Makromineral merupakan unsur yang sangat dibutuhkan untuk fisiologis dan reproduksi ternak. Penelitian ini bertujuan untuk mengetahui kadar magnesium dan kalium dalam darah sapi sebelum dan sesudah pemberian molases mineral blok A dan B di Gunung Kidul. Sepuluh ekor sapi peranakan ongole yang memiliki predisposisi ambruk digunakan dalam penelitian ini. Sample darah diambil dari setiap sapi dan kadar magnesium dan kaliumnya diperiksa sebelum dan sesudah suplementasi menggunakan molases mineral blok A dan B. Hasil pemeriksaan magnesium dan kalium pada penelitian ini, diketahui bahwa kadar magnesium sebelum pemberian molases mineral blok 8 ekor sapi dengan kadar magnesium normal, 2 ekor sapi dengan kadar magnesium tinggi, setelah pemberian molases mineral blok 2 ekor sapi dengan kadar magnesium normal dan 8 ekor sapi dengan kadar magnesium tinggi. Kadar kalium sebelum pemberian molases mineral blok seekor sapi dengan kadar kalium rendah, 4 ekor sapi dengan kadar kalium normal dan 5 ekor sapi dengan kadar kalium tinggi, setelah pemberian molases mineral blok 4 ekor sapi dengan kadar kalium normal dan 6 ekor sapi dengan kadar kalium tinggi. Berdasarkan hasil penelitian disimpulkan bahwa 10 ekor sapi mengalami kenaikan kadar magnesium dan kalium setelah pemberian molases mineral blok A dan B.

Macrominerals is an elemen that needed for the livestock physiology and reproduction. This study aimed to know the levels of magnesium and potassium in the cattle’s blood before and after supplementing by mineral block molasses A and B in Gunung Kidul. A lot of ten ongole crossbreed which is have a collapse predisposition are used in this study. Blood sample are taken from every cow then its magnesium and potassium levels was tested before and after the supplementating by gamavet A and B. Magnesium and potassium examination results in this study, known that magnesium levels before mineral block molasses distribution has 8 cattles with normal magnesium level, 2 cattles with higher magnesium level, after mineral block molasses distribution has 2 cattles with normal magnesium level and 8 cattles with higher magnesium level. Potassium level before mineral block molasses distribution has a cattles with lower potassium level, 4 cattles with normal potassium level and 5 cattles with higher potassium level, after mineral block molasses distribution has 4 cattles with normal potassium level and 6 cattles with higher potassium level. Based on the results of this study it its concluded that 10 cows have increasing magnesium and potassium levels above normal after supplementating by mineral block molasses A and B.

Kata Kunci : magnesium, kalium, makromineral, sapi peranakan ongole, molases mineral blok