Abstract

To determine the effects of repeated trace mineral injections on heifer development and reproductive performance, commercial Angus heifers ( n = 290; 199 ± 34.3 kg) were utilized in a completely randomized design. Heifers were stratified by BW into 6 groups and assigned to injectable trace mineral (MM; Multimin90) or saline injection (CON) given post-weaning at 221, 319, and 401 ± 22 d of age. Throughout development, heifers grazed endophyte-infected fescue-red clover pastures and were supplemented with modified corn distillers grains (2.7 kg·heifer-1·d-1) and given access to free choice inorganic minerals formulated to meet or exceed NRC recommendations. Heifer BW and BCS were collected at trial initiation and 4-7 week intervals thereafter. Hair coat scores (HCS) and respiration rates (n = 30 heifers/treatment) were collected at 269, 310, and 361 ± 22 d of age. Additionally, blood and liver samples were collected at trial initiation and estrous synchronization from 30 heifers/treatment to determine trace mineral status. At 319, 372, and 421±22 d of age, antral follicle count and ovarian size were determined via ultrasonography. Two blood samples from all heifers were collected 10 d apart, concurrent with ultrasound dates, for puberty determination. Estrous synchronization was initiated and reproductive tract scores (RTS) were collected at 421±22 d of age. Heifers had AI at 430 ± 22 d of age. Heifer BW, BCS, and HCS did not differ (P ≥ 0.12) throughout development, except at 268 ± 22 d of age when BCS was greater (P = 0.03) for MM than CON. Respiratory rates were greater (P = 0.05) for MM than CON at 269±22 d of age, but did not differ (P ≥ 0.66) at 310 and 361 ± 22 d of age. Plasma Mn and Zn concentrations did not differ between treatments (P ≥ 0.54). However, MM had greater (P ≤ 0.01) plasma and liver concentrations of Cu and Se compared to CON. Interestingly, MM decreased (P = 0.02) liver Zn concentrations compared to CON and there was no difference (P = 0.60) in liver Mn concentrations. Antral follicle count and ovarian size did not differ (P ≥ 0.43) between treatments. Throughout development, the number of pubertal heifers was less (P < 0.01) for MM than CON. However, there was no difference (P ≥ 0.26) in RTS or AI pregnancy rates (36 and 37% for MM and CON, respectively). Supplementing an injectable trace mineral increased heifer Cu and Se status; however, no effect was noted on ovarian development or reproductive performance.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call