Protein and ammonia
Protein is what we sell, but it is far more complex than this simple statement. Protein is the key component in lean meat muscle, and is furthermore made up of amino acids. The body is an amazing biological machine than can consume protein – whether animal or vegetable, convert the protein into amino acids via proteases in the digestive system, transport them across the gut wall into the blood stream and then reconfigure them as muscle (or enzymes, or mucous, or many other proteinaceous substances).
It stands to reason that ingesting more protein is a good thing to ensure maximum muscle growth, but no – there are consequences. As I mentioned earlier, it is the amino acids which are the key factor in muscle growth, and lysine is the 1st limiting of these. Without sufficient lysine – an essential amino acids, meaning it cannot be synthesised in the body, no matter how much ‘protein’ we offer, the pig cannot grow.
In the raw materials we offer the pigs, each has a very different amino acid make up. Hipro Soya meal is about the closest match we have for animal protein and the amino acids are suitably balanced with good digestibility (around 87%). Rapeseed meal is also a good provider of lysine, but protein digestibility is only around 75%. However, there is always an oversupply of semi-essential and non-essential amino acids which are not required and the body, or are not digested thoroughly from the feed has to be excreted. In the body this process is known as deamination, which is carried out by the liver to initially produce ammonia, but then further enzymes convert the ammonia to urea which is excreted in the urine. Undigested and partially digested protein is also excreted in the faeces.
Urine and faecal protein in storage breaks down into ammonia by microbial action and at relatively modest levels in the atmosphere can cause reductions in growth rate and be a contributory factor in respiratory disease.
With the colder conditions over winter and subsequent reduced ventilation rates this becomes more of an issue. It is therefore important to discuss with your nutritionist or feed rep the most suitable diet for maintaining growth (through digestible lysine levels) weighed up against the cost of supplying it from the various raw materials.
There are additives which can go in the feed or the slurry to reduce ammonia production, but it may also be worth considering the additional cost of a diet with greater protein digestibility.
Courtesy of www.baynesnutrition.co.uk