found elsewhere in South and Southeast Asia. Five cow level variables, three herd level variables, and eight management variables remained significant (p?相似文献   

Risk factors associated with transmissible gastroenteritis in swine.

Commercial production data base records from 2 Illinois farms, on which epizootic or enzootic transmissible gastroenteritis (TGE) was experienced, were accessed for an epidemiologic study. Risk factors investigated were sow parity, source of sows, location of farrowing crates, and breeding practices. At farm 1, an epizootic was experienced; at farm 2, an epizootic of TGE followed by enzootic TGE was experienced. Initially, crude risk ratios were calculated for these risk factors, and the crude risk ratios were subsequently adjusted for confounders and interactions, using multiple logistic regression techniques. After adjustment, parity-3 sows were 2.3 times more likely to have litters with TGE than were sows of all other parities on farm 1, and parity-1 sows were 2.6 times more likely to have litters that experienced TGE than were sows of all other parities on farm 2. A single boar on each farm was linked to increased likelihood of a sow's litter contracting epizootic TGE on each farm. Enzootic TGE was maintained by the periodic influx of outside-source gilts on farm 2; these gilts were 2.2 times more likely to have litters with TGE than were sows derived from farm 2. Sows housed in farrowing crates located under the cold air inlet of farm 2 were 1.7 times as likely as sows located in other rows to have litters with enzootic TGE.     

Herd-related risk factors for decubital ulcers present at post-mortem meat-inspection of Danish sows

We quantified risk factors for the prevalence of decubital ulcers (noted in meat-inspection records) in the shoulder region of Danish cull sows. The potential risk factors (herd-owner characteristics, production facilities and management) were obtained through telephone interviews based on a questionnaire. Meat-inspection records were obtained from the Danish Bacon and Meat Council (DBMC). The prevalence of decubital ulcers was investigated in 23,794 sows from 207 sow herds undergoing mandatory post-mortem meat-inspection at the four Danish abattoirs under the DBMC slaughtering sows in the year 2000. Three factors were associated with decreased herd prevalence of decubital ulcers in the mixed model: using one’s own gilts for replacement, routinely using a hospital pen and production of pigs under certain welfare requirements. Two factors increased the prevalence: confined sows (stalled and tethered or tethered) and two persons working in the farrowing units instead of one.     

Managerial and environmental determinants of clinical mastitis in Danish dairy herds

Background

Several management and environmental factors are known as contributory causes of clinical mastitis in dairy herd. The study objectives were to describe the structure of herd-specific mastitis management and environmental factors and to assess the relevance of these herd-specific indicators to mastitis incidence rate.

Methods

Disease reports from the Danish Cattle Data Base and a management questionnaire from 2,146 herds in three Danish regions were analyzed to identify and characterize risk factors of clinical mastitis. A total of 94 (18 continuous and 76 discrete) management and production variables were screened in separate bivariate regression models. Variables associated with mastitis incidence rate at a p-value < 0.10 were examined with a factor analysis to assess the construct of data. Separately, a multivariable regression model was used to estimate the association of management variables with herd mastitis rate.

Results

Three latent factors (quality of labor, region of Denmark and claw trimming, and quality of outdoor holding area) were identified from 14 variables. Daily milk production per cow, claw disease, quality of labor and region of Denmark were found to be significantly associated with mastitis incidence rate. A common multiple regression analysis with backward and forward selection procedures indicated there were 9 herd-specific risk factors.

Conclusion

Though risk factors ascertained by farmer-completed surveys explained a small percentage of the among-herd variability in crude herd-specific mastitis rates, the study suggested that farmer attitudes toward mastitis and lameness treatment were important determinants for mastitis incidence rate. Our factor analysis identified one significant latent factor, which was related to labor quality on the farm.     

