A comparison between the measurement of the apparent digestibility coefficient in ponies based on the total faecal collection method and on the dietary marker titanium dioxide

Research to digestibility in horses is time- and labour intensive because the total faecal collection method has to be used. The use of a set of validated markers would make research more applicable in practice, faster and easier. Titanium dioxide is an inert matter which is shown to be a suitable digestibility marker in cattle and sheep. In this study, the use of TiO2 as a digestibility marker in ponies has been investigated. 4 ponies were treated according to a 4x4 Latin square with 4 different roughage:concentrate ratios, 100:0, 75:25, 50:50 and 25:75. Once a day, every pony received 100 g of a supplement in order to provide 5,7g TiO2. All day samples were analysed for dry matter, crude ash and titanium. Next, the apparent digestibilities of organic matter were calculated for the total faecal collection method and for the marker method. The organic matter digestibility increased linear with a decreasing roughage:concentrate ratio. The mean faecal recovery of TiO2 was 97% and no significant differences were found between the apparent digestibilities calculated with the 2 methods for all the rations. Further research is needed to determine whether titanium dioxide mixes homogenously in the digesta. Titanium dioxide would only be a very suitable digestibility marker in the pony if it is secreted constantly