Growth Traits, Breast Meat Yield and Quality of Broiler Genotypes under Hot Conditions

The study evaluated the body weight during growth (BWG), body weight at slaughter (BWS), breast meat yield (BMYg), percent breast meat yield (BMY) and breast meat quality (colour and drip loss) of geneti-cally featherless (scsc) broilers compared to their feathered sibs under hot conditions. Two hundred feather-less chicks and 200 feathered sibs were reared under hot conditions in two rooms (average temperature 29 to 33 ?C) divided into pens by genotypes and diets (control diet and 10%, 15% and 20% protein and energy reduction) for 50 days. Fattening traits (BWG and BWS), breast meat quantity traits (BMYg and BMY %) and breast meat quality traits [(colour: lightness(L*), redness (a*), and drip losses at 24 hours (h) and 72 hours (h) postmortem (PM)] were measured or calculated on 56 featherless and 39 feathered sibs. Results confirmed statistically significant improvements (P < 0.05) in favour of the scsc. On day 50, average values of body weight during growth (BWG), body weight at slaughter (BWS), breast meat yield (BMYg) and breast meat yield (BMY) in scsc vs. feathered sibs were: 2299 g vs. 1950 g, 2150 g vs. 1847 g, 390 g vs. 264 g, 18% vs. 14%, respectively. Breast meat colour at 24 h and 72 h PM was better in scsc with lower L* values (52.8 vs. 54.4 and 53.2 vs. 55.6) and higher a* values (3.2 vs. 2.5 and 4.2 vs. 3.2). Drip losses were lower in featherless birds compared to their feathered sibs at 72 h and 96 h PM (1.27% vs. 1.83% and 1.9% vs. 2.6%). Mortality on day 45 due to a heat wave of 38 ?C and low relative humidity (25%) led to the mor-tality of 2 out of 100 featherless birds (2%) and 30 out of 72 feathered sibs (42%). Thus, reduction in BWG, BWS, BMYg and BMY %, survival and breast meat quality of fast growing normally feathered birds under hot conditions can be counteracted by the introduction of the featherless (scsc) gene for cost effective com-mercial production in hot climate.