High temperature and oxygen supplementation can mitigate the effects of hypoxia on developmental stability of bilateral traits during incubation of broiler breeder eggs

Abstract

Hypoxia strongly affects embryonic development during the pre-hatch period. This study was conducted to investigate the effects of oxygen supplementation (O) and a 38.5°C high temperature (HT) at high altitude (HA, 1720 m) on morphological traits during a pre-hatch period and on relative fluctuating asymmetry (relative FA) and allometric growth during an early post-hatch period in broilers. A total of 720 eggs were obtained from a 45-week-old Ross 308 broiler breeder flock raised at sea level (2 m). The eggs were divided into six incubation condition (IC) groups and were incubated at HA. O groups were exposed to 23.5% O2 for 1 h daily from either days 0 to 11 (O0-11), days 12 to 21 (O12-21) or days 18 to 21 (O18-21) of incubation. HT groups were exposed to 38.5°C daily from either days 12 to 21 (HT12-21) or days 18 to 21 (HT18-21) of incubation. A control was maintained at 37.8°C and 21% O2. The hatched chicks were raised for 6 days at HA. Embryo/chick and beak lengths and head diameter were measured during pre- and post-hatch periods. The face, middle toe and shank lengths were measured for each chick. The relative asymmetry (RA), mean RA (MRA) and allometric growth of the lengths were computed and the existence of FA was demonstrated. The IC significantly affected the embryo length, with embryos of the O0-11 group shorter than embryos of the other O groups. Chicks were longer in the O and HT groups than those in the control, except for the O0-11. We found significant interactions between the IC and each development period for beak length. During the post-hatch period, the head diameter of the O0-11 was significantly smaller than that of the other groups, but not in O12-21. The interactions among IC, age and sex were significant for the RA of the face and middle toe lengths and for MRA. All the examined bilateral traits were evaluated as allometric growth. The FA for bilateral traits was determined in both sexes. The right (R) - left (L) and IR-Ll were the lowest in females for face length and in males for shank length from the O18-21 and in males for middle toe length from the O0-11 and HT18-21 groups. Therefore, the effects of factors such as HT and O2 could mitigate the adverse effects of HA-induced hypoxia on optimal developmental stability of bilateral traits of broiler.

Responses of developmental and physiological traits to manipulated incubation conditions in broiler embryos at hypoxic high altitude

“…This showed that metabolic activity of the embryo was affected differently by O 2 or heat exposure during this embryogenesis stage at hypoxic HA. A similar result was also reported at normoxia (2 m altitude), with increased liver weight by heat acclimation for 5 days after day 12 of incubation (Babacanoglu et al, 2006). Lourens (2008) indicated that deviations from 37.8 • C in the first or third week of incubation depressed embryo development.…”

“…Epigenetic changes concluding with adaptation to hypoxia play a key role in the systemic homeostatic responses to hypoxia Mutoh et al, 2012) which occurs by various physiological conditions (Semenza, 2003). Epigenetic adaptation to hypoxia by means of several practices during incubation may provide optimal embryonic development at HA (Babacanoglu and Güler, 2018). At HA, these practices might be O 2 supplementation to incubator and a higher incubation temperature because HA characterized by low atmospheric pressure resulting from air heat content causes the molecules to bounce off each other, and air temperature with increasing altitude decreases at a rate of approximately 6.5 • C per 1000 m. The results of recent studies on high incubation temperature indicated that embryos initially have an accelerated growth rate at a high incubation temperature.…”

“…For example, at the last stage of incubation, an increase in the O 2 level (25 %) resulted in improved embryonic growth (Lourens et al, 2007). A deviation of +0.7 • C from the optimum incubation temperature or an O 2 concentration of 23.5 % can mitigate the negative effects of hypoxia caused by HA (1720 m) for optimum embryonic development (Babacanoglu and Güler, 2018). Olkowski and Classen (1999) indicated that pulmonary hypertension or ascites susceptibility of broilers at sea level is associated with leading to cardiovascular failure due to rapid growth in broilers.…”

In ovo injection of testosterone to yolk sac modulates early posthatching development and physiology of male chick in broilers

“…The same measurements were repeated on the d 7 of chick age. The length of the chick was determined by measuring of the part between the tip of the beak and the last point of the middle toe of the chicks, lying so that the right wing was under the body, with the help of a fixed ruler with a scale of 0.1 mm ( Babacanoğlu and Guler, 2018 ). The head diameter was determined by measuring the distance from the beak hole to the junction of the beak ( Babacanoğlu and Yalçın, 2015 ).…”

“…The beak length was determined by measuring the distance from one ear hole to the other ear hole ( Babacanoğlu and Yalçın, 2015 ). The lengths of middle toe, face and shank were determined by measuring from the starting point of the middle toe to the tip, from the ear hole to the junction of the beak, and from the tip of the metatarsus bone to the point the sole of the foot, respectively ( Babacanoğlu and Yalçın, 2015 ; Babacanoğlu and Guler, 2018 ).…”