Effects of mineral supplementation on reproductive efficiency of Simmental heifers

The objective of the present research was to evaluate the effects of mineral supplementation on estrus onset, growth, and hematological and biochemical parameters in Simmental heifers. The study was initiated by a field survey to determine the reproductive problem of the exotic breed cattle raised by smallholders. Complete minerals were then formulated and fed to 18 Simmental heifers for 14 weeks across three groups as follows: P0, no supplementation (control), P1, supplemented with mineral feed in meal form, and P2, supplemented with mineral in block lick form. Each treatment consisted of six heifers stratified by body weight into six groups for replication. Parameters measured included estrus onset time, body weight gain, mineral intake, blood mineral levels, hematology, total protein, and progesterone levels. Simmental heifers raised by smallholders were delayed in onset of first estrus (20.4 months) and first calving (30.17 months). Heifers supplemented with minerals (P1 and P2) had an earlier estrus in the 2nd and 4th weeks, while in the control groups (P0), the first estrus appeared in the 8th and 9th weeks. Heifers supplemented with block minerals (P2) had lower body weight gain, and Fe, Zn, and progesterone levels than those supplemented with minerals in meal form (P1). The results showed that mineral supplementation in meal form positively affected estrus onset, growth rate, and biochemical parameters in Simmental heifers.