Academia Arena 2017;9(4) http://www.sciencepub.net/academia 9 Effect of Graded Levels of Spent Brewers’ Yeast (Saccharomyces cerevisiae) on Blood Parameters of Broiler Chickens Chollom Patricia Fremu 1 *, Agbo Ediga Bede 2 , Doma Umaru Dass 2 , Ocheme Julius Okojokwu 1 , Amos Gana Yisa 3 , Fidelis Nkasiobi Ikeji 3 1 Department of Microbiology, Faculty of Natural Sciences, University of Jos, Jos, Nigeria. 2 Department of Biological Sciences, Faculty of Science, Abubakar Tafawa Balewa University, Bauchi, Nigeria. 3 Federal College of Animal Health and Production Technology, National Veterinary Research Institute, Vom, Plateau State, Nigeria. *Corresponding Author: ciachollom@yahoo.com Abstract: Background: The rising prices of livestock feeds and the scarcity of conventional proteins and energy concentrates for the formulation of feeds have forced the animal scientists to search for alternative, cheaper and readily available protein and energy sources. Methods: Five experimental diets containing 0, 5, 10, 15 and 20% spent brewers’ yeast (Saccharomyces cerevisiae) were used to feed broiler chickens for 50 days. The experiments were in a completely randomized design with five treatments each replicated four times with 40 birds per treatment and 10 birds per replicate. Results: Packed cell volume (PCV) of birds ranged from 29.30 – 35.10% with the highest of 35.10 at 15% and the lowest of 29.31% at 10% levels of spent yeast replacement. The red blood cells (RBC) ranged from 2.40 – 2.83 x 10 6 /µl. The highest and lowest being 2.83 x 10 6 /µl and 2.40 x 10 6 /µl at 20 and 0% levels of spent yeast replacement respectively. The white blood cells (WBC) ranged from 2235.63 – 262.70 x 10 6 /µl with the highest of 262.70 x 10 6 /µl being at 20% level of spent yeast replacement. The lowest (235.63 x 10 6 /µl) was at 5% level of replacement. The haemoglobin (Hb) ranged from 9.63 – 11.40 g/dl. The highest and lowest were 11.40 and 9.63 g/dl at 20% and 10% levels of spent yeast replacements respectively. The serum biochemical indices showed that total protein ranged from 4.65 – 5.90 g/dl. The highest (5.90 g/dl) was at 5% level of spent yeast replacement. The lowest (4.65 g/dl) was at 0% yeast level. Serum albumin which ranged from 1.45 – 2.08 g/dl showed highest value of 2.08 g/dl at 5% spent yeast replacement level while the lowest of 1.45 g/dl was at 15 and 20% spent yeast replacement levels. Serum globulin ranged from 3.20 – 4.43 g/dl, the highest of 4.43 g/dl being at 20% spent yeast replacement. The lowest (3.20 g/dl) was at 0% spent yeast level. Urea ranged from 4.00 – 8.67 mml/l, the highest being 8.67 mm/l at 10% and the lowest (4.00mm/l) at 20% spent yeast replacement levels respectively. Creatinine ranged from 105.00 – 164.00 mml/l. The highest (164.00 mmol/l) was at 10% and the lowest (105.00 mmol/l) were at 5% and 20% spent yeast replacement levels respectively. These results showed that all blood parameters were not significantly (p > 0.05) affected by the dietary treatments. Conclusion: Therefore replacement of soya bean by spent yeast up to 20% level has no adverse effect on blood parameters of broiler chickens and can be used. [Chollom Patricia Fremu, Agbo Ediga Bede, Doma Umaru Dass, Ocheme Julius Okojokwu, Amos Gana Yisa, Fidelis Nkasiobi Ikeji. Effect of Graded Levels of Spent Brewers’ Yeast (Saccharomyces cerevisiae) on Blood Parameters of Broiler Chickens. Academ Arena 2017;9(4):9-13]. ISSN 1553-992X (print); ISSN 2158-771X (online). http://www.sciencepub.net/academia . 2. doi:10.7537/marsaaj090417.02 . Keywords: Spent Brewers’ yeast, Saccharomyces cerevisiae, Broiler, blood parameters. Introduction It has been reported that feed accounts for not less than 70% of the total cost of production in livestock ventures. Therefore, there is the need to focus on cheaper sources of feed ingredients in order to maximize profits and avoid losses. Spent brewers’ yeast is a by-product of the brewery and distillery industries. It contains protein, amino acids and vitamins therefore can replace soya beans as protein source in the production of good quality poultry feeds. It is cheap and available and humans do not consume it. It is usually dumped in the environment as a waste product. This practice increases biological oxygen demand (BOD). Its use in poultry feed formulation will therefore also serve as a way of its disposal. Yeasts have been used in feeds (Paryad and Mahmaudi, 2008; Huthail, 2014) as single cell proteins for their good protein, energy, amino acids, vitamins and crude fibre as well as metabolisable energy (ME) (Charlie, 2006). The objective of this study is to assess the effect of graded levels of spent brewers’ yeast on blood parameters of broiler chickens. Materials and Methods Experimental Diets