Effects of sex and age on the osmotic stability of Sahel goat erythrocytes

Adaptation of goats to the arid and semi-arid environments may involve adjustments in erythrocyte osmoregulation. Sexual dimorphic and age-related effects on osmotic stability of the goat erythrocyte were investigated to determine physiological variations. Apparently healthy male (n = 23) and non-pregnant dry female (n = 24) Sahel goats, aged <1, 1–1½, >1½–2, >2–2½, and >2½ years with mean body weights of 10.35–27.21 kg, were selected for the study from a semi-intensively managed flock. Heparinised venous blood of each goat was used to determine packed cell volume, erythrocyte count, mean corpuscular volume and osmotic fragility. Erythrocyte parameters did not vary with sex or age of the animal. Erythrocyte osmotic fragility (EOF), determined in hypotonic buffered saline, did not show sexual difference, but age elicited significant (p < 0.05) variation in the saline tonicities (8.0–9.0 g/L) at erythrocyte fragilities of 10–40 %, with highest and lowest mean values at the age of 1–1½ and >1½–2 years, respectively. Body weights increased (p < 0.05; r = 0.96) with age, and 85.8 % weight gain occurred in the transition from age of <1 to 1–1½ years, whereas subsequent weight gains in other age transitions were 8.3, 18.8 and 9.9 %, respectively. Sex and age did not influence saline tonicities at the median erythrocyte fragility. The effect of age on EOF at minimal hypotonicity, occurring after a period of rapid growth, seemed to associate the change in membrane stability with actions of growth-promoting hormones on lipid metabolism which could have altered the lipid content and permeability of erythrocyte membrane.