What does Amino Acids have to do with a Topline?

It's probably on a near daily basis that I see someone posting on Facebook asking how to build a topline on a horse. 

If only it were as simply as going down to the store and picking up "topline" off the shelf and voila...magically there.

Usually, the same suggestion of exercise crops up, which is certainly true.  A horse needs to engage the muscles the pick up and carry the back in order to build a topline.  Some horses with genetic predispositions may be prone to having a soft or dropped back, but exercise is certainly a factor.

However, the first 49 times I saw this conversation, I usually chimed in with feeding a balanced diet and usually I ended up getting...as a response. 

I feed high quality feeds


My horse is in XYZ training

My horse is too fat for grain

Or some other variation thereof, which is fine.  However, I wish people would be open to this basic thought process.

Amino acids make protein.  Protein is a building block of muscle.  Muscle is part of the topline.

Pretty simplistic, right? 

Amino acids are found in varying amounts in foodstuffs.  Mammals need nine that they cannot synthesize themselves.  Each one has a role to play in order to build protein needed in the body and they must be present in specific ratios.  If one is lacking, the building stops. 

Prior research indicates that the most limiting one in horses is usually lysine, so lysine supplements are readily available.  This is great in theory, since supplement lysine and the horses should be good to go...except if the diet is lacking in the rest of the amino acids, you are back to square one. 

I just read an artice from thehorse.com that began scratching at the surface of this topic wonderfully in response to "Will Whey Protein Improve Topline?" 

I just wanted to present a brief except to think about and digest. 

Grass hay is made up of medium- or low- quality protein and does not provide a great deal of lysine. This is particularly an issue if you limit your horse’s hay intake. Alfalfa, on the other hand, provides more lysine, so its protein is considered to be of better quality. Many performance horse owners I work with believe that they see a benefit in their horse’s topline when they feed some of the forage ration as alfalfa, and this might be part of the reason.

Another complicating factor associated with hay protein is that the more mature a hay is, the more protein is associated with the structural carbohydrate fractions. This is potentially important because protein digestion and amino acid absorption needs to occur in the small intestine. However, structural carbohydrates require microbial fermentation to be broken down to release the protein contained within. Microbial fermentation occurs in the hindgut, which comes after the small intestine. Therefore, any protein and amino acids released at that point have missed the opportunity to be absorbed and instead are converted by the bacteria to ammonia. So, while a hay analysis can suggest a particular forage has adequate amounts of protein it’s possible that not all that protein is actually available for the horse. This is likely a bigger concern for grass and grain hays because alfalfa has so much more protein and tends to have higher digestibility.

So for those thinking about toplines and what else could help, consider what you are feeding.  Is it balanced?  Is there a good source of protein?  Usually I suggest at least seeing if the ration is balanced with a ration calculator like FeedXL or at least feeding the recommended amount on the feed label. 

What about you?  Is balancing your feed of interest?  Do you feed a ration balancer or other mix aimed at getting that "perfect level" of nutrition?