Abstract
ABSTRACT Adequate environmental temperature control is essential for incubation efficiency. Layer breeder eggs (n=360) were weighed and distributed in a completely randomized experimental design with two treatments, consisting of two incubation temperatures (T1=37.5 °C, control; and T2=39.0 °C, hot), with two incubators per temperature, and 90 eggs per incubator, totaling 360 eggs. Hatchability, embryo mortality, and chick cloacal and body surface temperatures were not affected by incubation temperature. Eggs incubated at the hot temperature presented greater egg mass loss and higher eggshell conductance than those incubated at the control temperature. Layer chicks derived from eggs incubated at control temperature showed greater absolute weight, yolk-free egg mass, and heavier hearts than those from eggs submitted to heat stress during incubation. The control group presented lower base excess and ionized calcium blood levels. Incubating eggs at temperatures higher than those recommended compromises body and heart development of layer chicks and negatively affects blood ionized calcium availability, and therefore, bone mineralization during embryo development. Efficient temperature control during the incubation of fertile eggs is essential to obtain good quality layer chicks.
Highlights
Environmental temperature and humidity, airflow, and egg turning are some of the physical factors that influence incubation (Lourens et al, 2005; King’ori, 2011)
In addition to metabolic changes, organ weight is reduced when fertile eggs are exposed to high incubation temperatures (Leksrisompong et al, 2007; Lourens et al, 2007)
Three hundred and sixty fertile eggs laid by 47-weekold Hisex White layers breeders were weighed and randomly divided in two treatments: incubation at 37.5 °C (T1=control treatment) or at 39.0 °C (T2=hot incubation temperature treatment)
Summary
Environmental temperature and humidity, airflow, and egg turning are some of the physical factors that influence incubation (Lourens et al, 2005; King’ori, 2011). Environmental temperature is reported as the most critical physical factor affecting embryo development and hatchability (Yalçin & Siegel, 2003). Respiratory, cardiovascular, and metabolic status can be evaluated using blood markers, which are sensitive to temperature changes and are important indicators of the physiological responses of birds to stressors. In addition to metabolic changes, organ weight ( heart weight) is reduced when fertile eggs are exposed to high incubation temperatures (Leksrisompong et al, 2007; Lourens et al, 2007). Chicks with low heart weight may present metabolic disorders related to cardiovascular development (Leksrisompong et al, 2007)
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