The Effect of Copper and Zinc Sources on Liver Copper and Zinc Concentrations and Performance of Beef Cows and Suckling Calves

SIMPLE SUMMARY: During gestation, increased nutrient intake is required by the cow to meet the requirements of the maturing fetus, and if these requirements are not met, changes in fetal development can occur. However, little is understood about the effects of gestational manipulation of minerals on progeny growth and immune function. Minerals provided in an organic form have been shown to be more soluble and readily available to the body for absorption. Therefore, the objectives of this study are to determine if the source of gestational copper and zinc affects cow reproductive performance, calf growth, and calf health. Cows (n = 287) were assigned to an inorganic or organic source of copper and zinc prior to breeding, and the treatments continued until weaning. Cow body weight, pregnancy data, calf weaning weight, and antibody response were recorded. The cows receiving the inorganic treatment had heavier body weights and body condition scores at breeding in Year 2 of the study, while the cows on the organic treatment had heavier body weights at weaning in Year 2. The cows that received the organic mineral had improved pregnancy rates in Year 1. The calves from the organic treatment had heavier weaning weights but there was no influence on calf health. ABSTRACT: To determine the influence of the source of gestational and postnatal Cu and Zn supplementation on cow and calf performance, cows (n = 287) were assigned to one of the following two treatments: (1) inorganic (INORG) treatment, in which cows were supplemented with 15 mg of Cu (as CuSO(4)) and 15 mg of Zn (as ZnSO(4)) per kg of diet DM, or (2) organic (ORG) treatment, in which cows were supplemented with 15 mg of Cu (as Cu proteinate; Bioplex Cu, Alltech, Inc., Nicholasville, KY, USA) and 15 mg of Zn (as Zn proteinate; Bioplex Zn, Alltech, Inc., Nicholasville, KY, USA) per kg of diet DM. The treatments were initiated prior to breeding and continued throughout gestation until weaning. Liver biopsies were collected for analysis of mineral content. Cow body condition score (BCS), body weight (BW), pregnancy data, calf weaning weight (WW), and antibody response of the calves were recorded. The cows receiving the INORG treatment had a greater BW (p < 0.05) and BCS (p < 0.01) at breeding in Year 2, while the cows on the ORG treatment had a greater (p < 0.05) BW at weaning in Year 2. The cows that received the ORG mineral had improved (p < 0.05) conception rates in Year 1. The calves receiving the ORG treatment had heavier (p < 0.05) 205-day adjusted WWs.