Influence of paddock occupation time on the grazing activity of dairy cows in rotational systems

A survey was carried out in 42 dairy farms in 2017 in the highlands of Ecuador. It was observed that most of the farms used rotational grazing methods that vary widely in terms of occupation time: from 2 to 3 hours to several days, moving manually an electric fence to open up new paddock areas. Questioning the relevancy of extremely short occupation times, we hypothesised that differences in occupation times impact the eating behaviour of cows and ultimately milk production due to differences in exploration of the pasture and variation along the day in forage allowances. Three Pennisetum clandestinum-based pastures were grazed for 7 days each by 4 Holstein cows in-milk using differing in occupation times: long (7 d), medium (1 d) and short (3 h) and replicated in a crossed experimental design for 3 consecutive periods after a 30-d resting time. Two cows per pasture per period were equipped with iPhone S5 to compare grazing activity and movements on the paddocks during day-time. Preliminary results over a single period of measurement seem to indicate that cows grazing with medium term occupation times (1 d) tended to move over longer distances (3.42±1.07 km), than those in long and short occupation times (2.73±0.61 km and 2.37±0.35 km, respectively), while no difference was observed in total grazing time or average speed when grazing (approx. 0.3 km/h). Such a trend in travelled distances might be explained by high pasture exploration requirements in the medium occupation time since animals already know the paddock well for long term and, for short term, the newly offered forage is always presented with a similar structure along a narrow band on the same side of the paddock every three hours.