Protein and energy supplementation for grazing Iactating dairy cows

Ernesto Jahn B.1, Germán Klee G.1 y Nora Aedo M.2

Two trials, to evaluate the effect of concentrate supplementation to grazing lactating dairy cows, were carried out at Human Experiment Station, located at Los Angeles, Chile. European Holstein cows, grazing pasture during the spring—summer season were used. In trial 1, a red dover (Trifollum pratense) +white dover (Trifolium repens) +ryegrass (Lolium perenne) pasture was used. Treatments were: I. pasture + 1 kg concentrate (12% C.P.) and an additional amount ata rate of 1 kg/4 kg milk produced aboye 8 kg mil k/day; II. pasture, without supplementation. In trial 2, a white dover + ryegrass pasture was employed. Four treatments were compared: l.pasture, without supplementation; II. pasture + dry sugar beet pulp (S.B.P.), 1 kg/3 kg milk, aboye 12 kg milk/day; III. pasture + S.B.P., (1/3) aboye 17 kg/day; and IV. same as treatment III, until January 7 and a 14% C.P. concentrate (76% S.B.P., 24% rape seed meal) thereafter, at the same rate as treatment III. Both trials used a randomized block design, with 5 and 10 replicates for trials 1 and 2, respectively. ln trial 1, miik production was 14.2 and 12.9 kg/cow/day (P > 0.05), for treatments I and II, respectively. In trial 2, milk production was 17.7, 18.2, 17.7, and 17.1 kg/dey (P > 0.05). Concentrate intake was 2.3 in trial 1 and 0.0, 2.8, 1.2, and 1 .0 kg/cow/day, for treatment 1 to IV, respectively, in trial 2. Liveweight gains tended to be higher for cows that received supplement (P > 0.05).

1 Estación Experimental Quilamapu (INIA), Casilla 426, Chillán, Chile.
2 Estación Experimental La Platina (INIA), Casilla 439, Correo 3, Santiago, Chile.