Effect of graded levels of dietary corn steep liquor on growth performance, nutrient digestibility, haematology and histopathology of broilers
Feed cost shares almost 70 per cent of entire broiler production cost (Jin et al., 2013) and the majority of it is represented by corn and soybean meal (Santos et al., 2013). Although in diet formulation, the centre of attention is energy supply; the birds rear more efficiently by provision of more balanced nutrients principally the amino acids (AA) and protein. Protein, along with the other nutrients, is essential for life (Cheeke, 2005); so crude protein (CP) and AA balance should be primarily highlighted in the diet formulation. Protein is the most expensive nutrient in poultry diets (Beski, Swick, & Iji, 2015). The high cost and the restricted quantities of conventional protein feed ingredients constantly provoked poultry nutritionists to explore the nutritional potential of various by‐products and non‐conventional plant protein sources in terms of their biological appraisal. Agro industrial by‐products suggest a potential to reduce not only the feed's cost but also improve superiority of the diet. Tropical countries like Pakistan and Egypt have great potential of agro based untraditional feed resources, which can be accessible throughout the year to be used in poultry diets. Practice on non‐conventional ingredients plays its part to abridge the nutrient gap and make feed formulation more versatile. Accessible limited technical information minimise or prevent the exploration of alternative feed resources (Murakami et al., 2009), so experiments illuminating partial or complete replacement of conventional protein sources with alternative protein feed ingredient will aid in viable broiler production (Santos et al., 2013).
Corn steep liquor (CSL) is one of such untraditional by‐products of corn wet‐milling industry (having cost about US$ 0.20/L). It is viscous, slurry with light‐to‐dark brown colour having ensiled odour and acidic pH (Mirza & Mushtaq, 2006). It is liquid feed ingredient and is a blend of soluble proteins, free AA, reduced sugars (e.g., dextrose), natural organic acids (e.g., lactic acid) and different minerals and vitamins (IUCLID data Set, 2006). In chicken, digestibility of protein and carbohydrate of CSL is 93% and 65% respectively. The metabolisable energy on commercial basis is 1,555 kcal/kg (Rafhan Product Reference Guide, 2010). This product is practically free from fat, fibre and silica (Gupta, Desai, Talpada, & Shukala, 1990). The CSL is a superior source of unknown growth factors and increases the palatability of nutritionally balanced diet (Waldroup & Rutherford, 1971). In literature, very limited information is available concerning the use of CSL in broiler diet. Therefore, this study was conducted to appraise the nutritional potential of CSL‐based diets in broilers.