Beef production systems wilh Hereford steers on the sub-humid Mediterranean natural pasture. I. Animal behavior

Carlos Ovalle M.1, Julia Avendaño R.1, Ignacio Ruiz N.2

Beginriing from the post-weaning period three alternatives for fattening steers were evaluated. Steers grazed ah year ori natural range and received different supplemental feedings, depending on the uve weight goals programed for each alternative. During the post-weaning period iii the tau, the animais lost up to 0.28 kg/head/day. During the spring grazing season, yearuings and two year oid steers gained 0,911 and 0.980 kg/an./day, respective y. In the summer and first month of the fail, grazing the range only maintained the animais weight, at the most From this time on supplemental feeding was necessary on the semi-extensive (S) and extensive (E) alternatives. Steers with 420 kg at 29 months of age were obtained, when grazing on the range, with supplementai feeding during the first and second winter, with daily gains of 0.133 and 0.473 kg/an., respectiveiy, and with and initial weight of 148 kg, at the beginning of the first winter. Live weights of 420 kg we re reached before 29 months of age, when the initial weights and winter daily gains were higher. To obtain steers of 400 kg at 25 months of age, the supplemental feeding during the first and second winter should produce daily gains of 0.370 and 0,500 kg/an., respectively. Steers of 380 kg at 21 monthsof age were obtained on a more intensive alternative. To reach this goal, daily gain must be 0.360 kg/an./day during the first winter and 0.575 during a summer grazing period, of 167 days on the range. From the different alternatives studied, another possibility was visúalized, under which the animais can be removed from the range at the end of the firstspririg grazing period (15 to 16 months of age), to complete their fattening under more favorable conditions; on irrigated pastures, for instance.

1 Subestacion Experimental Cauquenes (INIA), Casilla 165, Cauquenes, Maule, Chile.
2 Instituto de Investigaciones Agropecuarias, Casilla 5427, Santiago, Chile