The effects of varying stocking densities on Guinea fowls (Numida meleagris) reared in a closed-barn system. II. Shackle line behavioral profiles and meat quality

Abstract

In this study, we assessed the potential effects of rearing at different stocking densities (low-SD: 6.6 birds/m², medium-SD: 9.3 birds/m², high-SD: 12 birds/m²) on the shackle line behavioral profile and meat quality traits of Guinea fowls in a closed-barn system for 13 weeks. Eighteen birds from each treatment at 13 weeks were subjected to tonic immobility (TI) test. The behaviors on the shackle line (straightening up, SU), total duration of wings flapping, TDWF) were measured for 60 sec after hanging, pause duration and blood flow ratio (%) were measured after birds were slaughtered, and meat quality traits were determined. The TI duration at slaughter age (90 d) was higher in medium- (478.1 sec) and high-SD (484.7 sec) birds than in low-SD birds (P = 0.027). The SU (% of birds), the first attempt for SU, TDWF, pause duration, blood flow duration and all meat quality traits were similar among SD treatments. However, drip loss of breast meat was higher in male birds (7.83 %) than in females (6.13 %) (P < 0.05). While no significant correlations were found between TDWF and breast meat quality traits, TDWF was strongly positively correlated with cooking loss in thigh meat of birds reared at low-SD (P < 0.05). Increased SU behavior in medium-SD birds was strongly associated with decreased cooking loss (r = -0.72) and decreased drip loss (r = -0.73) in the thigh meat of high-SD birds (P < 0.05). A strong positive correlation was found between SU behavior and blood flow ratio in low-SD birds (r = 0.72). Pause duration during struggling bouts and drip loss of the breast meat were very strong negatively correlated (r = -0.82, P < 0.05). Pause duration was also very strong positively correlated with blood flow ratio (r = 0.94, P < 0.01). No meat quality trait was significantly associated with TI duration in low- and high-SD birds. However, in medium-SD birds, increased TI duration was strongly associated with decreased blood flow ratio (r = -0.82, P < 0.05) and also strongly contributed to increased cooking loss (r = 0.72, P < 0.05) in breast meat. In conclusion, the SD-induced behavioral history during the rearing period and the fear status of the birds did not affect either behaviors on the shackle line or meat quality, which holds significant economic importance for the industry. Therefore, providing more space to Guinea fowls reared in closed-barns at high-SD by offering outdoor access (i.e. free-range systems) may enhance the overall welfare status and maintain meat quality.