In an italian ryegrass pasture under continuous stocking with sheep, biomass flows were estimated from 2 to 20 October 1999. Treatments corresponded to four different sward heights (5, 10, 15 and 20 cm) maintained by variable stocking. The experimental design was the randomized complete block design with three replicates. The fluxes were defined by morphogenetic and structural variables obtained from measurements performed on marked tillers. During the period in which the intended sward heights were established, significant effects in sward structure resulted in alterations on the biomass fluxes. The growth and intake fluxes showed a quadratic response with maximum values between 10 and 15 cm grazing heights, while the senescence flux increased linearly with sward height. Maximum daily live weight gain and animal yield per hectare were obtained within this interval, indicating this interval being the most appropriate to pasture management. The evaluation period was coincident with the floral induction phase, so the leaf lamina mass was progressively smaller and biomass fluxes showed a negative balance for all treatments.
intake; growth; marked tillers; morphogenesis; senescence; sheep
