Impact of supplementing diets with propolis on productive performance, egg quality traits and some haematological variables of laying hens
Propolis (bee glue) is a natural product collected by bees from various plants, particularly from flowers and leaf buds. As known, bees use propolis to overcome the inner walls of the hive and mix it with wax when building combs to protect the colony and larvae from pathogenic micro‐organisms (Krell, 1996) as well as the entrance against intruders (El‐Bassuony, 2009). Propolis consists of resin and vegetable balsam (50%), wax (30%), essential and aromatic oils (10%) as well as both pollen and other substances (5%) as organic debris (Burdock, 1998). Many researchers explained the effectiveness and the physiological role of propolis against a variety of viruses (Amoros et al., 1994), bacteria (Velikova et al., 2000), fungi (Murad et al., 2002) and moulds (Miyataka et al., 1997).
Also, the findings of Roodsari et al. (2004), Zeng et al. (2004), Guclu‐Kocaoglu (2010) and Mathivanan et al. (2013) showed that the use of propolis has a beneficial influence on daily gains, feed intake and conversion in different animal species, including poultry.
A similar trend was also observed by Galal et al. (2008), who found that the averages of egg numbers and egg production rate for hens treated with propolis at 100 and 150 mg/kg diet significantly (p < 0.05) increased than those of the control group, while the eggshell thickness for eggs produced from treated laying hens was significantly (p < 0.05) higher as compared to the control group. Also, the results of Seven et al. (2011) showed that the dietary supplementations of laying hens with flavomycin or propolis have significantly reduced the negative effects of heat stress on performances, nutrient digestibility and eggshell characteristics (p < 0.05).
With regard to the propolis supplementation on plasma cholesterol, the findings of El‐Neney et al. (2014) showed that plasma cholesterol was significantly reduced (p < 0.05) in Dokki 4 laying hens fed propolis compared to control. Also, they added that plasma total protein, albumin and globulin were significantly (p < 0.05) lower for control than those fed propolis.
Referring to blood components, they found that using different dietary propolis levels of treated groups led to a significant increase (p ≤ 0.05) in RBC and WBC, Hb, lymphocytes, eosinophils and monocytes percentages, while the basophils percentage was insignificantly affected.
In general, the use of propolis is pronouncedly increasing in medical science, but very limited data is available regarding its use in the field of poultry production. Therefore, this experiment aimed to study the effect of supplementing the diets of laying hens with propolis on the productive performance, egg quality traits and haematological parameters.