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Abstract
INTRODUCTION
Enteric diseases are an important concern to the poultry industry because of lost productivity, increased mortality, and the associated contamination of poultry products for human consumption. With increasing concerns about antibiotic resistance, the ban on sub-therapeutic antibiotic usage in Europe and other parts in the world, there is increasing interest in finding alternatives to antibiotics as growth promoters for poultry production. Prebiotics and probiotics are two of several approaches that have potential to reduce enteric disease in poultry and hence subsequent contamination of poultry products. Probiotic, which means “for life” in Greek (Gibson and Fuller, 2000), has been defined as “a live microbial feed supplement which beneficially affects the host animal by improving its intestinal balance” (Fuller, 1989).
Saccharomyces cerevisiae (SC), one of the most widely commercialized types of yeast, has long been fed to animals. Results of earlier studies with yeast fed to chickens, however, have not been consistent. It has been reported (Onifade et al., 1999) that feeding yeast to chicks improves body weight gain and feed/gain ratio. On the other hand, Madriqal et al. (1993) failed to observe a positive effect of feeding yeast on body weight of broiler chicks. Kanat and Calialar (1996) reported that active dry yeast effectively increases body weight gains without affecting feed/gain ratio in broiler chicks. In contrast supplementation of yeast to broiler diets improves feed/ gain ratio but not growth rates (Onifade et al., 1999). It has been reported that yeast could be an alternative to antibiotic-based drugs in feed in broiler chicks on new litter (Hooge et al., 2003) or on recycled litter (Stanley et al., 2004).
Phytobiotics may be explained as plant derived products added to the feed in order to improve performance of agricultural livestock. This definition addresses mainly the purpose of use in terms of a feed additive to healthy animals under common practical conditions of production of food of animal origin rather than the veterinary use for prophylaxis and therapy of diagnosed health problems. According to this definition, phytobiotics comprise very wide range of substances with respect to biological origin, formulation, chemical description and purity. Within this variety, some subgroups may be classified, such as herbs (product from flowering, non-woody and nonpersistent plants), botanicals (entire or processed parts of a plant, e.g. root, leaves, bark), essential oils (hydro distilled extracts of volatile plant compounds), and oleoresins (extracts based on non-aqueous solvents).
Tomatoes are the fourth most commonly consumed fresh vegetable and the most frequently consumed canned vegetable worldwide. There is emerging epidemiology data supporting the connection between increased tomato consumption and reduced risk for both cardiovascular disease and prostate cancer in humans. The animal studies suggest that diets containing tomatoes may decrease the risk or the progression of prostate cancer. Because of high antioxidant contents, and due to the frequency and the extent of tomato consumption, the supporting epidemiological and animal data, which connect increased intakes with decreased cancer and cardiovascular disease risk, tomato’s role in human diet is of undeniable importance as part of a healthy diet.