In France, for several years, reversions of fat and protein percentages have appeared in milks of intensively fed goats from 4-5 months to 7-8 months of lactation, which has unfavourable effects on cheese quality. Consequently we tried to assess the dietary effects on the percentage reversion risks. Two fibre sources were compared at a low and high roughage per concentrate ratios (R per C). Thirty two goats were allotted in 4 groups balanced in milk yield and composition. The mixed complete diet was composed with lucerne hay (A) or deshydrated lucerne blocks (D) at 60 per cent (H) or 30 per cent (L) total DM, beet pulp silage and concentrates. The level of dry matter intake was not significantly different. The milk yield was significantly higher in L diets limited in roughages (3.48 kg milk per d for L diets vs 3.10 kg milk/d for H diets). The type of lucerne had no affect on milk yield.