Dairy heifers’ performance in winter annual pastures under integrated crop‑livestock system

The objective of this work was to assess the rearing viability of dairy heifers grazing single or intercropped winter pastures, under crop-livestock integration system. The experiment was carried out in Castro, Paraná state, Brazil. A complete block design was used, in a factorial arrangement, with two animal categories – light-weight, with 192±40.9 kg, and heavy-weight animals, with 278±41.2 kg –, and two pasture types: annual ryegrass (Lolium multiflorum) intercropped with black oat (Avena strigosa), white clover (Trifolium repens) and red clover (Trifolium pratense); and single annual ryegrass pasture. A continuous grazing method with variable stocking was used, with 20-cm sward management height. Single annual ryegrass pasture provided an average daily gain (0.93±0.032 kg per day per animal) significantly higher than intercropped pastures (0.79±0.032 kg per day). Light animals had higher weight gain per hectare (3.54±0.163 kg ha-1 per day) than heavy animals (2.99±0.163 kg ha-1 per day), which was influenced by pasture type: light animals had best performance on single pasture, and heavy animals on intercropped pastures. Rearing dairy heifers is viable in the pasture phase of integrated crop-livestock systems.