Increased on-farm cow mortality (ie unassisted death and euthanasia) has been demonstrated in Swedish dairy herds during the last decade. Identifying risk factors associated with type of death is needed for future work in reducing cow mortality rates. The objectives of this case-control study were to quantify the relative proportion of unassisted dead cows among cows that die on-farm, and to identify risk factors associated with unassisted death (as opposed to euthanasia). In Sweden, cadavers and animal waste products are being processed into biofuel at destruction plants. Two destruction plants were visited three times in 2011-2012. All dairy cows (n = 556) entering the plants were examined. Farmers that had sent the cows were contacted by telephone to verify type of death. Of the 433 dairy cows included in the analysis, 30% had died unassisted. A stillbirth rate above or equal to the median in the study material (7%) increased the risk for unassisted death. The proportion of unassisted dead cows was lower than that found in other countries. The results indicate that it might be possible to study euthanasia and unassisted death as one group in Swedish dairy cows, because only one factor differentiating between the two types of death was identified. However, unidentified risk factors may still differ and, possibly more importantly, welfare implications may also differ between the two types of death which implies the need to separate them in future studies.

Good animal welfare is crucial for the success of circuses and zoos. Epidemiological studies of animal welfare that investigate associations between animal-based measures (ABMs) and resource- and management-based measures are needed. However, due to the relatively low numbers of animals within each species kept at individual facilities, such investigations can be difficult to carry out. In this paper, we report the analysis of a multi-facility epidemiological study using data from all regulatory inspections of circus and zoo animals in Sweden for 2010 to 2014. Information from 42 inspections of 38 circuses, and 318 inspections of 179 zoos was analysed. For ABMs assessed during routine inspections of circuses (n = 14) and zoos (n = 61), 9.1 and 14.3% did not comply with requirements for general care of hooves/claws and coat, 10.0 and 8.6% for body condition, and 0 and 1.7% for animal cleanliness, respectively. In addition, the zoo checklist assessed whether animals were kept in appropriate groups, finding non-compliance in 17.0% of inspections. The most frequent non-compliant resource- and management-based measures at routine inspections of circuses were for space (41.7%) and exercise requirements (38.5%). For zoos, 29.4% did not comply with space followed by 28.8% for enrichment requirements. In multivariable logistic regression analyses, zoos that had inadequate or unsafe housing and space design, inadequate bedding, or failed to meet nutritional requirements, were more likely to be non-compliant with at least one ABM. The checklists should be improved to better assess welfare status by including more ABMs; benchmarking of risks and trends over time is also recommended.

Veterinarians often give advice in a persuasive form, a style that has been shown to evoke resistance to change in clients experiencing psychological ambivalence (i.e. those who see both advantages and disadvantages to changing). With this style of communication, veterinarians run the risk of counteracting their purpose to encourage clients to follow recommendations. Motivational interviewing (MI) is a client-centered communication methodology that aims to facilitate clients’ internal motivation to change. In MI, Change Talk represents clients’ own statements expressing consideration of, motivation for or commitment to behavior change and has been shown to be strongly correlated with behavior change. Sustain Talk is corresponding statements related to maintaining the status quo. The aim of this exploratory study was to evaluate the potential of MI to facilitate behavior change in veterinary herd health management (VHHM) by investigating the effect of dairy cattle veterinarians’ MI skills on client Change and Sustain Talk. We recorded VHHM consultancies on 170 Swedish cattle farms performed by 36 veterinarians, randomly distributed into 2 groups: MI veterinarians (n = 18) had received 6-month training in MI and control veterinarians (n = 18) had not received any training. Veterinarians’ MI skills were assessed using the Motivational Interviewing Treatment Integrity coding system 4.2.1 and categorized as poor_untrained, poor_trained, near moderate and moderate. Client communication was coded using the Client Language Easy Rating coding system. The effect of MI skills on Change Talk, Sustain Talk and Proportion of Change Talk(Change Talk divided by the sum of Sustain Talk plus Change Talk) was investigated using cross-classified regression models with random intercepts for veterinarian and client (farm). The models also included additional explanatory variables (e.g. type of veterinarian and client’s satisfaction with the consultation). The veterinarian’s MI skills were associated with the client’s Change Talk, but results regarding Sustain Talk or Proportion of Change Talk were inconclusive. Clients of veterinarians reaching the highest (i.e. moderate) MI skills expressed 1.5 times more Change Talk than clients of untrained veterinarians. Clients of general large animal practitioners expressed less Sustain Talk than clients of animal health veterinarians and had higher Proportion of Change Talk. Results indicate that learning to practice MI may be one means to improve adherence to veterinary recommendations and to improve efficiency in VHHM services.

