The effect of a supplemental trace mineral injection on developing beef bull and heifer reproduction

Master of ScienceDepartment of Animal Sciences and IndustryKarol E. FikeTrace mineral supplementation is necessary for proper reproductive success. Little research has evaluated the effect of an injectable trace mineral product, in conjunction with a dietary mineral supplementation program, on reproduction. This thesis includes two separate studies evaluating the use of an injectable trace mineral product, in addition to a dietary mineral program, on the reproductive success of yearling bulls and heifers. In the first study, we hypothesized that when dietary trace mineral needs are met, administration of an injectable trace mineral product to developing beef bulls would cause a short-term increase in circulating trace mineral concentrations, but not alter semen quality nor ability to pass a breeding soundness examination. Trace mineral treatment did not affect scrotal circumferences and BW of bulls throughout the trial (P [equal to or greater than] 0.20). Trace Mineral bulls had greater (P [equal to or less than] 0.0001) trace mineral concentrations at 8 h post-treatment than Control bulls. Semen trace mineral concentrations on d 42 and 91 were similar (P [equal to or greater than] 0.52) between treatments. Sperm parameters improved (P [equal to or less than] 0.003) from d 42 to 91, but did not differ (P [equal to or greater than] 0.06) between treatments. A similar (P = 0.94) percentage of Trace Mineral (67%) and Control (68%) bulls passed a BSE 91 d post-treatment. In the present study, supplemental trace mineral injection was successful at raising circulating trace mineral levels, but did not alter semen trace mineral levels nor improve semen quality. In the second study we hypothesized that when dietary trace mineral needs are met, the use of an injectable trace mineral product in developing heifers would not affect pregnancy rates at single service fixed-time artificial insemination (FTAI). Trace Mineral heifers had greater (P = 0.02) pregnancy rates (51.28%) than Control heifers (25.58%). The percentage of Trace Mineral (30.77%) and Control heifers (47.50%) that displayed estrous behavior prior to FTAI as indicated by a red estrous detection patch was not different (P = 0.13) between treatments. In the present study, despite dietary trace mineral requirements being met, use of an injectable trace mineral injection improved pregnancy rates following FTAI, but did not affect estrous behavior