No abstract

Copper (Cu) and zinc (Zn) deficiency may cause poor weight gain, hematological changes, and immune failure in extensive beef cattle breeding systems. Diagnosis of the deficiency is based on plasma Cu and Zn concentrations; however, there are discrepancies regarding data interpretation. Here, plasma Cu and Zn concentrations are discussed as risk markers. We evaluated the effect of parenteral Cu and Zn supplementation on their plasma concentrations, weight gain, hematological parameters, and antibody titers to bovine herpes virus 1 (BoHV-1). Pre-weaning calves (n = 40; 99 ± 8 kg bw) from a typical breeding area of Argentina with background Cu and Zn deficiency were used. They were assigned to two homogeneous groups in a completely randomized design. Calves were subcutaneously injected with 0.3 mg/kg Cu and 1 mg/kg Zn (supplemented group), or saline solution (control), every 40 days during 120 days. Plasma Cu and Zn concentrations, hematological parameters, and weight were recorded. On days 40 and 80 of the trial, calves were vaccinated with inactivated BoHV-1. Antibody immune response was measured on days 80 and 120. Data were analyzed with a mixed model for repeated measures over time. Before treatment, plasma Cu was low and Zn was adequate in both groups. After treatment, plasma Cu increased and remained within a normal range, whereas plasma Zn remained constant. Supplemented animals had higher weight gain (p < 0.01); higher hematocrit, mean corpuscular volume, and mean corpuscular hemoglobin levels (p < 0.05); and higher immune response to BoHV-1 (p < 0.05). Our results suggest that Cu and Zn supplementation improved daily weight gain and the immune response of pre-weaning calves.

Selenium (Se) is an essential trace element with important functions in animals and whose deficiency is associated with reproductive failures. The aim of this study was to investigate the effect of Se concentrations during in vitro maturation (IVM) of Bos taurus oocyte within the reference ranges for Se status in cattle. For this purpose, Aberdeen Angus cumulus-oocyte complexes (COCs) were matured in IVM medium supplemented with 0, 10, 50, and 100 ng/mL Se (control, deficient, marginal, and adequate, respectively). The results demonstrated that marginal and adequate Se concentrations added during IVM increased viability and non-apoptotic cumulus cells (CC). Moreover, the addition of Se to culture media decreased malondialdehyde level in COC with all studied concentrations and increased total glutathione content in CC and oocytes with 10 ng/mL Se. On the other hand, total antioxidant capacity of COC, nuclear maturation, and the developmental capacity of oocytes were not modified by Se supplementation. However, 10 ng/mL Se increased hatching rate. In conclusion, supplementation with 10 ng/mL Se during in vitro maturation of Bos primigenius taurus oocytes should be considered to improve embryo quality.