PSVIII-29 Influence of oral drench and free-choice supplementation of organic-complexed trace minerals compared to inorganic trace mineral supplementation on pregnancy rates and calf performance.

Abstract Reproductive performance of cattle is dependent on nutrition; therefore, mineral supplementation is essential when preparing the animal for conception. The objective was to compare beef cow conception rates, reproductive performance, and calf gain when consuming mineral tubs with organic trace mineral sources along with a pre-breeding drench administration of trace minerals compared to mineral tubs with inorganic trace mineral sources. Commercial Angus cows (n = 204) with calves at side were allocated randomly to one of six pastures based on pre-study weight and body condition score (BCS), as well as calving date, cow age, and parity. These six pastures contained four multiparous groups and two primiparous groups and were assigned randomly within parity type to two treatment groups: 1) supplementation with tubs containing organic complexed trace minerals or 2) supplementation with tubs containing inorganic trace minerals. Tubs contained similar macrominerals and white salt was also available in all pastures. Mineral tubs were weighed and placed into pastures on d 0. Mineral intake was determined by measuring tub weights weekly. An estrous synchronization protocol was initiated on d 29 and 30. At CIDR insertion, 30 mL of an oral drench trace mineral solution (ProFusion, Zinpro, Eden Prairie, MN) was administered only to the groups receiving the organic mineral supplementation. CIDRs were removed prior to fixed-time artificial insemination (FTAI), and heat detection patches were applied (d 43 and 44). Following synchronization, FTAI was conducted at 66 h and estrus expression was determined by a missing heat detection patch or greater than 50% rubbed off the patch (d 45 and 46). Ten days after FTAI (d 56), fertile bulls were added to each pasture. The FTAI pregnancy status was determined by ultrasound ~39 d post FTAI (d 84 and 85), and calves were weighed. Overall pregnancy was determined at ~76 days post FTAI (d 121 and 122). Bulls were removed from pastures 60 days after FTAI and mineral supplementation ended (d 105). Pregnancy data were analyzed using the GLIMMIX procedure and performance data were analyzed using the MIXED procedure in SAS 9.4. Significance was declared at P < 0.05 and tendencies were observed between 0.05 ≤ P < 0.10. There were no significant differences between estrus expression (P > 0.5769), FTAI pregnancy rates (P > 0.3492), or average daily gain (ADG) in calves from birth to d 85 (P > 0.5751). Overall pregnancy rates were 97% for cows that received organic supplement and 92% for cows that received inorganic supplement (P = 0.1467). In this high performing herd, trace mineral source did not have an effect on FTAI pregnancy rates or calf performance, but there was a trend for a greater pregnancy rate in the cows supplemented with organic complexed trace minerals.