PSXIII-16 Supplementing organic-complexed or inorganic Co, Cu, Mn, and Zn to beef cows during gestation: physiological and productive responses of cows and their offspring until weaning

Abstract

Abstract Pregnant, non-lactating beef cows (n = 190; 117 ± 2.2 d of gestation; d 0) were assigned to receive: 1) sulfate sources of Cu, Co, Mn, and Zn (INR; n = 95) or 2) an organic complexed source of Cu, Mn, Co, and Zn (AAC; Availa®4, Zinpro; n = 95). From d 0 to calving, cows were maintained in a single pasture and individually offered treatments three times weekly. Cow BW and BCS were recorded on d -30, d 97, upon calving, and at weaning and liver biopsies performed in 30 cows/treatment. Milk production was estimated at 42 ± 0.5 d postpartum via weigh-suckle-weigh (WSW). Liver and longissimus muscle (LM) biopsies were performed in 30 calves/treatment upon calving and 24 h later, at WSW, and at weaning. No treatment effects were detected (P ≥ 0.49) for cow BCS, despite AAC cows having greater (P = 0.04) BW on d 97. Liver Co (P < 0.01) concentrations were greater for AAC compared to INR cows, and liver concentrations of Cu were greater (P = 0.02) for INR compared to AAC cows on d 97. Upon calving, INR cows had greater (P ≤ 0.01) liver Cu and Zn concentrations compared to AAC cows. Cows receiving AAC had greater (P = 0.04) hepatic mRNA expression of metallothionein 1A at calving, and their calves had greater (P = 0.04) hepatic mRNA expression of superoxide dismutase at weaning. Milk production did not differ between AAC and INR cows (P = 0.70). No treatment effects were detected (P ≥ 0.29) for mRNA expression of LM genes in calves at birth and weaning. Calf birth and weaning BW were similar (P ≥ 0.19) between treatments. Hence, supplementing AAC or INR to beef cows during the last 5 mo of gestation yielded similar cow-calf productive responses until weaning.