Objective: This study evaluated the effect of yeast products on growth performance, visceral organ weights, endogenous enzyme activities, ileal nutrient digestibility and meat yield of broiler chickens fed diets containing autolyzed whole yeast (WY) and yeast cell walls (YCW) at varying levels of inclusion.Methods: Nine dietary treatments consisting of WY or YCW included at 0.5, 1.0, 1.5, or 2.0 g/kg diet and a control diet without yeast supplementation was used in the experiment. Each of the nine treatments was replicated six times with nine birds per replicate. Birds were housed in cages, in climate-controlled rooms and fed starter, grower and finisher diets.Results: There was an improvement (p<0.05) in body weight gain and feed conversion ratio on d 10, 24, and 35 for birds fed 1.0 to 2.0 g/kg WY or YCW diet. Small intestine weight was heavier on d 10 and 24 for birds on higher levels of WY and YCW compared to the control group. On d 10 and 24, there was a significant increase (p<0.05) in tissue protein content and pancreatic enzyme activities (trypsin and chymotrypsin) of birds on 1.5 to 2.0 g/kg WY and YCW diets compared to the control group. Compared to the control group, birds on WY (2.0 g/kg diet) and YCW (at 1.5 and 2.0 g/kg diet) had better (p<0.05) protein digestibility on d 24. On d 35, there was significant improvement (p<0.05) in percentage of carcass, absolute and relative breast weight for broiler chickens fed WY and YCW mostly at 2 g/kg diet compared to birds on the control diet.Conclusion: Supplementation of diets with autolyzed WY and YCW products especially at 1.5 to 2.0 g/kg diet improved broiler chicken performance and meat yield through their positive effects on ileal protein digestibility and pancreatic enzyme activities.

The objective of this study was to assess the effect of dietary yeast products on broiler chickens challenged with salmonella lipopolysaccharide (LPS). The chicks were divided into 8 treatments with 6 replicates and 9 birds per replicate. The treatments consisted of a positive control (PC) [without supplementation and not challenged]; negative control (NC) [without supplementation but challenged]; whole yeast and challenged; yeast cell wall and challenged; yeast glucan and challenged; yeast mannan and challenged; zinc bacitracin and challenged; and Salinomycin and challenged. Whole yeast or Yeast cell wall was included at 2.0 g/kg diet. Yeast glucan or mannan was added at 0.20 g/kg diet. Zinc bacitracin (ZNB) and Salinomycin (SAL) was included at 50 and 60 ppm, respectively. Dietary treatments had no effect (P > 0.05) on feed intake (FI) at day 10. Supplementation with yeast and its derivatives improved (P < 0.05) body weight gain (BWG) and feed conversion ratio (FCR) on day 10. On days 24 and 35, LPS challenge declined FI, BWG, FCR, and flock uniformity (day 28) in the NC group compared to the PC group. Yeast products and antibiotics improved (P < 0.05) FI, BWG, FCR, and flock uniformity in LPS-challenged birds. On day 24, spleen weight increased while bursa weight decreased in the NC group relative to the PC group; this effect was reversed (P < 0.05) by feeding all yeasts and antibiotics. On day 24, application of all the dietary treatments ameliorated the changes observed in white blood cell, lymphocyte and monocyte counts as well as albumin and immunoglobulin G of NC birds. On day 35, all yeasts additives, ZNB and SAL improved (P < 0.05) the meat yield of broilers challenged with LPS. In conclusion, supplementation of diets with yeast and its derivatives can ameliorate the negative effects of salmonella LPS challenge on broiler chicks, thus improving the performance, flock uniformity, and meat yield.

