Oxidative stress in neonatal lambs and its relation to health status and passive colostral immunity

Oxidative stress (OS) related to birth in ruminants may increase susceptibility to diseases. However, information about the physiological changes related to OS in lambs is limited. This study was designed to evaluate changes in OS parameters [total antioxidant status (TAS, mmol Trolox Equiv./L), total oxidant status (TOS, μmol H₂O₂ Equiv./L)] and calculated oxidative stress index (OSi = TOS/TAS * 100, Arbitrary Unit) and its association with passive colostral transfer immunity and health status in neonatal Akkaraman crossbreed lambs. Control group of healthy lambs (n = 15) were blood sampled before (day 0) and after colostrum intake (on day 1, 2, 4, 7, 14 and 28) in order to evaluate the effect of colostrum intake on TAS, TOS and OSi over time. In addition, a group of lambs (experimental group, n = 60), based on their health status and different cut off value of IgG (mg/dL), was also blood sampled at 24 ± 1 h of colostrum ingestion to determine the relationship between OS parameters, IgG and health status. OS was evident at birth and gradually decreased in control group as TOS (days 0:8.06 ± 0.64, 1:7.05 ± 0.51, 2:5.23 ± 0.35, 4:5.05 ± 0.2, 7:5.13 ± 0.34, 14:3.75 ± 0.12 and 28:3.73 ± 0.15 μmol H₂O₂ Equiv./L), OSi (days 0: 8.35 ± 0.64, 1: 9.17 ± 1.05, 2:6.83 ± 0.6, 4:6.30 ± 0.20, 7:6.67 ± 0.59, 14:4.46 ± 0.19 and 28:4.87 ± 0.29 au) and TAS (days 0: 0.97 ± 0.02, 1:0.82 ± 0.04, 2:0.81 ± 0.05, 4:0.81 ± 0.02, 7:0.80 ± 0.03, 14:0.85 ± 0.02 and 28:0.79 ± 0.03 mmol Trolox Equiv./L) values changed over time. In the experimental group, the lambs died in the first week of the neonatal period had higher levels of TOS (10.3 ± 0.90 μmol H₂O₂ Equiv./L) and OSi (1.61 ± 0.22 au) than healthy ones (TOS:6.90 ± 0.36 μmol H₂O₂ Equiv./L, OSi:1.12 ± 0.11 au) (P < 0.001). The gradual decrease in OS in the neonatal period was accepted as a sign of improved antioxidant response. The study disclosed that deaths may develop when OS at birth is not balanced by suffıcient amount and quality of colostrum an important source of antioxidants such as enzymes and vitamins. The study presented may provide new information in the field of study on oxidative stress in neonatal lambs and help to prevent deaths in the first week of life. It can also be useful in developing preventive measures such as supplements of antioxidants to colostrum.