Suckling lamb presence influences the daily rhythm of total locomotor activity in grazing Pampinta dairy ewes

The objective of this study was to investigate the influence of different reproductive stages and livestock management conditions on the pattern of the daily rhythm of total locomotor activity in Pampinta dairy ewes. We recorded 24 hour(h)/day of total locomotor activity in 10 Pampinta dairy ewes during 2 different stages of 60 days each: in stage 1, the animals were pregnant and not lactating, and were subjected to a natural 10/14 light/dark (L/D) cycle with an ambient temperature of 17°C and relative humidity of 70%; in stage 2, the animals were lactating. During stage 2, the animals were divided into 2 equal groups, one group was milked 1 time a day with an automatic machine, and the animals of the other group only suckled the lamb. During this stage, all animals were subjected to a natural 13/11 L/D photoperiod with an ambient temperature of 25°C and relative humidity of 73%. A trigonometric statistical model was used to describe the main rhythmic parameters: mesor, amplitude, acrophase, and robustness of rhythm. Our results showed a daily rhythm of total locomotor activity in all periods considered. Two-way for repeated measure analysis of variance (ANOVA) was applied to study the effect of time (days of monitoring) and the experimental conditions on the studied parameters. The onset and offset times were defined as the time points at which the threshold amount of activity was reached at the rising and declining limbs of the daily pattern. The daily rhythm of total locomotor activity was different in the 2 stages considered and between the 2 groups during stage 2. The highest daily amount of activity per 24 hours was observed in the nursing ewes followed by the ewes milked by an automatic machine and pregnant ewes. Robustness of rhythm was highest in nursing ewes followed by the pregnant ewes and the ewes milked by an automatic machine. Only the acrophase was similar in the 2 stages and between the 2 groups of lactating ewes. In conclusion, the daily rhythm of total locomotor activity in Pampinta dairy ewes showed a low robustness value and was influenced by the different management conditions. The lamb's presence, and the consequent maternal care, strengthen the robustness of rhythm. Considering the total locomotor activity as an index of wellness in livestock, further studies are necessary to establish the characteristics of the daily rhythm of total locomotor activity in Pampita dairy ewes for the improvement of the wellness of this species widely used in Argentina.