The authors would like to make the following correction to the published paper [...]

Animal-based measures are a key part of welfare protocols, but to what extent these measures can report differences in welfare among pigs provided e.g. with different accesses to valued resources (i.e., whether the measures are valid) and whether a single measurement point is representative of the entire production period (i. e., whether the measures are reliable) is not well documented. In this study, a total of 814 finishing pigs were assigned to either 1 of 4 welfare improving treatments (increased space: 1.4 [S9] or 2.1 m(2) [S6] per pig, provision of roughage [R], extra provision of enrichments [E]) or to a control treatment (C). Animal-based measures of a refined version of the Welfare Quality (R) protocol were assessed weekly (Batch 1) or once during the period (Batch 2). All parameters showed poor reliability throughout the 10 weekly assessments of Batch 1. Among the clinical parameters, only few indicators showed differences between welfare improving treatments. Among the behavioural indicators, differences were recorded for manipulation of the pen (C > S6) and of enrichment materials (E > all other treatments). When aggregating indicators into domains (nutrition, health, environment, behaviour), the reliability did not improve, and treatment effects were recorded within the domain of nutrition (R > all other treatments), and behaviour (E > S9). When aggregating domains into a final welfare score, both reliability and validity, as defined for the study, were poor. These results call for attention over the interpretation of the animal-based measures obtained from a single welfare assessment.

European pig farmers are challenged by increasingly stringent EU regulations to protect the environment from pollution, to meet animal welfare standards and to make pig farming more sustainable. Economic sustainability is defined as the ability to achieve higher profits by respecting social and natural resources. This study is focused on the analysis of the economic resilience of intensive and extensive farming systems, based on data collected from 56 farms located in Denmark, Poland, Italy and Spain. Productive and economic performances of these farms are analyzed, and economic resilience is assessed through a survey including a selection of indicators, belonging to different themes: [i] resilience of resources, [ii] entrepreneurship, [iii] propensity to extensification. The qualitative data from the questionnaire allow for an exploration of how production systems relate to the three dimensions of resilience. Different levels of resilience were found and discussed for intensive and extensive farms. The findings suggest that intensive farms benefit from high standards and greater bargaining power within the supply chain. Extensive systems can achieve profitability through value-added strategies and generally display good resilience. Policies that support investment and risk reduction are essential for enhancing farm resilience and robustness, while strengthening farmer networks can improve adaptability.

Organic pigs must have permanent access to an open-air space, which typically consists of a barren concrete outdoor run. One way to improve the attractiveness of the outdoor run for pigs and facilitate the establishment of functional zones is through allocation of rooting or roughage materials in this pen area. Accordingly, we investigated the effects of straw (rooting material) and maize silage (roughage) provided under a roof in a concrete-floored outdoor run on the behaviour of organic fattening pigs raised in large groups. In one typical Danish commercial farm, we compared three adjacent, similarly sized pens. Each pen contained an indoor area and an outdoor run. Each outdoor run was divided by a 1 m-high concrete wall into an unroofed area and an area covered by a roof, where substrate could be allocated. One pen received no material under the roof (control), the second pen received straw, and the third pen received maize silage. The study took place from June 2021 to July 2022 and involved 8 batches of pigs. The population size per pen at arrival was (average +/- standard deviation) 384 +/- 22 pigs, weighing 37 +/- 4.8 kg. Pigs were sent to slaughter when their liveweight was approximately 115 kg, approximately 3 months after insertion. Based on footage, the number of pigs present in each area of the outdoor run, and of these the number of pigs in each body posture (lying; sitting; upright) and the number of pigs displaying activity behaviours when standing (exploring the ground; other behaviours than ground exploration) were instantaneously sampled at 10 min intervals from 09:00 h to 16:00 h on days 1, 7, 21, 35, 49, and 63 relative to the batch insertion. More pigs were seen in the roofed area of the outdoor run when either straw or roughage were allocated. Additionally, provision of straw induced more resting in the roofed area whereas allocation of roughage stimulated more ground exploration in the roofed area compared to control pens. Secondarily, pig's activity and outdoor run use were influenced by temporal effects (i.e., experimental day) and weather variations. Thirdly, a pilot study suggested that pigs compete for access to an enriched roofed area. Our study demonstrated the possibility of meeting the behavioural needs- and improving the welfare - of organics pigs housed indoors with access to outdoor run by providing roughage or bedding materials in a roofed area of the outdoor run.

