Optimising calf rearing and weaning by monitoring the real-time development of rumination

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1 Optimising calf rearing and weaning by monitoring the real-time development of rumination S. Butler, P. Thomson, S. Lomax, C. Clark Dairy Science Group, School of Life and Environmental Sciences, Faculty of Science, The University of Sydney Abstract Optimising calf rearing and weaning by monitoring real-time sensor-derived rumination development presents an opportunity to substantially improve animal health and productivity whilst reducing on-farm costs. Here we show the potential to monitor calf rumination using existing algorithms and for the first time, the detailed development of rumination and its variability between individuals. Observed and sensor derived rumination levels were associated (P < 0.001) with rumination commencing at approximately 14 days of age. However, a high level of variation was found between individual calves in both observed and sensor derived rumination levels and the development of rumination. Whilst differences in rumination development between calves may, in part, be associated with sensor performance, our work shows the potential to use remotely monitored rumination levels to customise feeding and health at an individual level to optimise the weaning process. Keywords: validation, rumination, sensor, dairy, calf, weaning Introduction The Australian Dairy Industry is evolving from smaller family owned and managed farms into large scale more intensified systems (Torsein et al., 2014). The move to larger farms means that optimising the performance of the individual animal, while maintaining animal welfare is becoming increasingly difficult. In order to maintain or improve levels of productivity from these systems, our focus needs to shift rapidly from the herd to optimising individual animal processes through technology assisted management. Calves form the basis of any successful cattle production system, with calf health and development vital for ongoing animal performance and farm profit (Gulliksen, et al., 2009). However, it is this rearing stage of a dairy animal s life, and in particular the initial month which requires the most significant investment, including veterinary and feeding expenses and higher mortality risk (Ortiz-Pelaez et al., 2008). With efficiency a key driving factor in the success of 122 Precision Livestock Farming '17

2 any dairy enterprise, finding the equilibrium compromise point between financial outlay while maintaining optimum calf growth and development is crucial. With ruminants, it is widely accepted that rumination impacts feed utilisation and intake, which are associated with weight gain, health and all round welfare of the animal (Burfeind et al., 2011; Ambriz-Vilchis et al., 2015). Furthermore, the development of the rumen in calves is directly associated with weight gain and overall physical development; therefore developing an accurate and easily measured system for monitoring rumen development provides the potential for optimising rearing and weaning times (Roth et al., 2009). A substantial decrease in feed costs and animal health inputs to the weaning stage is possible with closer monitoring of rumination on an individual basis, however, using visual observations to monitor rumination is both impractical, difficult and costly. Multiple studies have described the potential of sensor-based rumination and activity monitoring to be used as an indicator of animal welfare and health including the early detection of subclinical disease (Clark et al., 2015, Talukder et al., 2015). However, there is a gap in knowledge regarding the use of sensors to remotely monitor the progress of calf rumination development and its variability between animals. The objectives of this study were to (1) validate a collar-based sensor system for monitoring calf rumination (2) determine the variability in rumination development between calves. Material and methods The use of animals was approved by the Animal Ethics Committee of the University of Sydney (N00/5-2013/3/5998). Two experiments were conducted at the University of Sydney s Corstorphine dairy research farm, Camden from 12 th May to 9 th July All calves were fitted with SCR heat and rumination (HR) long distance (LD) Tags on collars (Hi Tag, SCR Engineers Ltd., Netanya, Israel). These collars consisted of a tri-axial accelerometer. Collars were placed on calves with a sensor and counterweight (total weight of 707g) to ensure that the sensor maintained its position at 5 to10 cm behind the left ear. Rumination duration data were stored in 20 minute intervals, which were downloaded to a farm computer and collated. In Experiment 1, 6 calves (aged 3 months ± 7 days) were grouped housed in open pens 42m x17m with a small shelter, fresh water and feed offered ad libitum (see Table 1). Individual animal rumination duration was recorded by continuous visual observation and with the sensor system between 0800h and 1100h for 10 days. The same observer performed all observations, with the observer positioned outside the pen. The onset of rumination was defined as the Precision Livestock Farming '17 123

