Physiological Responses in Broiler Chickens Administered Lycopene During the Hot-Dry Season

Abstract

This study evaluates the effects of lycopene administration on body weight, mortality, cloacal temperature, and haematological responses, in broiler chickens exposed to heat stress. 40 day-old broiler chicks were divided into control and lycopene groups, 20 chickens each. Each bird in the control group received olive oil (1 ml.kg−1), and lycopene at 10 mg.kg−1 mixed with olive oil was given to each bird in the lycopene group by oral gavage once daily for 28 days. The dry- and wet-bulb temperature of the broiler chickens’ pen was recorded three times daily from days 8 to 28. The body weights were measured weekly. The incidence of mortality was recorded. The cloacal temperatures were measured on days 14, 21 and 28. The blood samples were collected for haematological analyses, on day 28. The results indicated a high overall temperature-humidity index (31.24 ± 0.43 oC) of the thermal micro-environment of the broiler chickens. There was no significant difference (P > 0.05) in body weight. The percentage mortality in the control group was relatively higher compared to the lycopene group. Lycopene reduced the cloacal temperature responses and the daily fluctuations in broiler chickens. The decreased (P < 0.05) heterophil:lymphocyte ratio and percentage erythrocytes haemolysis were recorded in the lycopene group. In conclusion, lycopene administration reduced mortality and improved cloacal temperature and haematological responses without exerting any significant beneficial or negative effects on the body weight in broiler chickens exposed to heat stress.

Keywords

• cloacal temperature
• erythrocytes fragility
• heat stress
• heterophil:lymphocyte ratio
• mortality
• temperature fluctuations