Cows mobilize body reserves during early lactation, which is reflected in the milk fatty acid (FA) profile. Milk FA can be routinely predicted by Fourier-transform infrared (FTIR) spectroscopy, and be, thus, used to develop an early indicator for bodyweight change (BWC) in early lactating cows in commercial dairy farms. Cow records from 165 herds in Denmark between 2015 and 2017 were used with bodyweight (BW) records at each milking from floor scales in automatic milking systems. Milk FA in monthly test-day samples was predicted by FTIR. Predictions of BWC were based on a random forest model and included parity, stage of lactation, and test day milk production and components (fat, protein, and FA). Bodyweight loss was mainly explained by decreased short-chain FA (C4:0–C10:0) and increased C18:0 FA. The root mean square error (RMSE) of prediction after cross-validation was 1.79 g/kg of BW (R² of 0.94). Model evaluation with previously unseen BWC records resulted in reduced prediction performance (RMSE of 2.33 g/kg of BW; R² of 0.31). An early warning system may be implemented for cows with a large BW loss during early lactation based on milk FA profiles, but model performance should be improved, ideally by using the full FTIR milk spectra.

Antimicrobial use (AMU) in veal production is high compared to other bovine production types and has been suggested as an area with potential for AMU reduction. High AMU is a public health concern due to its association with antimicrobial resistance (AMR). Identifying farm characteristics associated with AMU could provide valuable insights for stakeholders seeking to monitor and implement initiatives to reduce AMU. This study aimed at investigating farm characteristics associated with AMU in Danish rosé veal farms, which is the main veal production type in Denmark. The AMU and characteristics included were extracted from two Danish national databases; The Danish Central Husbandry Register (CHR) and the Danish Veterinary Medicines Statistics Program (VetStat). Characteristics included were farm size, mortality, number of suppliers, sites per farm, and farm-level composition of animals with regards to sex and breed. The 118 farms included in the study received 41 % of the total amount of antimicrobials prescribed for Danish calves and young stock in 2020 measured in Animal Daily Doses (ADD). A multivariable linear regression model with the annual average farm-level AMU as outcome was created. AMU was measured as ADD per 100 animals per day (ADD100) and square root-transformed in the model. Increasing farm size and number of suppliers and decreasing proportion of crossbred bulls were found to be significantly associated with higher AMU. However, proportion of crossbred bulls was correlated with proportion of females. Separating the effects of breed and sex was not possible, partly due to the highly summarised data structure. Mortality and number of sites were not significantly associated with AMU. Farms with the type "starter-farms" has previously been shown to have a higher AMU compared to other rosé veal farm types. An important finding in this study was that grouping multiple sites into farms by using ownership data made it possible to summarise AMU for the full line of production from arrival at the veal farm to exit for slaughter. The results and approaches from this paper present an opportunity for repeated evaluation of farm characteristics associated with AMU, which could be used to continuously adapt and target AMU monitoring and control. In addition, it is done on existing surveillance data which keeps the cost of the study low in terms of data collection and data management.

Background: Bovine respiratory disease (BRD) is a major driver of antimicrobial use in veal calf production systems. Although vaccination may reduce disease incidence and antimicrobial treatments, field evidence supporting clinically relevant reductions in antimicrobial use remains limited. This study evaluated the clinical efficacy of a combined intranasal (IN) and parenteral (subcutaneous/intramuscular; SC/IM) vaccination strategy targeting bovine respiratory syncytial virus, Histophilus somni, and Mannheimia haemolytica under commercial conditions. Methods: A randomised controlled field trial was conducted on two Danish veal calf farms between November 2019 and April 2020, including 880 calves allocated to a vaccinated group (n = 445) or an unvaccinated control group (n = 435). Health outcomes included morbidity, antimicrobial use, mortality, growth performance, and slaughterhouse pulmonary and pleural lesions and were analysed using mixed-effects models. Results: Vaccination significantly reduced BRD-associated morbidity across all evaluation periods (from day 5 after arrival to slaughter), with relative reductions of 18.8–24.6% and 30% fewer antimicrobial treatment days. Pulmonary and pleural lesions were significantly less frequent in vaccinated calves (≈36% reduction). No statistically significant differences were observed in growth performance or mortality. Conclusions: Combined IN + SC/IM vaccination was associated with lower BRD-associated morbidity, antimicrobial treatments, and slaughterhouse respiratory lesions under commercial conditions.