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

Beliefs, mindset and personality of farm managers working in large commercial dairy herds: Association with calf on-farm mortality

This study aimed to describe the attitudes and personalities of farm managers (FMs) in large Estonian dairy herds and analyse the potential associations with calf mortality. The study included FMs from 114 free-stall farms with at least 100 cows. Each participant completed a questionnaire that comprised questions about the respondent and various statements to reveal their attitudes towards calves, calf mortality, and farming in general. A 7-point Likert scale was used to record the responses. The data on the number of live births and deaths and animal movement data were gathered from farm records and the Estonian Agricultural Registers and Information Board. The yearly calf mortality risk (%) during the first 21 days (YAG) and mortality rate between 22-90 days of age (OAG) adjusted for the animal time-at-risk were then calculated for each herd. Univariate negative binomial regression analysis was used to identify associations between calf mortality risk/rate, and the studied statements and variables with a p-value < 0.25 were included in a k-modes clustering analysis. The mean calf mortality risk was determined to be 5.9 % (range 0.0-26.8 %) during the first 21 days and mean calf mortality rate was 1.8 (range 0.0-9.2) deaths per 100 calf-months during 22-90 days of age. In both age group analyses, two FMs´ clusters formed based on 17 pre-selected statements. The FMs of the high-mortality cluster were found to be dissatisfied with the calf mortality levels. In the YAG analysis, FMs from high-mortality cluster gave lower priority to the issue of calf mortality, placed high importance on the influence of workers on calf mortality, and were more satisfied with the staff's performance compared to FMs of the cluster of herds with lower calf mortality. They were additionally less satisfied with their own performance and felt less recognized by the farm staff. They were also more inclined to try new products and practices on the farm and demonstrated greater empathy towards cattle. In the OAG analysis, the FMs from the higher-mortality cluster viewed reducing calf mortality more costly, had a less ambitious and target-driven management style, and rated their self-performance lower. This study determined that FMs working in herds with high calf mortality were dissatisfied and did not prioritize addressing calf mortality compared to managers working in farms with lower calf mortality. FMs' attitudes and management styles were associated with calf mortality, while the respondents' personality traits had little influence.

Application of multiblock analysis to identify key areas and risk factors for dairy cow persistence

The present study analysed the importance of individual variables and different thematic blocks of production areas, management, and herd infectious disease status on cow persistence, characterised by herd on-farm mortality rate (MR), culling rate (CR), and mean age of culled cows (MAofCC) applying multiblock partial least squares (mbPLS) analysis. This study included 120 free-stall dairy herds with ≥ 100 cows. Data on the previous year's predominant cow housing system and management practices were collected, and on-farm measurements and cow scoring were performed. Bulk tank milk (BTM) and heifer blood samples (10 samples per herd) were collected and analysed for antibodies against the selected pathogens. In total, 172 variables were aggregated into 14 thematic blocks. The annual CR, MR, and MAofCC values were calculated for each herd. Thematic blocks with significant impact on cow persistence (included herd MR, CR and MAofCC) were 'infectious diseases' (block importance index out of all blocks = 13.6%, 95% CI 10.3; 20.5), 'fertility management' (16.3%, 95% CI 6.8; 26.9), 'lactating cow management' (11.5%, 95% CI 6.4; 17.8), 'milking' (11.3%, 95% CI 3.2; 17.1), 'herd characteristics' (10.1%, 95% CI 6.3; 14.2), 'close-up period management' (9.7%, 95% CI 2.7; 15.7), 'calving management' (7.9%, 95% CI 3.1; 11.4) and 'disease management' (7.3%, 95% CI 0.2; 12.0). Variable categories with the highest importance in explaining composite outcome including herd MR, CR and MAofCC were rear-end and udder lesions in ≥ 20% of the cows, BTM and heifers seropositive to bovine respiratory syncytial virus, vaccination against bovine herpesvirus 1, twice daily milking and herd location in Northwest region. Larger herd size, higher levels of milk yield, and rearing predominantly Holstein breed cattle were herd factors associated with poorer cow persistency. Grazing cows and having semi-insulated barns were associated with lower CR and MR, respectively. Heat detection and farm pregnancy testing strategies were significant factors in the fertility block. Using disposable dry papers for teat cleaning and not using any wet teat-cleaning tools were risk factors for high MR. A robotic milking system was protective for increased herd MR and CR. A high pre-calving body condition score and poor rear body cleanliness of ≥ 30% of cows were associated with inferior herd persistency outcomes. Calving in group pens with deep litter bedding was associated with a lower CR. Multiblock PLS model is innovative tool that helped to identify most influential farming areas but also single risk factors associated with cow persistency described by multiple parameters.

