Effect of ginger (Zingiber officinale Roscoe) and organic selenium on growth dynamics, blood melanodialdehyde and paraoxonase in broilers exposed to heat stress

ABSTRACT A total of 480 1-week-old chicks of about similar average weight, and size were divided into 6 groups. One group served as control, and was fed only basal diet, second group was fed ginger at the rate of 5 g/kg (T1), third group was given organic selenium (Se) at the rate of, 0.3 mg/kg diet (T2), fourth group was given organic Se at the rate of 0.4 mg/kg (T3), fifth group was fed with organic Se at the rate of 0.3 mg/kg + 5 g/kg ginger (T4), sixth group was given organic Se at the rate of 0.4 mg/kg + 5 g/kg ginger (T5). Mean feed intake was significantly (P < 0.05) high in T3 and T5 while body weight was significantly (P < 0.05) high in T3 compared to the control. Mean feed conversion ratio (FCR) was significantly (P < 0.05) high in T2, T3 and T5 compared to the control. Dressing percentage was significantly (P < 0.05) high in T4 and T5 compared to the control. Serum Antibody titre against Newcastle disease and paraoxonase (PON1) were significantly (P < 0.05) high in the T4 and T5 groups compared to the control while melanodialdehyde (MDA) concentration was significantly (P < 0.05) low in the same groups. Results of this study showed that ginger at the rate of 5 g/kg and Se at the rate of 0.4 mg/kg were more effective in improving the growth performance, immune response and antioxidant status in broiler chickens exposed to high ambient temperature.


Introduction
High ambient temperature causes major problems in the poultry industry in the form of high mortality, low feed intake and feed efficiency (Khan et al. 2012a;Chand et al. 2014). Metabolic rate and body temperature of birds are comparatively higher than that of mammals . During high environmental temperature, birds are susceptible to oxidative stress (Rehman et al. 2017). During heat stress, birds have limited physical resources to cope with the new challenge and birds need to redistribute the body reservoir of protein and energy at the cost of stunt growth (Khan et al. 2012a).
The body produces free radicals continuously for the need of normal physiological functions, but their excessive level may cause damage to the plasma membrane and organelles . Nutritional approaches are considered to lessen the undesirable effects of heat stress by maintaining feed intake, water and electrolyte balance or by the supplementation of antioxidant vitamins, essential oils, minerals and natural herbs Rahman et al. 2014a;Majid et al. 2015;Abudabos et al. 2016;Chand et al. 2017). Supplementation of diets with natural antioxidants is a favourable strategy to decrease the lethal effects of heat stress in birds .
Selenium (Se) is an essential trace element. It upregulates the main components of the antioxidant defense mechanism of controlling its major Se-containing antioxidant enzymes and body's glutathione pool. Glutathione-peroxidase (GSHPx) contains Se as an integral component. Dietary organic Se supplementation reduced lipid peroxidation products and improved the immune system (Cai et al. 2012).
Active constituents in the herbal plants are discovered as a source of antioxidants (Khan et al. 2012b;Raza et al. 2016). Ginger (Zingiber officinale) is best and commonly used spices. It is powerful appetizer and carminative . It is known as a valuable medicine because of its action as anti-asthmatic and stimulant of the gastrointestinal tract (Zhang et al. 2009). Ginger supplementation has been reported to improve the actions of GSHPx and superoxide dismutase (SOD) and reduces melanodialdehyde (MDA) in broilers (Khan et al. 2012b). Ginger eliminates the lipid peroxidation in the cell via enhancing antioxidative action (Zhao et al. 2011). To the best of our knowledge, no study is available in the published literature on the effect combined effect of ginger and Se in broiler under heat stress. Therefore, the objective of this study was to evaluate the effect of ginger and Se on the production performance, immune status and antioxidant capacity of broiler exposed to heat stress.

Experimental design and birds husbandry
A total of 480-day-old broiler chickens were purchased from the local market in Peshawar and divided into 6 groups with 8 replicates. Cleaning and fumigation were performed before the arrival of the chicks. Wood shaving was used as litter for chicks. For the maintenance of better management, all the necessary materials (drinkers, feeders and bulbs) were provided to chicks.
Birds were fed starter, grower and finisher commercial cornbased basal diet with ad libitum access to fresh water, for 42 days (Table 1). Organic Se (SEL-PLEX, Alltech, selenium 1000 mg/kg) used in this experiment was yeast-bound. Ginger was obtained in the fresh form and dried in oven at 70°C for 3 days and then milled in a metal jar in the powder form and stored at room temperature. One group served as control, and were fed only basal diet, second group was fed ginger at the rate of 5 g/kg (T1), third group was given organic Se at the rate of, 0.3 mg/kg diet (T2), fourth group was given organic Se at the rate of 0.4 mg/kg (T3), fifth group was fed with organic Se at the rate of 0.3 mg/kg + 5 g/kg ginger (T4), sixth group was given organic Se at the rate of 0.4 mg/kg + 5 g/kg ginger (T5). The temperature and humidity were determined at an interval of 6 h per day (Table 2).

Performance traits
Weighed amount, of feed was provided, to the broilers two times a day and leftover feed was weighed the following morning. At the start, all the chicks were weighed. Weight gain on a weekly basis was determined by deducting weight at day one from body weight at day seven of each week. Overall, weight gain was calculated, from weekly body weight gain. Feed conversion ratio, (FCR) on a weekly basis was calculated on the basis of feed intake and weight gain. Two chicks, per replicate were randomly selected, weighed, and slaughtered, at the age of 42 days. Feet, head, and visceral organs, were detached and weighed again for the determination of the dressing percentage.

Blood collection
At the end of the experiment, blood (5 ml) was collected from two birds per replicate by cutting the jugular vein and centrifuged at 3000 rpm for 10 min. The serum was stored −20°C until analysis.

