A BEEF PRODUCTION SYSTEM FROM DAIRY BULLS UNDER PASTURE IN THE SOUTH OF CHILE

Abstract

In order to evaluate the productive and economic performance on a pastures system, was conducted an experiment with 21 autumn-born Friesian young dairy bulls of 4 months of age and 140 ± 17.07 kg LW, kept on pasture for 511 days. During the winter period and for 111 days, three treatments were imposed: T1, young dairy bulls with ad lib supplementation of pasture silage plus 4 kg of grain per animal per day; T2: young dairy bulls fed as T1 plus 2 kg of grain supplementation per animal per day; and T3: dairy steers with the same supplementation of treatment T2. Treatments were isoproteic, 11% crude protein, and isoenergetic, aproximately 2.3 Mcal kg-1 metabolizable energy on dry matter basis. The study finished at 21 months of age when the young bulls attained an average weight of 508 kg and the steers reached 461 kg LW. Daily live weight gains of 0.705a, 0.623ab and 0.583b kg animal-1 were statistically different (p < 0.05). Differences were also statistically different (p < 0.05) for dressing percentage, reporting values of 56a, 58a and 55b%, while the rib eye area reported values of 74.8a, 80.9a and 65.5a cm2 (p > 0.05) for T1, T2 and T3, respectively. Values of pH were 6.08a, 5.89ab and 5.52b (p < 0.05). It was concluded that young dairy bulls under a pasture system can obtain high live weight but they do not get enough fat cover, but steers attained slaughter weight with adequate fat deposit required by the industry. The gross margin indicated a good performance of both types of animals under the production system used.