Associations of neonatal acute phase response with first lactation performance in dairy cows

During the first 3 wk of life, the immune system of newborn ruminants starts to work, as indicated by fluctuations in the concentrations of proinflammatory cytokines and acute phase proteins (APP). They have been shown to be markers for short and long-term weight gain in ruminants. This observational study investigated these proteins as possible indicators of first lactation performance of dairy cows. A total of 117 dairy calves from a single farm were enrolled in the study. Serum and fecal samples were taken once a week for the first 3 wk of life. Cryptosporidium spp. infection and its treatment were monitored and accounted for in statistical analysis. The concentrations of the APP serum amyloid A (SAA) and haptoglobin (Hp), and the proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) were analyzed in serum. After the first lactation, health and performance data of the cows were retrieved, and associations between APP and cytokine concentrations with first lactation outcomes were investigated through linear and logistic regression. This study found a negative association between the concentration of Hp in the second week of life and average daily weight gain at one year. The SAA concentration measured during the second and third weeks of life was positively associated with age at first calving. IL-6, SAA, and Hp measured in the second week of life were positively associated with calving to conception interval. The concentrations of IL-6 and TNF-α during the first week of life were associated with higher odds of reproductive issues during the first lactation period. These markers can be used to help understand underlying processes that influence animal health and production. In conclusion, inflammatory responses during the first week of life are related to reproductive success, whereas the second and third weeks of life seem to influence the future productive performance in dairy cows.

Calf care workers' attitudes and personality and their association with calf mortality in large-scale dairy farms

Although calf mortality is a multifactorial problem, little is known about the attitudes and personalities of calf care workers (CCWs) and their association with calf mortality. This study aimed to describe the attitudes, satisfaction, and personality of CCWs in large Estonian dairy herds and to analyze their associations with herd calf mortality. A questionnaire registering CCWs' attitudes toward their work and calf mortality, personality characteristics, satisfaction and importance of different job-related factors was developed. In total, completed questionnaire data of 161 CCWs from 108 large (>100 cows) Estonian dairy farms were analyzed. Herd-level yearly calf mortality risk (MR) was calculated. Cluster analysis and variance partitioning analysis were applied to reveal the explanatory capacity of CCWs' attitudes and personalities on calf mortality. The mean yearly herd-level calf MR was 5.4% during the first 21 days of life and 2.7% during 22-90 days of life. Although good calf health and low calf mortality was important for CCWs, dead calves were often seen as inevitable. CCWs were generally doubtful regarding their capacity and available knowledge to influence calf mortality. In high-mortality herds, CCWs were dissatisfied with the calf health situation and farm working equipment and felt that the situation was out of their control. Despite striving, they had less faith that farmworkers could affect the outcomes, such as calf mortality. CCWs' personality domains explained <5% of the variance in the herd's calf MR, whereas their attitudes and satisfaction explained 20% of the variability in calf MR. The current study revealed the importance of the attitudes and satisfaction of CCWs on calf mortality and highlighted the need to allocate proficient assistance to herds with high calf mortality to mitigate calf health problems and the resulting consequences for CCWs.

Cow culling patterns in eight commercial Estonian dairy herds and farmers' behaviour in reporting culling reasons

