This study was guided pursuant to the approval (dated 18.09.2020 and numbered 2020/13) of the Local Ethics Board for Animal Experiments of Directorate of Veterinary Control Centre Research Institute.
Animals and experimental design
In the study, 300 1-day-old male broiler chickens (Ross 308) were used as animal material. After a 7-day acclimation period, chicks were randomly placed in two identical rooms at two different ambient temperatures [24°C; thermoneutral (TN) and 35°C; cyclic heat stress (CHS)] and 3 different HFV levels (0, 2 and 4 ml/L water) in accordance with a 2×3 trial design. The study was carried out with 5 replications and 10 chickens were used in each replication. The broiler chick were placed in a total of 30 pens, 15 in each room, which were 121×110×108 cm in size with sawdust litter, containing a hanging manger, drinker and automatic heaters. The temperature of the trial rooms, which were kept at 33°C for the first 7 days, was gradually reduced to 24°C until the 21
st day. After day 21, one house was kept in TN conditions (approximately 24°C) but the other house (CHS) was kept at 34°C for 8 h per day (09:00-17:00) and then 24°C for 16 h/h to (from 17:00 to 09:00) and during the study, a 24-h lighting program was applied to the chickens and the intensity was around 40 lux/m
2 (
Sarýca et al., 2015).
Feed
The feeds and organic HFV used in the study were obtained from a private company. Broiler starter feed was used between days 0-11, grower feed between days 11-24, finisher feed between days 25-42 (Table 1). Since HFV was given with drinking water, the feeds used in the study were the same for all animals. Every day at 16:00, the drinkers of all groups were turned off for 1 hour and the animals were dehydrated. At the end of this period, each treatment group was given 100 ml of pure water through a 1 liter drinker and 100 ml of pure water was added to the experimental groups until the water was consumed by adding HFV to the experimental groups and then the hanging chicken drinkers were activated and the experiment was continued with fresh water.
Determination of performance parameters
Weight gain (WG) was determined by individually weighing all animals on days 7, 14, 21, 35 and 42 of the study. The amount of feed consumed in each compartment was taken into account in calculating the FI and FCR value. The FCR value was expressed as the amount of feed consumed per unit body weight gain (g/g). The chickens that died during the experiment were recorded daily and taken into account in the calculation of the FCR value. The chickens that died during the experiment were recorded and were taken into account when calculating the FCR.
Determination of carcass characteristics and internal organ weights
On the 42
nd day of the study, depending on complete chance, 10 chickens from each group, 2 animals from each replication, 60 chickens in total, were selected from the chickens that were starved from the evening and slaughtering was performed by the cervical dislocation
(Tekce et al., 2020). Hot carcass weights were obtained by weighing at room temperature approximately 45 minutes after slaughter, while cold carcass weights were obtained by weighing after 24 hours at 4°C (
Sabaw and Muhammed, 2021). All weights were obtained by weighing on a balance (SHIMADZU BL-3200H, Germany) sensitive to 0.001 g. Carcass characteristics and internal organ weights were measured as a percentage of body weight.
Feed analysis
A raw nutrient analysis of the feeds used in the research was conducted using a Near-infrared spectroscopy device. The nutrient contents and chemical composition of the basal feed used in the experiment are given in Table 1.
Analyzes of hawthorn fruit vinegar
The total phenolic compound quantities were determined using a Folin-Ciocalteu reagent and the method described by
Singleton et al., (1999), with slight modifications (
Gülçin et al., 2002). The total phenolic content of HFV was determined as 1551.29 mg gallic acid equivalent (GAE)/L. The 2, 2'-Azino-bis (3-etilbenzttiyazolin-6-sülfonik asit) (ABTS•+) scavenging activity was determined using the method described by
Köksal et al., (2009). It was determined that the ABTS scavenging activity of HFV was 11.075 (IC50, μg/mL). Phenolic component and organic acid profile analyzes of HFV were determined using the high-performance liquid chromatography (HPLC) method (
Coklar and Akbulut, 2017). The phenolic compound and organic acid profiles is presented in Table 2.
Biochemical analysis
Serum total antioxidant capacity was determined by colorimetric method (
Erel, 2004); serum total oxidant capacity (
Erel, 2005) and serum malondialdehyde (MDA)
(Ohkawa et al., 1979) was determined by spectrophotometric method; serum IgG
(Li et al., 2000) and corticosterone
(Sahin et al., 2003) concentrations was determined by the ELISA method. Serum-free fatty acid (FFA) and triacylglyceride (TAG) levels were determined by HPLC method (
Sherma, 2003). Serum levels of glucose, minerals, alanine aminotransaminase, aspartate aminotransferase, alkaline phosphatase, total cholesterol, low-density lipoprotein, high-density lipoprotein, glucose parameters were measured with a fully automatic biochemistry device Cobas 8000 (Roche, Germany).
Statistical analysis
The data obtained from the trials were evaluated using the 2×3 factorial statistical analysis model (General Linear Model procedure) with the help of SPSS 23.0 program. Duncan multiple comparison test was used to compare the effects of the doses of the additives and the T-test (Independent Samples T Test) was used to compare the effects of heat stress.
