Forage particle size and forage preservation method modulate lying behaviour in dairy cows

Abstract

It has been suggested that reducing forage particle size as well as feeding hay compared to silage may improve forage intake. Little is known, however, how such ration characteristics affect other aspects of cattle behaviour. Therefore, this study investigated the lying behaviour of cows in response to particle size reduction (LONG versus SHORT; Trial 1) and preservation method (SILAGE versus HAY; Trial 2) of forages which constituted ≥ 80% of the rations’ dry matter. Two feeding groups with 10 (Trial 1) and 9 Holstein cows each (Trial 2) received the experimental rations for approximately 5 weeks. Cows were housed in a free-stall barn with straw-bedded cubicles and rubberized floor in the alleys. Lying behaviour was recorded using HOBO Pendant® acceleration data loggers during the last 3 weeks of the experimental period as well as for 3 consecutive days during the week preceding the experiment, the latter serving as a baseline covariate to consider individual cow lying behaviour.SHORT-fed cows (Trial 1) had a longer daily lying time (+ 1.1 h/d; P = 0.003) and tended to have more lying bouts (+ 3.1; P = 0.090) than cows fed the LONG ration. In both groups, a preference towards the left lying side (57.4%) was observed. A similar pattern was observed for both groups with regard to rumination time while lying. Cows fed SILAGE or HAY (Trial 2) did not differ with regard to lying times (12.8 h/d). However, cows on HAY tended to lie less on the left side (- 1.1 h/d; P = 0.098) and had less lying bouts per day (- 2.5 bouts/d; P = 0.039). Consequently, these cows showed nearly an equal preference for the left and right lying side with 49.1% and 51.6%, respectively; whereas cows on SILAGE tended to prefer the left lying side (55.6%), also when ruminating. In contrast, cows on HAY tended to reduce rumination time on the left lying side (- 0.61 h/d; P = 0.079).Effects observed may be attributed to changes in eating behaviour as well as the amount of feed ingested in a given time period. Under the conditions investigated, time budgets for lying may be limited and changes of the forage characteristics (e.g. particle size reduction) could mitigate these constraints.