Winter feeding and 1 underweight appy

Question
QUESTION: You are the only expert in this category. Thank you for your time!
We live in Oregon it is in the high 20's to mid 40's now.We have been told two give our horses 2lakes of hay each and one 3lb can oats each 2 times a day(morning and night) They are in the pasture from about 10a.m. to 6 p.m.
Our appy appears to be losing weight.She is 13,Our horse get ridden a lot with 4H and high school equestrian team.We are new to horses(about 7 months now).Here is what we are doing.
The appy gets 1/2 Equus Golden senior 1/2 oats. 1/2 cup soy powder and 2 flakes of hay.
All the horses have been wormed and are on daily wormer in feed.
How do I figure out exactly how much to feed each horse?
They all seem to be eating fine(no sloppy food falling out of mouth or balling up hay.)
The appy is was a little pudgy when we got her @1300lb. +.Now she is 1070lb with weight tape.
Any advice would be appreciated.

Blessings
Mike

ANSWER: Hi,

Why do you have a 13yo on senior feed?

You need to put her onto a performance mix to meet the athletic demands on her body.  I'm in Australia so I can't give you a brand, but look for a well balanced performance mix.  Ask your feed supplier for something suitable for the activity/intensity that you are doing.  You don't mention what type of activity - dressage, showjumping, eventing etc but pick one that suits whatever is being done.

You will not have to add grain to this mix, if it's the right mix it should supply sufficient grain.  You could mix it with some chaff to add nutrients and act as a filler.  You will also not need the soy as the protein should also be balanced.  Continue with the good quality hay.

Why are you worming daily?  Is it a big problem in your area?  I only worm my competition horses every 3 - 6mths.  This is sufficient for most cases.  I don't like feeding chemicals on a daily basis if I can avoid it.  If you are in doubt stop the daily wormer for 2 months then take a fresh sample of manure to a vet for a worm egg count.  This will quickly, and cheaply, tell you if you have a worm problem.

Cheers

---------- FOLLOW-UP ----------

QUESTION: Thank You ,
That is good advice I haven't heard yet.
1.We are using a senior grain because the people we take advice from said it wont make the horse"hot".
2.When Shasta continued to lose weight they told us she might need a daily wormer.

I will take a manure sample to the vet and ask about the performance mix. Oh yes, the girls are in 4H and they do lots of trotting ,loping, and some obsticles work.

Answer
Hi,

1. Senior feeds are such for two reasons. 1. they are maintenance levels of energy and protein only (which is why your horse is losing weight, she's using more energy and protein than she's receiving in her feed). 2. They often have a digestive additive and are processed so they are more digestible by the older horse's tract which is not as efficient as a younger horse.  The lack of being 'hot' is simply that she's not getting enough nutrients to have energy to be hot!!

2.  I can't think of any circumstances where a daily wormer is necessary.  Yes, some people use them and it's very much a personal choice, but I like to keep the diet as natural as possible and limit chemicals as much as I can.

Cheers