Submitted to: Journal of Animal Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/25/2004
Publication Date: 8/1/2004
Citation: Ahola, J.K., Baker, D.S., Burns, P.D., Mortimer, R.G., Enns, R.M., Whittier, J.C., Geary, T.W., Engle, T.E. 2004. Effect of cu, zn, and mn supplementation and source on reproduction, mineral status, and performance in grazing beef cattle over a two-year period. Journal of Animal Science 82: 2375-2383. Interpretive Summary: Both supplementation (at National Research Council recommended concentrations) and source of copper, zinc, and manganese impact the concentration of these minerals in the liver and plasma of multiparous beef cows, although the effect of these differing body mineral concentrations on reproduction or calf performance is unclear. After one year without supplemental copper, zinc, and manganese, pregnancy rate to a synchronized artificial insemination can be affected and season-long reproductive performance may be impacted. Additionally, trace mineral source may impact pregnancy rate to a synchronized artificial insemination, particularly if the insemination was administered based on an observed estrus. Finally, under certain conditions, kilogram of calf weaned per cow exposed can be affected by both trace mineral supplementation and source, although the effects are not well understood and deserve further attention in future research trials.
Technical Abstract: Beef cows (n = 178 yr 1; n = 148 yr 2) were used to evaluate the effects of Cu, Zn, and Mn supplementation and source on reproduction, mineral status, and performance in grazing cattle during late gestation through breeding. Cows were blocked by expected calving date, age, BW, body condition score, and liver mineral status and assigned to treatments consisting of: 1) Control (no supplemental Cu, Zn, or Mn); 2) Organic (ORG; 50% organic and 50% inorganic Cu, Zn, and Mn); and 3) Inorganic (ING; 100% inorganic CuSO4, ZnSO4, and MnSO4). Supplemented cows had greater liver Cu (P < 0.01), Zn (P < 0.05), and Mn (P < 0.01) concentrations compared to controls, while liver Cu concentration was greater (P < 0.01) in ORG than ING cows. At the end of yr 2, supplemented cows had greater liver Cu (P < 0.01) concentration relative to controls while control cows had greater liver Mn (P < 0.02) concentration than supplemented cows following yr 1. In yr 1, pregnancy rate to AI did not differ (P = 0.07) between control and supplemented cows. In yr 2, supplemented cows had a higher (P < 0.05) pregnancy rate to AI than controls. Pregnancy rates to an observed estrus were higher (P < 0.05) among supplemented cows than controls. In yr 1, kg of calf weaned per cow exposed was greater (P < 0.05) in controls compared to supplemented cows and kg of calf weaned per cow exposed was greater (P < 0.05) in ING than ORG treatments. However, in yr 2, kg of calf weaned per cow exposed was greater (P < 0.05) in controls compared to supplemented, and tended (P = 0.09) to be greater in ORG than ING treatments. In summary, supplementation and source of trace minerals affected mineral status and productivity of cows.