Location: Poultry Research
Project Number: 6064-32630-011-003-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2021
End Date: Aug 30, 2026
To assess effects of dietary strategies to mitigate effects of necrotic enteritis and resultant effects on growth and productivity in commercial broiler chickens. Evaluate the effects of dietary mineral sources and concentrations on subclinical enteric infections in broilers.
The reduction of calcium content has shown to increase Ca digestibility and reduce excess Ca which may lead to pH alterations in the gastrointestinal tract and amino acid utilization, and the concentrations of nitrogen entering the hindgut. Dietary treatments will consist of a 3 × 2 factorial arrangement of treatments subjected to a necrotic enteritis challenge and an unchallenged control treatment. Main effects consist of 3 dietary calcium concentration feeding programs (0.95, 0.85, and 0.75%; 0.85, 0.75, and 0.65%, and 0.70, 0.60, and 0.55%) in the starter, grower, and finisher diets, and a commercial limestone source with 2 particle sizes of 700 and 250 microns. Limestone particle size of 1,800 microns will be obtained from a commercial manufacturer and ground to 700 and 250 microns. This will avoid other confounding factors of geological origin, physical and chemical properties of using limestone from different sources. Unchallenged-control treatment will be fed the higher dietary calcium feeding program with a limestone particle size of 250 microns. Prior to experimentation limestone samples will be analyzed for particle size and distribution, mineral composition, and solubility. Experimental diets will be formulated with corn and soybean meal as the primary ingredients adequate in amino acids, vitamins, and minerals except for calcium. Experimental diets will be supplemented with phytase to provide 0.165% and 0.150% points of calcium and non-phytate phosphorus, respectively. Phytase source will be an Escherichia coli and will be included at 1,500 phytase units per kg. Titanium dioxide will be added at 0.5% as an indigestible marker for the determination of calcium and amino acid digestibility. Diets will be analyzed for amino acids, calcium, phosphorus, and phytase concentrations. At 21 d of age, tibias will be broken using a texture analyzer to calculate shear force required to fracture the bone Tibia’s and dried and placed in an ash oven for the determination of breaking strength and bone ash. At 21 and 35 d of age, apparent digestibility of apparent calcium and amino acid digestibility will be determined.