Animal welfare is of increasing public interest, and the pig industry in particular is subject to much attention. The aim of this study was to identify and compare areas of animal welfare concern for commercial pigs in four different production stages: (1) gestating sows and gilts; (2) lactating sows; (3) piglets; and (4) weaner-to-finisher pigs. One welfare assessment protocol was developed for each stage, comprising of between 20 and 29 animal welfare measures including resource-, management- and animal-based ones. Twenty-one Danish farms were visited once between January 2015 and February 2016 in a cross-sectional design. Experts (n = 26; advisors, scientists and animal welfare controllers) assessed the severity of the outcome measures. This was combined with the on-farm prevalence of each measure and the outcome was used to calculate areas of concern, defined as measures where the median of all farms fell below the value defined as ‘acceptable welfare.’ Between five and seven areas of concern were identified for each production stage. With the exception of carpal lesions in piglets, all areas of concern were resource- and management-based and mainly related to housing, with inadequate available space and the floor type in the resting area being overall concerns across all production stages. This means that animal-based measures were largely unaffected by perceived deficits in resource-based measures. Great variation existed for the majority of measures identified as areas of concern, demonstrating that achieving a high welfare score is possible in the Danish system.

The main objective of this study was to test the efficiency of a management system combining metabolic clustering of cows based on Fourier-transform mid-infrared (FT-MIR) spectra of milk and targeted treatment of metabolically imbalanced cows with propylene glycol drench. We hypothesized that cows identified in a metabolically imbalanced status during early lactation were associated with subsequent impaired health, reproduction, and production, and that treatment with propylene glycol treatment would improve health, reproduction, and production relatively more in these cows than in control cows. We completed a prospective, randomized controlled trial with 356 early-lactation cows in 2 private dairy herds in Denmark from December 2017 to April 2018. Milk samples of cows were collected before treatment, from 4 to 9 d in milk, and after treatment, from 22 to 27 d in milk. Milk samples were analyzed using FT-MIR spectroscopy. We also measured 4 milk metabolites (β-hydroxybutyrate, isocitrate, malate, and glutamate) and fat and protein contents. Based on FT-MIR spectra and cluster analyses, cows were clustered into groups of metabolically imbalanced and healthy cows. Within each group, cows were allocated randomly to treatment with propylene glycol (500 mL for 5 d) or no treatment. We analyzed the effect of the treatment on cow-level variables: metabolic cluster, milk metabolites, fat and protein contents, and fat-to-protein ratio at a milk sampling after the treatment. Furthermore, we analyzed daily milk yield, calving to first service interval, and disease occurrence. Results showed only a few effects of propylene glycol treatment and few interactions between treatment and metabolic clusters. We found no significant main effects of propylene glycol treatment in any of these analyses. A negative effect of the imbalanced metabolic cluster was found for the outcome of calving to first service interval for multiparous cows. In conclusion, we found a longer calving to first service interval in metabolically imbalanced cows, but we were not able to demonstrate overall benefits from the applied detection of cows in imbalanced metabolic status in early lactation and follow-up by treatment with propylene glycol.