Mortality, death interval, survivals, and herd factors for death in gilts and sows in commercial breeding herds

The objectives of this study were to measure death intervals and survival, to determine mortality rate and mortality risks, and to investigate the association of herd factors with mortality risk in individual female pigs. This study was conducted by obtaining female data with lifetime records of 65,621 females born between 1999 and 2002, and herd data with mean measurements of 5 yr from 2000 to 2004 in 105 herds. Annualized mortality rate was calculated as the number of dead females divided by the sum of life days in all gilts and sows, multiplied by 365 d. Mortality risk was calculated as the number of dead females divided by the number of surviving females at farrowing in each parity. Death interval in gilts was defined as the number of days from birth to death, and that in sows was the number of days from the last farrowing to death. A Cox proportional hazards model was used to obtain the survival probability by parity. Logistic regression analyses were used to investigate the association of herd factors with mortality risk in individual females in each parity. Of the 65,621 females, the mortality risk was 9.9%, and the annualized mortality rate was 3.9%. Of the 6,501 dead females, death intervals in gilts and sows were 294.7 and 55.0 d, respectively. In gilts, survival probability rapidly decreased at 33 and 50 wk of age, around the first mating and the first parturition. In contrast, survival probability in sows decreased at wk 1 after farrowing, and rapidly decreased at wk 20 and 21 after farrowing in all parity groups that were around a subsequent peripartum period. The percentages of death on wk 0, 1, and 2 after the last farrowing in all the dead sows were 6.5, 23.5, and 10.1%, respectively. Approximately 10% of deaths also occurred from wk 20 to 21 after the last farrowing. Death interval in parity > or =5 was the shortest among all parity groups (49.2 d; P < 0.05). Mortality risks in parities 0 and 1 were 1.44 and 1.83%, respectively. As parity increased from 2 to > or =5, mortality risk increased from 1.63 to 5.90%. Herd factors (greater herd mortality, less herd productivity, and smaller herd size) were associated with greater mortality risk in individual females in parity 0 to > or =5, parity 4 and > or =5, and parity 1 to 4, respectively (P < 0.05). In conclusion, females in peripartum periods, gilts, and high-parity sows are at a greater risk of dying. Increased care should be implemented for prefarrowing females and early-lactating sows.     

Management of dairy heifers and its relationships with the incidence of clinical mastitis

AIM: To describe aspects of management of dairy heifers before calving and determine risk factors for clinical mastitis postpartum in heifers, at the herd level, under pasture-based management systems in the Waikato and Taranaki regions of New Zealand. METHODS: Dairy herdowners (n=578) provided information via a prospective survey about their practices for rearing heifers and management of mastitis. A proportion of herdowners (n=250) subsequently provided data on the cases of clinical mastitis in their herds, including the date, cow identification, age and quarter affected from cases occurring in the 4 months after the planned start of calving (PSC) in the subsequent lactation. The relationship between management factors and the proportion of heifers diagnosed with clinical mastitis within a herd was examined using bivariate and multivariate analyses. RESULTS: The herd average percentage of heifers with clinical mastitis was 13.6 (95% confidence interval (CI)=12.3-14.9)%, and multiparous cows with clinical mastitis was 9.0 (95% CI=8.2-9.8)% in the first 4 months of lactation. There were positive relationships between the proportion of heifers with clinical mastitis and average milk production per cow (kg milksolids/ lactation; p<0.001), number of cows milked per labour unit (p=0.003), stocking rate (<> 3.30 cows/ha; p=0.002), and incidence of clinical mastitis in multiparous cows (%/120 days; p<0.04), in the final multivariate model. The proportion of heifers with clinical mastitis per herd was lower in herds that milked their lactating cows in multiple groups (p=0.02). CONCLUSIONS: The risk of clinical mastitis in heifers was significantly associated with management practices. It may be possible to reduce the incidence of clinical mastitis in heifers by modification of management practices at the herd level, and further studies are required to investigate this.     

Length of productive life of sows in four pig farms in the tropics of Mexico

The objective of this study was to determine the effect of some factors on the length of productive life (LPL), the number of parities (NP), and the culling interval (CI) of sows. The information from 2003 to 2009 of 3,746 sows with LPL and NP records and 5,819 sows with CI records from the four farms of Yucatan, Mexico was used. LPL was defined as the number of days between the first farrowing and culling or death and CI as the number of days between the last farrowing and culling. To determine the effects of farm, litter size at first farrowing (LSF1) and age at first farrowing (AF1) on LPL and NP, and of farm, LSF1 and culling reason on CI general linear models were used. Means and standard errors for LPL, NP, and CI were 496.4 ± 8.42 days, 3.35 ± 0.04 parities, and 48.3 ± 0.52 days, respectively. All factors had significant effects (P < 0.05) on LPL, NP, and CI. The sows from farm 2 stayed longer (806.0 days) and had more parities (5.25) than the sows from the other farms. Sows with the smallest litters (≤8 piglets) at first farrowing stayed the least time in the farm (675.1 days) and had the fewest parities (4.49). Gilts farrowing the first time before 331 days of age stayed longer time in the farm (726.4 days) and had more parities (4.81) in comparison with 331–348 and more than 348 days age groups. With respect to CI, the sows in farm 3 stayed the longest time in the farm. Sows with more than five parities were culled sooner after their last farrowing. In conclusion, differences between farms for LPL, PN, and CI were found. Females that farrowed at a short age and those with large litters stayed longer in the herd. Old sows and those culled for reproductive reasons stayed the least time in the herd after their last farrowing.     

