The objective of this study was to investigate the effects in ovo injection of black cumin (BC) extract on chick's quality and response of thermally challenged broiler chickens. A total of 700 hatching eggs of broiler chickens (Marshall) were assigned to 7 treatments of 100 eggs each and incubated using the conventional protocol (37.8°C) for the first 10 d and then exposed to a high temperature (39.6°C) for 6 h daily from day 10 until day 18 of the incubation. At embryonic day 17.5, the eggs were randomly allotted to 7 treatment groups, viz.: eggs without in ovo injection (WA), eggs injected with 0.9% saline solution (SA), 3 mg ascorbic acid (AA), 2 mg BC (TB), 4 mg BC (FB), 6 mg BC (SB), and 8 mg BC (EB) extracts. Experiment was laid out in a Completely Randomized Design. After hatching, the chicks were reared separately according to in ovo treatments for 8 wk. Data were collected on hatchability, chick quality, internal organs, growth performance, plasma superoxide dismutase, malondialdehyde, and triiodothyronine (T 3 ). The results showed that the hatchability of the eggs in the AA group was similar to that of SB eggs and higher than that of the other treatment groups. The intestinal weights of SB and EB birds were significantly higher ( P < 0.05) than those of TB, SA, and WA. The final weights of the birds of SB and AA were higher ( P < 0.05) than those of other treatments. The feed conversion ratio of the birds of TB and FB was comparable to that of EB and WA but higher than that of SB and AA. At hatch, the creatinine of the birds in SA and WA was similar to that of EB, FB, and TB but higher ( P < 0.05) than that of AA and SB. Also, the plasma malondialdehyde, T 3 , and superoxide dismutase of SB and AA birds were better ( P < 0.05) than those of the control groups. Overall, it was concluded that 6 mg of BC extract improved the antioxidant status and posthatch performance of thermally challenged broiler chickens.

The chicken hatching egg is a self-contained life-supporting system for the developing embryo. However, the post-hatch performance of birds depends on several factors, including the breeder management and age, egg storage conditions and duration before incubation, and the incubation conditions. Studies have determined the effect of incubation factors on chick post-hatch growth potential. Therefore, chick physical quality at hatch is receiving increasing attention. Indeed, although incubation temperature, humidity, turning and ventilation are widely investigated, the effects of several variables such as exposure of the embryo to high or low levels, time of exposure, the amplitude of variations and stage exposures on embryo development and post-hatch performance remain poorly understood. This review paper focuses on chick quality and post-hatch performance as affected by incubation conditions. Also, chick physical quality parameters are discussed in the context of the parameters for determining chick quality and the factors that may affect it. These include incubation factors such as relative humidity, temperature, turning requirements, ventilation, in ovo feeding and delay in feed access. All these factors affect chick embryo physiology and development trajectory and consequently the quality of the hatched chicks and post-hatch performance. The potential application of adapted incubation conditions for improvement of post-hatch performance up to slaughter age is also discussed. It is concluded that incubation conditions affect embryo parameters and consequently post-hatch growth differentially according to exposure time and stage of exposure. Therefore, classical physical conditions are required to improve hatchability, chick quality and post-hatch growth.

No abstract

No abstract

No abstract