Hello

The main thing with older horses is to be aware of how they are doing. It is good practice to take a note of their body condition score, so that you are alerted if they are gaining or losing weight,

I would have his teeth checked and floated if necessary by your vet and ask them at what interval he should be having his teeth refloated. This will depend on the condition of his mouth.

Senior horses can find it more dificult to get all of the nutritive value out of the food that they eat. In these cases a feed designed for seniors can be helpful, as they are more nutrient dense. If tooth loss becomes a problem, then some of the all in one feeds that replace some of the hay or grass requirements, can be helpful.

I think it would be a good idea to use a supplement such as platinum, to ensure that he is getting all the micro nutrients that he requires.

To help the older horse get the most out of the food that he eats, you can also add in a probiotic. Yeast cultures are also helpful to create the optimum gut environment.

http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/hrs3184

http://www.umext.maine.edu/onlinepubs/PDFpubs/1010.pdf

Remember to make any changes to diet very gradually over a period of a couple of weeks, to allow the gut bacteria time to adjust

http://www.platinumperformance.com/senior/

please reply if you have further questions