The Effects Of Different Levels Of Ca And Mg Of Different Dcad Diet On Periparturient Dairy Cow's Ca Regulation

Twenty-four multiparous cows were randomly divided into eight groups and were individually fed diets supplemented with one of eight mineral additives diets for 21-day prepartum.â… :(LDCAD+ high Ca+ high Mg),â…¡:(LDCAD +high Ca +Low Mg),â…¢:(LDCAD +Low Ca+ high Mg ),â…£:(LDCAD +Low Ca+ Low Mg ),â…¤:(HDCAD +high Ca+ high Mg),â…¥:(HDCAD +high Ca+Low Mg),â…¦:(HDCAD +Low Ca+ high Mg),â…§:(HDCAD +Low Ca+ Low Mg). Dietary cation-anion difference (DCAD) for precalving diets was approximately -6.5 meq/100g DM (Na⁺K-Cl-S) for four LDCAD diets. Dietary cation-anion difference (DCAD) for precalving diets was approximately +17 meq/100g DM (Na⁺K-Cl-S) for four HDCAD diets. The experimental determine the effects of different levels calcium and magnesium concentrations in different DCAD diet on the serum ion balance status. The results were as follows:1. The DMIs of the eight groups were reduced but no statistical significant difference were observed anong the groups (P>0.05).2. The urinary pH values of theâ… ,â…¡,â…¢,â…£groups were significantly Lower (P<0.01) thanâ…¤,â…¥,â…¦,â…§groups. The anionic salts had significantly effect on the urinary pH values(P<0.01).3. The serum Ca concentrations of the eight groups no statistical significant difference were observed anong the groups (P>0.05) before 21d to 6d days of calving. The serum Ca concentrations ofâ… ,â…¡,â…¢,â…£groups were significantly higherâ…¤,â…¥,â…¦,â…§groups (P<0.05) before 4d days of calving to after 7d days of calving .The serum Ca concentrations ofâ… ,â…¡,â…¢groups was significantly higherâ…¤,â…¥,â…¦,â…§groups(P<0.01) on the calving day and after 1 day of calving. The anionic salts in diet had significantly effect on the serum Ca concentrations (P<0.01) before 4 days to after 7 days of calving. Interaction of anion salts and Ca in diet had significantly effect on the serum Ca concentrations (P<0.05) after 1day of calving.Interaction of anion salts and Ca in diet had significantly effect on the serum Ca concentrations (P<0.01) after 3 and 7 days of calving. Interaction of anion salts and Mg in diet had significantly effect on the serum Ca concentrations (P<0.01) after 3 days of calving.4. The serum Mg²⁺ concentrations of the eight groups no statistical significant difference were observed anong the groups (P>0.05) before 21d to 9d days of calving.The serum Mg²⁺ concentrations ofâ… ,â…¢groups were significantly higherâ…¥,â…§groups(P<0.05) before 6,4,2days of calving. The serum Mg²⁺ concentrations ofâ… group was significantly higherâ…£,â…¤,â…¥,â…¦,â…§groups (P<0.05) on the calving day. The serum Mg²⁺ concentrations ofâ… ,â…¡were significantly higherâ…£,â…¥,â…§groups (P<0.05) after1 day of calving. The serum Mg²⁺ concentrations ofâ… group was significantly higherâ…£,â…¥,â…§groups (P<0.05) after 3 days of calving day. The anionic salts in diet had significantly effect on the serum Mg²⁺ concentrations (P<0.05) before 6,4,2 days of calving. The anionic salts and Mg concentrations in diet had significantly effect on the serum Mg²⁺ concentrations (P<0.01) . The Mg concentrations in diet had significantly effect on the serum Mg²⁺ concentrations (P<0.01) before 6 days of calving to after 1 day of calving.5. The serum P and K⁺ concentrations of the eight groups no statistical significant difference were observed anong the groups (P>0.05). The serum Na⁺ concentrations ofâ… ,â…¡,â…¢groups were significantly higherâ…¤,â…¥,â…¦,â…§groups(P<0.05)before 2 days of calving. The serum Na⁺ concentrations ofâ… ,â…¡,â…¢,â…£groups were significantly higherâ…¤,â…¥,â…¦,â…§groups(P<0.05)on calving day. The serum Na⁺ concentrations of the LDCAD groups were significantly higher HDCAD groups(P<0.05)before 2 days of calving and on calving day.6. The serum PTH concentrations ofâ…¢,â…£groups were significantly lowerâ…¤,â…¥,â…¦groups(P<0.05)before 4 days of calving. The serum PTH concentrations ofâ… ,â…¡,â…¢,â…£groups were significantly lowerâ…¤,â…¥,â…¦,â…§groups(P<0.05)on calving day and after 1,3 days of calving. The serum PTH concentrations of the LDCAD groups were significantly lower HDCAD groups(P<0.05)before calving,calving day and after calving.The LDCAD diet had significantly increased the serum Hy concentrations (P<0.05).7. The urinary Ca²⁺ concentrations ofâ… ,â…¡,â…¢,â…£groups were significantly higherâ…¤,â…¥,â…¦,â…§groups (P<0.05). Different Levels of Ca and Mg of different DCAD diet had no significantly effect the urinary Ca²⁺ concentrations (P<0.05). The urinary Hy concentrations ofâ… ,â…¡,â…¢,â…£groups were significantly higherâ…¤,â…¥,â…¦,â…§groups (P<0.05). Different Levels of Ca and Mg of different DCAD diet had no significantly effect the urinary creat concentrations (P<0.05).8. LDCAD diets trended to increase the standard milk yield (P>0.05), and reduced the severity of udderedema and incidence of retained placenta.