Reasons and risk factors for on-farm mortality in Estonian dairy herds

Abstract

Mortality of dairy cattle causes financial loss for the farmer and reflects animal welfare status. The aim of this study was to determine the on-farm mortality (unassisted death and euthanasia), reasons, as well as risk factors for on-farm mortality in Estonian dairy cattle. Data of years 2013 and 2014 about all cattle from dairy herds in Estonia was collected from the Estonian Agricultural Registers and Information Board. The dataset included records of 363,380 animals from 2,616 herds. Multivariable Weibull proportional hazard models with herd as random effect were composed for detecting significant associations between potential risk factors and on-farm mortality (composed outcome including unassisted death and euthanasia). Data from Estonian Livestock Performance Recording Ltd was used to determine the reasons for on-farm mortality.The overall mortality rate (MR) including unassisted death and euthanasia was 6.95 per 100 animal-years. Mortality was highest in male (MR = 55.96 per 100 animal-years, 95% CI 54.53; 57.42) and female (MR = 27.70 per 100 animal-years, 95% CI 26.99; 28.43) calves up to three months old and lowest in female cattle aged 12-18 months (MR = 0.99 per 100 animal-years, 95% CI 0.89; 1.10). The main farmers´ stated reasons for dairy cow mortality were 'Metabolic and digestive disorders' and 'Feet/claw disorders'. The main reasons for on-farm mortality among youngstock were 'Metabolic and digestive disorders', 'Respiratory and infectious diseases' and 'Other reasons'. The risk factor analysis was carried out in three age categories: <3 months, 3-23 months and ≥24 months. Estonian Holstein breed was associated with significantly higher risk of mortality compared to Estonian Red breed cattle in every age group. The hazard of on-farm mortality was significantly higher for herds with over 400 animal-years compared to smaller herds in all age groups. Regional differences in mortality hazard were present in the model of youngstock over 3 months and adult cattle. Seasonal differences in mortality rate were present and differed by age groups. This is the first study revealing the on-farm mortality and related risk factors in Estonian dairy cattle population.

Herd-level risk factors for cow and calf on-farm mortality in Estonian dairy herds

“…Identifying herd-level risk factors for onfarm mortality is highly relevant for many stakeholders such as farmers, veterinary advisors and authorities, and of great value especially for larger herds where intervention can positively affect a larger number of animals. As shown in previous studies, the two most vulnerable groups of cattle in terms of mortality are young calves and adult cows [11,27,28]. Therefore, the aim of the present study was to determine herd characteristics and management routines associated with dairy calf and cow on-farm mortality.…”

“…Although there are no studies evaluating the long-term trends of dairy cattle mortality in Estonia, recent data indicate that on-farm mortality rates (MRs) in the Estonian dairy cattle population have increased. The overall on-farm MR of Estonian dairy cattle was 6.95 [95% confidence interval (CI) 6.87; 7.04] per 100 animalyears during 2013 and 2014 [11], whereas the MR in 2018 was 7.59 (95% CI 7.45; 7.72) per 100 animal-years [12].…”

“…Numerous studies have arrived at the conclusion that on-farm mortality has a high between-herd variation [11,25,26], indicating that dairy cattle health and welfare vary heavily across herds and it would therefore be worthwhile to analyse the differences in their management systems. Identifying herd-level risk factors for onfarm mortality is highly relevant for many stakeholders such as farmers, veterinary advisors and authorities, and of great value especially for larger herds where intervention can positively affect a larger number of animals.…”

A 13-Year Retrospective Study of the Beef and Dairy Cattle Losses at Neudamm Farm in the Khomas Region of Namibia

“…The focus on dairy farms is towards ensuring healthy cows at their maximum level of production. Dairy cow mortalities have been reported to be on the increase in many countries and mortality rates of 1-8% have been reported (Thomsen and Houe, 2006;Mee, 2013 andReimus et al, 2017). Most mortalities in dairy cows have been reported to occur during early lactation (Alvåsen et al, 2014), in particular, during the first 30 days of lactation (Thomsen and Houe, 2006).…”

“…At cow level, age at first calving, season of calving, lactation stage and milk yield influence cow mortality (Thomsen and Houe, 2006). Calving problems, digestive disorders, metabolic disease, musculoskeletal problems, mastitis, unknown causes (Thomsen and Houe, 2006), fertility problems (Ahlman et al and 2011;Reimus et al, 2017), feet/claw disorders and trauma (Svensson et al, 2006) have been documented as potential causes of assisted and unassisted cow mortality in dairy herds. Seasonal variations in older cow mortalities have also been reported in Estonia .…”