THE RELATIONSHIP BETWEEN BEHAVIOUR AND MORPHOMETRIC TRAITS IN YOUNG CHICKENS
Authors: TOYE A. A. , RAJI T. B. 
Published: December 2024

The correlation between behavioural (anxiety, sociality and cognition in Open Field, T-Maze, Forced Approach and Voluntary Approach tests) traits on the one hand and morphometric traits including body weight, length of body parts (Body length, Body girth, Shank length, Keel length, Wing length) and associated growth rates, Body mass Index, and Body girth: Body length ratio) from age 1 to age 8 weeks on the other, was examined in a cohort of 44 chickens consisting of 22 local (Yoruba Nigerian Local Chicken) and 22 exotic (11 Hubbard Broiler and 11 Isa Brown Layer) chickens. The levels of correlation between 160 directly measured and derived traits (of which 44 were behavioural) was determined by the use of the Pearson's method. A matrix of correlation coefficients of all 12,720 possible unique pairwise comparisons was generated. Of the 5104 Behavioural vs. Morphometric trait correlations, Low (-0.3< r < 0.3), Medium (0.3 <r< 0.7 and -0.3>r<-0.7) and High (0.7<r<1.0 and -0.7 r < -0.7) inter-trait correlations were observed in 83%, 16% and 1% of cases respectively, and the highest Positive and Negative Coefficients observed were 0.75 and +0.75 respectively By contrast, in the 6730 unique Behavioural vs. Behavioural plus Morphometric vs. Morphometric trait correlations, Low, Moderate and High inter-trait correlations were observed in 18%, 26% and 56% of cases respectively, and the highest Positive and Negative Coefficients observed were 1.00 and + 1:00 respectively. Consideration of absolute coefficient values revealed a median coefficient of 0.27 (Low Correlation). All coefficients of correlation equal to or exceeding +0.33/- 0.33 were significant (p < 0.05). The highest positive coefficients of correlations (r 0.7, High Positive Correlation) between behavioural and non-behavioural traits correspond to a link between Latency to cross the first square in an Open Field Test (which embodies anxiety and locomotory components) at age 7 weeks and Body size (BW, BL, SL, WL, BG) as shown in Table 2 and Figure 1. High coefficients of correlation were also observed between Latency to cross the first square in an Open Field Test (which embodies anxiety and locomotory components) at age 7 days and Body size (BW, WL, KL, SL, BMI) as shown in Table 2 and Figure 1. In addition, high positive correlation (r0.7) was observed between Time resting in an OFT at age 48 days on the one hand, and body size (BW, BG, GLR, BMI) as shown in Table 2 and Figure 1. The high negative coefficients of correlation occurred between Time ambulating in an Open Field Test (Behavioural traits) at age 6 weeks on the one hand and body weight, body shape and fatness indices (Morphometric traits) including BW, BG. GLR and BMI (Figure 1 and Table 2). These data point to the potential utility of morphometric traits as heurictic/surrogate markers for behavioural traits in poultry breeding and management. Further, they suggest that determinants of activity in a stressful environment may determine body weight and size of chickens as has been observed in humans and laboratory animals with consequences for the incidence and progression of non-communicable metabolic dysfunction/diseases and their sequelae., and/or alternatively, that determinants of early body weight and size determine activity in under anxiety inducing stress, as has been shown in the relationship between obesity and stress related health conditions in humans. Further studies will partition the genotype and environmental influences on the high correlation between behaviour and morphometric traits reported here, and will define the underlying molecular basis of the former.