3 time when regurgitation took place, specifically when a bolus came up the esophagus and reached the mouth and ending when the bolus was swallowed. In Experiment 2, another 6 calves were fitted with the same sensors to determine rumination development in calves from 12 th May 2016 to 9 th July 2016 ensuring 40 days of data collection for each calf. Calves were situated in pens as per Experiment 1 and offered the same feed. Table 1. Lucerne hay and grain-based concentrate nutritive value CP NDF ADF DMOD ME (MJ/kg DM) Lucerne hay Grain-based pellets The association between rumination duration (minutes) summed for the 3 hour periods collected via direct observation (independent variable) and sensor derived rumination was determined using a linear mixed model fitted using a restricted maximum likelihood (REML) procedure in Genstat for Windows version 14 (VSN International Ltd, Hemel Hempstead, Hertfordshire,UK) with the individual calf as a random effect. Rumination development data was collated using Microsoft Excel into daily totals for each calf and presented using a rolling 7-day average. Results and Discussion In experiment 1, there was a highly significant (P < 0.001) association between observed and predicted (sensor derived) calf rumination duration. However, this association was variable for individual animals (Figures 1a-f) with poor associations typically due to an under prediction of observed rumination levels. Previous work (Burfield et al., 2011) has shown similar inconsistencies and they hypothesise that the frequency of rumination sounds and movements may be different in calves compared to cows, reducing the accuracy of sensor systems. Thus, further work is required to determine the differences in the rumination process between calves as a first step towards increasing the accuracy of sensor derived rumination for all calves. In experiment 2, rumination had commenced for all calves by 14 days after birth (Figure 2). In line with these findings, the previously accepted consensus across published literature is that rumination starts at 2 weeks of age if animals are not on sole milk diet, with rumination times increasing until leveling out to 5 hours per day at between 5 to 6 weeks of age (Roth et al., 2009, Fericean et al., 2010). However, in our study there was variability between animals in this timing with some calves ruminating 7 days after birth. Further, by 40 days after birth 124 Precision Livestock Farming '17

4 rumination levels between calves ranged between 39 to 300 minutes per day (Figure 2). Our findings highlight the need for further research to elucidate the differences in rumination between calves and the potential to customise feeding management to align with calf need. a Figure 1a-f: The association between observed and predicted (sensor derived) rumination duration (minutes) for (a) calf 1; y = 1.13x ; R² = 0.95 (b) calf 2; y = 0.55x ; R² = 0.34 (c) calf 3; y = 0.14x + 2.8; R² = 0.12 (d) calf 4. (y = 1.06x + 1.8, R² = 0.93 (e) calf 5; y = -0.18x , R² = 0.10 and (f) calf 6. y = 0.70x R² = 0.65 Precision Livestock Farming '17 125

5 Figure 2. Rumination duration (minutes/day) profiles for the 6 calves after birth Conclusions New technology is providing key insights into the development of rumination in dairy calves. Further work is required to determine the differences in the rumination process between calves as a first step towards increasing the accuracy of sensor derived rumination for all calves. Our findings also highlight the need for further research to elucidate the differences in rumination development between calves and the associated opportunity to customise feeding management at an individual calf level to align with calf need. Acknowledgements The authors gratefully acknowledge the help of the University of Sydney Corstorphine farm staff for helping conduct this research, in particular Kim McKean. 126 Precision Livestock Farming '17

6 References Ambriz-Vilchis, V., Jessop, N., Fawcett, R., Shaw, D. and Macrae, A Comparison of rumination activity measured using rumination collars against direct visual observations and analysis of video recordings of dairy cows in commercial farm environments. Journal of Dairy Science, 98(3) Burfeind, O., Schirmann, K., Von Keyserlingk, M., Veira, D., Weary, D. and Heuwieser, W Technical Note: Evaluation of a system for monitoring rumination in heifers And Calves. Journal of Dairy Science 94(1) Clark, C., Lyons, N., Millapan, L., Talukder, S., Cronin, G., Kerrisk, K. and Garcia S Rumination and activity levels as predictors of calving for dairy cows. Animal 9(4) 1-5. Fericean, M., Palicica, R. and Rada, O The Behaviour of Calves. Journal of Agricultural Science 42(2) Gulliksen, S., Lie, K. and Østerås, O Calf health monitoring in Norwegian dairy herds. Journal of Dairy Science 92(4) Ortiz-Pelaez, A., Pritchard, D., Pfieiffer, D. and Mawdsley, J Calf mortality as a welfare indicator on British cattle farms. The Veterinary Journal 176(2) Roth, B., Keil, N., Gygax, L. and Hillmann, E Influence of weaning method on health status and rumen development in dairy calves. Journal of Dairy Science, 92(2) Talukder S., Thomson P., Kerrisk K., Clark C. and Celi P Evaluation of infrared thermography (IRT) body temperature and collar mounted accelerometer and acoustic technology for predicting time of ovulation of cows in a pasture-based system. Theriogenology Torsein, M., Jansson-Mörk, M., Lindberg, A., Hallén-Sandgren, C. and Berg, C Associations between calf mortality during days 1 to 90 and herdlevel cow and production variables in large Swedish dairy herds. Journal of Dairy Science 97(10) Precision Livestock Farming '17 127