Poultry feed industry worldwide has been using antibiotics for more than 50 years. But the use of antibiotics as growth promoters was completely banned in 1999 by the European Union (EU) (European Commission, 2001). This was due to increases in microbial resistance to antibiotics and residues in chicken meat products which might be harmful to consumers.
In Pakistan poultry feed industry is using antibiotics. But internationally their alternatives mannan oligosaccharides (MOSs) are being used. MOSs, which are derived from the cell wall of Saccharomyces cerevisiae, have shown promising effects, such as decreasing pathogenic microflora of the gut, stimulating a strong immune response, and elevating the strength of the intestinal mucosa in poultry. Exact mechanisms by which MOSs show positive effects are not known but some suggestions are they provide nutrients, they aid in digestion of foods and inhibit harmful bacteria in the gut (Owings et al.1990). Gastrointestinal normal flora plays an important role in the health and performance of poultry (Thong song et al.2008). It is therefore of vital importance, both from an animal and human health perspective, to obtain natural alternatives like mannan oligosaccharide (MOSs).
MOSs have been shown to increase growth in broilers (Yusrizalet al. 2003), turkeys (Kannanet al.2005), and results of many trials indicated that MOSs can be one of the best alternatives to antibiotic growth promoters (Hoogeet al.2003), and even trace amounts of MOSs added to a ration were quite effective in increasing the health status and production of poultry (Savage et al. 1997). Stanczuk et al., reported that supplementation of rations with MOSs and inulin (0.1% and 0.4% MOS in diet) did not significantly affect live body weight (BW), feed intake (FI), or feed conversion efficiency (FCE) in turkeys in an 8-week trial (Stanczuket al., 2005).

Actigen a product by Alltech, Inc., is having advanced form of mannan oligosaccharide, which was offered in feed to broiler birds in this trial. It acted as alternative to antibiotics without affecting the performance of birds, It protected the birds from pathogens. Keeping in view the situations the present project was planned. In this studymannan oligosaccharide (MOS) was evaluated on broiler (5*6*15=450) as antibacterial and growth promoter alone or in combination with antibiotic (neomycin) in environmentally control shed of Poultry Research and Training Centre, Department of Poultry Production, UVAS-Ravi Campus, Pattoki. Duration of this trial was 35days.The parameters of this experiment were feed intake, body weight gain, feed conversion efficiency, mortality, carcass characteristics, and slaughter parameters, estimation of ALT, AST and cholesterol from blood. Statistically data was analyzed by using ANOVA in completely randomized design (CRD) with help of a special computer based statistical package (SAS9.1, 2002-03).The results showed that there was significant difference in feed intake when birds were fed with 0.1% MOS with antibiotic from other dietary treatments. MOSs and antibiotics alone or in combination depicted significant results upon weight gain. They were significantly different from control. There was significant decrease in FCE in groups where MOSs was used in combination with antibiotic and more in 'A' 'B' and 'D' respectively. There was significant decrease numerically regarding mortality but statistically there difference was non-significant. Effect of dietary treatments on relative organs weight was non-significant. There was also a non-significant effect on dressing %age. Regarding sera ALT level there was significant decrease in treatment groups than control group. Value of AST level was also significantly less in treatment groups than control group. There was not a significant difference in serum values of triglyceride. Cholesterol level decreased in treatment groups 'B' and 'C' significantly than control but increased significantly in groups 'D' and 'E' than control group. The outcome of this study is that MOS have definite effect on bird's performance and could be used in combination or as an alternative to antibiotics. It is cost effective and beneficial for human health and poultry industry of Pakistan.