Grazing management and pasture composition on paired farms which differed in the incidence of bloat

Abstract

Abstract Farm practices, pasture species, and pre‐ and post‐grazing herbage masses were monitored monthly from June 1990 to April 1991 and from August to November in 1991 and 1992 on 16 pairs of dairy farms. Each pair included one farm with a history of bloat despite routine use of preventatives (bloat‐prone) and one farm which historically rarely observed bloat in the absence of chemical use (bloat‐free). Farms within a pair were on similar soil types and herds had similar genetic backgrounds. The incidence of bloat during spring was low in all years. Bloat‐free farms averaged less ryegrass (58 versus 66%) and more grasses other than ryegrass (25 versus 17%) in pasture and higher pre‐ and post‐grazing herbage masses than bloat‐prone farms in 1990 and 1991. Bloat‐free and bloat‐prone farms did not differ in white clover content, soil fertility, milksolids production, or stocking rate. The differences in pasture species and herbage mass suggested that differences in management between bloat‐free and bloat‐prone farms may be associated with incidence of bloat under mild bloat conditions, but their role in influencing the occurrence of severe bloat could not be assessed.