Biometric measurements of body and internal organ traits of indigenous chickens on free range in South-Eastern Nigeria
A biometric study of the body conformation and internal organs of the indigenous chickens on free range in rural areas of Imo State in South-Eastern Nigeria was conducted using 5 Local Government Areas. It was observed that the predominant plumage colours were black (51.25%) and brown (36.25%) for the hens while the cocks were predominantly black (30.36%) and red (25.01%). The dressed colour of the birds was majorly yellow and white comprising of (70.68%) and (29.32%) for the hens and (77.75%) and (22.25%) for the cocks, respectively. Shank colour was black (95.4%) and white (4.65%) for the hens, while the cocks were (54.24%) black and (46.76%) white respectively. The mean shank length, neck length and back length of 6.725±0.09 cm, 11.11±0.20 cm and 17.77±0.29 cm were estimated for the hens, while the cocks had mean shank length, neck length and back length of 7.79±0.13 cm, 11.35±0.30 cm and 18.29±0.44 cm, respectively. The mean body weights of the hens and cocks were 868.48±21.18 g, and 1032±57.84 g, respectively with cocks being significantly (P<0.05) higher in body weight and back length than hens. The mean biometric and internal organ measures of chickens per Local Government Area (LGA) were also investigated with no significant (P>0.05) differences among chickens in the five LGAs except for weight of proventriculus and full intestine. Regression equations for the prediction of body weight using the biometric and internal organ measurements were obtained under two functional forms (linear and semi-log) which showed a weak coefficient of determination (R2) ranging between 7.5 to 24.3% for biometric measurements, and a strong coefficient of determination (R2) ranging between 21.4 to 98.89% for internal organs. There was no significant correlation coefficient (r) between the biometric measurements taken, but strong and significant correlation (r) was shown between internal organs and body weight. Therefore, indigenous chickens of South-Eastern Nigeria exhibit wide variability among phenotypes in terms of physical appearance, biometric measurement and internal organ characteristics. More so, the internal organs can be predicted more effectively than biometric measurements by the body weight, using regression models of the two functional forms; and significant indirect selection can be made to improve internal organs like gizzard weight using the bodyweight, due to significant correlation coefficient established.
Keywords: - biometric, internal organs, prediction equation, indigenous chicken, extensive, South -Eastern Nigeria.