The effect of system of harvesting grass for silage on the output of silage and milk per hectare

Abstract

SummaryFour systems of harvesting grass for silage were evaluated in terms of in-field losses, in-silo losses and milk output per hectare. The systems were: single-chop flail harvester direct cutting (SCD); doublechop flail harvester direct cutting (DCD); mown with a rotary mower and picked up with a precisionchop harvester either immediately (PCU) or after wilting until the dry-matter concentration had increased by approximately 100 g/kg (PCW). The in-field and in-silo losses were measured at each of three consecutive harvests during 1984 and during the following winter the resulting silages were evaluated through eight British Friesian cows in a balanced change-over design experiment using four periods each of 5 weeks duration.There was a greater quantity of herbage ensiled with the two direct cutting systems (SCD and DCD) than with the systems involving pre-mowing and picking up with the ensiled yields, being 12·4, 11·8, 10·8 and 10·8t OM/ha for the SCD, DCD, PCU and PCW systems respectively. These differences were only partly reflected in greater mechanical in-field losses with the pre-mown systems.Losses during the in-silo period tended to be greater with the wilted than the unwilted silages being 98, 76, 83 and 132 g/kg OM with the SCD, DCD, PCU, and PCW systems, respectively.Animals offered the PCW silage tended to have a higher silage organic-matter intake and had a significantly higher milk yield than those offered the other silages with fat corrected milk yields being 25·1, 24·5, 24·5 and 25·9 kg/day for the SCD, DCD, PCU and PCW systems, respectively. Milk outputs per hectare, at 30·3, 27·8, 25·7 and 240 for the SCD, PCD, PCU and PCW systems respectively, was lowest for the PCW treatment.