Effect of prepartum feeding of anionic and cationic diets on plasma macro minerals and vitamin D homeostasis in crossbred cows

The effect of feeding prepartum anionic diet on feed intake, plasma levels of seven major minerals considered for formulating anionic diet and calcium homeostasis was studied in Karan Fries cows. Commonly available feeds and fodders were analyzed for their macro minerals content to calculate their dietary cation anion clifference (DCAD) value. Fourteen pregnant Karan Fries cows were divided into two equal groups and were fed with cationic (14.58 and meq/100g DM) and anionic (−11.82 meq/100g DM) diet, respectively. Both the treatments were started 45 days before expected date of calving. After parturition, both the groups were fed with cationic dietupto 45 days. Both the groups were fed isonitrogenous and isocaloric diets containing concentrate and roughage in 45:55 ratio. Roughage portion was made up of 45 parts wheat -straw and 55 parts green maize/sorghum. Prepartum feed intake in both the groups was not affected by dietary treatments, but, there was significant increase in feed intake in anionic group during postpartum period. After calving, there was significant increase in plasma calcium (11.1 vs 8.9 mg/dl), phosphorus (4.8 vs 3.6 mg/dl) and magnesium (2.4 vs 1.8 mg/dl) in anionic group compared to cationic group of cows. An increase in plasma PTH, hydroxyproline and better utilization of 25-OH vitamin D was observed in anionic group which might be responsible for its higher plasma calcium concentration. It is inferred that feeding anionic diet 45 days prepartum increased calcium availability at the time of calving through increased PTH, better conversion of 25 OH vitamin D to 1, 25 (OH)₂ D and increased bone mobilization.