Improving Cassava Quality for Poultry Feeding Through Application of Biotechnology

The continuous increase in cost of conventional energy sources caused by inadequate supply and stiff competition between human, animals and various industries for many decades has resulted to the need to source for suitable, readily available and cheap energy sources for poultry production globally. One such alternative is cassava. A native to South America, cassava is now found in abundance in most tropical countries. Due to lack of excellent post-harvest technologies, large quantities of cassava are wasted. An increased use of cassava in poultry feeding will go a long way to reduce this wastage and also reduce the high cost of poultry feed. However, the utilisation of cassava in poultry nutrition has been hindered by its lower nutritional value, especially protein and amino acids, presence of some ANF and dustiness when poultry feed is produced with cassava meal. Traditional processing methods have only succeeded in taking the inclusion level of cassava to 40% in some poultry diets. Researchers and poultry nutritionists have become interested in developing multi-pronged technologies and processing methods to increase cassava utilisation in poultry nutrition to reduce wastage, improve its nutritional value and maximise production. This chapter highlights the application of different technologies and the importance of biotechnology in improving the quality of cassava and increasing its utilisation for poultry feeding

Responses of Broiler Chickens to Dietary Yeast and Yeast Components

Four experiments were conducted to examine the growth promoting effect of different levels of autolyzed whole yeast (WY), yeast cell wall (YCW) and enzymatically hydrolyzed cell wall components, yeast α-mannan (YM) and yeast β-glucan (YG), in broiler chickens. The mechanisms underlying these effects in broilers were determined. The potential of these yeast products as possible alternatives to in-feed sub-therapeutic antibiotics was determined by measuring their effects on broiler performance, meat yield and immune-regulation under mild stress. In the first experiment, lower levels of supplementation of autolyzed WY and YCW (0.5 and 1.0 g/kg) did not have a significant effect on performance, visceral organ weight, digestibility and intestinal enzyme activities. However, WY and YCW at 1.5 or 2.0 g/kg had marked improvement in bird performance response for both whole yeast and yeast cell walls. In experiment two, feeding lower levels of YM (0.05 and 0.10 g/kg diet) to unchallenged birds did not have significant effect on the parameters considered. However, YM supplemented at 0.15 and 0.20 g/kg diet were superior to the control group in the majority of the parameters recorded (gross performance, protein digestibility and meat yield). Birds fed diets containing YG did not have any effect in most of the parameters considered. In experiment 3, the effect of autolyzed WY (2.0 g/kg diet), YCW (2.0 g/kg diet), yeast mannan (0.20 g/kg diet), YG (0.20 g/kg diet) and zinc bacitracin (50 ppm diet), Salinomycin (60 ppm diet) was compared with a control group (without supplementation) in broilers under mild stress of Salmonella lipopolysaccharide challenge (LPS). The LPS challenge increased bird rectal temperature and immune response (haematological and serum metabolite), with a resultant decrease in performance, meat yield, flock uniformity and spleen weight. However, supplementation with autolyzed WY, YCW, YM, YG or antibiotics (Salinomycin and zinc bacitracin) improved performance, flock uniformity and meat yield in challenged birds. These improvements were associated to ability of these additives to reduce the level of LPS-induced immune responses. These additives, possibly through different mechanisms, improved most parameters (performance, flock uniformity, haematological indices, plasma metabolites and meat yield) considered. In a further trial, YCW and zinc bacitracin when supplemented to the diets of birds unchallenged or challenged with Eimeria and Clostridium perfringens (CP) showed the growth enhancing and challenge-ameliorating effects. In unchallenged broilers, supplementation of yeast cell wall and bacitracin tended to improve performance relative to the control group. Eimeria and CP resulted in poorer feed intake, body weight gain, FCR, meat yield and flock uniformity. The challenge also resulted in a higher number of intestinal lesions. There was no effect of the challenge or dietary treatments on the pH of duodenal, ileal, jejunal and caecal digesta. Challenge resulted to an increase in CP count. The Lactobacillus and the Bifidobacteria caeca count decreased in CP challenged birds. Both YCW and zinc bacitracin supplementation decreased CP counts and increased Lactobacillus and Bifidobacteria counts. This may be associated to the better performance, meat yield, flock uniformity and lesion score observed in the study. Challenge or supplementation did not significantly influence the mortality of birds. The results of these studies provided evidence that autolyzed WY (at 1.5-2.0 g/kg diet), YCW (at 1.5-2.0 g/kg diet) and YM (at 0.15-0.20 g/kg diet) exhibited some growth enhancing effects. Furthermore, WY and YCW (both included at 2.0 g/kg diet) as well as YM and YG (both included at 0.20 g/kg diet) showed immunomodulatory controlling abilities which led to improved growth performance in both mildly stressed and disease-challenged broiler chickens