Browsing by Author "Mushinge, Bernadette Mwansa"

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    Evaluation of various Phytase enzymes for application in broiler feeding
    (Stellenbosch : Stellenbosch University, 2015-03) Mushinge, Bernadette Mwansa; Pieterse, E.; Hoffman, Louwrens C.; Stellenbosch University. Faculty of Science. Dept. of Animal Sciences.
    ENGLISH ABSTRACT: Feed costs form a major component of broiler production and the industry is always investigating ways of reducing feed costs. Phytase is an innovation that releases phosphorus from feed ingredients and as a consequence improves the nutritive value of broiler diets. A 34 day experiment was conducted to determine the effect of three different types of commercial phytase (HiPhos, OptiPhos and Quantum blue) at two levels (standard and three times the standard level) on production parameters, carcass characteristics and bone mineralization of broilers. Positive control (PC) diets were formulated based on the lower end of National Research Council (NRC) recommended values. Negative control (NC) diets were formulated on the PC diets less the matrix value for HiPhos 2000FTU (HP200). A positive control diet and negative control diet were compounded for three phases; starter, grower and finisher. Therefore eight diets were mixed: 1. Positive control (PC); 2. Negative control (NC); 3. NC + 2000FTU HiPhos (HP200); 4. NC + 1000FTU OptiPhos (OP400); 5. NC + 1000FTU Quantum blue (QB200); 6. NC + 6000FTU HiPhos (HP600); 7.NC + 3000FTU OptiPhos (OP1200) 8.NC + 3000FTU Quantum blue (QB600). The experiment involved 5120 day old broilers that were allocated to a completely randomised design with eight treatment diets and eight replications. The purpose of the study was, firstly to compare the effects of three different types of commercial phytase supplemented to maize-soya bean based diets on broiler performance outcomes. Secondly, to investigate the effects of each phytase at two inclusion levels. Thirdly, to evaluate the effects of three types of phytase on internal organs and intestinal morphology. At the end of the study, supplementation of phytase to NC diets improved live weight, average daily gains and cumulative gains. However, improvements were not comparable to those of the PC group. Breast colour, pH, and temperature, dressing percentage, internal organs, as well as thigh and wing portions were not affected by phytase inclusion. Cold carcass weight, breast and drumstick portions differed significantly between treatments. Gizzard weight expressed as a percentage of live weight differed significantly between treatments. Significant differences between treatments were also observed for intestinal morphometric observations. Phytase supplementation did not have an influence tibia length, tibia diameter, robusticity index, bone breaking strength, percent ash, percent phosphorus and percent calcium. Dry tibia weight, calcium to phosphorus ratio and the length of the tibia in relation to live weight differed between treatments. Computed tomography scans showed tibia structural abnormalities. Overall, phytase supplementation to negative control diets did not meet the phosphorus requirements for proper bone formation of broilers. In addition phytase supplementation at both inclusion levels did not pose a risk to the immune status of the broiler as internal organs were not negatively affected.