Incubation temperature manipulation during fetal development reduces adiposity of broiler hatchlings

Abstract

Broilers are known as an efficient source of lean meat. Genetic selection resulted in broiler strains with large body size and fast growth, but a concomitant increase in fat deposition also occurred. Other than reducing nutrient intake, there is a lack of alternative methods to control body fat composition of broilers. The present study assessed whether incubation temperature (machine temperatures: 36ºC, 37.5ºC, and 39ºC; eggshell temperatures: 37.4 ± 0.08°C, 37.8 ± 0.15ºC, and 38.8 ± 0.33°C, respectively.) from d 13 affects broiler hatchling fat deposition. We analyzed adipocyte hypertrophy and proliferation in 3 body regions; weight and chemical composition of yolk-free chicks and yolk sacs; and serum lipid profile. Increased incubation temperature reduced abdominal and cervical adipocyte size. Independently of temperature, cervical adipocytes were smaller and showed higher proliferation than adipocytes in the abdominal and thigh regions. Smaller cervical adipocytes were observed in birds from eggs incubated at 36ºC and 39ºC. With regard to weight and composition of chicks, ash content as a percentage of dry matter was the only variable affected by temperature; it was higher in chicks from eggs incubated at 36ºC than at 39ºC and showed no significant difference between chicks incubated at 39ºC and 37.5ºC. Absolute and relative weights of yolk sacs were higher from eggs incubated at 39ºC than at 36ºC, and these two treatments did not differ from the 37.5ºC control. Absolute measures of yolk sac lipids, moisture, dry matter, and crude protein content were lower in chicks from eggs incubated at 36ºC, and no significant differences were found for these variables between chicks from eggs incubated at 37.5ºC and 39ºC. Hatchlings from eggs incubated at 36°C had significantly higher cholesterol levels than chicks incubated at the other 2 temperatures, but no additional effects on blood lipids were detected. Incubation temperature manipulation during fetal development altered cervical and abdominal adipocyte size in broiler hatchlings and could become a tool in hatcheries to manipulate chick quality, although further studies are needed to evaluate its long-term effects.

Incubation Temperature during Fetal Development Influences Morphophysiological Characteristics and Preferred Ambient Temperature of Chicken Hatchlings

“…The body uses heat exchange mechanisms as well as the metabolic rate of energy production to ensure the maintenance (43). The similar hormone rates suggest similar metabolic and growth rates and, consequently similar heat production, and this appear to be reinforced by similar incubation length and body mass showed in the present and also in a previous study [ 45 ]. In our view, the thinner and more vascularized skin occurrence without thyroid hormone changes allowed HT chicks to major conductive heat loss, indicated by the higher temperature at the body surface, enabling maintenance of body temperature without regulatory metabolic changes.…”

Poultry Egg Incubation: Integrating and Optimizing Production Efficiency

“…It was demonstrated that eggshell temperature increases from the second third of incubation at 36-39°C incubation temperature (Sgavioli et al, 2015;Almeida et al, 2016;. This increase is related with the greater metabolic heat production by the fetus during this high growth rate phase (Lourens et al, , 2007.…”

“…This shows that the embryo is able to react to minor temperature fluctuations inside the egg, and that it attempts to regulate its internal temperature within a very narrow range (Tzschentke & Nichelmann, 1997). Based on these findings, studies were carried out to assess the effects of incubation temperature on embryo temperature, thermal manipulation during incubation, and in-ovo injection of the anti-stress nutrients, such as vitamin C, as means to induce possible thermal adaptation of poultry during rearing or to promote phenotypic changes to meet specific objectives (Sgavioli et al, 2013(Sgavioli et al, , 2015Ferreira et al, 2015;Almeida et al, 2016;Morita et al, 2016 a,b).…”

Effects of different egg turning frequencies on incubation efficiency parameters

“…Commercial setters usually operate with a turning frequency of 24 times per day until the 18th D of incubation ( Freeman and Vince, 1974 ). However, in some studies, the setters were programmed to turn the eggs at a frequency of 12 times per day during the incubation process ( Almeida et al., 2015 ; Morita et al., 2016 ; Zhong et al., 2018 ). For example, in a study by Leandro et al.…”