Establishing treatment protocols for clinical mastitis.

Each farm has a unique mix of mastitis pathogens and management procedures that have evolved over time. The herd veterinarian should work with the manager/owner to systematically develop treatment protocols that meet the needs and management of the farm. To establish a mastitis treatment protocol, it is necessary to develop a system to routinely identify clinical mastitis cases, develop a herd-specific severity level assessment system, manage the clinical mastitis cases based on severity level and culture result (when available), avoid antibiotic residues, and monitor the success of the system and alter the protocol as necessary.     

Low reproductive performance and high sow mortality in a pig breeding herd: a case study

Sow performance is a key component of the productivity of commercial pig farms. Reproductive failure in the sow is common in pig production. For every 100 sows served, 89 should farrow. In absence of specific diseases such as porcine parvovirus, pseudo-rabies, swine fever, leptospirosis and brucellosis, management failures are the most important causes of loss. A syndrome associated with reproductive inefficiency, and post-service vaginal discharge and high sow mortality in a commercial pig farm is described. Pregnancy failures exceeded 20% and sow mortality exceeded 12% for two consecutive years. The abnormal post-service vaginal discharge rate was 1.7% during the period of investigation.An investigation involving an analysis of farm records, a review of breeding management practices, clinical examinations, laboratory analysis and examination of urogenital organs was conducted.The main contributing factors found were a sub-optimal gilt breeding management, an inadequate culling policy in combination with a sub-optimal culling rate and the presence of cystitis in more than 1% of the urogenital organs examined. The high sow mortality rate was related to an aged breeding herd.A control programme was recommended based on management changes involving oestrus detection, movement of gilts post-service, hygiene in the service area, boar exposure post-service and urinary acidification. This programme failed to increase the farrowing rate due to incomplete implementation of the recommendations made. The farrowing rate increased to 86.5% subsequent to a farm manager change in January 2005, which resulted in complete implementation of the control programme.     

Eradication of Salmonella Yoruba in an integrated pig herd

An integrated SPF herd with 320 sows was found infected with Salmonella Yoruba during an annual control among sows, aiming to verify freedom from Salmonella infections. It is believed that the infection was introduced to the herd by purchase of feed. The herd performed an age segregated rearing system. Sows and piglets were reared at a central farm, while growers (25-100 kg body weight) were reared at sub-estates. The growers were free from the infection, and as a consequence a specially designed eradication program was designed. Farrowing and weaning were defined as periods of risk for sows and piglets, respectively. Consequently sows were isolated and individually tested for presence of Salmonella one week before and one week after farrowing. The offspring were tested one week post weaning. To verify freedom from disease among piglets they were also tested another time before transfer to the uninfected sub-estates. Piglets with undefined status regarding Salmonella were denoted animals at risk and not transferred to the sub-estates. Instead they were transferred to a third estate, rented to house pigs at risk. The program was successful. It allowed full production during performance, and the herd was declared free from S. Yoruba seven and a half months after the initial diagnosis.     

Management and environmental factors associated with annual sow culling rate: A path analysis

The relationships between management and environmental factors and annual sow culling rate were investigated in 152 Minnesota swine breeding herds. Data were obtained through a postal survey. A general path model was hypothesized to describe relationships among variables. Multiple least-squares and logistic regressions were used to test the statistical significance of pathways. The associations between the indepen variables and the annual culling rate (ACR) were decomposed into direct, indirect, and common cause associations.

