The associative effects resulting from the proportions of neutral detergent fibre (NDF) and non-fibre carbohydrate (NFC) were explored and assessed by in vitro gas production. Total mixed rations (TMR) composed primarily of alfalfa and corn-soybean concentrate were fed to growing cashmere goats. Treatments were defined by three proportions of NFC and NDF, namely 2.00 (TMR1), 2.35 (TMR2), and 3.00 (TMR3) that were used to grow cashmere goats, and these TRMs were incubated for 48 hours to evaluate their influence on associative effects. The results indicated that the associative influences of these treatments on gas production occurred within the cultures predominantly at 2 – 8 hours, and disappeared gradually as culture time was extended. TMR2 and TMR3 incubation increased gas production compared with that observed in the other groups at all incubation times (P >0.05), and these groups exhibited positive associative effects, particularly during the early hours of incubation (P <0.05). TMR3 displayed the best associative effect.