The animal health and welfare status in European organic dairy production does not in all aspects meet the organic principles and consumers’ expectations and needs to be improved. To achieve this, tailored herd health planning, targeted to the specific situation of individual farms could be of use. The aim of this study was to apply herd health planning in a structured participatory approach, with impact matrix analysis, not previously used in this context, in European organic dairy farms and to assess changes in animal health and welfare. Herd health planning farm visits were conducted on 122 organic dairy farms in France, Germany and Sweden. The farmer, the herd veterinarian and/or an advisor took part in the farm discussions. The researcher served as facilitator. Baseline data on the animal health status of the individual farm, collected from national milk recording schemes, were presented as an input for the discussion. Thereafter a systematic impact matrix analysis was performed. This was to capture the complexity of individual farms with the aim to identify the farm-specific factors that could have a strong impact on animal health. The participants (i.e. farmer, veterinarian and advisor) jointly identified areas in need of improvement, taking the health status and the interconnected farm system components into account, and appropriate actions were jointly identified. The researcher took minutes during the discussions, and these were shared with the participants. No intervention was made by the researcher, and further actions were left with the participants. The number of actions per farm ranged from 0 to 22. The change in mortality, metabolic diseases, reproductive performance and udder health was assessed at two time points, and potential determinators of the change were evaluated with linear regression models. A significant association was seen between change in udder health, as measured by the somatic cell count, and country. At the first follow-up, a significant association was also found between change in the proportion of prolonged calving interval and the farmers’ desire to improve reproductive health as well as with an increase in herd size, but this was not seen at the second follow-up. The degree of implementation of the actions was good (median 67%, lower quartile 40%, upper quartile 83%). To conclude, the degree of implementation was quite high, improvement of animal health could not be linked to the herd health planning approach. However, the approach was highly appreciated by the participants and deserves further study.

Antimicrobial use in pig farming is influenced by a range of risk factors, including herd characteristics, biosecurity level, farm performance, occurrence of clinical signs and vaccination scheme, as well as farmers’ attitudes and habits towards antimicrobial use. So far, the effect of these risk factors has been explored separately. Using an innovative method called multiblock partial least-squares regression, this study aimed to investigate, in a sample of 207 farrow-to-finish farms from Belgium, France, Germany and Sweden, the relative importance of the six above mentioned categories or ‘blocks’ of risk factors for antimicrobial use in pig production. Four country separate models were developed; they showed that all six blocks provided useful contribution to explaining antimicrobial use in at least one country. The occurrence of clinical signs, especially of respiratory and nervous diseases in fatteners, was one of the largest contributing blocks in all four countries, whereas the effect of the other blocks differed between countries. In terms of risk management, it suggests that a holistic and country-specific mitigation strategy is likely to be more effective. However, further research is needed to validate our findings in larger and more representative samples, as well as in other countries.

Raising calves and youngstock is an essential part of beef production. High on-farm mortality (unassisted death and euthanasia) is a consequence of poor animal health and welfare, and is economically unfavourable. The present study aimed to identify the reasons and risk factors for beef calf and youngstock on-farm mortality, using registry data for the years 2013 to 2015. Cox regression models were applied for the data of four age groups: calves up to 30 days (n=21 075), calves 1 to 5 months (n=21 116), youngstock 6 to 19 months (n=22 637) and youngstock ⩾20 months of age (n=9582). We found that dystocia, small birth weight and older parity of the mother increased the mortality hazard in calves up to 30 days of age. A summer birth was a common protective factor against mortality for calves up to 30 days and calves 1 to 5 months of age, compared with birth in other seasons. Among calves 1 to 5 months old, being the offspring of a first-parity cow was associated with significantly higher risk of death compared with calves who were the offspring of third- or higher-parity cows. A high herd-level stillbirth rate was associated with higher mortality hazard. The most commonly reported reasons for calf mortality were digestive disorders and respiratory disease. According to the models of youngstock from 6 months of age, male sex was a risk factor for mortality. Cattle having more than 10% dairy breed experienced a higher mortality risk in the ⩾20 months age group. No significant differences were found across regions, herd size or different breeds in any of the calf or youngstock groups. Metabolic and digestive disorders, as well as traumas and accidents, were the most common causes of mortality in beef youngstock older than 6 months. We can conclude that in young calves, animal-level factors associated with calving had a high impact on mortality. Further, timing calving for the warmer spring months would benefit calf survivability. Further studies including complementary information about farm factors adapted across the whole youngstock period is highly needed to provide sound recommendations in reducing on-farm mortality.

