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Abstract

A study was conducted to evaluate the response of broilers to changes in the duration of feeding starter, grower and finisher diets when grown to 49 days. A total of 2560 day-old commercial broiler chicks of mixed sex (straight run) were assigned to 32 pens and sixteen (16) treatments were randomly assigned resulting in a completely randomized design. Diets were formulated to meet nutrient levels typical of the current local industty. Diets were changed from starter (222g CP/kg, 12.77 MJ ME/kg) at 10, 15, 20, 25, or 28 days to grower (202 g CP/kg, 12.76 MJ ME/kg) and from grower to finisher (198g CP/kg, 12.77 MJ ME/kg) at 36, 41, 43, 46 days of age or not at all. Broilers grown to 49 days attained the desired weight of 2400g on all feeding programs evaluated. Feed consumption responses over time were quadratic for the durations of feeding starter diet (R2.99.9%), grower diet (R2=87.5%) and finisher diet (R2=99.2%). Similarly responses of live body weight gain were quadratic for the durations of feeding starter diet (R2=99.9%), grower diet (R2=96.1%) and finisher diet (R2=99.2%). Feed conversion and calorie conversion showed significant (p<0.001) linear trends for the duration of feeding starter diet (R2=91.08 and 93.6%) and finisher diet (R2.81.2 and 81.1%), respectively but not the grower diet (R2=1.4%). Abdominal fat (AF) as a percentage of body weight at slaughter showed a quadratic (R2=87.3%) response to the duration of feeding starter diet, peaking at 20 days and then declined. AF showed an inverse linear response (R2=78.4%) as a function of duration of finisher diet The cost of starter, grower, and finisher diets showed significant differences (p<0.001) between treatments. However, total feed cost per bird was not significantly (p>0.506) affected by the different treatments. Margin over feed cost (MOFC), marginal physical product (MPP), and the value of the marginal product (VMP) were not significantly affected (p>0.325) by treatments. However, it was noted that utilising a program consisting of starter 1-20d and grower 21-49 days as an alternative to the current industry program can improve the industry MOFC by approximately 10%.

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