Introducing structural elements into the free resting area in loose-housing systems with horned dairy cows: Effects on lying behaviour and cleanliness

The transition of tie-stalls to loose housing systems is often accompanied by starting dehorning. Deep-litter and straw-flow systems can be more cost-effective and advantageous for various aspects of the welfare of dairy cows than cubicle loose housing. However, the number of social encounters and disturbances of lying animals can be higher in these systems especially for animals with horns. The use of structural elements may improve the situation and the aim of this project was to investigate the potential effects of structural elements in the free resting area on resting behaviour, animal cleanliness and straw usage in herds of horned dairy cows.On five commercial farms that keep horned dairy cows in a deep-litter system, data were collected in situations without and with a structural element present. Lying behaviour was recorded by scan sampling for each individual animal every 5min. The cleanliness of the cows was assessed at the beginning and end of the four-day recording period. The proportion of scans in which animals were lying in 24h, during day and at night as well as the change in cleanliness were analysed using linear mixed models. Straw usage was evaluated by counting the number of bales used on each of the four days on four farms.The proportion of lying was higher with the structural elements present than without for 24h (p<0.001) and at night (p<0.001), while no effect was found during the day (p=0.964). This was particularly true for high-ranking and middle-ranking animals (interaction rank*structure: p=0.007), for which lying time increased by about 1h on average, while for low-ranking animals it increased only about 10min. The strength of the effect, however, varied considerably between individual farms. Animals were also less dirty with the structural element present than without (p=0.008). For straw usage, no uniform trend was found on the farms.In conclusion, the results indicate a positive effect of the presence of a Y-shaped structural element in the free resting area of straw yard systems on lying time and cleanliness of horned dairy cows. The use of structural elements in straw yard or comparable systems thus has the potential to improve the welfare of horned dairy cows and furthers keeping of horned cows as an alternative to dehorning.