AbstractThe aim of this study was to identify genomic regions associated with 305‐day milk yield and lactation curve parameters on primiparous (n = 9,910) and multiparous (n = 11,158) Holstein cows. The SNP solutions were estimated using a weighted single‐step genomic BLUP approach and imputed high‐density panel (777k) genotypes. The proportion of genetic variance explained by windows of 50 consecutive SNP (with an average of 165 Kb) was calculated, and regions that accounted for more than 0.50% of the variance were used to search for candidate genes. Estimated heritabilities were 0.37, 0.34, 0.17, 0.12, 0.30 and 0.19, respectively, for 305‐day milk yield, peak yield, peak time, ramp, scale and decay for primiparous cows. Genetic correlations of 305‐day milk yield with peak yield, peak time, ramp, scale and decay in primiparous cows were 0.99, 0.63, 0.20, 0.97 and −0.52, respectively. The results identified three windows on BTA14 associated with 305‐day milk yield and the parameters of lactation curve in primi‐ and multiparous cows. Previously proposed candidate genes for milk yield supported by this work include GRINA, CYHR1, FOXH1, TONSL, PPP1R16A, ARHGAP39, MAF1, OPLAH and MROH1, whereas newly identified candidate genes are MIR2308, ZNF7, ZNF34, SLURP1, MAFA and KIFC2 (BTA14). The protein lipidation biological process term, which plays a key role in controlling protein localization and function, was identified as the most important term enriched by the identified genes.

Human approach tests are generally accepted as valid measures of the human-animal relationship and hence are widely included in on-farm welfare assessment protocols. Most measures of avoidance response to human approach in production animals have been developed and tested under experimental conditions rather than on commercial farms, thereby making the results less relevant for operational on-farm animal welfare assessment. By contrast, the current study was conducted on calves in their home pens. On 110 Norwegian dairy farms, 548 group-housed calves (aged 22-288 days) were tested individually for their behavioural response to an unfamiliar human approach by a single test person. To conduct the test, the respective calf manager administered concentrates to the manger, followed by the test person who approached each animal in turn in a standardised manner. The avoidance response of the individual calf was categorised as 0 to 5 (maximal to no avoidance) in reaction to an attempted approach and head touch by the test person. The statistical analyses showed that heifer calves were more avoidant compared to bull calves, as were younger bulls compared to older bulls, and that overall avoidance increased in calves that were not tested first.

In modern pig production up to 50 % of the sows are slaughtered each year. So far, only few studies have focused on how sows are handled and moved within slaughterhouses. We examined effects of group size on the behaviour of sows and the ease of moving them from the entrance of a slaughterhouse and towards the lairage pens. The study included 30 truck loads of cull sows (and a few breeding boars, as they were transported to slaughter together with the sows; 1917 sows and 55 boars). The sows were transported between 4.2-7.5 hours in fully air-suspended two-deck trucks, approved for transport of sows. Half of the loads were moved from the trucks as full loads (32-95 sows per load), the other half split into smaller groups of 5-6 sows. The behaviour of sows and handlers was observed directly, while they were entering the slaughterhouse and walked along a downward sloping concrete aisle measuring 1.1 m (width) and 13.2 m (length) ramp, approaching a 90 degrees corner on the way to the lairage pens. Differences in the behaviour of the handlers between the two treatments were minor, but moving sows in smaller groups did, contrarily to our expectations, prolong the duration of the procedure, probably due to the sorting into smaller groups onboard of the truck. The results confirmed that passing a corner may constitute an obstacle for the ease of moving sows, especially when they were moved as full loads, as a higher proportion of these sows stopped or blocked the aisle near the corner, than the sows moved in smaller groups. In addition, a higher proportion of the sows moved as full loads turned 180 degrees against the direction of intended movement. In conclusion, modulation of the group size of sows upon arrival at a slaughterhouse affected their behaviour and the ease of movement. Further studies are needed to examine cost-benefit of low group size when moving sows in terms of animal welfare, human well-being and logistics.

Ovaj prirucnik predstavlja pregled ekspertize poljoprivrednih proizvođaca, konsultanata, naucnih saradnika i tehnicke literature iz oblasti održavanja zdravlja svinja. Preporuke su namenjene poljoprivrednicima i konsultantima kao vid podrske u procesu optimalne proizvodnje svinja. U obliku jednostavne kontrolne liste prirucnik daje pregled mogucih uzroka i poremecaja u ponasanju iz glavnih problematicnih oblasti i sugerise mere za njihovo korigovanje.

