Effects of inorganic copper injection in beef cows at late gestation on fetal and postnatal growth, hematology and immune function of their progeny.

To determine if Cu injection during late gestation can affect fetal and postnatal growth, hematology and immune function of progeny, 70 multiparous pregnant Angus cows, at 219 ± 15 d of gestation, were ranked by BW and BCS and randomly assigned to one of two treatments: Cu + (n = 35) in total 160 mg of Cu were administered subcutaneously in two moments (80 mg per moment) at 64 ± 15 d and 54 ± 15 d prepartum; and Cu- (n = 35), in total of 16 ml of sterile NaCl solution (9 g / l) were administered subcutaneously in two moments (8 ml per moment) at 64 ± 15 d and 54 ± 15 d prepartum. Calves from both treatments were weaned at 260 ± 15 d of age, male calves were separated from female calves and stockered on natural pastures until 690 ± 15 d of age, then placed into a feedlot for 104 d before slaughter. At the beginning of the experiment, cows Cu serum concentration was similar (P = 0.34) between treatments and these reflected a severe Cu deficiency (Cu + = 24.2 ± 1.5 μg/dl; Cu- = 22.2 ± 1.4 μg/dl). At calving, Cu serum concentration was greater (P < 0.01) in Cu + cows than Cu- cows. Copper serum concentration in calves from Cu + cows was greater at birth (P = 0.02) and 75 ± 15 d of age (P < 0.01) and tended (P = 0.07) to be greater at 160 ± 15 d of age compared to calves from Cu- cows. Calf BW at birth did not differ (P > 0.10) between treatments, however, calf BW adjusted at 75 d of age tended to be greater (P = 0.10) in calves from Cu + cows compared to calves from Cu- cows. Calf ADG from birth to 75 d of age was greater (P = 0.04) in calves from Cu + cows compared to calves from Cu- cows. Calf hematological parameters and titers of neutralizing antibodies against BHV-1 after primary and secondary vaccination against respiratory diseases did not differ (P > 0.10) between treatments. During finishing period, steers BW, 12th rib fat thickness and LM area were not affected (P > 0.10) by treatments. In summary, inorganic Cu injection during late gestation in Cu deficient beef cows allows to increase Cu serum concentration in calves from birth to 160 d of age. This event was associated with an increase in ADG and a tendency to increase BW during the first 75 days of life. After 75 days of age, any effect on the offspring performance was not observed.