Performance of piglets of high weaning weight receiving different types of diets and levels of protein during the starter phase

The annual production and accessibility to bovine grazing, of the gramineous forages forming part of the natural range dominated by Prosopis caldenia Burk., was determined at the “Rancho Grande” ranch in San Luis Province, Argentine, differentiating production in open range from that in undergrove sites and also according to seasonal vegetative growth. In an area closed off to grazing in August 1988, the plant species resulting from summer and winter growth were harvested at the end of these cycles in April and December 1989, respectively. The percentages of area represented by open range, undergrove and inaccessible sites (30, 68, and 2, respectively) were calculated by the method of Canfield. Annual production of the forage species was 1 064 kg MS/ha. The majority of the cool season forage production is supplied by Piptochaetium napostaense (Speg.) Hackel on open range; while warm season production is supplied mostly by Cynodon hirsutus S. M. Stent. and Sporobolus cryptandrus on open range and by Setaria leucopila (Lam-Scrib.) K. Schuman. and Setaria leiantha Hackel in undergrove locations.