Effects of fat content and source as well as of calcium and potassium content in the diet on fat excretion and saponification, litter quality and foot pad health in broilers

Abstract

Summary Fat content of poultry diets and a formation of soaps from fatty acids and macro minerals in the intestinal tract of animals are often discussed in regard to nutrient digestibility and energy value, but the information about the effects on litter quality and foot pad health is limited. Therefore this study was conducted to investigate the potential impact of fat and soap contents in broilers’ excreta on dry matter (dm) content of excreta and litter as well as on development and severity of foot pad dermatitis. In a first experiment a total of 200 broilers (in two consecutive trials) were housed in floor pens littered with wood shavings and were fed diets differing in fat content (55 or 110Â g/kg dm), fat source (mixed fat, palm oil and palm fatty acid distillate, PFAD) and also in dietary calcium and potassium levels (7.5/6.0 resp. 15.0/14.5Â g/kg dm). Samples of excreta and litter were taken and foot pad health of the birds was recorded weekly according to a macroscopic score of 0 to 8. In a second experiment with 104 broilers half of the birds were exposed daily for 8 hours to litter (wood shavings) enriched with a mix of two soaps (potassium oleat and stearate, 50:50) in a concentration of 2 resp. 5% at different dm contents of the litter (85 resp. 65%). A weekly macroscopically assessment of the foot pad health was done. In Trial 1 high dietary fat contents or the use of palm oil or PFAD led to considerable fat losses via excreta (up to 134Â g/kg dm). If there were, in parallel, high dietary contents of Ca and K, a remarkable saponification was observed (up to 92.9Â g/kg dm), but this did not go along with lower litter quality or higher FPD scores. Also in the 2nd experiment the exposure to high soap contents in the litter did not have negative effects on foot pad health. Only slight lesions were observed over the experimental period. As a result of this study it can be assumed that the formation of soaps in the intestinal tract of broilers from fatty acids and minerals did not have marked influences on the development and severity of foot pad dermatitis. Overall, foot pad health was enhanced by high fat excretion, which might be due to the binding of potassium in soaps. Thus, it could not be absorbed – and therefore would not be excreted via urine and cause poorer litter quality. The observed effect of high dietary fat contents on fat and soap excretion may give reason for a critical assessment regarding energy value and costs, when fat is used at higher dietary levels, especially when substituting cereal energy.