Animal health planning activities are not always providing a satisfactory positive impact on herd health and welfare. Moreover, evaluating the impact of advisory programmes is complex due to multiple interacting elements that influence its outcome. Therefore, measuring solely health outcomes is not sufficient: the whole process of the implementation and use of such programmes should be evaluated. In order to evaluate the impact of an intervention with a Herd Health and Production Management (HHPM) programme a process evaluation framework was designed and used. The intervention involved 20 organic dairy cattle farmers and their advisors, in both France and Sweden. In both countries 20 organic dairy farms were selected as control herds. The evaluation of the HHPM programme was based on: (a) the compliance to the programme; (b) the programme’s functions influencing herd health management practices and stimulating dialogue between farmers and advisors; (c) its effectiveness in terms of improving herd health compared with control farms. Complete compliance to the programme was fulfilled by 21 out of 40 farmers–advisors. Results from a questionnaire showed that the programme functioned as intended (e.g. by allowing early identification of herd health problems), stimulated change in farmers’ herd health management practices and farmer–advisor dialogue. Even though the majority of the users perceived that the programme contributed to herd health improvements, no significant differences in health outcomes were found when compared with control farms 12 months after the start of the intervention. The programme allowed creating an environment promoting the exchange of information between farmers and advisors, necessary to define pertinent advice in a farm-specific situation. Future research should aim at improving methods for the evaluation of the effect of advisory programmes, by identifying early indicators for effective advice and developing methods to evaluate the quality of advisory situations without interfering with them.

Production diseases in dairy cows are multifactorial, which means they emerge from complex interactions between many different farm variables. Variables with a large impact on production diseases can be identified for groups of farms using statistical models, but these methods cannot be used to identify highly influential variables in individual farms. This, however, is necessary for herd health planning, because farm conditions and associated health problems vary largely between farms. The aim of this study was to rank variables according to their anticipated effect on production diseases on the farm level by applying a graph-based impact analysis on 192 European organic dairy farms. Direct impacts between 13 pre-defined variables were estimated for each farm during a round-table discussion attended by practitioners, that is farmer, veterinarian and herd advisor. Indirect impacts were elaborated through graph analysis taking into account impact strengths. Across farms, factors supposedly exerting the most influence on production diseases were ‘feeding’, ‘hygiene’ and ‘treatment’ (direct impacts), as well as ‘knowledge and skills’ and ‘herd health monitoring’ (indirect impacts). Factors strongly influenced by production diseases were ‘milk performance’, ‘financial resources’ and ‘labour capacity’ (directly and indirectly). Ranking of variables on the farm level revealed considerable differences between farms in terms of their most influential and most influenced farm factors. Consequently, very different strategies may be required to reduce production diseases in these farms. The method is based on perceptions and estimations and thus prone to errors. From our point of view, however, this weakness is clearly outweighed by the ability to assess and to analyse farm-specific relationships and thus to complement general knowledge with contextual knowledge. Therefore, we conclude that graph-based impact analysis represents a promising decision support tool for herd health planning. The next steps include testing the method using more specific and problem-oriented variables as well as evaluating its effectiveness.

