Mineral profile of crossbred F ₁ Holstein x Gyr dairy cows during the transition period in summer and winter

_{^{Perfil mineral de vacas F1 Holandês x Gir durante o período de transição no verão e inverno}}

ABSTRACT

The transition period is often a great challenge for dairy cows and mineral imbalances are frequent. With the aim to better understand the mineral profile of F₁ Holstein x Gyr dairy cows and their performances under the different conditions of summer and winter, we collected blood samples to measure calcium, magnesium and phosphorus. Samplings were performed during summer and winter, on 15 and 13 pluriparous F₁ Holstein x Gyr dairy cows, respectively. Blood sampling started 4 weeks prior to the expected calving date until 30 days postpartum. The mean concentrations of all three minerals had a different pattern during the transition period in each season, representing the interaction time x season. Calcium concentration was lower in winter and more animals suffered from subclinical hypocalcemia (100%) then in summer (38.46%). Magnesium concentration was also lower in winter and 46.67% of animals had hypomagnesemia, contributing for the higher hypocalcemia frequency observed in the same season. A high proportion of animals had hyperphosphatemia what can represent an environmental problem and more attention should be given to it. The high frequency of animals with subclinical hypocalcemia is alarming once that can lead to greater consequences.

Keywords:
hypocalcemia; hypomagnesemia; milk fever; hyperphosphatemia