Comparative characterization of carcass traits and physicochemical properties in market-age Kadaknath native chicken and commercial broiler chicken meat: A pilot study

Introduction

In recent years, there has been a noticeable shift in consumer preference toward native chicken meat in India, largely driven by perceptions of improved flavour, texture, and traditional value. Among indigenous breeds, Kadaknath occupies a distinct niche due to its pigmentation and perceived health attributes. However, its production profile differs markedly from that of commercial broilers, particularly in terms of growth rate and time to market. Commercial broilers, shaped by decades of intensive selection, achieve rapid body weight gain within a short production cycle. Selection emphasis on feed efficiency and muscle accretion has resulted in pronounced hypertrophy of the pectoralis major (Havenstein et al., 2003) [1] . By contrast, Kadaknath follows a slower growth trajectory, typically reaching marketable size only after 24-28 weeks. From a biological standpoint, these differences are not limited to body weight alone. Muscle development, connective tissue organization, and metabolic properties evolve continuously with age. Consequently, when birds are compared at their respective market ages-as in the present study-the comparison inherently integrates both genetic differences and physiological maturity effects. This distinction is important. Traits such as tenderness, for instance, are influenced not only by genotype but also by age-dependent factors including collagen cross-linking, fiber architecture, and proteolytic activity (Dransfield and Sosnicki, 1999; Purslow, 2005) [2,3] . Therefore, rather than attempting to isolate genotype alone, the present study adopts a market-age systems approach, which more closely reflects real production and consumption contexts.

Materials and Methods

Experimental Design

Six Kadaknath chickens (25 weeks) and six commercial broilers (6 weeks) were evaluated. Individual pre-slaughter live weights were recorded.

Slaughter and Carcass Evaluation

Carcass Traits

In this dataset, broilers showed numerically higher values for most carcass weight parameters. However, only giblet weight reached statistical significance (p=0.0087). The magnitude of this difference was large (g ≈ 2.

3), suggesting a meaningful biological effect despite the limited sample size.

Cut-Up Parts

The contrast in carcass partitioning was more pronounced.

Broilers exhibited markedly higher breast weight and yield, whereas Kadaknath birds showed greater drumstick weight and leg yield. These differences were statistically significant and associated with large to very large effect sizes.

Physicochemical Traits

Muscle pH and WHC did not differ significantly between groups. However, shear force values were consistently higher in Kadaknath birds. Given the nearly 19-week difference in slaughter age between groups, this pattern is unlikely to be incidental.

Effect Sizes

Large effect sizes were observed for breast weight, leg yield and shear force, supporting robust differences despite small sample size. [4,5] .

Discussion

Tenderness and Connective Tissue Maturation

The shear force results warrant closer consideration. In the present dataset, Kadaknath birds exhibited values more than four times those of broilers. This difference is unlikely to arise from measurement variability alone. A plausible explanation lies in age-dependent connective tissue development. As birds age, collagen undergoes structural modification through cross-link formation, increasing its resistance to thermal and mechanical disruption (Purslow, 2005) [3] . Given that Kadaknath birds were slaughtered at a substantially later stage, the observed increase in shear force is consistent with established meat science principles (Dransfield and Sosnicki, 1999) [2] .

Role of Proteolysis

Post-mortem proteolysis contributes to meat tenderization through degradation of myofibrillar proteins. In younger animals, this process tends to be more effective relative to connective tissue strength. In older birds, however, increased structural rigidity may limit the impact of proteolysis (Marcinkowska-Lesiak et al., 2016) [6] .

pH and WHC Stability

The similarity in pH values suggests comparable ultimate glycolytic decline. WHC, which is closely linked to protein denaturation and structural integrity, also showed no significant difference. However, given the sample size, moderate differences cannot be ruled out.

Comparative context

The present findings are consistent with global studies comparing slow-and fast-growing poultry genotypes. Fanatico et al. (2007) [7] reported higher shear force values in slower-growing birds, while Rajkumar et al. (2016) [4] observed similar carcass partitioning patterns in indigenous breeds. Importantly, the effect sizes observed here (g > 2.0 for several traits) are at the higher end of reported values, suggesting a particularly strong divergence between the systems evaluated.

Conclusion

Within the constraints of this dataset, clear differences emerge between market-age Kadaknath and broiler chickens. Broilers show greater breast yield, while Kadaknath exhibits higher leg yield and markedly increased shear force. These findings are best interpreted as reflecting differences in growth trajectory and physiological maturity. While the results are robust for traits with large effect sizes, further studies with expanded design are required to isolate genotypespecific effects. 2005 [8] Slow-growing vs fastgrowing broilers 63 d vs 42 d Fast-growing ↑ Slow-growing ↑ Slow-growing ↑ Growth rate influences muscle fiber size and connective tissue Rajkumar et al., 2016 [4] Aseel vs commercial broiler 16 wk vs 6 wk Broiler ↑↑ Native ↑ Native ↑ Slower growth linked to higher collagen maturity Singh & Pathak, 2017 [5] Kadaknath [8] and Rajkumar et al.

Comparative Literature

(2016) [4] similarly reported elevated shear force values in slow-growing or indigenous genotypes. Connective tissue maturation and collagen cross-link density have been identified as major contributors to increased mechanical resistance with advancing age (Dransfield and Sosnicki, 1999; [2] Purslow, 2005) [3] . The magnitude of effect sizes observed in the present study (g > 2.0 for several traits) exceeds many reported values in comparable genotype studies, suggesting strong divergence between extended-growth native systems and accelerated broiler production paradigms.

Acknowledgement

AcknowledgementThis research was funded by Department of Poultry Science, Madras Veterinary College, TANUVAS, Chennai -07, Tamil Nadu, India.

References

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