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Assessment of early-stage thermal variation on embryonic mortality, hatchability, growth performance, and carcass characteristics of broiler chickens




Wall, Brittany

Type of Degree

Master's Thesis


Poultry Science

Restriction Status


Restriction Type


Date Available



Timing and duration of thermal variation (TV) alters egg moisture loss, hatchability, chick BW, and performance. The objective was to evaluate the effect of TV during early-stage incubation on embryonic mortality, hatchability, post-hatch body weight, performance, carcass characteristics, and incidence and severity of 2 meat quality defects. Ross 708  Yield Plus breeder eggs (54 to 59 g) were allotted by weight into incubator egg trays. From ED 4 to 11, TV was applied, and eggs were incubated at 1 of 3 temperatures (n = 2 incubators per treatment); 97.5F (COLD), 99.5 F (CON), or 101.5 F (HOT). Incubators returned to the control temperature of 37.5 C from ED 11 to 21. Chicks were vent sexed, allotted to floor pens by TV treatment and sex (n = 6 replicates per treatment), fed a common diet in 3 phases, and processed at d 34. Wooden Breast (WB) and White Striping (WS) scores were determined 24 h post-processing by manual palpation. Incubation data were analyzed as a 1-way (TV) and performance and processing data were analyzed as a 2-way (TV  sex) ANOVA using the GLIMMIX procedure of SAS. Means were separated at P ≤ 0.05 with the PDIFF option. No differences were observed in embryonic mortality, hatchability, or proportion of chick sexes. HOT eggs were lighter than COLD eggs (P < 0.0001) at ED 18. COLD chicks were heavier at hatch than HOT and CON chicks (P = 0.001), likely due to hatch patterns among TV treatments. HOT chicks were heavier than COLD chicks (P < 0.0001) on d 9, 23, and 32 post-hatch. Greater overall BWG was observed in HOT and CON compared with the COLD (P = 0.0285). Birds from CON incubators had greatest overall feed intake (FI; P = 0.0084). COLD birds tended to have a 25-g reduction in breast weight (412 vs. 438 and 443 g; P = 0.0656) which resulted in a 6% decrease in breast meat yield compared with CON and HOT birds (P = 0.004). Altering incubation temperature did not impact WB or WS incidence or severity (P > 0.3762). These results underscore the importance of careful incubation temperature management to optimize broiler growth performance and carcass yields.