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29Objective: This study assessed the effect of different levels of xylanase, β-glucanase and phytase on intestinal 30 enzyme activities and tibia bone development in broiler chickens fed wheat-based diets. 31Methods: Twelve experimental diets were formulated using a 3 × 2 × 2 factorial design (three doses of phytase and 32 two doses of both xylanase and β-glucanase) and offered to 648 day-old Ross 308 male chicks having 6 replicates 33 groups with 9 birds per replicate and lasted for 35 days. 34Results: An interaction between the enzymes products improved (p<0.01) the activity of chymotrypsin. Protein 35 content at d10 was highest (p<0.001) with addition of phytase while general proteolytic activity (GPA) (p<0.02) and 36 lipase activity (p<0.001) were decreased. At d24, there were improvements in protein content (p<0.01) and lipase 37 (p<0.04) with supplementation of superdose phytase. Addition of superdose phytase decreased in chymotrypsin 38 (p<0.02), trypsin (p<0.01) and GPA (p<0.001). The optimum dose of xylanase decreased the chymotrypsin activity 39 (p=0.05), while the GPA (p<0.001) was increased with the optimum level of β-glucanase. Superdose phytase 40 supplementation at d10 improved maltase (p=0.05), sucrase (p<0.001) and alkaline phosphatase (p<0.001) activities 41 in the jejunum while aminopeptidase activity was highest (p<0.005) with the low level of phytase. Protein content of 42 jejunum mucosa was bigger (p<0.001) in birds fed superdose phytase while maltase activity (p<0.001) at d24 was 43 reduced by this treatment. Sucrase (p<0.04) and aminopeptidase activities (p<0.001) improved when diets 44 supplemented with low levels of phytase. Tibia bone breaking strength was highest (p<0.04) with addition of low 45 level of superdose phytase or optimum level of β-glucanase. Bone dry matter content decreased (p<0.04) when diets 46 supplemented with phytase. 47Conclusion: From the results obtained in this study, supplementation of superdose phytase was the most effective, 48 however, the cost-benefit analysis of the use of such a dose needs to be evaluated. 50Wheat is an important energy source in poultry diets in many regions of the world, including Europe, 54Canada, Australia and New Zealand. However, the nutritive value of wheat is limited by its content of soluble non-55 starch polysaccharides (NSP), which are indigestible and impede the digestion of other nutrients. Like most grains, 56 wheat also contains phytate, the main reservoir of phosphorus, which is not digested by birds due to their limited 57 secretion of phytase [1]. The exogenous enzymes that were used in this study, xylanase, β-glucanase and phytase, are 58 now extensively used as additives in poultry diets and their physical effects are generally well understood, but the 59 mechanisms behind their actions are still being researched. Research results to date have been used to determine or 60 predict the optimum dose of xylanase and β-glucanase enzymes in wheat-and barley-based diets and efforts have 61 been made to set the same for phytase...

Objective: Pellet durability, particle size distribution, growth response, tibia bone characteristics and energy retention were measured to evaluate cassava as an alternative energy source to replace maize in broiler diets with or without Ronozyme (A+VP) enzyme composites.Methods: A total of 480 one-day broiler chicks were randomly assigned to 8 treatments in a 4×2 factorial arrangement. Four levels of cassava: (0%, 25%, 50%, 75%) and 2 levels of enzymes (0 and 500 g/tonne) were used. Each treatment was replicated six times, with ten birds per replicate.Results: The particle size distribution in the diets showed an increasing trend of small particles with increase in cassava level. Pellet durability decreased (p<0.05) with cassava inclusion. Feed intake was highest in birds fed diets with medium cassava level at 1 to 24 d and 1 to 35 d of age. The body weight gain of birds reduced (p<0.037) as cassava level increased, but it increased (p<0.017 when enzymes were added. The feed conversion ratio was high (p<0.05) when cassava level was increased, but it reduced (p<0.05) when enzymes were added. The dressing percentage (DP), and weight of drumsticks reduced (p<0.05) with increasing cassava level. Enzyme supplementation increased (p<0.05) DP, and weight of breast, thighs and drumsticks. Ash content, weight, length, width, and bone strength decreased (p<0.05) when cassava level was increased, however, they were increased with enzyme addition. The contents of Ca, K, and Zn were raised (p<0.001) with increasing cassava level. Enzyme inclusion increased (p<0.001) all mineral contents in tibia bones. Body fat and energy retained as fat decreased (p<0.001) as cassava level increased. Enzyme inclusion increased (p<0.05) body protein content and energy retained as protein.Conclusion: Although broiler performance was depressed by high levels of cassava inclusion, it was not affected by low levels, which further improved by enzyme supplementation.

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