Shortening the dry period (DP) has been proposed as a strategy to improve energy balance (EB) in cows in early lactation. This study evaluated the effects of shortening the DP on milk yield (MY), EB and residual feed intake (RFI) in two breeds; Swedish Red (SR) and Swedish Holstein (SH). Cows were blocked by breed and parity and then randomly assigned to one of two treatments; short DP of 4 weeks (4W, n=43) or conventional DP of 8 weeks (8W, n=34). Cows were kept and fed under the same conditions, except for the 4 weeks when the 4W group were still lactating prepartum and thus kept with the lactating cows. Milk yield and BW were recorded and body condition score (BCS) was rated from 10 weeks prepartum to 12 weeks postpartum. Dry matter intake (DMI) was recorded for lactating cows postpartum. Milk yield was reduced by 6.75 kg/day during the first 12 weeks postpartum (P<0.001) for the 4W cows compared with 8W cows, but there was no significant difference in total MY (3724 kg compared with 3684 kg, P=0.7) when the milk produced prepartum was included. Protein content was higher in 4W cows (3.42%) than in 8W cows (3.27%) (P<0.001) postpartum. In the 8W group, cows lost more BCS after calving (P<0.05). Cows of SR breed had higher BCS than cows of SH breed (SR=3.7, SH=3.2, P<0.001), but no differences in BW were found between breed and treatment. Energy balance was improved for cows in the 4W group (P<0.001), while feed efficiency, expressed as RFI, was reduced for 4W cows than for 8W cows (5.91 compared with −5.39, P<0.01). Shortening the DP resulted in improved EB postpartum with no difference between the breeds and no milk losses when including the milk produced prepartum.

Determining welfare status in a population is the first step in efforts to improve welfare. The primary objective of this study was to explore a new epidemiological approach for analysis of data from official competent authorities that pertain to compliance with animal welfare legislation. We reviewed data already routinely collected as part of Swedish official animal welfare inspections for 2010–13, using a checklist containing 45 checkpoints (CPs). These covered animal-, resource- and management-based measures of equine welfare. The animal-based CPs were measures that directly related to the animal and included social contact, body condition, hoof condition and cleanliness. Non-compliance with one or more of the animal-based CPs was used as a binary outcome of poor equine welfare; 95% confidence intervals (CI) were estimated using the exact binomial distribution. Associations were determined using multivariable logistic regression, adjusting for clustering on premises. Resource- and management-based CPs (model inputs) were reduced by principal component analysis. Other input factors included premises characteristics (e.g. size, location) and inspection characteristics (e.g. type of inspection). There were 30 053 premises with horses from 21 counties registered by the Swedish Board of Agriculture. In total 13 321 inspections of premises were conducted at 28.4% (n=8532) of all registered premises. For random inspections, the premises-prevalence of poor equine welfare was 9.5% (95% CI 7.5, 11.9). Factors associated with poor equine welfare were non-compliance with requirements for supervision, care or feeding of horses, facility design, personnel, stable hygiene, pasture and exercise area maintenance, as well as the owner not being notified of the inspection, a previous complaint or deficiency, spring compared with autumn, and not operating as a professional equine business. Horses at premises compliant with stabling and shelter requirements had significantly better welfare if they also complied with documentation requirements. We present a novel approach for analysis of equine welfare data from regulatory inspections by the official competent authorities, and propose on-going analyses and benchmarking of trends in animal-based measures over time. We also suggest how such a database could be further improved to facilitate future epidemiological analyses of risk factors associated with poor equine welfare. The study has implications for other competent authorities and researchers collaborating in the area of animal welfare epidemiology.

