Effect of supplementation of monensin and chromium in close-up diets on some production and reproduction parameters in Holstein dairy cows

Effect of supplementation of monensin (Mon), chromium (Cr) and their interaction in close-up period was investigated on 30 pregnant multiparous dairy cows in a completely randomized design with four treatments. Treatments were: 1) un-supplemented cows (CON), 2) Mon supplemented cows (400 mg Mon/d), 3) Cr supplemented cows (0.03 mg Cr/metabolic BW); 4) Mon-Cr supplemented cows (400 mg Mon/d plus 0.03 mg Cr/metabolic BW). The production and fertility parameters were recorded. Dry matter intake, milk yield, milk composition as well as open days did not show significant difference among treatments. Placenta delivery time was earlier in supplemented cows with Mon-Cr (120 minutes) compared to the control group (243.1 minutes) (p