Productive, reproductive, and physiological response of Holstein cows to dicalcium phosphate supplementation in tropical dairy systems

Abstract

Seventy-two commercial Holstein cows, which produced 3500 liters of milk in their previous lactation and averaged 3.5 calvings with a live weight of 492 kg ± 16, were used to determine the effect of dicalcium phosphate supplementation in cows grazing on grasses of the genus Cynodon Dactylon. The treatments were: A) supplementation with 50 g/cow/day of dicalcium phosphate; B) supplementation with 25 g/cow/day of dicalcium phosphate; and C) no dicalcium phosphate supplementation. Supplementation was mandatory. Milk production improved significantly with the addition of dicalcium phosphate supplementation (11.4, 12.1, and 12.3 kg/cow/day) at supplementation levels of 0, 25, and 50 grams/cow/day. Blood base excess (-0.8, 2.0, and 2.4 mval/liter) and urine pH (7.36, 7.40, and 7.41) were lower in non-supplemented animals. Reproduction also showed a significant improvement, with a decrease in the calving-to-gestation interval (176, 154, and 132 days) at supplementation levels of 0, 25, and 50 grams of dicalcium phosphate. The results indicate that under the studied conditions, it is highly advisable in the tropics to supplement the basal diet with at least 25 grams/cow/day of dicalcium phosphate.