[The lying and rumination behavior of healthy dairy cows housed in tie stalls is associated with bedding depth]

The lying and rumination behavior of dairy cows is internationally used as an animal welfare indicator. Dairy cow housing in Switzerland is subordinated to detailed legal requirements. It is particularly described that the lying area for cows must be covered with a sufficient amount of bedding. In the current study, we investigated whether bedding depth influences the lying and rumination behavior and thus, the animal welfare of healthy dairy cows housed in tie stalls. Bedding depth was categorized as ≤ 2 cm and > 2 cm. The lying and rumination behavior of 145 cows from 33 farms was recorded and analyzed considering farm effects; 105 cows were housed on ≤ 2 cm bedding, and 40 cows on > 2 cm bedding. Cows on > 2 cm bedding had on average a one hour longer daily lying time compared with cows on ≤ 2 cm bedding (mixed-effects linear regression: mean difference [cows on > 2 cm bedding - cows on ≤ 2 cm bedding] = 60,7 min/d; standard error = 28,6 min/d; p-value = 0,037). The odds of a cow to lie while ruminating were significantly higher in cows on > 2 cm bedding against cows on ≤ 2 cm bedding (mixed-effects logistic regression: Odds ratio = 1,27; CI95% [1,17-1,38]; p-value  2 cm can make a significant difference in the lying and rumination behavior of healthy dairy cows housed in tie stalls. Consequently, the animal welfare of dairy cows in tie stalls is improved by providing at least 2 cm of bedding.