Disease prevention through biosecurity measures is believed to be an important factor for improvement of the overall health status in animal production. This study aimed at assessing the levels of implementation of biosecurity measures in pig production in four European Union (EU) countries and to describe possible associations between the biosecurity level and farm and production characteristics. A cross-sectional study was conducted in 232 farrow-to-finish pig herds in Belgium, France, Germany and Sweden between December 2012 and December 2013. The biosecurity status in each of these herds was described and quantified by using the risk-based scoring tool Biocheck.UGentTM (www.biocheck.ugent.be). Production and management characteristics, obtained from the herd management system and by interviewing the farmer, were analysed for their association with the biosecurity level. A causal path was designed to study statistical associations. The results showed that there was substantial room for improvement in the biosecurity status on many pig farms. Significant differences (P<0.01) both in internal and external biosecurity levels were observed between countries. The external biosecurity status, combining all measures taken to prevent disease introduction into the herd, was highest in Germany and lowest in France. The internal biosecurity status, combining all measures taken to prevent within herd disease transmission, was highest in Sweden and lowest, with a large variation, in Belgium. External biosecurity scores were in general higher compared to internal biosecurity scores. The number of pathogens vaccinated against was significantly associated with internal biosecurity status, suggesting an overall more preventive approach towards the risk of disease transmission. A higher external biosecurity was associated with more weaned piglets per sow per year. Furthermore also the weaning age and the mortality till weaning were highly associated with the number of weaned piglets per sow per year. The negative association observed between the biosecurity level and the estimated frequency of treatment against certain clinical signs of disease as a proxy for disease incidence is consistent with the hypothesis that a higher biosecurity level results in healthier animals. These findings promote an improved biosecurity status at pig farms and are of relevance in the discussion on alternative ways to keep animals healthy with a reduced necessity of antimicrobials; Prevention is better than cure!

Dairy cow mortality is an important animal welfare issue that also causes financial losses. The objective of this study was to identify farm characteristics and herd management practices associated with high on-farm cow mortality in Swedish dairy herds. A postal questionnaire was sent to farmers that had either high or low mortality rates for 3 consecutive years. The questionnaire consisted of five sections: ‘About the farm’, ‘Milking and housing’, ‘Feeding’, ‘Routines’ and ‘Lame and sick cows’. A total of 145 questionnaires were returned (response rate=33%). Ten of the 77 characteristics investigated met the inclusion criteria for multivariable analysis. The final logistic regression model included: herd size, breed, use of natural service bull, bedding improvement frequency and pasture system. Herds with Swedish Holstein as the predominant breed (odds ratio (OR) 22.9, 95% confidence interval (CI) 5.2 to 101.8) or with mixed breeds (OR 5.5, 95% CI 1.7 to 17.5) had a greater risk of being high mortality herds than herds that were predominantly Swedish Red (OR 1). Herds larger than 100 cows (OR 19.6, 95% CI 3.5 to 110.4) and herds with 50 to 99 cows (OR 13.8, 95% CI 3.2 to 60.6) had greater risk of mortality than herds numbering 35 to 50 cows (OR 1). Being a high mortality herd was also associated with having cows on exercise lots during the summer season (OR 3.6, 95% CI 1.3 to 9.9) compared with on pasture. A missing answer on the question of bedding improvement frequency was associated with high mortality herds. Overall, this study suggests that characteristics that are related to intensification of the dairy industry are also associated with high on-farm mortality of dairy cows.

This study evaluated whether differences in milk fever incidence among Swedish dairy herds could be explained partly by differences in mineral feeding during the last weeks of gestation. A case–control study was performed on dietary risk factors for a high incidence of milk fever at the herd level using information regarding feeding and management of the dry cows collected in a written questionnaire distributed by post in spring 2008. The study was conducted from September 2004 to August 2007. Data on the diets fed to dry cows, with an emphasis on the amounts of minerals (Ca, P, Mg and K) fed 3 weeks before calving and at calving, were obtained from 30 herds belonging to the 100 Swedish herds with the highest recorded incidence of veterinary treatment for milk fever (>8.8%) and from 22 herds with no recorded milk fever treatments. Multivariable logistic regression analysis showed that a linear increase in the total amount of K and less than 26 g of Mg/day fed to dry cows 3 weeks before calving was associated with an increased risk of high milk fever incidence. A large increase in the amount of dry matter (DM) fed (>3.1 kg DM extra per day at calving compared with 3 weeks before calving) was associated with a higher incidence of milk fever, but no differences were found for Ca or P intake. Breed composition, herd average milk yield and age composition of the herd did not explain any of the observed differences between the case and the control herds. The results indicate that differences in the frequency of milk fever among herds can be associated with differences in mineral feeding of the dry cows. A high amount of K in the diet may increase the risk of milk fever linearly, whereas Mg should probably be fed at a higher level than the current Nordic recommendation to prevent milk fever.