The mean ACR of the 152 farms was 39% ± 2% rm(SE). Using path-analysis techniques, only the type of flooring during gestation, the size of the herd and the lactation length had a direct relationship with ACR. The type of housing during gestation and farrowing were related indirectly to the ACR. Their association was mediated by the type of flooring during gestation and the weaning age. Herds housing their sows in total confinement during gestation were most likely to keep them on partially or totally slatted floors which were associated with a higher ACR. Sows kept in crates during the farrowing period were more likely to have a short lactation length which was associated with a higher ACR.

Most associations between the use of preventive veterinary services and the ACR were due to association with other variables. Herds using veterinary preventive medicine were most likely to have a short lactation length, a large number of females, and sows housed in total confinement during gestation and in crates during the farrowing period. All of the aforementioned variables were associated with a high ACR.

The relationships of other management and environmental factors with the ACR were due to common cause associations. These factors included having the sows individually identified, using a more comprehensive recording system, mainly a hand-mating system, testing regularly for pregnancy and housing sows in total confinement during the breeding period. The strongest associations with the ACR were the type of flooring during gestation and the size of the herd.     

Eradication of some infectious pig diseases by perinatal tiamulin treatment and early weaning

From 10 days before the expected date of farrowing onwards, 97 sows infected by Mycoplasma hyopneumoniae and Treponema hyodysenteriae were given tiamulin daily at a dosage of 20 mg/kg bodyweight via the feed. Three days before farrowing the sows were washed with a disinfectant and transferred to an isolated farrowing house. The sucking piglets remained with their dams for five days, during which time the sows continued to receive the tiamulin-containing feed. The sucking piglets also received tiamulin daily at a dosage of 30 mg/kg bodyweight. At six days old the weaker piglets of the litter were returned to the original herd, together with their dams. A total of 574 piglets of about 1.5 kg bodyweight each were transferred to an isolated and previously disinfected pig farm and reared there. A total of 13.8 per cent of these pigs died by 50 days old. On the isolated farm, 10.9 per cent of the 829 second generation piglets born to the 101 first generation sows, died up to the age of 50 days. On the isolated farm about 2000 pigs were subjected to repeated clinical, pathological and laboratory examinations for M hyopneumoniae, T hyodysenteriae, Aujeszky's disease virus and Leptospira species during the three year period of study. No evidence of infection with any of these agents was found in the 2000 pigs of the isolation herd, although the original sow herd had been latently infected by these pathogens. No maternally derived antibodies against these pathogens were detectable in sera of three-day-old sucking piglets of the second and third generations.     

Voluntary feed intake by lactating sows

Data from 3559 lactations in the Moorepark herd over a seven-year period were analysed. An increase in intake was associated with increasing litter size, increasing parity and lower pregnancy weight gain. Higher farrowing house temperatures were associated with lower intakes resulting in sows farrowing in July eating 10% less than sows farrowing in mid-winter. Higher weaning age was also associated with increased consumption. Review of the literature shows a number of other factors to be associated with variation in intake including breed of sow, system of feeding and system of sow management. Intake of higher energy diets is sometimes depressed but energy consumed may be increased. Sows fed low protein diets in pregnancy consume more of high protein diets in lactation but this is not so when a high protein pregnancy diet is fed.     

Economic effects of mastitis prevention strategies for dairy producers

For efficient disease management in dairy production, the influence of disease prevention strategies on farm profitability must be known. A survey of mastitis control practices, milking machine function and maintenance, and cow environmental conditions was conducted with 406 dairy producers on the Michigan Dairy Herd Improvement-somatic cell counting program responding. These survey data, in conjunction with Dairy Herd Improvement production data, were used to develop a model estimating the marginal value products of mastitis control practices. Lost milk production associated with increased somatic cell count was calculated for each herd. Mastitis control practices, milking machine function and maintenance, and cow environmental conditions were used as independent variables in an analysis of covariance model with lost milk production as the dependent variable. Variables significant in explaining changes in production from increased somatic cell count were the use of teat dip, use of sanitizer in the wash water, milking cow bedding, summer nonlactating cow housing, summer calving locations, type of regulator, alternating pulsation, and rolling herd average milk production. The marginal value product (change in revenues received) from the use of iodine, chlorhexidine, and quaternary ammonium-type teat dips were $13.79, $16.09, and $22.17/cow/year, respectively, and these changes were statistically significant. However, sanitizer in the wash water was associated with a decrease in production. Management practices that have previously been shown to be economical and did not appear in the final model included nonlactating cow therapy and single-use paper towels.     

