Abstract

This study evaluated the effect of ascorbic acid (AA) supplementation on erythrocyte osmotic fragility (EOF) of guinea fowls across seasonal variations in the Northern Guinea Savannah zone of Nigeria. Forty healthy mixed sex guinea fowls were randomly assigned to control (n = 20) and experimental (n = 20) groups. Experimental birds received oral AA at 50 mg/kg body weight, while controls received none. Meteorological parameters, including dry- and wet-bulb temperatures, relative humidity, and temperature-humidity index (THI), were recorded during rainy, Harmattan, and hot-dry seasons. Blood samples were collected after three weeks, and EOF was determined by exposing erythrocytes to graded NaCl solutions (0.10–0.90%). Results revealed seasonal variations in THI, with the hot-dry season posing the greatest thermal load, followed by the Harmattan and rainy seasons. Haemolysis increased with decreasing NaCl concentration across all groups. Control birds exhibited significantly higher (P < 0.05) haemolysis than AA-supplemented birds during hot-dry and Harmattan seasons, whereas no significant differences were observed during the rainy season. The findings suggest that oxidative stress-induced erythrocyte fragility is most severe in the hot-dry season and that AA supplementation reduces haemolysis by enhancing erythrocyte membrane stability. Supplementation with AA is therefore recommended during hot-dry and Harmattan seasons to improve resilience and productivity in guinea fowls.

Key words: Ascorbic acid, Erythrocyte osmotic fragility, Guinea fowls, Oxidative stress, Thermal stress