Diet composition and energy balance of cows grazing on Mediterranean woodland

Abstract

The study was conducted to determine the role of browse in the nutritional status and performance of beef cattle grazing on Mediterranean woodland. Measurements of the botanical intake composition (using N-alkane control release capsules and profile) and of the energy expenditure (EE) and balance (using the heart rate method) were carried out on six pregnant cows in the late summer, and on the same cows when nursing in winter and after weaning in late spring. Broiler chicken manure (poultry litter, PL) was given freely during late summer and in winter. Throughout the three periods the metabolizable energy (ME) concentrations of the consumed diet were 6.23, 8.78, 7.65 MJ/kgDM, respectively and the intakes were 8.59, 9.60, 7.92 kgDM/day, respectively; the ME intake, the EE and the retained energy (all in units of kJ/(kgLW 0.75 ⁎day) were 583, 524 and 58, respectively, in late summer; 960, 634 and 326, respectively, in winter; and 665, 475 and 190, respectively, in late spring. The proportions of woody plants in the consumed diet were 63%, 15% and 59% in the respective periods. The proportion of PL supplement in the diet was 37% in late summer and 35% in winter. We conclude that browse can provide 60% of the MEI, and thus the performance of cows grazed on woodland was comparable with that of cows grazed on herbaceous ranges in this region.