The Effect of Adding Herbal Extracts to Drinking Water on Body Temperature, Level of Thyroid Hormones and H:L Ratio in the Blood of Broiler Chickens Exposed to Elevated Ambient Temperature

Iwona Skomorucha,Ewa Sosnówka-Czajka

doi:10.2478/aoas-2021-0014

Iwona Skomorucha, Ewa Sosnówka-Czajka

Open Access

https://doi.org/10.2478/aoas-2021-0014

Copy DOI

Abstract

Abstract The aim of the study was to determine the effect of supplementing drinking water with extracts from lemon balm, sage and nettle on body temperature, level of thyroid hormones and the heterophil to lymphocyte (H:L) ratio in the blood of broiler chickens exposed to elevated rearing temperature. One-day-old Ross 308 chicks were divided into four groups: group I (CON) and experimental groups II (LB), II (S) and IV (N), in which, from 22 to 42 days of rearing, drinkers were supplemented with lemon balm extract, sage extract or nettle extract (2 ml/l water), respectively. In addition, at 5 weeks of growth, all the groups were exposed to elevated ambient temperature (up to 30°C) for 5 days, after which the recommended thermal conditions were reinstated. During the study, mortality, rectal temperature and radiated temperature of the broilers were monitored. Blood was collected from 10 birds per group to determine the concentration of thyroid hormones (T3 and T4) and to make blood smears. The H:L ratio was determined based on the percentage of heterophils (H) and lymphocytes (L). The herbal extracts from lemon balm, sage and nettle, added to drinking water at 2 ml/l, reduced the blood level of the thyroid hormone (triiodothyronine) and rectal temperature in the experimental broilers during the initial period of thermal stress. Chickens receiving the nettle extract were also characterised by lower radiated temperature of the unfeathered body, a lower H:L ratio in the blood during the increase in ambient temperature, and the lowest mortality percentage. It can therefore be considered that the dietary supplementation of nettle, in the form and concentration used in this study, had the most favourable effect on the physiological status of the birds (body temperature, level of thyroid hormones and H:L ratio) exposed to elevated ambient temperatures (30°C), and thus on their welfare.

Highlights

High ambient temperature is a major stressor for farm animals (Attia and Hassan, 2017; Abd El-Hack et al, 2020)
The authors noted lower rectal temperature in broiler chickens supplemented with milk thistle extract and exposed to high ambient temperature compared to the control group
In our study, the measurement of rectal temperature on day 5 of the exposure to high ambient temperature showed no differences between birds supplemented with herbal extracts in drinking water and the control birds

Summary

Introduction

High ambient temperature is a major stressor for farm animals (Attia and Hassan, 2017; Abd El-Hack et al, 2020). Attia and Al-Harthi (2015) and El-Shoukary et al (2014) observed that supplementing 1% Nigella sativa seeds to the diets of broiler chickens exposed to elevated ambient temperatures, increased their daily weight gains, considerably reduced the number of panting birds, and decreased the. Common and highly valued herbs include lemon balm, sage and nettle, which show various health-promoting benefits, and thanks to the presence of essential oils they have sedative and anti-stress effects These plants show strong antioxidant properties (Poulios et al, 2020; Bonetti et al, 2016; Kasapidou et al, 2014), which makes them useful for reducing stress induced by high air temperature. The literature reports no information concerning the use of these herbs to alleviate the effects of heat stress on the avian body

Objectives

Methods

Results

Conclusion