Prevalence of clinical mastitis in 38 Waikato dairy herds in early lactation

AIM: To determine the prevalence of clinical mastitis in spring-calving dairy herds in the Waikato Region of New Zealand and to identify factors associated with variation in the prevalence of clinical mastitis between herds. METHOD: A total of 799 quarters from 595 dairy cows from 38 dairy herds were diagnosed by herd owners as having clinical mastitis between 8 July and 21 August 1997. Quarters diagnosed with clinical mastitis were sampled for bacterial culture and somatic cell count, and the presence of clots in the milk and the presence of udder oedema were assessed by a technician or veterinarian. RESULTS: Clinical mastitis was diagnosed in an average (+/-s.e.m.) of 9.9% (+/-0.8%, range 0.9-21.4%) of calved cows within the herds. Bacteria were not cultured from an average of 12.4 % (+/- 2.0%, range 0.0-45.5%) of cows and 22.3% (+/- 2.4%, range 0.0-54.0%) of quarters diagnosed as having clinical mastitis. There were significant differences between herds in the proportion of cows diagnosed with mastitis and in the proportion of clinical mastitis cases from which bacteria were not cultured. A decreased prevalence of clinical mastitis (p<0.001) was associated with an increased percentage of the herd treated with dry cow antibiotics. An increased prevalence of clinical mastitis (p<0.0001) was associated with both an increased percentage of cows treated in the previous season with lactating cow antibiotics and an increased percentage of heifers in the herd. Herds that were fed supplements before or during lactation had a higher prevalence of clinical mastitis than herds that were not fed supplements (p<0.001). An increased proportion of quarters diagnosed with clinical mastitis that did not culture bacteria was associated with an increased prevalence of clinical mastitis (p<0.001). The proportion of quarters that the technician or veterinarian found with evidence of clinical mastitis (i.e. a somatic cell count >500,000 cells/ml and the presence of either clots or udder oedema) within a herd was inversely related to the proportion of quarters within a herd from which no bacteria were isolated. CONCLUSION: There was a large variation in the prevalence of clinical mastitis and in the proportion of clinical quarters from which no bacteria were grown between herds. Management factors such as the use of dry cow therapy, feeding regimes and heifer replacement rates all affected the prevalence of clinical mastitis. Herd owners appear to differ in the sensitivity and specificity of their diagnosis of clinical mastitis, with bacteria not isolated from up to 50% of quarters diagnosed with clinical mastitis in some herds. Improvements in the specificity of herd owner diagnosis of clinical mastitis may reduce the use of antibiotics for mastitis during lactation and hence may reduce the risk of antibiotic contamination of milk supplied for human consumption.     

Re-modelling the Piggery Breeding Unit May Affect the Farrowing Rate

The objective of this retrospective cohort study was to clarify the effect of re-modelling the breeding unit on farrowing rate. The original study population included 63 sow herds that participated in the Finnish herd surveillance system. In these herds, the breeding units were re-modelled between 1995 and 2002. Information about the production system and other herd data for the last year before and the second year after re-modelling were available for 47 herds. The herds had an average of 68.5 (SD 45) sows per herd. Data were collected during one farm visit per herd. Initially, all herds had individual cages in their breeding units. The piggeries had either re-modelled their cages or switched to a group housing system with deep-litter, solid or slatted (partly or totally) floors. Farrowing rates were gathered from the national database, and data were tested with a linear regression model. Re-modelling did not have an effect on farrowing rate if initial reproductive performance of the herd was neglected. However, when farms were stratified according to performance prior to the beginning of study, namely into 'farms with initially high farrowing rate' (HF) and 'farms with initially low farrowing rate' (LF), the re-modelling had a significant effect on farrowing rate. In the HF farms, re-modelling caused a decrease in farrowing rate. Correspondingly, farrowing rate increased after remodelling in the LF farms. Farrowing rate was also influenced by mean parity of sows and by proportion of sows culled because of leg problems. This study could not show a profound impact of the design of the breeding unit on the fertility of the sow in the modern commercial production environment if the farm's reproductive performance before re-modelling was neglected. However, when initial performance was taken into account, re-modelling revealed significant, although varying effects on farrowing rate.