Effect of breed and age on egg quality characteristics of two South African locally developed dual-purpose chicken breeds

Indigenous chickens are essential to rural livelihoods across Africa, providing meat and eggs for household nutrition and thus ensuring food security. However, information on egg quality traits of Potchefstroom Koekoek and Boschveld breeds remain limited, which is vital for identifying differences in performance, inform targeted breeding and management methods, and improve overall productivity. Hence, this study was conducted to explore the influence of breed and age on egg quality traits of Potchefstroom Koekoek and Boschveld chickens. A total of 100 chickens were randomly selected (n = 50 for each breed) and 800 eggs were randomly collected from the two breeds at 28, 32, 36, and 40 weeks of age, with 400 eggs collected per breed. An electronic weighing scale was used to measure egg weight (EW), shell weight (SW), and yolk weight (YW), while a digital Vernier calliper was used to measure egg width (EWD) and egg length (EL). Internal egg quality traits, including yolk ratio (YR), albumen weight (AW), albumen ratio (AR), yolk-to-albumen ratio (Y/A), and egg volume (EV), as well as external egg quality traits, including egg shape index (ESI), shell ratio (SR), shell surface area (SSA), and unit surface shell weight (USSW), were also determined. The findings revealed that Boschveld chickens had significantly higher EW (46.28 ± 0.33), SW (5.90 ± 0.03), EL (49.76 ± 0.32), EWD (36.55 ± 0.31), SSA (70.59 ± 0.39), YW (14.27 ± 0.12), EV (37939.80 ± 694.97), and Y/A (55.76 ± 0.51) than Potchefstroom Koekoek chickens. Age also had a significant effect on egg quality traits, with most traits increasing with advancing age and the highest values observed at 40 weeks. Overall, Boschveld chickens displayed superior performance in several key egg quality characteristics compared to Potchefstroom Koekoek chickens. In conclusion, both breed and age significantly influenced egg quality traits, and may assist management decisions and may provide baseline information for future breeding programmes.