The main aim was to assess the impact of mastitis on technical and economic results of a dairy herd under current Swedish farming conditions. The second aim was to investigate the effects obtained by withdrawing milk with high somatic cell count (SCC). A dynamic and stochastic simulation model, SimHerd, was used to study the effects of mastitis in a herd with 150 cows. Results given the initial incidence of mastitis (32 and 33 clinical and subclinical cases per 100 cow-years, respectively) were studied, together with the consequences of reducing or increasing the incidence of mastitis by 50%, modelling no clinical mastitis (CM) while keeping the incidence of subclinical mastitis (SCM) constant and vice versa. Six different strategies to withdraw milk with high SCC were compared. The decision to withdraw milk was based on herd-level information in three scenarios: withdrawal was initiated when the predicted bulk tank SCC exceeded 220 000, 200 000 or 180 000 cells/ml, and on cow-level information in three scenarios: withdrawal was initiated when the predicted SCC in an individual cow’s milk exceeded 1 000 000, 750 000 or 500 000 cells/ml. The accuracy with which SCC was measured and predicted was assumed to affect the profitability of withdrawing milk with high SCC and this was investigated by applying high, low or no uncertainty to true SCC. The yearly avoidable cost of mastitis was estimated at €8235, assuming that the initial incidence of mastitis could be reduced by 50%. This cost corresponded to 5% of the herd net return given the initial incidence of mastitis. Expressed per cow-year, the avoidable cost of mastitis was €55. The costs per case of CM and SCM were estimated at €278 and €60, respectively. Withdrawing milk with high SCC was never profitable because this generated a substantial amount of milk withdrawal that was not offset by a sufficient increase in the average price per delivered kg milk. It had the most negative impact on net return when high incidence of mastitis was simulated. Withdrawing milk with high SCC based on low-uncertainty information reduced the amount of withdrawn milk and thus resulted in less negative effect on net return. It was concluded that the current milk-pricing system makes it more profitable for farmers to sell a larger amount of milk with higher SCC than to withdraw milk with high SCC to obtain payment premiums, at least in herds with mastitis incidences within the simulated ranges.

A genetic analysis of longitudinal binary clinical mastitis (CM) data recorded on about 90 000 first-lactation Swedish Holstein cows was carried out using linear random regression models (RRM). This method for genetic evaluation of CM has theoretical advantages compared to the method of linear cross-sectional models (CSM), which is currently being used. The aim of this study was to investigate the feasibility and suitability of estimating genetic parameters and predicting breeding values for CM with a linear sire RRM. For validation purposes, the estimates and predictions from the RRM were compared to those from linear sire longitudinal multivariate models (LMVM) and CSM. For each cow, the period from 10 days before to 241 days after calving was divided into four 1-week intervals followed by eight 4-week intervals. Within each interval, presence or absence of CM was scored as ‘1’ or ‘0’. The linear RRM used to explain the trajectory of CM over time included a set of explanatory variables plus a third-order Legendre polynomial function of time for the sire effect. The time-dependent heritabilities and genetic correlations from the chosen RRM corresponded fairly well with estimates obtained from the linear LMVM for the separate intervals. Some discrepancy between the two methods was observed, with the more unstable results being obtained from the linear LMVM. Both methods indicated clearly that CM was not genetically the same trait throughout lactation. The correlations between predicted sire breeding values from the RRM, summarized over different time periods, and from linear CSM were rather high. They were, however, less than unity (0.74 to 0.96), which indicated some re-ranking of sires. Sire curves based on the time-specific breeding values from the RRM illustrated differences in intercept and slope among the best and the worst sires. To conclude, a linear sire RRM seemed to work well for genetic evaluation purposes, but was sensitive for estimation of genetic parameters.

