Characterisation of local Ghanaian chickens: growth performance evaluation based on Richards growth model and genetic size scaling.

The Richards growth model was fitted to body weight-age data of local and SASSO T44 chickens to describe their growth performance. Males had higher (P < 0.05) asymptotic mature weights than females. Within the local chicken population, birds from the savannah zone had higher (P < 0.05) asymptotic mature weights compared to forest chicken which ironically had higher body weights at hatch. Male local chicken had lower maturing rates compared to the females. Female local chicken were superior to SASSO T44 females in terms of maturing rate. On the average, local chickens took relatively longer time (78.4-83.3 days) to reach the point of inflection than the SASSO T44 population (74.2-79.8 days). However, there were no significant differences (P > 0.05) in the age at inflection among local chicken populations. The shape parameter for SASSO T44 chicken (0.053-0.370) and maturation rate for local chicken (0.177-0.198) were the most critical parameters. Scaling the body weights into degree of maturity highlighted the degree to which genotypes matured over time. Female chickens had the highest (P < 0.05) degree of maturity at all ages. The local chicken populations were also metabolically older than SASSO T44 chickens. Results of this study provide an opportunity to develop breeding strategies for local chicken by modifying either management practices or their genetic makeup to positively affect their growth and productivity.