| Three experiments were conducted using prepartum cows having ligh or low milk yield to examine the effect of anionic salts on acid-base balance, ion-balance, umen fermentation or lactation performance.In Exp. 1, ten prepartum Holstein cows with low milk yield background were used to study the effect of feeding anionic salts on acid-base balance, ion-balance, and lactation performance. The result showed that feeding the anionic salt slightly decreased the dry matter intake (DMI) prior to parturition, but had a higher DMI postpartum. From the 3rd day after feeding urine pH values in anionic salt treatment decreased significant (7.31 vs 8.09; P = 0.08), but much higher than those expected. Fecal pH values did not exhibit a change consistent with urine pH occurring with feeding anionic salts, suggesting that fecal pH could not be used as an indicator of acid-base status of dry cows. Feeding anionic salts resulted in an increase in urine Ca concentrations (P<0.031), a tendency in decreased blood P concentrations and increased blood Mg concentrations, but had no effect on calcium and other ion concentrations in plasma (P>0.1). When cows were at low milk yield level, feeding anionic salts would not have any advantages for preventing the postpartum diseases.Exp. 2 was conducted to study the effect of anionic salts fed to dry cows with a high producing background on acid-base balance, ion-balance, and lactation performance. In this experiment, alfalfa hay in the diet was replaced by Chinese wildrye grass hay and twenty eight non-lactating Holstein cows in their last 3 wk of gestation were random assigned a control diet of a diet included anionic salts. The urine pH values were dropped to 6.24 (P<0.01) after feeding anionic salts for 5 days, and incidence of retained placenta decreased from 43.7% to 12.5% (P<0.05). In the first 1, 2 and 4 month after parturition, feeding anionic salts had a significant promotion on fat corrected milk yielding (38.9 vs 32.4; 44.8 vs 36.5; 38.8 vs 33.2; P < 0.05), and tended to yield more milk fat, but had no effect on other milk compositions (P>0.1). When the anionic salts were fed, total Ca concentrations in plasma did not effectively increased, whereas there was a tendency of increased Mg concentrations, decreased P concentrations and unchanged other ions in plasma.In Exp. 3, four 3-year old Holstein steers installed with permanent rumen cannulae were used in a crossover design to investigate the effect of aionic salts on rumen fermentation, blood parameters and ruminal digestions of starch and fibers. When anionic salts were fed, rumen pH values were dropped on day 5 (6.71 vs 7.15, P = 0.05) and day 7 (6.67 vs 7.03, P = 0.02), and this drop did not exist afterwards, indicating adaptation of rumen microorganisms to anionc salts. The anionic salt did significantly change whole blood parameters reflected by decreased pH values (P<0.1), pCO2 (P<0.05), base excess (P=0.01) and the concentration of HCO3- in plasma (P<0.01). As steers fed anionic salt diets, ruminal fermentation parameters including concentrations of ammonia nitrogen and total VFA, and individual VFA molar percentages was unaffected (P>0.1). No differences were also found in urine-N and glucose concentration in plasma, and in rumen digestion of starch, NDF and A OF between treatment and control...
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