The present study aimed to reveal the culling-related metrics, identify the culling reason patterns for cows by developing and implementing the cow culling form (CCF), and analyse the concordance of farmers' stated culling reasons with those identified based on the CCF. A CCF was developed to register the disease history and conditions of cows that were related to culling. CCFs were completed by farm managers and veterinarians in eight dairy herds over a one-year period for slaughtered (n = 686) and dead (n = 250) cows. Completed CCFs were interpreted by the study authors to identify underlying, intermediate, influential, and immediate culling reasons. The identified culling reasons were compared to those reported by producers. The mean annual cow culling rate of the study farms was 31.8%, and the average on-farm mortality was 9.3%. Of the 250 cows that died on the farms, 43.6% were euthanised. Only 2% of the cows were slaughtered due to low milk yield. In total, 260 and 119 unique three-reason culling codes were created for slaughtered and dead cows, respectively. Single disease or condition causing slaughter or death of cows was identified in 44.8% and 52.0% of the cases, respectively. Producers' reported culling reasons concurred with the underlying culling reason in 72.6% and 63.6% of slaughtered and dead cows, respectively. A high variety of agreements between the farmers' reported and CCF-based culling codes was identified across single culling reasons. Improved registration of culling reasons is required to support informed herd-based decisions.

Implementation of a pre-calving vaccination programme against rotavirus, coronavirus and enterotoxigenic Escherichia coli (F5) and association with dairy calf survival

Background

Diarrhea is one of the most common diseases and causes of death in calves during the first month of life. Pre-calving vaccination programme (PVP) against the most common diarrhea-causing pathogens could help to avoid this threat if hyperimmune transition milk (TM) is fed to calves throughout the whole susceptibility period. The aim of this retrospective cohort study was to reveal the implementation practices of PVPs in large commercial dairy farms and to compare calf-level mortality hazards during the first year of vaccination (V+ period) and a year before implementing the vaccination programme (V- period). A questionnaire was filled out in 15 large-scale dairy farms in Estonia that used PVP. The farms were assigned into three groups based on compliance with the vaccine directions for use and TM feeding practices. Calf-level time-to-event data was analyzed with an observation period of 21 days and on-farm mortality due to diarrhea being the event of interest.

Results

During the V+ period, a significant decline in diarrhea-induced calf mortality was identified in three out of six herds that followed vaccination instructions and fed TM for at least 14 days. On average, calf mortality hazard due to diarrhea decreased among these herds (hazard rate ratio (HR) = 0.72, 95% confidence interval (CI) 0.63; 0.81). In the group of correctly vaccinating herds where TM was fed for less than 14 days, diarrhea-induced calf mortality decreased in two herds and remained unchanged in two herds with average diarrhea-induced calf mortality hazard declining significantly during the vaccination period (HR = 0.24, 95% CI 0.14; 0.41). Among the three farms that deviated from the vaccination instructions, the average calf mortality hazard increased in the V+ period (HR = 1.61, 95% CI 1.21; 2.14).

Conclusions

This study revealed that implementing a PVP might aid to reduce diarrhea-induced calf mortality in large commercial dairy farms. There is a need to increase veterinarians´ and farmers´ awareness about the importance of including pregnant heifers into the vaccination programme and emphasize the importance of prolonged feeding of hyperimmune TM to calves.

Refining livestock mortality indicators: a systematic review

Background: Livestock mortality impacts farmer livelihoods and household nutrition. Capturing trends in livestock mortality at localised or national levels is essential to planning, monitoring and evaluating interventions and programs aimed at decreasing mortality rates. However, livestock mortality data is disparate, and indicators used have not been standardised. This review aims to assess livestock mortality indicator definitions reported in literature, and define the ages where mortality has greatest impact. Methods: A systematic review was conducted, limited to articles focussed on mortality of cattle, sheep and goats. Peer-reviewed articles in Web of Science until year 2020 were assessed for inclusion of age-based definitions for mortality indicators and data on age distribution of mortality. Indicator definitions for each species were collated and similar terms and age groups most targeted were compared. The cumulative distribution of age at mortality was compared across studies graphically where possible; otherwise, age patterns for mortality were collated. Results: Most studies reported mortality risk rather than rate, and there was little agreement between indicator definitions used in the literature. The most common indicators reported were perinatal and neonatal mortality in cattle, and for perinatal, neonatal and pre-weaning mortality indicators for sheep and goats. Direct comparison of age distribution of mortality was only possible for cattle, which found that approximately 80% of all mortalities within the first 12 months had occurred by six months of age. A significant finding of the study is the variation in age groups for which mortality is reported, which impedes the comparison of mortality risk across studies, particularly for sheep and goats. Conclusions: This study demonstrates the importance and value of standardising mortality risk indicators for general use, including a young stock mortality risk indicator measuring mortality in the highest risk period of birth to six months of age in cattle, sheep and goats.

