Twenty Friesian cows were used to study the effect of dietary cation-anion differences on digestibility, rumen fermentation and milk production. Animals were divided into four groups. All groups were fed a basal diet consisting of 30 kg berseem, 6 kg concentrate feed mixture (CFM), 6 kg rice straw &75g soya bean meal (SBM) as a carrier for anionic salts/head/day. Anionic salts were used to control DCAD of the ration at the following levels (groups): treatment (1): Control group was fed the basal diet without anionic salts; treatment (2): DCAD was controlled to be 0 mEq/ Kg DM; treatment (3): DCAD was controlled to be negative 150mEq/Kg DM; treatment (4): DCAD was controlled to be negative 150mEq/Kg DM by using Anio - Norel (commercial product).
Animals received treatments three weeks before expected calving date and stopped at delivery day.
Results obtained showed that:
1. Rumen pH was affected by treatment, values were 7.5, 6.9, 6.6 and 7.1 for groups (1, 2,3and 4 respectively).
2. Organic matter digestibility ranged between 59.43% for group (3) and 57.23% for group (4).
3. Crude fiber digestibility was not significantly (P< 0.05) affected by treatment.
4. Treated groups showed lower 305 days milk yield when compared with control group (P> 0.05).
5. Treatments didn't affect milk components significantly (P< 0.05) except for milk fat where it was lower for treatment (4) compared with other treatments.