Exogenous enzymes: their use in dairy cows

Exogenous enzymes are widely used, with basic purposes like:

• increasing the capacity to use nutrients contained in raw materials
• eliminate anti-nutritional factors from food

Currently , the use of phytases and carbohydrases covers practically all monogastric feed in intensive farms.

Enzyme research

1876 . The history of enzyme research is closely linked to the history of biochemistry, the first time the term “enzyme” (from the Greek yeast) was used was in 1876 and it is attributed to the German physiologist Wilhelm Fiedrich Kühne.

1860 . Louis Pasteur concluded in his work, that fermentation is catalyzed by enzymes.

1926 . The first enzyme, cannavalia enzyformis bean urease, is crystallized.

1930 . The prolific author of the theory of the origin of life together with Oparin, John Burdon Sanderson Haldane in his treatise “Enzymes” wrote: “Interactions by weak bonds, between the enzyme and its substrate, could be catalysts of a reaction” this idea is the center of our current knowledge about the action mechanisms of enzymes.

Enzyme use in ruminants

Regarding the use of enzymes in ruminants, in 1960 Wise Burroughs’ team at “Iowa State University”, published the use of an enzyme conjugate belonging to MSD (Merck, Sharp & Dohme) Agro-Zyme in calf diets.

Already in this first article on the use of enzymes in ruminant diets, there are interesting results:

• Increases in average daily gain and conversion are not associated with improved digestibility of dry matter, organic matter, protein or cellulose in diets supplemented with the enzyme.

• Subsequent work showed that supplementation with cellulases or xylanases (Fibrolytic) can improve rumen digestibility. This changes the site where nutrients are used which improves energy efficiency.

Some of the reasons that justify the use of enzymes in ruminants are:

1) the digestibility of organic matter in ruminants rarely exceeds 90%

2) more and more agroindustrial by-products of low quality are commonly used

3) the faster availability of carbohydrates which normally stimulates microbial population growth

4) the presence of different sized polysaccharides can have a prebiotic effect

5) the use of exogenous enzymes can cause effects of multifactorial origin. In summary, what is sought in an enzyme is that it improves the use of nutrients or that it can change the site where nutrients are broken down and used by the animal.

At a first glance and in a simplistic manner it seems clear that exogenous enzymes should be used in ruminants since they increase the use of fibrous parts and ruminal utilization.

In an interview granted to Galician media the Director of Agriculture and Natural Resources of the University of South Dakota (USA) Alvaro García indicated: “The digestibility of forage fiber determines the profitability of livestock.” There are several alternatives to achieve this:

1) Selection of grains and forages of higher nutritional value

2) Improve the degradation capacity of the rumen microbiota

3) Use of additives that modify the pattern of rumen fermentation

4) Development of more efficient feeding practices

5) The use of unconventional foods

6) Use of chemical or biological treatments in fodder,

7) Use of exogenous enzymes to increase the digestibility of cell walls and/or starch (Rojo-Rubio et al. 2007).

In ruminants, the enzymes used must have the characteristics of any such product being marketed as:

• appropriate amounts of coenzymes
• cofactors and activators to optimize activities
• have a composition that does not vary by batch
• be thermostable under manufacturing processes
• be totally safe