Effect of short-term pre-hatch heat shock of incubating eggs on subsequent

Abstract

________________________________________________________________________________ AbstractThe aim of this study was to investigate the effect of thermal conditioning of broiler chickens during embryonic development on subsequent performance under standard rearing conditions. During incubation eggs from 32-, 45-and 56-week old Ross 308 broiler parent stock were subjected to a 2 h heat shock of 39 °C on days 14 and 15 of incubation. Eggs in the control were incubated throughout incubation at 37 °C. Chicks were feather sexed and equal numbers of each sex were placed in each pen per treatment, and reared for 42 days. Live weight, mortality and feed conversion ratio (FCR) were used as measures of performance. The final (six-week) live weights of broilers from young, mid and older parents for the treatment and control groups were 2113 ± 13.8 vs. 2159 ± 20.0, 2084 ± 29.2 vs. 2139 ± 20.0 and 2096 ± 17.6 vs. 2131 ± 24.3 g, respectively. The six-week live weight of the heat-treated group (2098 ± 12.0 g) was significantly lower than that of the control (2143 ± 12.2 g). The 1-6 week mortality figure was significantly lower in the heat-treated group of chickens from the young (83) and mid parent (77) groups compared to their controls (130 and 119), respectively. However, in the treatment group the incidence of mortality in broilers from the older parent group was significantly higher (105) than that of the control (79). The overall mortality without considering the parent age group was significantly lower in the treatment group (265) than in the control group (328). Mean FCR (g feed/g gain) of the chickens of the three parent groups was 1.79 ± 0.02 vs. 1.75 ± 0.03, 1.85 ± 0.03 vs. 1.77 ± 0.02 and 1.80 ± 0.03 vs. 1.77 ± 0.03 for the treatment vs. control groups, respectively, but the difference was significant only in the mid age parent group. These results suggest that prenatal thermal conditioning is not detrimental to broiler growth under standard rearing conditions in the absence of thermal stress. However, survival rate was improved but live weight and FCR were in some cases significantly poorer. ________________________________________________________________________________

Growth performance, histological and physiological responses of heat-stressed broilers in response to short periods of incubation during egg storage and thermal conditioning

“…In contrast, studies by 41 – 43 , demonstrated that a decrease in body weight from hatching until 6 weeks of age for chicks hatched from eggs exposed to different thermal conditioning regimes. Sengor et al 41 exposed eggs to TC at 39 °C for 2 h per day at E14 and E15, while 42 subjected eggs to 39.6 °C or 40.6 °C.…”

“…In contrast, studies by 41 – 43 , demonstrated that a decrease in body weight from hatching until 6 weeks of age for chicks hatched from eggs exposed to different thermal conditioning regimes. Sengor et al 41 exposed eggs to TC at 39 °C for 2 h per day at E14 and E15, while 42 subjected eggs to 39.6 °C or 40.6 °C. Similarly, Zaboli et al 43 found that thermal conditioning of Ross 308 eggs at 39.5°C and 65% relative humidity for 12 h per day from E7 to E16 led to a decrease in body weight when contrasted with the control group.…”

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“…Este tipo de efecto se puede minimizar controlando la ventilación en los galpones y regulando su temperatura interna. Sin embargo, para ello se requieren sofisticados diseños de vivienda, que demandan altas inversiones, haciendo inviable su uso en producciones con bajos recursos económicos (Sengor et al, 2008). Cuando la temperatura ambiental (TA) aumenta; activa la zona de termo neutralidad del ave, induciendo una condición de estrés, con la consecuente generación de: hipertermia aguda, alcalosis respiratoria, desequilibrio electrolítico, reducción del consumo, baja tasa de crecimiento y aumento en la mortalidad (Brossi et al, 2009).…”

Estimulações térmicas durante o desenvolvimento embrionário de frangos de corte

“…Estudos mostram que o imprinting das funções corporais estimula a eficiência nas granjas. Alguns autores citam a adaptabilidade ao calor em frangos de corte expostos a alterações na temperatura de incubação , enquanto que outros SENGOR et al, 2008) não encontraram efeito no desempenho zootécnico. Diversos estudos têm relatado as consequências de estresse térmico na produção animal nos últimos anos levando em consideração razões de bem-estar animal e índices econômicos.…”