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

BACKGROUND

On-farm mortality (unassisted death and euthanasia) is the unwanted loss of animals, and it comes with negative economic consequences. On-farm mortality rates reflect a herd's animal welfare status. The objective of this historical longitudinal single cohort study was to identify the associations between herd characteristics, animal housing conditions and management routines and within-herd calf and cow mortality rates in participating Estonian dairy herds. All farmers enrolled in the voluntary production recording system with a herd size of 20 or greater cow-years in 2015-2017 were contacted by mail or telephone between October 2017 and March 2018. The survey included questions about management routines and housing conditions of calves up to 3 months of age and of cows. In total, 214 completed questionnaires were returned, corresponding to a 63.3% response rate. The within-herd mortality rate of calves (aged 21-90 days) and cows (cattle over 24 months of age) in years 2017-2018 were calculated and used as outcome variables. Negative binomial and linear regression models were applied for risk factor analysis in calf and cow datasets, respectively.

RESULTS

The median within-herd mortality rate for calves aged 21 to 90 days was 0.15 per 100 calf-months (quartiles 0.00; 0.36). The median within-herd mortality rate for cattle over 24 months of age was 4.57 per 100 cow-years (quartiles 2.44; 6.86). Factors significantly associated with increased mortality of calves were larger herd size, higher proportion of stillbirths and abortions in a herd, prophylactic administration of vitamins to all calves and housing pre-weaned calves in single pens only compared with housing in both single and group pens. Also, farmers who attended more frequent trainings had higher calf mortality rates. Calving in a group pen or in a tie-stall compared with calving in multiple systems was associated with higher calf mortality rates. Higher cow mortality rates were present in herds that had a higher proportion of stillbirths and on farms where employees handled cows. Housing cows in free-stall barns, grazing cows and more frequent hoof trimming were protective for cow on-farm mortality.

CONCLUSIONS

This study identified the importance of housing conditions for on-farm cow and calf mortality rates. Our study results suggest that providing good care might ensure better health and welfare of dairy cows and calves.

On-farm mortality and related risk factors in Estonian dairy cows

Mortality (unassisted death and euthanasia) reflects the health and welfare state of the cows and is associated with undesirable financial consequences for the farmer. The objective of this retrospective observational study was to identify risk factors associated with on-farm mortality in dairy cows. Data for a study period between January 1, 2013 and December 31, 2015 were retrieved from the Estonian Agricultural Registers and Information Board and Estonian Livestock Performance Recording, Ltd. Cows from milk-recording herds with ≥20 cow-years were included. Analyses included data of 86,459 primiparous cows from 409 herds and 109,314 multiparous cows from 410 herds. Cows were followed from the day of calving until exit from the herd due to on-farm death or euthanasia (defined as mortality), slaughter, or selling. Associations between risk factors and mortality were assessed using Weibull proportional hazard models. The mortality rate (MR) was lower in primiparous cows (MR = 5.09 per 100 animal-years, 95% confidence interval [CI] 4.93; 5.26) compared to multiparous cows (MR = 8.28 per 100 animal-years, 95% CI 8.13; 8.44). The early lactation period was associated with greater mortality hazard. Animal-level factors significantly associated with higher mortality hazard in primiparous and multiparous cows were Holstein breed, older age at first calving, having an assisted calving or stillborn calf. In multiparous cows, male sex of the calf, birth of twins/triplets, older parity, longer previous inter-calving interval and milk somatic cell count over 200,000 cells/ml at the last test-milking of the previous lactation were associated with greater mortality hazard. Lower milk yield, somatic cell count over 200,000 cells/ml and fat/protein ratio over 1.5 at first test-milking were associated with greater mortality hazard during the lactation. Cow mortality risk was greater in larger herds, in herds with lower cow conception rate and poorer longevity of cows. Also, lower herd average milk fat/protein ratio and decreasing herd size (for multiparous cows) as well as Northeast region were herd level risk factors. This study outlines the importance of herd management and good health of the cows at dry-off and during early lactation and ensuring easy calving to reduce mortality of cows.

Reasons and risk factors for beef calf and youngstock on-farm mortality in extensive cow-calf herds

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.