This study aimed to identify current weak points in animal welfare in Danish dairy production at herd level using the Welfare Quality (R) (WQ) protocol, and at national level using the Danish Animal Welfare Index (DAWIN) protocol. The DAWIN was developed as a monitoring tool for the welfare of the Danish dairy cow population, derived from the aggregation of DAWIN assessments at herd level. The DAWIN dairy cow protocol covers 29 measures (13 resource- and 16 animal-based measures) that were weighted and aggregated into a final overall population welfare score. A total of 3,591 cows from 60 dairy herds were assessed throughout 2015. Results from both the WQ and DAWIN were presented at six criteria levels in order to identify specific areas of concern relating to animal welfare at herd versus population level. Both protocols indicated a good general level of welfare across study herds, but also identified insufficient water supply as the main area of concern. In addition, resting comfort (ie time needed to lie down, collisions with barn equipment, cleanliness of rear body parts, animals lying outside of the designated lying area) and disease (in terms of the proportion of cows with chronically elevated somatic cell counts) were identified as problematic areas. The two assessment protocols both identified behavioural deficits, but in the WQ it was due to zero-grazing systems in contrast to the insufficient numbers of cow brushes in the DAWIN protocol. Despite differences in the aggregation, similar areas of concern were identified at criteria level.

Manuali pefshin ekspertizen e fermereve, konsulenteve, eksperteve te fushes dhe literaturen teknike per mirembajtjen e shendetit te derrave. Rekomandimet kane per qellim te mbeshtesin fermeret dhe konsulentet ne zhvillimin e mbareshtimit optimal te derrave. Ky manual permban lista te kontrollit, ne te cilat renditen shkaqet e mundshme dhe crregullimet e sjelljes per fushat me problematike te derrave, si dhe sugjeron masa per korrigjimin e tyre.

The aim of this study was to describe metabolism of early-lactation dairy cows by clustering cows based on glucose, insulin-like growth factor I (IGF-I), free fatty acid, and β-hydroxybutyrate (BHB) using the k-means method. Predictive models for metabolic clusters were created and validated using 3 sets of milk biomarkers (milk metabolites and enzymes, glycans on the immunogamma globulin fraction of milk, and Fourier-transform mid-infrared spectra of milk). Metabolic clusters are used to identify dairy cows with a balanced or imbalanced metabolic profile. Around 14 and 35 d in milk, serum or plasma concentrations of BHB, free fatty acids, glucose, and IGF-I were determined. Cows with a favorable metabolic profile were grouped together in what was referred to as the "balanced" group (n = 43) and were compared with cows in what was referred to as the "other balanced" group (n = 64). Cows with an unfavorable metabolic profile were grouped in what was referred to as the "imbalanced" group (n = 19) and compared with cows in what was referred to as the "other imbalanced" group (n = 88). Glucose and IGF-I were higher in balanced compared with other balanced cows. Free fatty acids and BHB were lower in balanced compared with other balanced cows. Glucose and IGF-I were lower in imbalanced compared with other imbalanced cows. Free fatty acids and BHB were higher in imbalanced cows. Metabolic clusters were related to production parameters. There was a trend for a higher daily increase in fat- and protein-corrected milk yield in balanced cows, whereas that of imbalanced cows was higher. Dry matter intake and the daily increase in dry matter intake were higher in balanced cows and lower in imbalanced cows. Energy balance was continuously higher in balanced cows and lower in imbalanced cows. Weekly or twice-weekly milk samples were taken and milk metabolites and enzymes (milk glucose, glucose-6-phosphate, BHB, lactate dehydrogenase, N-acetyl-β-d-glucosaminidase, isocitrate), immunogamma globulin glycans (19 peaks), and Fourier-transform mid-infrared spectra (1,060 wavelengths reduced to 15 principal components) were determined. Milk biomarkers with or without additional cow information (days in milk, parity, milk yield features) were used to create predictive models for the metabolic clusters. Accuracy for prediction of balanced (80%) and imbalanced (88%) cows was highest using milk metabolites and enzymes combined with days in milk and parity. The results and models of the present study are part of the GplusE project and identify novel milk-based phenotypes that may be used as predictors for metabolic and performance traits in early-lactation dairy cows.

