Effects of maternal Cu, Mn, and Zn supplementation from different sources on physiological and productive responses of cows and their offspring.

Seventy-two non-lactating, pregnant Angus cows (initial body weight (BW) = 637 ± 13 kg; body condition score (BCS) = 5.5 ± 0.07 yr; and age = 6.1 ± 0.57; exposed to AI = 54 and Bull = 18) were ranked by pregnancy type, BW, and BCS and assigned to receive a supplement containing: 1) Cu, Mn, and Zn sulfate source (INR; n = 24), or 2) Cu, Mn, and Zn organic-complexed source (ORG; n = 24), or 3) Cu, Mn, and Zn hydroxychloride source (HDX; n = 24). From d -11 (d of gestation 195 ± 5.1) to calving, cows were allocated to rangeland pasture. From d 0 until calving, cows were gathered and fed the treatments thrice a week. Cow BW and BCS were recorded, and blood was collected on d -11 and -10, upon calving, and at weaning. Liver biopsies were performed in all cows on d -10 and upon calving (cows and calves). Longissimus muscle (LM) biopsies were performed, and blood was collected in all calves upon calving. Calves were weaned on d 260, backgrounded for 99 d, and then sent to a commercial feedyard. Calves blood samples were collected on days 245, 260, 264, 268, 275, 280, and 288. No differences were detected (P ≥ 0.31) for cow BW and BCS changes among treatments during gestation, and mineral sources did not improve (P ≥ 0.16) mineral liver concentrations of Zn, Mn, Se, and Co at parturition. However, there was a tendency (P = 0.07) for HDX to have improved liver Cu concentration vs. ORG and INR cows. Cows fed HDX and ORG had improved (P ≤ 0.03) BCS at weaning, and BCS changed from parturition to weaning vs. INR cows. No treatment differences were detected (P ≥ 0.21) for calf birth measurements, IgG levels, mRNA expression of hepatic enzymes, or LM genes associated with muscle and adipose tissue development. At weaning and during the backgrounding, no treatment differences were detected (P ≥ 0.21) for offspring performance, health outcomes, plasma cortisol, serum nonesterified fatty acids (NEFA), and serum beta-hydroxybutyrate (BHBA). However, a tendency for a treatment × d interaction was detected (P = 0.07) for haptoglobin concentrations, which was reduced (P < 0.01) in calves from cows supplemented with HDX vs. calves from cows supplemented with ORG and INR 15 d after weaning. No treatment effects were noted (P ≥ 0.35) for final BW, feedyard ADG, and carcass traits between treatment groups. Overall, different sources of Cu, Mn, and Zn supplemented to late-gestating beef cows yielded similar cow-calf productive responses from birth to finishing.