Effect of different magnesium sources on digesta and excreta moisture content and production performance in broiler chickens

Reducing litter moisture is an effective measure to reduce the incidence of footpad dermatitis. Dietary mineral levels affect intestinal conditions with regard to osmolarity and water reabsorption. Magnesium is often used as a laxative, preventing reabsorption of water from the digesta, and as a consequence, more moisture in the excreta. The objective of the current experiment was to evaluate Mg in broiler diets as a model for reduced intestinal water reabsorption. Effects of magnesium source (magnesium sulfate, magnesium oxide, and magnesium chloride), each at 3 levels (0.255, 1.02, and 2.04 g·kg-1 diet), were studied. Measured effects were digesta moisture levels throughout the gastrointestinal tract and the moisture level of the excreta. The 10 treatments were randomly assigned to cages within 6 blocks, resulting in 6 replicates per treatments with 18 birds per replicate. Adding magnesium to the diet of broilers linearly increased the excreta moisture content, following the pattern MgCl > MgSO4 = MgO. This rejects the hypothesis that MgO and MgCl are less laxative sources compared with MgSO4. The magnesium sources most likely changed the water reabsorption in the distal gastrointestinal tract, as confirmed by the increased digesta moisture percentage in the ceca and colon. Increasing dietary MgSO4 linearly reduced BW gain and feed intake, though absolute differences were minor. The results of this experiment show that Mg addition in the diet may be used as a model to study wet litter caused by reduced intestinal water reabsorption.