Goats locomotion energy expenditure under range grazing conditions: Seasonal variation

The estimation of the energy cost of various activities using calorimetric techniques in conjunction with direct field observations can be used to est imate energy expended in the daily activities of free-ranging animals. The objective of this study was to observe and quantify the grazing activities and to estimate the energy expenditure due to locomotion of goats in open r ange. The study was carried out at 'Finca de Bonaya' privately-owned site, which extends over 1,482 ha, located in the Nevada mountain-range, Almeria. The l ocal altitude varies from 1,100 to 2,000 m above sea level. The area has a mediterranean mountain climate, with annual precipitation ranging from 400 to 700 mm and average daily temperatures from 4.7 degrees C in winter to 23 .0 degrees C in slimmer. Landscape is characterised by holm oak wood and pi ne wood, degradation scrubs and hydrophilic grasses communities. The experimental flock grazed on 3 routes during the whole year. The goats were released to graze during the day and then returned to an enclosed shed . The type of goat management was considered as semi-extensive. Direct obse rvation was used to simulate the total distance walked, the vertical ascent or descent, and to quantify other grazing activities. Data on activities o n range and distance travelled were taken on 3 days in each season. The ene rgy expenditure of locomotion was calculated from the horizontal and vertic al components of travel and the corresponding costs, which had been previou sly obtained by calorimetry. There was no significant seasonal effect on period devoted to specific acti vities on range (P>0.05). However, significant changes in the estimated dai ly energy expenditure and extra energy expenditure due to locomotion of the animals at pasture were found in different seasons (P<0.05). Grazing and w alking were the primary activities of goats throughout the study, accountin g for 51.7 and 42.0% of the animals' daily period on range, respectively. D aily travelled distances by goats on range fluctuated from 12,777 m in summ er to 8,100 m in autumn, with an annual average of 9,954 m, which represent s a mean speed of 20.8 m/min calculated over the whole period on range. The mean annual vertical ascent or descent was 500 m. Estimated heat productio n due to locomotion ranged from 130.9 to 88.5 kJ/kg(0.75) per day in summer and autumn respectively. These values account for an increased metabolizab le energy (ME) requirement at pasture above maintenance of 46.6 and 31.6%, respectively, assuming a ME requirement for maintenance of 401 kJ/kg(0.75) per day for the restrained goat.