Horrendous news Sabrina, i hope your friend is coming to terms with her losses x
This is the first i have heard of an increase in losses at birth due to weather/condition ? is there any scientific evidence ?
I do know that i have not fed any of mine ponies over winter (other than hay) I do tend to let them loose weight as naturally as possible over winter, so that they have chance to gain correctly in the spring/summer (if we get one) even if suspected in foal !
I am of the opinion that too much modified feed / supliments / rugs / pampering does them no end of harm !!!! it only serves to make us feel better !!