Dietary Intake of the Parturient Cow

SUMMARY Observations have been made on 10 cows at calving to relate feed, calcium and phosphate intakes to serum calcium and whole blood inorganic phosphate levels. The effect of milk secretion was also considered. There was a reduction in the appetite, and in the calcium and phosphate intakes of cows as calving approached. This reduction was greater in the older cows. After calving, appetite returned to normal and rose to 20 per cent above precalving levels within 7 days of calving. All types of feed offered were refused by animals when they lost their appetite. The individual cow regressions of serum calcium and whole blood inorganic phosphate on feed intake before calving were very variable; after calving, these regressions became positive except for the regression of blood phosphate on feed and phosphate intake which tended to be negative in young cows. These findings are discussed in relation to the serum calcium and blood inorganic phosphate changes in normal cows and in one case of milk fever.