Effect of a moderate dietary fat supplementation on the digestive function in the horse

Abstract

Supplementing athletic horses with fat to meet their high energy requirements may have a detrimental impact on the digestibility of fibre when fat was supplemented at the expense of an iso-energetic amount of non-structural carbohydrates (Jansen et al., 2000, 2002, 2007). The objective of this study was to determine the effect of a moderate fat supplementation on the total tract apparent digestibility and the colonic bacterial ecosystem. Six fistulated horses (449 +/- 33 kg) used in a double (3x3) Latin square experiment received a diet consisting of a forage-to-concentrate ratio of 67:33 on DM basis. Three fat concentrations were tested in the concentrate: 4.0, 7.0 and 8.8 % DM, respectively. Mean daily DM intake was 1.7% BW divided in two equal meals of hay and concentrate. The apparent digestibility (DM, TDF, NDF, ADF, Fat) was measured by total collection of faeces during 5 days. The anaerobic flora (total, cellulolytic, amylololytic, lacticolytic) and VFA concentrations and pH were determined in the colonic content collected 4 hours after the morning meal. The total fat intake 42, 59 and 69 g/100 kg BW for the rations composed of 4.0, 7.0 and 8.8% of fat in the concentrate. The digestibilities of DM, fat, TDF, NDF and ADF were not altered by the fat supplementation. In agreement with Jansen et al. (2007), the pH, total and cellulolytic bacterial concentrations in the content of the hindgut were not modified. Consequently, a moderate fat supplementation increased the energetic supply without any adverse effects on the hindgut ecosystem.