Evaluation of lucern / grass silage and concentrate supplements for dairy heifers

Francisco Lanuza A.1, Fernando Klein R., Juan Carlos Dumont L., Sergio Iraira H., Juan Bolt Q., Rodolfo Saldaña P. y Lorena Soto S.

Grass from a permanent pasture and tlrst-cut lucern were mixed in a 3:1 proportion and stored as silage at the Remehue Regional Research Center, Osorno, Chile. Conventional direct cut harvesting equipment was used and no silage preservative was added. The silage was plastic-sealed and protected with soil added on the topo The silage was fed ad-libitum to each of 21 growing heifers (180-220 kg) during 10 weeks. The heifers were kept in individual pens and randomly blocked in three treatments: T1: withoutconcentrate; T2: 1.5 kg of concentrate/day; T3: 3.0 kg of concentrate/day (16% CP, 2.64 Mcal/kg ME). A mixture of 8 g of minerals and water ad-libitum were also offered to each heifer. An appropriate silage fermentation was achieved (pH 3.88; N-NH3 9.93% as total N), and nutritive parameters were 17.2% DM, 16 % CP, 70% in vitro digestibility, 37.4% ADF, and 2.3 Mcal/kg ME. Average silage consumption was 4.76., 4.24b , and 4.17b kg DM/day (P < .01) for T1, T2 and T3, respectively. Weight gain for T1 was 0.533 kg/day, whereas heifers in T2 and T3 treatments achieved values of 0.863 and 1.143 kg/day, respectively (P < .0 1). Weight increments at grazing were similar in all treatments, approaching 1.0 kg/day. lt is conc1uded that the fermentation properties ofa silage based upon a mixture ofpermanent pasture and first-cut lucern are satisfactory, animal consumption ofthis type of silage is optimum, and live weight gains are high even without concentrate supplements.

Key words: lucern/grass mixture silage, dairy heifer, forage supplements.

1 Instituto de Investigaciones Agropecuarias, Centro Regional de Investigaciones Agropecuarias, Centro Regional de Investigación Remehue, Casilla 24 – D, Osorno, Chile. e-mail: flanuza@inia.cl.

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