Peptones: a puff or a promise?

Before I delved into the world of peptones, I only knew the word from being a scruffy Dutch surf-rock band (www.peptones.nl). However, more research into peptones taught me that they are used in microbiological culture media to support the nutritional requirements of micro-organisms. They are also used in industrial fermentations, the production of human and veterinary vaccines, human food and even animal feed, of which the latter of particular interest of course.

Definition
But what are peptones outside the music business then? Wikipedia describes peptones as being "derived from animal milk or meat digested by proteolytic digestion." This actually means that peptones are extremely bio-active short molecule chains made up of small groups of amino acids, not as long as traditional proteins. You may also know them as protein hydrolysates or forms of peptides. One distinguishes 3 types of raw materials for the manufacture of peptones: – animal origin (bodies, muscles,…) – dairy origin (acid casein, whey,…) – vegetable origin (soy, cotton, corn, broad bean,…). For application in animal feed, animal derived peptones seem to have a better amino acid profile than vegetable derived peptones. Peptones – primarily being produced via an enzymatic digestion process – have been on the market for quite some years, although the practical application does not seem to take off that quickly.

Research studies
Let’s take the example of marine peptones, as in protein hydrolysates derived from fish. Some studies have been done in calves, pigs and poultry, although limited. A Canadian study by Jenkins et al (1981) looked at soluble partially hydrolyzed fish protein concentrate as a protein source in liquid diets for herd replacement and veal calves. According to the researchers, partially hydrolyzed fish protein concentrate can provide satisfactorily up to 50% of the protein in liquid diets for herd replacements and veal calves for good feed efficiency and calf performance. However, a withdrawal period may be required to optimize veal quality (a possible fishy taste may be present in the meat).

In swine diets, marine peptones showed a reduction in stomach scouring, lower mortality rates and increase weight gain 6-10% post weaning (Hansen- øye, 2002 and Bodø Sildoljefabrikk, 2008) . In poultry, studies have shown 8-12% improvement in gain/feed and growth improvement when marine peptones were fed at 25g/bird during the first 14 days. (It was administered via the drinking water lines, increasing water intake by 20-80%) (Ecuador broiler producer, 2008). In pet food, peptones are primarly used as a flavour enhancer to improve dry food consumption. A study by Folador et al (2006) studied salmon protein hydrolysate (SPH) and salmon meal with crushed bones (SMB) as palatability enhancer in dog diets. In the experiment, dogs consumed more of the SPH diet compared with the control, and similar amounts of the SMB and control diets. The intake ratios for each were 0.73 and 0.52, respectively.

Results are variable
Although results are variable, waste fish products can supply high protein feed ingredients. The fish processing industry generates over a million metric tons of fish waste per year and the major wastes (heads, viscera, skin, and skeleton) are underutilized and often create disposal problems and environmental concerns. The possibility to convert these fish products in valuable animal feed ingredients is therefore a good and sustainable option. Research has indeed shown that certain protein fragments can actually stimulate the immune system and have a positive effect on performance, but when it comes to practical application there is limited ongoing commercial use of fish peptones today.

New membrane technology
Nevertheless, the process of converting fish by-products into valuable animal feed ingredients gets more sophisticated and more economical as more insights are gained how to convert (often fatty) fish material into valuable ingredients. Recently, the process for creating marine peptones has been improved using a membrane purification process. This membrane technology, developed by Norcape Biotechnology and GE Water & Process Technologies is a refining process and enables the production of different and more pure end-products. For the technical insights I recommend reading an article on this subject in Feed Tech 12.10 . Several companies; Copalis in France, ABt/Seagarden in Norway end Bluewave Marine in Peru have started  producing peptones using the membrane technology. Three more sites -using the membrane technology (Europe & Americas) are planned in total. This new supply and commercial scale applications will allow even more applications to be evaluated in tonnage farming quantities rather than the historical kg laboratory feed test. 

Puff or promise?
In terms of final feed cost, the decision comes down to "mix/formulation". As always, there will be an upper limit to how much high cost feed ingredients are used. Some producers of fish protein isolates are claiming over 300% payback in feed conversion. Because animal studies so far have been limited and variable, more animal studies have to be conducted to determine where and how peptones will fit as a valuable ingredient for the future or whether it is just being puffed by the producers.