Haematological responses and erythrocyte osmotic fragility in pregnant Yankasa ewes and their lambs

The aim of the study was to evaluate blood cellular responses and erythrocyte osmotic fragility (EOF), as an index of oxidative stress, in pregnant Yankasa ewes and their lambs. Blood samples were collected from each ewe at pre-gestation, gestation (weeks 3, 10 and 17, corresponding to early-, mid-, and late-gestation, respectively), prepartum (weeks 18 and 19), postpartum (immediately after lambing, weeks 1 and 3); and from their lambs postpartum. The blood samples were used to determine blood cellular parameters and EOF. Results revealed higher (P < 0.05) packed cell volume (PCV) and red blood cell (RBC) counts at mid-gestation than prepartum and postpartum values. Neutrophil-lymphocyte ratio was higher (P < 0.05) on parturition day compared to other stages. There was no significant (P> 0.05) difference in EOF during the different stages in the dams. On the day of lambing, PCV, haemoglobin and lymphocyte counts were higher (P < 0.05) in lambs than dams, but lower neutrophil count was recorded in the lambs compared to dams. The EOF was lower in lambs than their dams (P < 0.05) on the day of lambing. In conclusion, the mid-gestation PCV and RBC values were higher than pre- and post-partum values, whereas parturition influenced neutrophil-lymphocyte ratio compared to other stages. The results showed that most blood cellular changes occurred during the periparturient period, when most life-threatening disorders affect ewes. Erythrocyte membranes of lambs were more resistant to hypotonicity, indicating that the erythrocyte membranes of the lambs were less vulnerable to oxidative stress damage than those of their dams. Hence, Yankasa lambs may be more resistant to immediate postpartum oxidative stress than their dams.