Phosphorus Fertilization of Pangolagrass Pastures and Phosphorus, Calcium, Hemoglobin and Hematocrit in Blood of Cows

A study was made of the effect of phosphorus applied as fertilizer in the form of super, super+lime, rock, colloidal, triple and basic slag to pangolagrass pastures on the phosphorus, calcium, hemoglobin and hematocrit composition of the blood of grazing cows from 1950 to 1965. The effects of four seasons of the year and age of cattle on these substances were studied.Over-all average phosphorus concentration for the control cows was 4.3, compared to 5.1 mg. per 100 ml. of plasma for the six phosphate treatment groups. September and December were generally higher than those in March and June (P<0.01). Heifers at 1 yr. and cows at 15 to 17 yr. of age had approximately 1 mg. per 100 ml. more (P<0.01) phosphorus in the plasma than intermediate age cows.Calcium was not influenced by the phosphatic treatments. In March the average value of all cows was 9.8 compared to 11.3 mg. per 100 ml. plasma in September (P<0.01). Values for calcium decreased (P<0.01) from 11.0 to 11.5 mg. per 100 ml. plasma up to 6 yrs. of age, to 8.9 to 9.9 during the period of 11 to 17 yr. of age.Hemoglobin values did not vary significantly due to phosphorus fertilizer treatments of the pastures. Twelve grams of hemoglobin per 100 ml. blood was found in March compared to 13.0 gm. during December (P< 0.01). Values of 12.3 to 13.3 gm. per 100 ml. were observed during the first 9 yr. of age, but from 10 through 17 yr. of age values decreased to 11.3 to 12.3 gm. per 100 ml. blood (P<0.05).Average hemacrit values ranged from 48.1 for cows on colloidal to 52.1 for animals in the superphosphate treatment group (P<0.01). Values obtained in June and September were lower (P<0.01) than those in December and March. Hematocrit values for cows 1 to 8 yr. old ranged from 50 to 54% compared to values of 46 to 50 during 9 through 17 yr.of age (P<0.05).