Alternative trace mineral supplementation strategies for improved cow performance

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This study will help to develop best animal management practices to improve cow-calf sector profitability and trace mineral (TM) supplementation programs for improved beef cow performance. This work will provide producers with evidence-based recommendations for mineral supplementation strategies during the breeding season and mitigate some potential reproductive impacts of high sulfate water. Injectable TM solutions are not currently licensed in Canada for cattle; however, use of effective injections may ensure that all cows have adequate TM status entering the breeding season. A reduction on non-pregnant cows would then lead to greater calving rates, increasing the pounds of calf weaned and economic returns to the cow-calf enterprise. A 3 year replicated study will be managed over three breeding seasons and will involve approximately 240 mature beef cows. The study will investigate the benefits of administering a TM injectable (compared to supplement TM free choice alone) on reproductive outcomes. Baseline values of mineral status will be measured 4 wk pre-calving, and cows will be randomly allocated to treatment after blocking by age. At 4 wk pre-calving, 4 wk pre-breeding, and at pregnancy 40 cows per treatment will have a blood sample drawn to determine mineral serum concentration. At 4 wk pre-calving, 4 wk pre-breeding, at breeding, and at pregnancy, a body condition score will be determined for all cows. A 63-d natural breeding program will be managed during the breeding season. Pasture clippings and water samples will be collected pre- and post-calving and monitored for mineral concentration throughout the study period. Blood samples will be analyzed for TM concentration. Ultrasound will be used to determine pregnancy 35 d after breeding. Reproductive performance will be evaluated by measuring overall pregnancy rate and calving rate. Calf weaning weights will also be recorded each yr to determine kg of calf weaned per treatment. Calf birth dates will be recorded to determine differences in calving distribution between treatments.A partial-budget analysis will be used to compare provision of MultiMin 90 with no provision of injectable mineral.