ABSTRACT.
Effeet of the perennial ryegrass-white clover pasture phenological stage cutting date upon the dry matter yield, ensilability and silage quallty

Hernán Felipe Elizalde V.1, Nolberto Teuber K.1, Antonio Hargreaves B.1, Francisco Lanuza A.1 y Alfredo Scholz B.2
 

The investigation was performed during two periods at the Remehue Experiment Station (INIA). The objectives ofthe trial were: a) To determine the effect of the phenological stage of growth on yield of forage and quality produced by a perennial ryegrass white clover pasture. b) To determine the fermentation qualiy and chemical composition of silages obtained by a sward cut at different phenological stages. To perform this work, five phenological stages were considered: boot (B), ear emergency (E.E.), blooming (Bl), milky aqueous grain (MAG), and hard mealy grain (HMG). The sward was ensiled in experimental silos, without wilting nor additives. The dry matter yield was evaluated with values determined respectively for B., E.E., B.L., MAG and HMG as follows; first period: 4.3; 6.0; 8.9; 9.5 and 7.2 ton/ha, and for the second period: 2.5; 4.2; 5.6; 6.1 and 6.1 ton/ha. The quality of the grass was determined by chemical analysis. In both years as the grass matured, its dry matter content increased while the crude protein (C.P.) content and in vitro digestibility (I.V.D.) decreased. In the case of C.P. the reductionwas from 17.1 for B to 6.9 for HMG, and inthe case ofl.V.D. the reduction was from 80.8 for B to 55.5 for HMG. Similartrends in the qualityof the silage were recorded as were observed for the fresh forage. As pasture maturity progresses, its quality declines. Relating to this, the sward harvested at the B stage was the one presenting the best conditions to be ensiled because it had a better nutritive quality and good fermentation characteristics.

Keywords: ryegrass, phenological stage, silage, laboratory silos, chemical composition.
1 Estación Experimental Remehue (IN lA), Casilla 24-O, Osorno, Chile
2 Memorante Universidad Austral de Chile, Valdlvia. Actualmente actividad privada.