Growth rate, phenotypic correlation and repeatability estimates of body weight and linear body traits of Cobb and Arbor Acre broiler strains

Abstract

Correlation coefficients are useful tool in animal breeding as a means of predicting potential response. In this study, body weight (BW) and linear body traits records of Arbor Acre and Cobb broiler strains obtained at 3 – 8 weeks were used to compare the growth performance of the strains as well as estimate the phenotypic correlations (rp ) among BW and the linear body traits. Repeatability (R) values of BW and the linear body traits were estimated at weeks 3, 5 and 7. Atotal of 200 day old chicks, 100 each of Arbor Acre and Cobb were used for the study. The linear body traits considered were body length (BL), shank length (SL), chest circumference (CC), keel length (KL), wing length (WL) and drum stick length (DSL). Significant differences (P<0.05) were observed between the strains for BW and the linear body traits at the various weeks. BW differed significantly at weeks 5, 6 and 7, which ranged from 1036.67 ± 36.93 – 1736.67 ± 46.41 for Arbor Acre and 930.00 ± 20.59 – 1563.33 ± 33.26 for Cobb. Arbor Acre showed significant (P<0.05) superiority to Cobb in their linear body traits in most of the weeks. BW had high significant (P<0.05; P<0.01) positive rp with the linear body traits, which ranged from 0.535 (KL) – 0.842 (BL) for Arbor Acre and 0.523 (SL) – 0.834 (BL) for Cobb. The rp among the linear body traits in both Arbor Acre and Cobb were positive but ranged from moderate to high. The R estimate of BW of Arbor Acre and Cobb were all very highly repeatable at weeks 3, 5 and 7 ranging from 0.90 – 0.99. R values for the linear body traits ranged majorly from moderate {(0.31 – 0.67 and 0.37 – 0.69)}to high {(0.78 – 0.97) and 0.97) and (0.71 – 0.92)} for Arbor Acre and Cobb, respectively across the weeks evaluated. The result of this study indicates that Arbor Acre could be a strain of choice for rearing in our study area owing to its superiority over Cobb in terms of growth performance. All the linear body traits measure were good estimators of BW in both strains as well as each other, implying that any phenotypic selection on one trait will lead to improvement of others. The high repeatability estimates of body weight and some of the linear traits indicate that fewer records would be required to adequately characterize the inherent growing ability of the birds at the various stages of growth.