No abstract

There has been an unprecedented increase in global animal production, especially in subtropical and tropical areas in the last two decades (Renaudeau et al., 2012). The increase in the demand for food is due to a rise in human population (Godfray et al., 2010). Due to its potential role to provide food and livelihood securities (Paswan et al., 2014), poultry production, especially broiler production, are expected to meet the critical shortage in animal protein needed by Africa (Hatab et al., 2019).There has been growing concerns on the impacts of climate change on livestock production. For example, in West Africa, the expected increase in average temperature by 2°C-6°C by the year 2100 (Sylla et al., 2016) portends a serious challenge to sustainable broiler production. Due to the climatic challenge, heat stress events are expected to become more frequent in livestock species (Rahimi et al., 2020). A study by Tawfeek et al. (2014) showed that high ambient temperature adversely affected the performance of broiler chickens under high ambient temperature. However, the authors indicated that supplementation of antioxidants ameliorated the effects of thermal stress on the birds. Therefore, the diets of the birds are required to be adjusted to the climatic conditions (Attia & Hassan, 2017;Nir, 1992;Suganya et al., 2015) and also to the prevailing economic status of the countries where they are produced.The fast rate of development of the poultry production in tropical countries has also engendered a situation of overdependence on

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.