Abstract
The aim of the study was to evaluate the ameliorative effects of lycopene and vitamin E, administered individually and in combination, on laying hens during the hot-dry season. The dry-and wet-bulb temperature were recorded daily from 06:00–18:00 h during the 5-week experimental period. Daily and weekly hen-day egg productions, egg weight, eggshell thickness and eggshell weight were determined using standard procedures. The dry-bulb temperature (23.0°C – 39.0°C) and temperature - heat index (24.4°C − 35.0°C) recorded show that the hens were subjected to heat stress during the season. Egg production in the laying hens in lycopene (62.4 ± 1.1 %), vitamin E (62.1 ± 1.2%) and lycopene + vitamin E (62.7 ± 1.0 %) groups were higher (P < 0.05) than in controls (56.0 ± 0.8%). Eggshell was thickest in lycopene + vitamin E group (0.28 ± 0.02 mm), compared to lycopene (0.23 ± 0.02 mm) and vitamin E group (0.22 ± 0.02 mm). The thickness was lowest (P < 0.05) in control hens (0.18 ± 0.02 mm), compared to any other group. Similarly, control laying hens recorded the least (P < 0.05) in eggshell weight (6.7 ± 0.02 g), compared to the weights recorded in lycopene + vitamin E, lycopene and vitamin E groups (7.3 ± 0.24 g, 7.3 ± 0.3 g and 7.2 ± 0.3 g, respectively). In conclusion, lycopene and vitamin E ameliorated the risk of adverse effects of heat stress by increasing hen-day production, eggshell weight and eggshell thickness during the hot-dry season.
Laying performance, digestibility and plasma hormones in laying hens exposed to chronic heat stress as affected by betaine, vitamin C, and/or vitamin E supplementation