Stepping behavior and muscle activity of dairy cows on uncomfortable standing surfaces presented under 1 or 4 legs

The comfort of dairy cattle while standing has important implications for housing design. Research has examined how cattle respond to standing surfaces by presenting options under all 4 legs or under a single leg, but no work, to date, has compared presentation methods. This study examined behavior and muscle activity when cows stood on rough floors under all 4 legs or just 1 hind leg. Three treatments were tested: smooth concrete under all 4 legs (0-ROUGH), a rough surface under all 4 legs [2cm × 2cm × 4cm trapezoidal protrusions (4-ROUGH)], and a rough surface only under 1 hind leg, with other legs on smooth concrete (1-ROUGH). Twenty-four healthy Holstein cows stood on each surface for 1h/d in a repeated-measures design. Surface electromyograms (SEMG) were used to evaluate muscle fatigue and total activity. Muscle fatigue was measured using SEMG to evaluate (1) static contractions when cows were continuously weight bearing on each hind leg, before and after 1h of standing, and (2) dynamic contractions associated with steps during 1h of standing. Behavioral measures included steps per minute, time between each consecutive step, and the latency to lie down after testing. The number of legs affected by roughness influenced both behavioral and physiological responses to flooring. Cows on 1-ROUGH stepped twice as often with the rough-treated leg and one-half as much with the hind leg on smooth concrete compared with other surfaces. Similarly, on the 1-ROUGH surface, total muscle activity was reduced in the leg on the rough surface, and muscle activity was more sustained (3× higher) in the other hind leg, suggesting that cows avoid possible discomfort under 1 leg by using muscles in the other. In the 4-ROUGH treatment, time between steps was more variable than on the other 2 treatments (coefficient of variation, 4-ROUGH: 245; 1-ROUGH: 208; 0-ROUGH: 190±5.8%), likely because cows could not move away from this uneven flooring. Thus, the method of presentation of stimuli used to evaluate comfort while standing altered the response. Stepping rate and SEMG changed when roughness was under a single leg, whereas timing between consecutive steps was more variable with rough flooring under all 4 legs. These results have implications for the design of experiments evaluating standing comfort in the future.