Effect of different levels of copper nanoparticles and copper sulphate on performance, metabolism and blood biochemical profiles in broiler chicken
Copper (Cu), a crucial microelement required for proper physiological functions in chickens, is frequently added to poultry diets at high concentrations, at levels that often exceed the birds’ requirements (Świątkiewicz, Arczewska‐Włosek, & Józefiak, 2014), as a possible alternative to an antibiotic growth promoter. It enhances animal performance, but an excess of Cu in the diet can also have adverse effects, including iron and calcium deficiency due to antagonism between those elements; this may cause a reduction in viability (Miroshnikova, Arinzhanov, Kilyakova, Sizova, & Miroshnikov, 2015) and increased toxicity (Cao et al., 2016). The digestibility of Cu salts is very low, and approximately 80% of Cu is excreted in the faeces (McDowell, 1992), causing the environmental pollution (Leeson, 2009). Many studies have shown the beneficial effects of Cu supplementation in different forms and levels (inorganic and organic), from 4 to 400 mg/kg in poultry diets. However, the delivery technique and bioavailability of Cu might have different effects on Cu utilisation. In this experiment, we used copper nanoparticles (Cu‐NP) as a feed additive delivered by in ovo injection to embryos and/or in drinking water given to post‐hatched chickens. Considering their unique physicochemical characteristics and based on recent results, we hypothesised that Cu‐NP would have greater bioavailability and thus be more efficient than Cu salts (Joshua, Valli, & Balakrishnan, 2016; Mroczek‐Sosnowska, Sawosz et al., 2015). Additionally, it has been demonstrated that in ovo feeding may be a new and safe method to provide external nutrients to the embryo before it hatches. This could increase nutrient utilisation, to a greater extent than post‐hatched supplementation, thereby reducing the excretion of these elements into the environment (Das et al., 2010; Mroczek‐Sosnowska, Łukasiewicz et al., 2015). It has been documented that Cu‐NP has beneficial effects on the animal performance and could be used to replace copper sulphate (CuSO4) (Wang, Wang, Ye, Tao, & Du, 2011; Mroczek‐Sosnowska, Sawosz et al., 2015; Mroczek‐Sosnowska, Łukasiewicz et al., 2015; Miroshnikov, Yausheva, Sizova, & Miroshnikova, 2015; Muralisankar, Saravana Bhavan, Radhakrishnan, Seenivasan, & Srinivasan, 2016; El‐Basuini et al., 2016). However, far less is known about the mechanism of action of Cu‐NP in improving chicken performance, particularly regarding nutrient digestion and metabolism.
It has been well documented that increasing Cu levels in the diet could reduce cholesterol and triglyceride levels in the blood of chickens (Rahman et al., 2001; Skrivanova, Skrivan, Marounek, Tumova, & Sevcikova, 2004). Furthermore, it was shown that in ovo administration of Cu‐NP and CuSO4 affected the blood serum, which reduced concentrations of glucose and cholesterol, but increased levels of calcium, phosphorus and iron in broiler chickens (Mroczek‐Sosnowska et al., 2013).
It has been demonstrated that Cu‐NP and CuSO4 can affect the immune status and muscle development of chickens and chicken embryos (Goel, Bhanja, Mehra, Majumdar, & Pande, 2013; Mroczek‐Sosnowska, Sawosz et al., 2015; Mroczek‐Sosnowska, Łukasiewicz et al., 2015). Furthermore, it was demonstrated that Cu‐NP and CuSO4 positively affected fish performance and immune response (El‐Basuini et al., 2016). To evaluate whether the whole body responses to the treatments could be linked to molecular responses, the expression of selected genes related to immune status and muscle development was measured.
Recently, we reported that the metabolic rate of broiler embryos could be affected by the in ovo administration of Cu‐NP (Scott et al., 2016). We demonstrated that the administration of 50 mg/kg of Cu‐NP increased the metabolic rate of broiler embryos; however, this improvement did not alter the growth of the embryos. Therefore, we hypothesised that in ovo injection of Cu‐NP could have prolonged effects on broiler performance during the rearing period.