Determination of MDA
MDA was determined by the procedure, of Chand et al. (2016) using a spectrophotometer. Briefly, the serum sample of about 200 µl was mixed with 20% citric acid (pH 3.5), 0.81% sodium dodecyl sulphate and heated gradually at 94.9°C for 1 h. Then the mixture of pyridine and butanol was added, mixed and centrifuged at 400 rpm, for 10 min. The supernatants were collected and measured at 352 nm in a spectrophotometer (IRMECO Model U2020).

Antibody titre against Newcastle disease (ND)
Antibody against ND was determined by the method described by Khan et al. (2014b) through hemoagglutination-inhibition test.

Statistical analysis
Data was statistically analysed through analysis of variance (ANOVA) using the method described by Steel and Torrie (1997) through Statistical package (STATISTIC-2010).

Results
Mean feed intake of broiler supplemented with ginger and Se under heat-stressed condition is given in Table 3. During the second week and fourth, feed intake was significantly  (P < 0.05) high in the treated groups compared to the control. Feed intake was significantly (P < 0.05) high in broilers fed with combination of Se and ginger. During fifth week, significantly (P < 0.05) high feed intake was found in T1 and T5 compared to during sixth week and overall mean basis.
The effect of supplementation of ginger and Se on the body weight is given in Table 4. During second and sixth weeks, mean body weight was significantly (P < 0.05) high in the treated groups compared to the control. During third week, except T2, significantly (P < 0.05) high body weight was found in the treated groups compared to the control group. In the fourth week, significantly (P < 0.05) high body weight was recorded in T2, T3, and T5 compared to the control. Significantly (P < 0.05) high body weight was observed in T2, T3 and T5 compared to the control. Overall, significantly (P < 0.05) high body weight was observed in T3.
Mean FCR of control and treated groups of broiler under heat stress is given in Table 5. Mean FCR was significantly (P < 0.05) high in the treated groups compared to the control in the second and third weeks. During fourth week, FCR increased significantly (P < 0.05) in T3 compared to control. During fifth week, significantly (P < 0.05) high FCR was observed in the treated groups except T1 and T4. Significantly (P < 0.05) improved FCR was recorded in the treated groups compared to the control. Overall mean FCR was significantly (P < 0.05) high in T2, T3 and T5 compared to the control.
Mean Dressing percentage, antibody titre against ND, MDA and PON1 in broiler chicks, fed with different levels of organic Se and ginger under heat stress are given in Table 6. Mean dressing percentage, PON1 and ND titre were significantly (P < 0.05) high in T4 and T5 as compared to the control. Similarly, serum MDA concentration decreased significantly (P < 0.05) in T4 and T5.

Discussion
Most of the studies have documented the effect of Se and ginger singly. This is the first study, which investigated the comparative effect of single and combined effect of ginger and Se. The results of this study revealed that supplementation of  Mean within the same column, with different superscripts, differ significantly (P < 0.05). different levels of organic Se and ginger improved feed intake, in all the supplemented, groups under heat-stressed broilers. The lower feed intake in the control group may be due to the decreased metabolic rate and altered metabolism that lead to lower feed consumption and ineffective digestion. Se has been known for proper utilization of protein, lipids and carbohydrates, although there are conflicting reports published in the literature on feed intake, weight gain and feed efficiency under high ambient temperature as reviewed by Habibian et al. (2015). The differences could be due to dose, duration and organic or inorganic form of Se. The high feed intake, body weight and FCR in the ginger supplemented group may be due to the fact that ginger increases the palatability (Khan et al. 2012b). Ginger supplementation also increases the secretion, of gastrointestinal, enzymes like lipase, maltase, and disaccharidase, (Zhang, et al. 2009). In this study, serum MDA concentration decreased while PON1 concentration improved in the treated groups. Best results were found in birds fed with ginger and Se. During high heat temperature, mitochondrial respiratory chain activity increases resulting in high level MDA in the serum . MDA is the indicator of oxidative stress and is the end product of polyunsaturated fatty acid peroxidation . High level of MDA is the result of higher lipid peroxidation (Abudabos et al. 2018). Heat stress increases the production of free radicals and reduces the concentration of antioxidants . Studies have also documented that serum MDA level decreased with dietary supplementation of Se in broiler chickens (Habibian et al. 2015). It has been suggested that Se is a part of several antioxidant enzymes thereby suppressing the production of free radicals and inhibits lipid peroxidation (Khan 2011). Second, in Se deficiency, the absorption of vitamin E is suppressed, leading to the reduced antioxidant activities in the body (Habibian et al. 2015). According to Ghaffari et al. (2011), antioxidative activity of paraoxonase enzyme in the serum was improved when diet was supplemented with Se and vitamin E. Findings, of our results, are in line with, the results of Zhang et al. (2009) who recorded better activities of antioxidant enzymes and decreased level of MDA content when birds were given Ginger (5 g per kg). In this study, the level of antibody titre increased in chickens supplemented with ginger and Se. Heat stress is known for reduced immune response in chickens . The higher immune response may be due to the increased weight of the lymphoid organs, enhanced phagocytic activity and higher production of antibodies (Khan et al. 2012a). Se is critical for the proper functions of the immune organ and its deficiency may lead to decreased phagocytic activities and lower production of interleukin and T-helper cells (Habibian et al. 2015). The supplementation of Se in broiler diet has improved the immune response in chickens by supporting the immune organs, production of antibodies and phagocytic activities of the cells.
From the results of this study, it was concluded that combined supplementation of ginger and Se had no synergistic effect on the performance of broiler chickens, however, the antioxidant capacity and immune response were improved when ginger and Se were used in combined form.

Disclosure statement
No potential conflict of interest was reported by the authors.