Alternative trace mineral supplementation strategies for improved cow performance

这项研究将有助于制定最佳的动物管理实践，以提高母牛-小牛部门的盈利能力和微量矿物质（TM）补充计划，以提高肉牛的生产性能。这项工作将为生产者在繁殖季节提供基于证据的矿物质补充策略建议，并减轻高硫酸盐水的一些潜在生殖影响。目前，可注射TM溶液尚未在加拿大获得用于牛的许可;然而，使用有效的注射剂可以确保所有奶牛在进入繁殖季节时都具有足够的TM状态。减少非妊娠奶牛的数量将导致更高的产犊率，增加断奶小牛的体重和奶牛-小牛企业的经济回报。一项为期3年的重复研究将在3个繁殖季节进行管理，将涉及约240头成年肉牛。本研究将研究TM注射剂给药（与单独补充TM自由选择相比）对生殖结局的益处。将在产犊前4周测量矿物质状态的基线值，并在按年龄区组后将奶牛随机分配至治疗组。在产犊前4周、配种前4周和妊娠时，每次处理40头奶牛将采集血样以测定矿物质血清浓度。在产犊前4周、配种前4周、配种时和妊娠时，测定所有奶牛的身体状况评分。在繁殖季节将进行63天的自然繁殖计划。将在产犊前后采集婴儿粪便和水样，并在整个研究期间监测矿物质浓度。将分析血样的TM浓度。在配种后35天将使用超声波确定妊娠。将通过测量总体妊娠率和产犊率来评价生殖性能。每年还将记录小牛断奶体重，以确定每次给药断奶的小牛kg。将记录小牛出生日期，以确定治疗组之间产犊分布的差异。将使用部分预算分析比较提供MultiMin 90与不提供可注射矿物质。

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.