Effect of supplemental trace minerals on novel measures of bull fertility

Authors: Geary, Thomas; Waterman, Richard; VAN EMON, MEGAN - Montana State Extension Service; RATZBURG, COLE - University Of Wyoming; LAKE, SCOTT - University Of Wyoming; EIK, BRAD - Montana State University; ARMSTRONG, DOUG - Montana State University; Zezeski, Abby; HELDT, JEFF - Micronutrients Usa Llc

Submitted to: Translational Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/3/2019
Publication Date: 12/16/2019
Citation: Geary, T.W., Waterman, R.C., Van Emon, M.L., Ratzburg, C.R., Lake, S., Eik, B.A., Armstrong, D.R., Zezeski, A.L., Heldt, J.S. 2019. Effect of supplemental trace minerals on novel measures of bull fertility. Translational Animal Science. 3(1):1813-1817. https://doi.org/10.1093/tas/txz102.
DOI: https://doi.org/10.1093/tas/txz102

Interpretive Summary: The objective of this study was to evaluate effects of copper and zinc supplementation on traditional and novel measures of fertility in peripubertal bulls. Angus (n = 48; Yr 1) or Angus-Hereford (n = 80; Yr 2) bull calves were fed a growing diet from weaning at 189 ± 2.2 (Mean ± SEM) d of age without mineral supplementation until 264 (Yr 1) or 307 (Yr 2) d of age. Within year, bulls were blocked by sire (Yr 2), stratified by body weight (283 ± 4.3 kg, Yr 1; 360 ± 2.5 kg; Yr 2) and randomly assigned to one of four trace mineral supplements provided daily in Calan gate equipped pens (4 bulls/pen) for 84 d: 1) zinc with no copper (ZN; 299 mg/d; n = 32), 2) copper with no zinc (CU; 131 mg/d; n = 32), 3) zinc and copper (ZNCU; n = 32), and 4) no copper or zinc (CON; n = 32). Liver biopsies were collected from all bulls at the beginning and end of supplementation and semen was collected every 28 d during supplementation. Fertility measures included a breeding soundness evaluation (BSE) and flow cytometry measures of viability, 3 h viability, acrosome integrity, DNA integrity, mitochondrial potential, and oxidative radicals. Bulls in Year 1 were not liver Cu deficient on d 0 and liver Cu and Zn were lower on d 84 than d 0. Bulls in Year 2 were liver Cu deficient on d 0 and liver Cu and Zn were increased on d 84 in those bulls receiving each respective mineral. Bulls receiving ZNCU had greater ADG than CU bulls (P = 0.05). All fertility measures improved from d 0 to 84 in bulls and were not affected (P > 0.10) by mineral supplementation. After 28 d of mineral supplementation, ZNCU bulls had greater (P > 0.02) live sperm (54 vs 43%) and sperm with intact acrosome (68 vs 56%) than CU bulls and tended to have greater (P = 0.08) live sperm than ZN bulls (46%). Mineral supplemented bulls had greater (P = 0.04) percent live, reactive oxygen resistant sperm (39%) than CON bulls (31%). After 56 d of mineral supplementation, sperm from ZNCU bulls had greater (P = 0.04) mitochondrial energy potential than CU bulls. None of the fertility measures were different between mineral supplementation treatments by 84 d of supplementation. In summary, mineral homeostasis mechanisms for peripubertal bulls are extremely efficient. Copper and zinc mineral supplementation of peripubertal bulls did not have major improvements in any laboratory or chute-side measures of bull fertility. Bulls with extreme mineral deficiencies or diet antagonists may respond to supplementation differently.

Technical Abstract: This study was conducted to evaluate effects of copper and zinc on fertility in young bulls. After weaning, bulls were fed a growing diet without trace mineral for 75 to 118 days during a two-year study. Bulls were divided to receive either no mineral supplement (CON), zinc supplement (ZN), copper supplement (CU), or ZNCU for 84 days. Liver biopsies were collected from all bulls at the beginning and end of treatment and semen was collected every 28 days during treatment to evaluate fertility. Bulls in Year 1 were not copper deficient on d 0 and liver copper and zinc were lower on day 84 than day 0. Bulls in Year 2 were copper deficient on day 0 and liver copper and zinc were increased on day 84 in those bulls receiving each respective mineral. Bulls receiving ZNCU had grew faster than CU bulls. Bull fertility improved from day 0 to 84 and was not affected by mineral treatment. On specific days of semen testing, only very minor differences in fertility were detected. In summary, bulls were very efficient with mineral recycling. Copper and zinc supplements did not improve any laboratory or chute-side measures of bull fertility. Bulls with extreme mineral deficiencies or diet antagonists may respond to supplementation differently.