This study aimed to identify organic dairy major farm types (MFTs) in seven European countries, describe these MFTs in an open research database and assess central characteristics of the MFTs. This was conducted in a three-step procedure including (1) Identification of organic MFTs in seven European countries: Austria, Switzerland, Germany, Denmark, Lithuania, Poland and Sweden, based on existing data from dairy databases and consultations with experts within the respective fields of knowledge; (2) Collection of data on farm characteristics, management procedures, production level and herd health from at least 10 farms per MFT and country and (3) Creating an open research database on MFT characteristics, description of essential characteristics of MFTs and assessment of similarities and differences between farms within and across MFTs. The results indicate variations in herd characteristics such as production level, herd size, farm size, housing system, milking system and cow health status between organic dairy farms in these seven European countries. It also indicates variations in management strategies such as feeding, animal health management and recruitment strategies across the organic dairy sector in Europe. These variations seem to be associated with differences between regions and countries in the conditions for organic dairy production, such as topography, land availability and regulations.

The objective of this study was to develop a generic risk management system based on the Hazard Analysis and Critical Control Point (HACCP) principles for the prevention of critical negative energy balance (NEB) in dairy herds using an expert panel approach. In addition, we discuss the advantages and limitations of the system in terms of implementation in the individual dairy herd. For the expert panel, we invited 30 researchers and advisors with expertise in the field of dairy cow feeding and/or health management from eight European regions. They were invited to a Delphi-based set-up that included three inter-correlated questionnaires in which they were asked to suggest risk factors for critical NEB and to score these based on 'effect' and 'probability'. Finally, the experts were asked to suggest critical control points (CCPs) specified by alarm values, monitoring frequency and corrective actions related to the most relevant risk factors in an operational farm setting. A total of 12 experts (40 %) completed all three questionnaires. Of these 12 experts, seven were researchers and five were advisors and in total they represented seven out of the eight European regions addressed in the questionnaire study. When asking for suggestions on risk factors and CCPs, these were formulated as 'open questions', and the experts' suggestions were numerous and overlapping. The suggestions were merged via a process of linguistic editing in order to eliminate doublets. The editing process revealed that the experts provided a total of 34 CCPs for the 11 risk factors they scored as most important. The consensus among experts was relatively high when scoring the most important risk factors, while there were more diverse suggestions of CCPs with specification of alarm values and corrective actions. We therefore concluded that the expert panel approach only partly succeeded in developing a generic HACCP for critical NEB in dairy cows. We recommend that the output of this paper is used to inform key areas for implementation on the individual dairy farm by local farm teams including farmers and their advisors, who together can conduct herd-specific risk factor profiling, organise the ongoing monitoring of herd-specific CCPs, as well as implement corrective actions when CCP alarm values are exceeded.

Organic pig husbandry systems in Europe are diverse - ranging from indoor systems with concrete outside run (IN) to outdoor systems all year round (OUT) and combinations of both on one farm (POUT). As this diversity has rarely been taken into account in research projects on organic pig production, the aim of this study was to assess and compare pig health, welfare and productivity in these three systems. Animal health and welfare were assessed using direct observation and records of 22 animal-based measures, comprising 17 health-, 3 productivity- and 2 behavioural measures. These were collected in pregnant sows, weaners and fattening pigs during direct observations and from records within a cross-sectional study on 74 farms (IN: n = 34, POUT: n = 28, OUT: n = 12) in eight countries. Overall, prevalence of several animal health and welfare issues was low (e.g. median 0% for pigs needing hospitalisation, shoulder lesions, ectoparasites; <5% for runts, tail lesions, conjunctivitis). Exceptions in particular systems were respiratory problems in weaners and fatteners (IN: 60.0%, 66.7%; POUT: 66.7%, 60.0%), weaning diarrhoea (IN: 25.0%), and short tails in fatteners (IN: 6.5%, POUT: 2.3%). Total suckling piglet losses (recorded over a period of 12 months per farm) were high in all three systems (IN: 21.3%; POUT: 21.6; OUT: 19.2%). OUT had lower prevalences of respiratory problems, diarrhoea and lameness of sows. POUT farms in most cases kept sows outdoors and weaners and fatteners similar to IN farms, which was reflected in the results regarding several health and welfare parameters. It can be concluded, that European organic pigs kept in all three types of husbandry system showed a low prevalence of health and welfare problems as assessed by our methodology, but respiratory health and diarrhoea should be improved in weaners and fatteners kept indoors and total piglet mortality in all systems. The results provide benchmarks for organic pig producers and organisations which can be used in strategies to promote health and welfare improvement. Furthermore, in future research, the identified health and welfare issues (e.g. suckling piglet mortality, weaning diarrhoea) should be addressed, specifically considering effects of husbandry systems.

