Ryegrass endophyte, cow health and milksolids production for the 1993/94 season

Abstract

Four 2.5 ha farmlets based on endophyte-infected (H) and endophyte-free (L) ryegrass were established with or without white clover (kc) in March 1993. Fifteen cows were allocated to each farmlet before 3-week test periods in spring, summer and autumn. Milk yield and composition (fat, protein, lactose), cow rectal temperature, liveweight, condition score and incidence of ryegrass staggers were measured. Pasture sampling included assessments of yield, botanical composition, alkaloid, and endophyte content. H and L endophyte ryegrass treatments contained 94 and 26% endophyte, respectively, in March 1994. Herbage accumulation on all treatments was similar over the season (20 May 1993 - 19 April 1994). Treatments did not affect milk production in the October test period. Interaction between endophyte and clover in the January/February period showed cows on the L + C treatment produced more milk than all others (10.3 vs 9.0 l/cow/day). However, in the March test period a different interaction was apparent as cows on the H+C treatment produced produced less milk than all others (4.7 vs 6.3 l/cow/day), and all cows on H endophyte showed clinical ryegrass staggers. Milk production responses were not directly related to the endophyte status of the pastures in any test period. Treatment trends for green herbage consumed in March were similar to those for milk production. Keywords: Acremonium lolii, dairy cows, grazing, lolitrem B, Lolium perenne, milk production, ryegrass staggers