The Smell of Ammonia


I was told that whey powder is quite good for horses (protein?)? And have just started feeding my gelding a mineral type mix which has whey powder in it. He is on medium work – schooling, bush riding and dressage (low level) on weekends, and also gets good quality oaten hay, soaked barley and lupins, and cracked wheat. I have noticed his urine has a strong smell which it didn’t before, and his manure is a bit whiffy too – could this be the whey? If the whey powder is not the problem, I was hoping to get it direct from the dairy to feed to him. Would you recommend this?

 J. Alexander, Darling Downs WA


It is highly likely the whey powder is causing that woeful ‘knock me down with a feather’ ammonia smell. Urine contains urea, a byproduct of protein metabolism. Bacteria in the environment break urea down to ammonia but it only becomes abnormal when there is a lot more urea than usual. This can occur when too much protein in the diet beyond what a horse needs has to be metabolised to be excreted, making more urea, more ammonia. Same thing can happen in spring as new growth of grass is far higher in protein than mature growth, sometimes bloating and even loose manure will result when switching rapidly to a higher protein feed.

Amino acids are the building blocks of protein, some like lysine and leucine are known as ‘essential’ which means that they have to come from the diet and others like alanine and glutamine are ‘non essential’, they can be manufactured by the horse. Imagine a necklace of coloured beads; each bead would represent one amino acid. A string of coloured beads would represent a protein with each combination of colours representing a specific protein.

The strong smell of ammonia can occur even if the horse is getting adequate protein for his needs but is deficient in one or more of the essential amino acids. If there wasn’t enough of lysine for example, the proteins that need lysine can’t be manufactured and the unused amino acids have to be excreted. It would be like the coloured beads, run out of one colour and you can’t finish making the necklace.

A quantity of Lucerne can be a good choice if protein or a particular amino acid is deficient. However, I would not recommend feeding a protein supplement like whey unless your horse actually needs it. Since grass and hay are usually high in protein horses generally don’t need supplementing with more unless in a higher needs group such as growing horses or pregnant/lactating mares. One way to tell if your horse needs supplementing is whether he is having trouble building muscle or topline. If not then your horse has to drink more water, and urinate more to excrete the excess. If the key essential amino acids are deficient, Balanced Equine has Equine Amino for this purpose.

What can be ironic is that a horse on a high grain diet can be protein deficient as he won’t need to eat so much pasture and/or hay for his energy needs and ends up missing out on this protein source.

Article originally published in the Q&A section of the June – July 2009 issue of Hoofbeats magazine (Vol 31 No 1), updated since.

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