Effects of chronic heat stress and ammonia concentration on blood parameters of laying hens

Dapeng Li; Qin Tong; Zhengxiang Shi; Hao Li; Yu Wang; Baoming Li; Geqi Yan; Hui Chen; Weichao Zheng

doi:10.1016/j.psj.2020.03.060

Effects of chronic heat stress and ammonia concentration on blood parameters of laying hens

Poult Sci. 2020 Aug;99(8):3784-3792. doi: 10.1016/j.psj.2020.03.060. Epub 2020 Apr 24.

Authors

Dapeng Li¹, Qin Tong¹, Zhengxiang Shi², Hao Li¹, Yu Wang¹, Baoming Li¹, Geqi Yan¹, Hui Chen³, Weichao Zheng¹

Affiliations

¹ College of Water Resources & Civil Engineering, China Agricultural University, 100083, Beijing, China; Key Laboratory of Agricultural Engineering in Structure and Environment, 100083, Beijing, China; Beijing Engineering Research Center on Animal Healthy Environment, 100083, Beijing, China.
² College of Water Resources & Civil Engineering, China Agricultural University, 100083, Beijing, China; Key Laboratory of Agricultural Engineering in Structure and Environment, 100083, Beijing, China; Beijing Engineering Research Center on Animal Healthy Environment, 100083, Beijing, China. Electronic address: shizhx@cau.edu.cn.
³ College of Animal Science and Technology, Hebei Agricultural University, 071000, Baoding, Hebei, China.

Abstract

Less evidence is available currently to reveal whether the immune system and productivity of laying hens change under long periods of ammonia exposure in hot climate. The present study was conducted to determine the effects of chronic exposure to high temperature and ammonia concentrations on health, immune response, and reproductive hormones of commercial laying hens. A total of five hundred and seventy six 20-week-old laying hens (Hy-Line Brown) were used in this study. Birds were housed in cages (4 birds per cage) and received 16-wk treatments in 6 artificial environmental chambers. Hens were allocated to 6 treatments: treatment 1 (T1, 20°C, ≤5 ppm, control group), treatment 2 (T2, 20°C, 20 ppm), treatment 3 (T3, 20°C, 45 ppm), treatment 4 (T4, 35°C, ≤5 ppm), treatment 5 (T5, 35°C, 20 ppm), and treatment 6 (T6, 35°C, 45 ppm). Blood samples were collected at 22, 26, 30, 34, and 38 wk of age and plasma IgG, IgM, IgA, corticosterone (CORT), total antioxidant capacity (T-AOC), luteinizing hormone (LH), estradiol (E2), and follicular stimulating hormone (FSH) were measured. The results of this study showed that high ambient temperature and excessive ammonia increased the concentration of IgG but decreased the concentration of IgA, T-AOC, LH, FSH, and E2 of hens compared with those of the control birds. From the age of 34 wk, significantly increased concentrations of IgG were observed in hens exposed to moderate and high levels of ammonia. CORT level showed marked differences between the treatments only at the age of 26 wk. In addition, LH and E2 of hens demonstrated significant differences among the treatments in the middle and later stages of the experiment, while FSH levels of the control birds were significantly higher than the others at the age of 38 wk. Excessive ammonia in high temperature was a physiological stress factor that had a negative effect, which inhibited immune function and impacted the reproductive hormones.

Keywords: ammonia; blood parameter; heat stress; immunity; laying hen.

MeSH terms

Ammonia* / pharmacology
Animals
Blood Chemical Analysis / veterinary
Chickens*
Female
Hormones / blood
Hot Temperature*
Immunity / drug effects
Oxidoreductases / blood
Stress, Physiological*

Substances

Hormones
Ammonia
Oxidoreductases