Heart Rate and Heart Rate Variability Change with Sleep Stage in Dairy Cows.

Changes to the amount and patterns of sleep stages could be a useful tool to assess the effects of stress or changes to the environment in animal welfare research. However, the gold standard method, polysomnography PSG, is difficult to use with large animals such as dairy cows. Heart rate (HR) and heart rate variability (HRV) can be used to predict sleep stages in humans and could be useful as an easier method to identify sleep stages in cows. We compared the mean HR and HRV and lying posture of dairy cows at pasture and when housed, with sleep stages identified through PSG. HR and HRV were higher when cows were moving their heads or when lying flat on their side. Overall, mean HR decreased with depth of sleep. There was more variability in time between successive heart beats during REM sleep, and more variability in time between heart beats when cows were awake and in REM sleep. These shifts in HR measures between sleep stages followed similar patterns despite differences in mean HR between the groups. Our results show that HR and HRV measures could be a promising alternative method to PSG for assessing sleep in dairy cows.

Machine learning prediction of sleep stages in dairy cows from heart rate and muscle activity measures.

Sleep is important for cow health and shows promise as a tool for assessing welfare, but methods to accurately distinguish between important sleep stages are difficult and impractical to use with cattle in typical farm environments. The objective of this study was to determine if data from more easily applied non-invasive devices assessing neck muscle activity and heart rate (HR) alone could be used to differentiate between sleep stages. We developed, trained, and compared two machine learning models using neural networks and random forest algorithms to predict sleep stages from 15 variables (features) of the muscle activity and HR data collected from 12 cows in two environments. Using k-fold cross validation we compared the success of the models to the gold standard, Polysomnography (PSG). Overall, both models learned from the data and were able to accurately predict sleep stages from HR and muscle activity alone with classification accuracy in the range of similar human models. Further research is required to validate the models with a larger sample size, but the proposed methodology appears to give an accurate representation of sleep stages in cattle and could consequentially enable future sleep research into conditions affecting cow sleep and welfare.

Risk factors for bobby calf mortality across the New Zealand dairy supply chain.

The objective of this study was to identify risk factors for morbidity and mortality of bobby calves across the whole dairy supply chain in New Zealand. A case-control study was carried out in the 2016 spring calving season. A total of 194 bobby calves, comprising 38 cases (calves that died or were condemned for health or welfare reasons before the point of slaughter) and 156 controls (calves deemed acceptable and presented for slaughter) were included in the study. Case and control calves were selected by veterinarians located at 29 processing premises across New Zealand. Information regarding management of selected calves on-farm, during transport and at the processor was obtained retrospectively via questionnaires administered to supplying farmers, transport operators and processing premises personnel. Associations between management variables and calf mortality (death or condemnation) were examined using multivariable logistic regression models. Factors associated with an increased risk of calf mortality included time in the farm of origin's calving season, duration of travel from farm to the processor and processing slaughter schedule (same day or next day). Every additional week into the farm's calving season increased the odds of mortality by a factor of 1.2 (95%CI 1.06, 1.35). Similarly, each additional hour of travel time increased the odds of mortality by a factor of 1.45 (95% CI 1.18, 1.76). Risk of mortality was significantly greater for calves processed at premises with a next day slaughter schedule than those processed at premises with a same day slaughter schedule (OR 3.82, 95% CI 1.51, 9.67). However, when the data set was limited to those cases that died or were condemned in the yards (i.e. excluding calves that were dead or condemned on arrival) the effect of same day slaughter was not significant. In order to reduce bobby calf mortality and morbidity, transport duration should be kept as short as possible and a same day slaughter schedule applied. While these factors can be regulated, New Zealand's pastoral dairy system means that calves will inevitably be transported for slaughter across several months each spring. Although farm management factors did not apparently influence the risk of mortality in this study, the effect of time in farm's calving season suggests there may be farm-management related factors that change over the season. This requires further investigation.

Cow Lying Behaviour and Bedding Quality Changes during Five Weeks on a Stand-Off Pad.

Bedding quality and cow lying time were measured during five weeks in a normal farm practice (NFP) off-paddock system with no bedding refreshment. Two groups of 100 non-lactating dairy cows were compared to groups of 8 cows with fresh bedding (FB). The cows were on a woodchip pad for 18 h/d at a space allowance of 5.4 m2/cow, with 6 h/d on pasture for 5 weeks. Lying times were recorded continuously for 60 cows per group using accelerometers. Bedding moisture content was measured weekly. Data for each NFP group were analysed and compared with those of their respective FB group using repeated measures. The lying time declined over five weeks from 11.6 h/day during the first week to 5.6 h/day during the fifth week (SED = 0.3; F1,25 = 351.56; p < 0.001). The moisture content of the bedding increased over the five weeks and was significantly higher for both NFP groups (NFP Group 1: F5,59 = 8.33; p < 0.001; NFP Group 2: F5,61 = 5.54; p < 0.001) than those of the respective FB groups. The percentage of total time lying when in the paddock increased for the NFP groups, reaching 15% in the last week of the trial. During five weeks on a stand-off pad, bedding quality deteriorated, and cows lay down less, to such an extent that welfare was compromised.

Sodium fluoroacetate (1080): assessment of occupational exposures and selection of a provisional biological exposure index.

AIM: Sodium fluoroacetate (1080) is used for control of vertebrate pests in New Zealand. Little is known about chronic effects in humans, but animal studies demonstrate potential for adverse fetal, male fertility, and cardiac effects. We aimed to employ analyses of 1080 to help assess the degree of exposure of bait formulators and distributors, and identify specific tasks where exposure reduction appeared most indicated. We also aimed to utilise the (limited) 1080 toxicity data to assess the significance of the analytical results. METHOD: Exposures during various activities were assessed by monitoring air levels and blood and urine concentrations. To help evaluate the results, a provisional "biological exposure index" (BEI) was later derived, by extrapolating from experimental data. RESULTS: Early monitoring indicated exposures were highest in relation to (cereal) bait manufacturing and aerial carrot baiting procedures. A provisional BEI of 15 microg/L for 1080 in urine was proposed. CONCLUSION: Further protective measures and ongoing workplace monitoring are required, particularly in the above situations. Compliance with the current BEI cannot guarantee complete safety. Any information regarding chronic adverse effects in humans, along with the associated urine levels, would assist risk assessment. Further investigation of the human kinetics of fluoroacetate would be helpful.

Research on vertebrate pesticides and traps: do wild animals benefit?

New Zealand has a range of carnivorous and herbivorous mammals that were originally introduced for recreational, financial, aesthetic and biocontrol reasons, but which now pose significant threats to conservation and animal health values. Research is undertaken to develop new tools and strategies to manage these pests. Captive trials that are carried out include those to determine the toxicity of poisons, the efficacy of fertility control agents, and welfare impacts of poisons and traps. Field trials are undertaken to test the efficacy of poisons and traps, and large-scale management trials carried out to optimise control strategies. Although this research is aimed at managing animals, including killing them, we believe that there are benefits to both individual animals and animal populations that far exceed any cost of harm to individuals that are managed (often killed). We suggest that there are three levels of beneficiaries: the individuals of the pest species that are killed, the individuals in the surviving population, and the individuals and populations of other species. We provide examples of how wild animals can benefit from vertebrate pesticide and trap research.