Impact patterns of human–animal relationship (HAR) and herd stress level on udder health were investigated in a cross-sectional study on 30 German and Danish organic dairy herds also taking into account influencing factors regarding housing and management. Cow behavior (avoidance distance, tolerance to tactile interaction, release behavior) was assessed in tests, milkers' behavior recorded during milking, and information about contacts with animals during routine work gathered by interview. Additionally, stockpersons' attitudes were recorded via questionnaires. Fecal cortisol metabolites were measured in approximately 30 focal cows on each farm and used as a proxy to determine the level of distress within the herd. Management and housing were assessed on-farm. The following herd udder health indicators were calculated: the prevalence of mastitis quarters (≥100,000 cells/mL), and, from milk recording data over 1 yr retrospectively, the average somatic cell score and the self-cure rates during lactation per herd. Multivariable regression models with stepwise selection were calculated at herd level. The following HAR-related factors were associated with better udder health (in at least 1 of the final models): stockpersons' higher agreement on patience being important when moving the cows and on necessary contact to cows being pleasant, higher amount of positive interactions with cows during milking, more docile cows in the release behavior test, no routine change of milkers, more contact time during routine work, no active heifer habituation to milking, and performance of barn controls beyond routine work. Lower fecal cortisol metabolite levels were related to higher self-cure rates during lactation. Concerning housing, management, and herd characteristics, the following known factors were related to impaired udder health for at least 1 of the indicators: straw yards, automatic milking system, higher average lactation number, and less antibiotic udder treatments. The results confirm earlier findings that HAR is associated with udder health and should therefore be considered in future research and mastitis control programs. First indications of negative associations between herd stress level and mastitis curing capacity should be followed up in future studies.

Unbalanced metabolic status in the weeks after calving predisposes dairy cows to metabolic and infectious diseases. Blood glucose, IGF-I, non-esterified fatty acids (NEFA) and β-hydroxybutyrate (BHB) are used as indicators of the metabolic status of cows. This work aims to (1) evaluate the potential of milk mid-IR spectra to predict these blood components individually and (2) to evaluate the possibility of predicting the metabolic status of cows based on the clustering of these blood components. Blood samples were collected from 241 Holstein cows on six experimental farms, at days 14 and 35 after calving. Blood samples were analyzed by reference analysis and metabolic status was defined by k-means clustering (k=3) based on the four blood components. Milk mid-IR analyses were undertaken on different instruments and the spectra were harmonized into a common standardized format. Quantitative models predicting blood components were developed using partial least squares regression and discriminant models aiming to differentiate the metabolic status were developed with partial least squares discriminant analysis. Cross-validations were performed for both quantitative and discriminant models using four subsets randomly constituted. Blood glucose, IGF-I, NEFA and BHB were predicted with respective R 2 of calibration of 0.55, 0.69, 0.49 and 0.77, and R 2 of cross-validation of 0.44, 0.61, 0.39 and 0.70. Although these models were not able to provide precise quantitative values, they allow for screening of individual milk samples for high or low values. The clustering methodology led to the sharing out of the data set into three groups of cows representing healthy, moderately impacted and imbalanced metabolic status. The discriminant models allow to fairly classify the three groups, with a global percentage of correct classification up to 74%. When discriminating the cows with imbalanced metabolic status from cows with healthy and moderately impacted metabolic status, the models were able to distinguish imbalanced group with a global percentage of correct classification up to 92%. The performances were satisfactory considering the variables are not present in milk, and consequently predicted indirectly. This work showed the potential of milk mid-IR analysis to provide new metabolic status indicators based on individual blood components or a combination of these variables into a global status. Models have been developed within a standardized spectral format, and although robustness should preferably be improved with additional data integrating different geographic regions, diets and breeds, they constitute rapid, cost-effective and large-scale tools for management and breeding of dairy cows.

