A bioperformance enhancing adjuvant of.Formula (I) R1O[BO]n[AO]mR2 where BO is butylene oxide and each AO is independently propylene oxide or ethylene oxide n is from 1 to 12 m is from 0 to 20 R1 is optionally substituted C4-20 alkyl or optionally substituted C4-20 alkenyl and R2 is hydrogen or optionally substituted C1-3 alky.