Ashleigh Wildridge, S. Garcia, P. Thomson, C. Clark, E. Jongman and K. Kerrisk
Dairy Science Group, Faculty of Veterinary Science, School of Life and Environmental Sciences, University of Sydney, Camden, NSW, 2570, Australia.
Faculty of Veterinary Science, University of Sydney, Camden, NSW, 2570, Australia.
Animal Welfare Science Centre, Faculty of Veterinary and Agricultural Sciences,
University of Melbourne, Parkville, Victoria, 3010, Australia.
Corresponding author ashleigh.wildridge@sydney.edu.au
Dairy cattle typically respond to hot weather by reducing feed intake and locomotion, increasing water consumption and seeking shade. This often leads to reductions in milk production (at least partially due to
reduced dietary intakes) which may be further amplified in a system with voluntary cow traffic (due to a reduction in milking frequency). In this study it was hypothesised that access to small intermittent shade sources along a laneway between a feed source and a milking facility would result in improved voluntary cow movement (compared to no shade provision) during summer (December 2015). Four groups of six cows were introduced to a laneway of approximately 930m in length where they were exposed to either a SHADE or NO SHADE treatment. SHADE consisted of five 3m x 3m x 2.4m (L x W x H) shade structures were evenly spaced along the laneway between a feeding area and the milking facility; these structures were removed for the NO SHADE treatment. Each group of cows was exposed to each treatment twice.
Behaviour and location of cows was recorded between 10:00 and 17:00 each day. SHADE cows were
more likely to leave the feeding area and move further towards the milking facility than NO SHADE cows
(P < 0.001). NO SHADE cows had higher average body temperatures and respiration rates (P < 0.001) and spent less time ruminating and more time grazing (P < 0.001 and P = 0.017 respectively) than SHADE cows. The results of this preliminary investigation suggest that the provision of intermittent shade along a laneway might enhance voluntary cow movement and cow comfort during hot conditions.
When the environmental temperature humidity index (THI) is high, dairy cattle behave and perform differently to reduce the heat load on their bodies. Feed intake and locomotion normally decrease to reduce the amount of body heat produced (West 2003), and shade and water-seeking behaviour increase to further reduce heat load (Blackshaw and Blackshaw 1994). As a result, cow performance and milk production often decline during hot weather (Ominski et al. 2002). In an automatic milking system (AMS) operating with voluntary cow traffic, further reductions in production may be seen due to a reduction in milking frequency (MF) caused by decreased activity (Speroni et al. 2006). In this system type, feed is typically used to encourage cows to volunteer to be milked and travel within the farm (Prescott et al. 1998), however, as feed intake eclines during hot weather, alternative methods of encouraging cow movement may need to be enforced. Water consumption (Meyer et al. 2004) and the use of shade (Kendall et al. 2006) both increase in desirability to the cows as THI rises and it is possible that the manipulation of these resources may create opportunity to encourage voluntary cow movement. As access to water should not be restricted at any time, particularly during hot weather due to the welfare implications associated with this, investigations into the manipulation of shade as an incentive to encourage voluntary cow movement during hot weather is preferred. Shade is an affective aid for cooling cattle and is often utilised for long periods of time by cattle when ample space is provided (Schütz et al. 2010). Because of this, it was predicted that the use of small shade sources would
encourage cows to use the shade with competition from other cows preventing excessive amounts of time spent under them. It was hypothesized that the provision of small intermittent shade sources along a aneway would result in improved voluntary cow traffic between a feed source and an automatic
milking facility
The main objective of the current study was to determine if the provision of intermittent shade sources along a laneway would encourage voluntary cow movement during hot weather. Analysis of the approximate distance travelled by each cow at each observation identified that when shade was available, the cows were
more likely to travel further towards the milking facility than when shade was not offered indicating that the small shade sources did not result in long periods of shade use. This shows promise for the use of shade as an incentive to encourage voluntary cow movement and warrants further investigation. Cows in the SHADE treatment had a lower respiration rate and body temperature compared to cows in the NO SHADE treatment.
This result was expected as shade protects the cows from direct solar exposure (Kendall et al. 2006) and is known to reduce respiration rate (Schütz et al. 2014) and body temperature (Tucker et al. 2008). Cows under the SHADE treatment spent 6.0% more time ruminating and 5.6% less time grazing than NO SHADE cows. Greater levels of rumination would be expected as when relief from hot weather is not provided rumination time is often reduced (Soriani et al. 2013). The greater grazing time for NO SHADE cows was not expected due the impact of hot weather on appetite (Kadzere et al. 2002), however, greater time spent in the feeding area and no access to shade would have provided greater opportunity for NO SHADE cows to graze. All efforts were made to restrict the availability of grass in the test area; however, the cows would still spend time
‗grazing‘ after the feed allocation was depleted. Because of this, total feed consumption is unlikely to be significantly different between the treatments.
