Abstract
In a cold climate, ensuring indoor air quality and heat preservation simultaneously has always been a difficult problem in the poultry house. The current study was carried out in order to determine the effects of chronic low temperature and ammonia concentration on productive performance and egg quality of commercial laying hens. 576 18-week-old Hy-line Brown hens were used in this study. Birds were housed in cages and received for 20-week exposure to low temperature and ammonia in six artificial environmental chambers. Birds were randomly assigned into six 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, 8 °C, ≤5 ppm), treatment 5 (T5, 8 °C, 20 ppm) and treatment 6 (T6, 8 °C, 45 ppm). Daily feed intake (DFI), feed efficiency (FE), egg production (EP) and body weight (BW) were recorded and calculated from 19 weeks of age. Egg samples were collected at 22, 26, 30, 34 and 38 weeks of age and egg weight (EW), shell breaking strength (SBS), albumen height (AH), yolk weight (YW), shell weight (SW), shell thickness (ST) and Haugh unit (HU) were measured. The results of the present study indicated that low temperature and excessive ammonia decreased the EP of hens compared with those of the T1 birds. Low temperature increased DFI of hens thereby FE showed significant differences among treatments. During the early period of the experiment, low temperature treatment increased the BW of laying hens, but this trend of increase was suppressed by the treatment of ammonia with the prolongation of the experimental period. Egg quality was also affected by low temperature and excessive ammonia. At different experimental periods, egg quality traits of hens exposed to the cold and ammonia stress presented significant differences compared to those of control birds. The present study indicated that the effect of ammonia was more pronounced on hens than that of low temperature at the early and peak laying period in terms of several main traits of productive performance and egg quality under long term hens breeding.
Highlights
Poultry are exposed to various environmental stressors including adverse climatic conditions, harmful gases, dust and infectious diseases throughout their lives [1,2]
The present study indicated that the effect of ammonia was more pronounced on hens than that of low temperature at the early and peak laying period in terms of several main traits of productive performance and egg quality under long term hens breeding
A significant 2-way interaction between ammonia concentration and age was found for Daily feed intake (DFI), feed efficiency (FE), egg production (EP) and body weight (BW) while the 2-way interaction between temperature and ammonia concentration and temperature and age for BW was not significant
Summary
Poultry are exposed to various environmental stressors including adverse climatic conditions, harmful gases, dust and infectious diseases throughout their lives [1,2]. It has been demonstrated that the health and welfare of animals are markedly affected by low ambient temperature [3,4]. The thermal neutral zone for the metabolic and productive activity is around 18–23.9 ◦ C for adult laying hens [5]. It was reported that the optimum temperature for the thermoneutral zone was between. 19 and 22 ◦ C for laying hens [6]. The ambient temperature varies from –5 to +5 ◦ C in many regions of the world during winter months [7,8].
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