Daytime summer access to pasture vs. free-stall barn in dairy cows with year-long outdoor experience: A case study

摘要

With its documented health and behavioural benefits, one would expect dairy cows to have near unconditional preference for pasture. However, dairy cow preference is multifaceted with numerous factors contributing to the choices and or actions of the cow. Experience is one such factor that may play a role in the level of preference that a dairy cow displays for pasture. In the current case study, we investigated if cows, when given the choice, would go to and remain at pasture under Eastern Canadian summer climatic conditions. Two important components were introduced in the case study: the use of a herd with year-round experience with the outdoors and the provision of the same feed options (both fresh cut forage and haylage) inside and on pasture. In doing so, the effects of a novel, outdoor environment and feed preference could be mitigated. 32 organic Holstein cows (parity average +/- SD: 2.8 +/- 2.0) averaging 9211 kg/cow milk production were submitted to a 6-d test cycle comprised of three consecutively and randomly applied 2-d phases repeated 4x over the course of 8 weeks. During these phases, cows were restricted to a free-stall barn (forced-indoor), restricted to pasture (forced-outdoor), or provided the access to both options (free-choice) for a 7-h period. Live observations of activities (drinking, eating haylage, eating fresh forage, lying, and other) were conducted every 2 min by scan sampling during the forced-outdoor and choice phases. A group level analysis with a Friedman test followed by an Asymptotic General Independence test was used to analyze the difference in time spent performing each activity between weeks and hours when forced-outdoor. The number of cows on pasture during the free-choice phase was averaged by week and hour. A 2-sample t-test was also used to compare time doing activities inside (free-choice phase) to those outside (forced-outdoor phase). When given the option, as a group, cows went to and remained at pasture for a majority of the time, with the exception of week 3 where a reduction in the number of cows on pasture was observed (from >90 to 40%), possibly due to inclement weather. No difference in activities were reported between the indoor vs. pasture environments. Eating fresh forage more than haylage was observed in both the indoor and pasture environments. The case study suggests that cows with outdoor experience have a strong inclination towards the outdoors and to elements such as eating fresh forages that is normally associated with the natural behaviour of grazing, providing a baseline for future research on the importance of providing outdoor access to cows for more sustainable dairy systems. (C) 2016 Elsevier B.V. All rights reserved.