Physical Body Deformity Effects on Differential Growth and Body Traits Development in Commercial Broilers

Abstract

Physical deformities have been a recurrent challenge on broiler production in the tropics. The effect of physical body deformity (PBD) on differential growth of 550 commercial broiler chicks of Ross308 strain from day-old to 56 days were evaluated. Experimental design was completely randomized Design (CRD), while treatment groups were normal birds (NB), crooked neck (CN), twisted Leg (TL) and crooked neck+twisted leg (CN+TL). Data were collected on body weight (BWT, g), drumstick length (DST, cm), wing length (WGL, cm), shank+toe length (STL, cm) and leg length (LEL, cm); and were subjected to General Linear model (GLM), _α=0.05, regression and Tukey’s Honestly Significant Difference (HSD) procedures of Statistical Analytical Systems software, SAS^® v8 (2008). Physical body deformity depressed broiler growth and development significantly (P<0.05) with small to large effects sizes (ds = -1.40 to 0.70). The differences in latent growth between deformity groups were significant (P<0.05), of practical ( dS>0.5) and large (f 2>0.4) importance from age 35 to 56 days. The CN+TL broiler group was most significantly depressed by physical deformity with linear growth speed of 0.43, and quadratic late growth speed of -0.19. Most adverse impact of the deformity conditions on growth and body development spanned from 35 to 56 days, and could lead to rejection of live birds at maturity and low profitability of small flock enterprises in the tropics.

Keywords: Commercial broilers, Physical abnormalities, Growth and development, Torticollis, Valgus-varus angulation