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Background: Culling is a major cost for dairy farms but also an essential part in managing herd productivity. This study aimed to identify the culling rates of Estonian dairy cows, identify the farmers' stated reasons and risk factors for culling. This observational study used registry data of all cows from herds with ≥20 cow-years in 2013-2015. Cow lactation-level analyses included data of 86,373 primiparous cows from 409 herds and 177,561 lactations of 109,295 multiparous cows from 410 herds. Weibull proportional hazard regression models were used to identify risk factors for culling due to slaughter or death. Results: The overall culling rate of Estonian dairy cows was 26.24 (95% CI 26.02; 26.46) per 100 cow-years. The most common reasons farmers stated for culling were feet/claw disorders (26.4%), udder disorders (22.6%), metabolic and digestive disorders (18.1%) and fertility problems (12.5%). Animal-level risk factors for culling were Holstein breed, older parity, lower milk yield breeding value, older age at first calving, longer previous calving interval, having assisted calving, stillbirth and birth of twins/triplets. Lower milk yield, somatic cell count over 200,000 cells/ml and fat/protein ratio over 1.5 at first test-milking after calving were associated with greater culling hazard during the lactation. Cows from larger herds, herds with decreasing size and higher milk yields had a higher culling probability. Conclusions: This study emphasises the need for improved management of hoof health and prevention of mastitis and metabolic diseases. It is essential to ensure easy calving and good health of cows around calving in order to lower the culling hazard.

Subclinical mastitis is one of the major health problems in dairy herds due to decreased milk production and reduced milk quality. The aim of this study was to examine the within-herd prevalence of subclinical intramammary infection caused by Mycoplasma bovis and to evaluate associations between M. bovis and cow daily milk yield, udder health, and milk composition. Individual cow composite milk samples (n = 522) were collected from all lactating dairy cows in 1 Estonian dairy farm in November 2014. Daily milk yield, days in milk, and parity were recorded. Collected milk samples were analyzed for somatic cell count, milk protein, fat, and urea content. The presence of M. bovis, Staphylococcus aureus, Streptococcus agalactiae, and Streptococcus uberis in the milk samples was confirmed by quantitative PCR analysis. The within-herd prevalence of M. bovis was 17.2% in the study herd. No association was observed between days in milk and parity to the presence of M. bovis in milk. According to linear regression analysis, the daily milk yield from cows positive for M. bovis was on average 3.0 kg lower compared with cows negative for M. bovis. In addition, the presence of M. bovis in milk samples was significantly associated with higher somatic cell count and lower fat and urea content compared with milk samples negative for M. bovis. In conclusion, subclinical M. bovis intramammary infection is associated with decreased milk yield and lower milk quality.

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High on-farm mortality is associated with lower financial return of production and poor animal health and welfare. Understanding the reasons for on-farm mortality and related risk factors allows focus on specific prevention measures. This retrospective cohort study used cattle registry data from the years 2013 and 2014, collected from cattle from all Estonian cow-calf beef herds. The dataset contained 78,605 animal records from 1321 farms in total. Including unassisted deaths and euthanasia (2199 in total) the on-farm mortality rate was 2.14 per 100 animal-years. Across all age groups of both sexes the mortality rate (MR) was highest for bull calves up to three months old (MR=7.78 per 100 animal-years, 95% CI 6.97; 8.68) followed by that for heifer calves (MR=6.21 per 100 animal-years, 95% CI 5.49; 7.02). For female cattle the mortality risk declined after three months of age but increased again among animals over 18 months. The reason for death stated by the farmers was analysed for cattle under animal performance testing. Other/unknown reasons, trauma and accidents, as well as metabolic and digestive disorders, formed the three most commonly reported reasons for death in cattle of all age groups. Weibull proportional hazard models with farm frailty effects were applied in three age categories (calves up to three months, youngstock from three to 18 months and cattle aged over 18 months) to identify factors associated with the risk of mortality. Male sex was associated with increased risk of mortality in cattle up to 18 months of age. No difference between breeds was found for cattle up to 18 months of age. Beef cattle breeds rarely represented or dairy breeds (breed category 'Other') had the highest mortality hazard (HR=1.41, 95% CI 1.11; 1.78) compared to Hereford. The hazard of mortality generally increased with herd size for calves, young stock and older bulls. In female cattle over 18 months of age there was no difference in mortality hazard over herd size categories. Herd location was controlled in the models and regional differences in mortality hazard were found. Common to all age groups, calving season was associated with increased risk of mortality.