The possibility of replacing clove (Syzygium aromaticum) essence for growth promoter, avilamycin, in broiler chickens diet

Due to being safety and possessing beneficial effects on wellbeing, efficiency and gut microbial population of poultry, phytogenics have been increased attention in recent years (Hashemi and Davoodi 2011). Dried flower bud of clove tree (Syzygium aromaticum) is used in food industry as a spice because of its aromatic property. Eugenol is the main component of clove essence, comprises 72 to 90 percent of the essence, and has antioxidant (Lee and Shibamoto 2001) and antimicrobial (Devi et al. 2010) properties. The studies on clove powder (Agostini et al. 2012), essence (Mohammadi et al. 2014a) and extract indicated the positive effect on broiler performance. Although the lack of clove derivatives effect on birds growth response has been also reported (Najafi and Torki 2010). Increased useful bacteria in gut (Agostini et al. 2012), improved nutrients digestibility (Dalkiliç and Güler 2009) and no effect on blood lipid parameters (Azadegan Mehr et al. 2014b) have been illustrated in broilers receiving clove components. Avilamycin, is a growth promoting antibiotic, improves growth performance (Kim et al. 2011) and nutrients digestibility (Saleh 2014) in broiler chickens as well. In few available studies, using clove extract (Dalkiliç and Güler 2009) and essence (Azadegan Mehr 2014b) have been shown similar effect on broiler performance to avilamycin. Hence, the experiment was carried out to investigate the possibility of replacing clove essence to avilamycin and its effect on growth performance, ileal nutrients digestibility, intestinal morphometry and some blood parameters of broiler chickens.
To perform the in vivo work, a total of 320 mixed sex broiler chicks (Ross 308) were allocated to 4 dietary treatments with 4 replicates and 20 birds each by employing a completely randomized design. Four experimental treatments including avilamycin (control) and three levels of 150, 300 and 450 ppm clove essence were fed to broilers for a period of 42 days. The birds were reared under standard conditions on deep litter pens with free access to water and feed. The diets based on corn and soybean meal were formulated to meet or exceed the nutrient requirements recommended by the National Research Council (1994), for starter (0 to 21 days) and grower (22 to 42 days) phases (Table 1). Feed intake (FI) and weight gain (WG) of birds were recorded at the end of each feeding phases, then feed conversion ratio (FCR) was calculated. To determine the ileal nutrients digestibility, the birds were fed with diets contacting 0.3% chromic oxide for three days, then two birds (one male and one female) form each pen were euthanized by CO2 asphyxiation on day 28 to collect the ileal contents. The contents were frozen (-20 °C), dried and along with feeds used for subsequent chemical analyses using the standards procedures (AOAC 2000). Chromic oxide content of feed and excreta samples was also measured by Fenton and Fenton (1979) method. Gizzard and cecal samples of the slaughtered birds were also collected to measure their pH values after preparing a suspension (1:10) with distilled water. To determine the morphometric parameters of the jejunal mucosa, a tissue sample (2 cm) of the proximal part was obtained and fixed in 10% buffered formalin. The samples were processed and embedded in paraffin and stained with haematoxylin and eosin. The morphometric parameters including villus height, villus width, crypt depth and thickness of muscle layer were made from 9 adjacent and vertically orientated villi and crypts (Iji et al. 2001). On day 35, two birds from each replicate were bled from their wing vein to measure the serum glucose, triglyceride, total cholesterol and HDL cholesterol concentrations using the commercial kits. LDL cholesterol level was calculated using the equation suggested by Friedewald et al. (1972). All data were subjected to statistical analyses using SAS (SAS Institute, 2002). The difference between means was compared by Duncan’s multiple range test.
Throughout the experimental period, daily FI and WG of broilers were decreased by all levels of clove essence, while the FCR was increased by 150 and 300 ppm (P In overall, even though the clove essence can reduce the concentration of serum cholesterol, it cannot be replaced for the growth promoter antibiotic, avilamycin, in broilers diet.