The main objective of this study was to estimate genetic correlations between fertility and production in first and second lactations as well as between fertility traits measured in the same way at different ages. The analyses were carried out for Swedish Red and White cows born from 1986 to 1996, in total about 578 000, 430 000, and 221 000 records in the heifer period, first lactation and second lactation, respectively. The fertility traits studied were: interval between calving and first insemination (CFI), interval between calving and last insemination (CLI), number of inseminations per service period (NINS) and number of treatments for reproductive disturbances (NREPT). Production was measured as the average of the energy-corrected milk yield from the second and third test-days in a lactation (ECM23). A linear, bivariate model that included effects of herd-year, month, age, and sire of the cow was applied. A relationship matrix containing sire and maternal grandsire of the sire was included. The (co)variance components for the random effects were estimated by use of a restricted maximum likelihood algorithm. The genetic correlations between fertility traits and production within first and second lactation were in the range of 0.1 to 0.3, all of them unfavourable. However, the genetic correlation between NREPT and ECM23 was close to zero within both lactations. The heritabilities, calculated without the herd-year variance included in the phenotypic variance, varied between 0.02 and 0.06 for the fertility traits with only minor differences between first and second lactation. The heritability of ECM23 was 0.35 in the first lactation and 0.28 in the second lactation. The genetic correlation between NINS during the heifer period and in first lactation was high, 0.7. The heritabilities for NINS and NREPT during the heifer period were very low, <0.01. In conclusion, there were only minor differences in inter-relationships between fertility and production in first and second lactation and the traits were negatively associated with each other. Based on the genetic correlation between NINS in the heifer period and NINS in first lactation, this study indicated that the traits at least partly are regulated by different sets of genes.

Acetone concentration in milk is correlated with subclinical and clinical ketosis and also with milk yield and reproductive efficiency. The purpose of this study was to assess a threshold of milk acetone at which cows tend to be adversely affected. The critical values were estimated on data from 11690 lactations where the change in daily milk yield from weeks 1 to 2 to weeks 5 to 6 of lactation was evaluated in relation to different milk acetone concentrations. Daily milk yield tended to be reduced in cows with acetone concentrations between 0·7 and 1·4 mmol/l, but responses were not entirely consistent. At concentrations >l·4 mmol/l, daily milk yield was clearly reduced. Long-term milk yield (day 0 to 100 and day 0 to 200) was about 190 kg of 40 g/kg fat-corrected milk (FCM) less in cows with acetone concentrations >l·4 vis-à-vis <0·7 mmol/l. Reproductive efficiency was also impaired in cows with acetone concentrations >l·4 mmol/l; 4·9 days longer interval from calving to first service (first parity and parity 2+ cows) and 5·7 times a greater risk of cystic ovaries (parity 1), compared with cows with milk acetone <0·7 mmol/l. However, no significant effects on long-term milk yield or on reproductive efficiency were found in cows with acetone concentrations 0·7 to 1·4 vis-à-vis <0·7 mmol/l. The results suggest that 1·4 mmol/l acetone in milk may be used as the most important critical value, as higher concentrations are detrimental to productivity. The interval 0·7 to 1·4 mmol acetone per I milk may be used as a warning class, since early lactation yield may be reduced.

The effects of acetone concentration in milk, feeding frequency, and intake of concentrates and energy in total diet on milk yield were studied in 38624 lactations from 474 herds during 3 years. Herd-related data on feeding factors were collected once per indoor feeding period. Milk acetone concentrations higher than 0·40 mmol/l were deemed to denote hyperketonaemia, whether subclinical or clinical. The lactation curves of ketotic cows had an abnormal shape, with an inverted peak in early lactation. Most of the reduction in milk yield took place during the first 100 days of lactation with an estimated loss of proportionately 0·085 (acetone concentration ≤0·40 v. >2·00 mmol/l). The loss in 200-day milk yield was estimated to 328 kg 40 g/kg fat-corrected milk (FCM) at an overall mean of 5056 kg. If a herd's performance is monitored by lactation curves, a low peak — and hence an apparently high persistency – can indicate a ketosis problem. More frequent feeding of concentrates was correlated with a proportionately 0·033 to 0·074 higher milk yield in multiparous cows, but inconsistent between years. A more variable proportional response (−0·035 to 0·131) was observed in primiparous cows depending on interactions with, for example, breed. A greater total energy supply, including a larger amount of concentrate (maximum in lactation), was correlated with a higher milk yield, about 0·06 kg FCM per day per MJ metabolizable energy and 0·5 kg FCM per day per kg concentrate, respectively. However, increased feeding of concentrates at calving (parity 1) and 15 days after calving (multiparous cows) was correlated with decreased milk yield, by about −0–3 and −0–5 kg FCM per day per kg concentrate, respectively.