The objective of our study was to assess effects of pasteurization of milk and group size on the prevalence of diarrhea and daily growth in organic pre-weaned calves. Our study was conducted in six organic dairy herds where 353 pre-weaned calves were randomly placed in groups of two or four calves from one week of age. Three herds used pasteurized milk in a first five-month period and un-pasteurized milk in a second five-month period and three herds used unpasteurized in the first and pasteurized in the second period. The number of colony forming units (CFU)/mL was measured from samples of pasteurized and un-pasteurized milk fed to the calves. Diarrhea was measured as fecal smear under and/or at the tail and hind legs and as liquid feces. Heart girth growth was estimated using inflexible measuring tape. Group size and pasteurization were not significantly associated with either diarrhea or daily growth.

Diarrhea and respiratory disease are major health problems for dairy calves, often causing calf mortality. Previous studies have found calf mortality to be higher in organic dairy herds compared to conventional herds. The aim of this study was to investigate the association between production system (conventional/organic), season (summer/winter) and calf mortality risk, diarrhea, signs of respiratory disease and ocular discharge, respectively, for dairy heifer calves aged 0-180 days. Sixty Danish dairy herds, 30 conventional and 30 organic, were visited once during summer and once during winter. During the herd visits, calves were clinically examined for signs of diarrhea, hampered respiration, nasal discharge, coughing and ocular discharge. Data on mortality were obtained from the Danish Cattle Database. Data were analyzed using logistic regression models, with mortality risk and disease measures as outcome variables for each of three calf age groups: 0-28, 29-90 and 91-180 days. In organic herds, odds of mortality among calves aged 0-28 days were 2.09 (95% confidence interval (CI): 1.38-3.15) times higher during winter compared to summer. Odds of nasal discharge for calves 0-28 days in organic herds were 10.3 (95% CI: 2.27-46.6), 10.7 (95% CI: 2.40-40.0) and 5.97 (95% CI: 1.29-27.6) times higher for organic and conventional herds during winter (OW and CW) and conventional herds during summer (CS) respectively, compared to organic herds during summer (OS). For calves aged 29-90 days, odds of nasal discharge were 8.22 (95% CI: 3.88-17.4), 8.06 (95% CI: 3.18-20.4) and 2.86 (95% CI: 1.08-7.55) times higher for OW, CW and CS respectively, compared to OS. Odds of nasal discharge for calved aged 91-180 days were 7.03 (95% CI: 3.95-12.5) and 4.27 (95% CI: 1.81-10.1) times higher for OW and CW respectively compared to OS. For calves aged 29-90 days, odds of coughing were 2.23 (95% CI: 1.06-4.71) and 3.82 (95% CI: 1.76-8.21) times higher for OW and CW compared to OS, while odds of coughing for calves aged 91-180 days were 2.09 (95% CI: 1.19-3.67) and 2.55 (95% CI: 1.39.4.67) times higher for OW and CW compared to OS. Odds of ocular discharge for calves aged 29-90 days were 0.22 (95% CI: 0.10-0.52), 0.27 (95% CI: 0.11-0.66) and 0.42 (95% CI: 0.18-0.99) times higher for OW, CW and CS compared to OS. In conclusion, mortality and morbidity of Danish dairy heifer calves are, for some variables and in certain age groups, dependent on production system and season.