Maxgrass (BP Chemicals Ltd), a product containing ammonium hexamethanoate, ammonium hexapropionate and carboxylic acids, has been claimed to restrict the extent of WSC fermentation in herbage during ensiling. This has been shown to result in increased DM intake and subsequent animal performance (Kennedy 1990). The objective of the present experiment was to further investigate the effects of this treatment of grass at ensiling and in particular to examine the interaction of the responses with levels of concentrate supplementation when offered to finishing beef cattle. Evaluation parameters included an assessment of additive effect on silage intake, animal performance and carcass characteristics.

Approximately 70 tonnes of primary growth grass was ensiled from 22-24 May 1990 into each of eight concrete covered, walled silos (4 per treatment). Grass was treated with Maxgrass (6 l/t) or left untreated. Seventy-two Continental cattle (460 kg) were blocked into groups of 9 according to liveweight and allocated at random to either untreated or Maxgrass treated silage supplemented with 0, 1.5, 3.0 or 4.5 kg/day of a 15% CP proprietary beef concentrate or slaughtered.