Thermal manipulations during the embryonic period have positive effects on thermotolerance and the productive performance of broilers subjected to acute heat stress. This study aimed to investigate the potential effects of Thermal manipulation during incubation (TMI) on productive performances and thermotolerance of broiler chickens growing in tropical climates. A total of 900 Cobb 500 broiler chicken eggs from a 35-week-old breeder flock were incubated in standard incubation conditions (37.8°C, 60% relative humidity) until day 7, when they were divided into 3 groups (300 eggs per group). The control group (C) was incubated at standard incubation conditions while T6 and T12 groups were subjected to, respectively, 6 hours/day and 12 hours/day of TMI (T° = 39.5°C, relative humidity = 65%, Embryonic day = 7-16). The relative embryo and albumen weight were determined from 10 to 18 days of incubation. The hatching event was checked between 450 and 504 hours of incubation, and egg hatchability, chick quality, and cloacal temperature were also determined. One hundred and twenty-five chicks from each incubation group were transferred to the farm and raised for 6 weeks. During this period, their post-hatch performances were determined. At week 6, blood samples were collected to measure T3, T4, and corticosterone hormone levels. Then, the 6-week-old broilers were slaughtered to determine meat yield and quality. Results showed that the chick’s rectal temperature was significantly reduced in T6 and T12 groups compared to the C group, while hatchability and one-day-old chick weight were not affected. Final body weight and feed conversion ratio were significantly improved in the T12 group, compared to other groups. Thermal manipulation during incubation for 6 and 12 hours significantly reduced mortality rate and pectoralis major muscle drip loss while it increased muscle pH at 24 hours post-mortem (pH24). Corticosterone, T3, and T4 plasma hormone levels at week 6 were also significantly reduced by TMI. Therefore, exposing hatching eggs to 39.5°C and 65% of relative humidity from days 7 to 16 of incubation for 12 hours/day is recommended for the poultry industry in tropical climates. Keywords: Chronic heat stress, Fast-growing broilers, Hatching and post-hatch performances, Thermal manipulation, Thermotolerance, Meat quality

Background. The sulfadoxine-pyrimethamine combination is a product used in the intermittent preventive treatment (IPT) of malaria in pregnant women in our country. To date, there is very little data on the teratogenic effect of this product. This study proposed to evaluate the teratogenic effect of sulfadoxine-pyrimethamine on chicken embryos. Methods. The teratogenic effect of the product was evaluated on chicken embryos at a dose of 1.3 mg/g sulfadoxine and 0.06 mg/g pyrimethamine. The product was injected before the start of incubation and on days 12, 14, 16, and 18 of incubation. One batch received a double injection of the product on days 16 and 18 of incubation. The quality of the hatched chicks was evaluated by the Tona Score followed by the determination of hematological and biochemical parameters. Results. From the aforementioned, it appears that the eggs treated with sulfadoxine-pyrimethamine significantly decreased the hatchability rate of the eggs. The chicks obtained were all of very good quality. Apart from a significant decrease in the weight of the chicks of the batch that received the injection twice and a significant increase in the weight of the yolk sac of the chicks of the batch that received the injection on day 16 compared to the control, no variation was obtained. A significant increase in the white blood cell count of the chicks compared to the control was reported in the chicks of the batch injected before incubation and on day 12, as well as a significant increase in the platelet count of the chicks of the batch injected twice. For biochemical parameters, no significant difference was reported in ALT and AST. Conclusion. Sulfadoxine-pyrimethamine decreased egg hatch and caused an increase in embryo and chick mortality as well as a loss in relative chick weight and an increase in relative yolk sac weight. More in-depth studies would be needed on sulfadoxine-pyrimethamine teratogenicity and the benefit/risk ratio of this drug during pregnancy.